mcs r TELECOMMUNICATIONS ISDN • Satellites • Fibre Optics Prescaler for multi-function frequency meter VAM-video/audio modulator Volume-6 Number-3 March 1988 ELEKTOR ELECTRONICS PVT LTD 52. C Proctor Road, Bombay-400 0< Telex: (Oil) 76661 ELEK IN CONTENTS CHMOS Industry standard moves Radio & Television PROJECT VAM - video'audio modulator Geneva calling ISON and satellites at Telecom 87 Computer and telecommunication revolution will bring its legal problems PROJECT: Prescaler for multifunction frequency meter PROJECT : Percolator switch Dual-trace oscilloscopes (part 3) PROJECT Microphone preamp. Editorial Electronic news Telecommunication New products . Appointments . . Switchboard Index of advertisers 4923261. 4921354 PROJECT Baby phone 3.03 Volume-6 Number-3 w** CAR PHONES Import of technology has become a very controversial topic in our country. Whether to import and perish or export and flourish is a difficult question tor which no simple answer exists. Elsewhere in this Issue, we report on the proposed import of car telephones. The issue assumes significance not merely because it is a sophisticated technology but also because the Prime Minister of India has shown his interest in the technology, "out ot the way” in Stockholm. Sophisticated technology is certainly a welcome aspect. But, in a country where until the other day, even possessing a telephone was considered a 'luxury”, the Idea of a car telephone cannot be sold easily. There can be two opinions on the timing of introducing the mobile cellular communication system in India. That is either now or a few years hence. The reason advanced for delaying the car phones is that improving and expanding the existing telecommunication network was more important than bringing a fancy equipment for a chosen few. A telecommunication expert, close to the Prime Minister, was himself opposed to the car telephones but interestingly the PM seems to have had a fresh thought on the issue. If the car telephone technology is obtained without any strings that may ! stranguldte the other essential projects in the country, at least on an 1 experimental basis, there can be no quarrel. If commercial interests alone prevail It would be a bad step. Front cover Artist's impression of a communications satellite in orbit around the earth, Copyright Seth Shostak/Sdence Photo Library 1988 3.05 ELECTRONICS NEWS • ELECTRONICS N Policy Review The annual budget time is the time for a review and forecast. The electronics in- dustry cannot escape this exercise. The inevitable change of policy and im- plementation in electronics is already The liberal import policy and the as- sociated “phased manufacturing prog- amme” have not helped in the indigeni- sation of the industry as envisaged. What is derisively called the “screwdriver technology’' has continued. The Electronics Commission has prop- osed a three-tier duty structure for the electronics industry and a fiscal policy for a minimum period of three years. The strategy aims at boosting invest- ment, upgrading technology through fis- cal incentives and pushing up exports. The commission has suggested that the raw materials should attract least amount of duty, if any and the compo- nents should be exempt from customs duty. However, the duty on the capital goods will continue and no concession is likely for this sector. Any concession to the capital goods imports only led to the import of second hand machinery and it also hampered investment in the capital goods sector. The commission docs not believe that higher duty on capital goods raises the prices of end products. The effect of high duties on capitals is not more than three percent on the end products. This conclusion has been made after analysing the CTV and VCR industries which justify high duty structure on the capital equipment required. For exam- ple, a plant with an installed capacity for producing 700,000 Cl'Vs per annum, when a 50 percent import duty is im- posed on the capital goods costing Rs. 25 crores in foreign exchange, enhances the cost of the plant by Rs. 12.50 crores. If the plant produced 500,000 tubes per annum, the average cost increase due to higher duty will be Rs. 50 per tube. Imports of SKD kits were also reviewed and the Electronics Commission was asked by Prime Minister's office to suggest measures to check this trend. The solution to this problem lies in rationalisation of the fiscal measures, ac- cording to the commission. Commenting on the Phased Manufactur- ing Programme, the commission refers to the case of telephone instruments. For this simple product, several licences have been given to many vendors to go in for foreign collaboration. This has proved to be a heavy drain on the foreign exchange and multiple technology im- ports affected standardisation. Too many Indian business groups chased too few foreign technologies and the country lost its negotiating lever. To boost investment, the commission has suggested accelerated use of elec- tronics to 3 percent of the GN P by 1 990s, 5 per cent of the GNP by 1995 and 7 per cent by the year 2000. This can be achieved by increasing the usage of elec- tronics in agriculture, industry, educa- tion, transportation, banking, communi- cation and other public utilities. A telephone exchange within 5 km hexa- gon by 1995. a local radio station in every district by 1995 and a radio in every home will be desirable. Instead of setling up electronic industrial complexes, the commission recommends setting up of TV and radio facilities to give a filip to downstream industries. The commission underlines the need for optimising the existing investments through easy availability of spares and by giving facilities on par with manufactur- ers to maintenance services organisa- tions. These organisations should be given the status of industry enabling them to import spares. To encourage domestic production to meet the internal demand, preferential treatment may be given to the manufac- turers of quality products. A target should be fixed that by 1990 roughly 80 per cent of the domestic demand should be met through domestic production. Three-year user forecast of technology and quantity should be mandatory for is- suing import clearance. Despite the fact that the domestic mar- ket for electronic products in the country has gone up sharply in the last decade, the real share of domestic production in the total consumption of electronic pro- ducts in the country has drastically come down. Similarly, the increased outlay of foreign exchange in this area has not been balanced with corresponding ex- World Bank’s Tips The World Bank has suggested that foreign collaborations in the electronic sector should be exempted from the Foreign Exchange Regulation Act. The bank has also called for the abolition of the 10 per cent price perferencc to the public sector units and greater freedom to the private sector to choose technologies, collaborators and the vol- ume of production. The objective of the electronic policy should be to ensure techno-economic viability and production at international cost and quality. It should also ensure production efficiency and continuous technology upgradation through liberal access to foreign technologies. The World Bank reports says that FERA restrictions should he removed from high-tech end products, industrial and telecommunication equipment, middle grade components, micro and mini com- puters and the software. Firms seeking high percentages of equity should be asked to emphasise on manpower train- ing and technology transfer programmes rather than on the export obligation as contained in the existing electronics pol- icy. The report says that FERA regulation to locate the industry in the backward areas served as a disincentive and this should be removed. Rates of royalty, which were recently increased to eight per cent should be hiked further. The bank feels that the encouragement given to the private setor recently should be further strengthened by placing the private and public sectors on the same competitive basis. Production levels of industries opened to the private sector should be regulated for sometime to allow the development of private sector competition. The prices should be linked to the per- formance of the most efficient firms and not the least efficient ones. The ineffi- cient production processes protected through policies also raise profit mar- gins. The profit margins in India are 25 per cent to 35 per cent against the inter- national norms of 10 to 15 per cent, ac- cording to the World Bank report. The bank also suggests removal of pro- tectionism slowly along with removal of import restrictions through gradual re- duction in customs duties. The report notes that unrestricted access to components of highly quality at low prices is necessary for efficient prouction of most end products and critical for effi- cient production of colour TV sets, mic- rocomputers, printers and EPABXs. Steps should be taken to reduce compo- nent costs by progressively lowering component import duties. The duty on components should be brought down to 35 per cent from the present 75 per cent and this could be ELECTRONICS NEWS • ELECTRONICS N done over seven years. Also, compo- nents such as digital lCs should be im- ported and not manufactured indigen- ously and a 20 per cent duty can be im- posed on them, according to the World Bank. The proposed policy changes suggested by the Electronic Commission and the contents of the World Bank report ap- pear to be common on a number of points. This has given rise to a view point that the policy has been made under the World Bank pressure. While the policy of the government and the World Bank may appear to be a con- cident, the World Bank has, for the first time, offered credits worth US S 150 million for electronics sector. The bank has indicated that there should be "single window clearance" and a continued im- provement in the policy areas of the elec- tronic sector. The attractive aspect of this credit offer is that the bank will not only finance fixed assets but also provide funds for working capitals. CS1 convention The world’s largest computer communi- cations network will become operational in India by August, 1988, connecting 430 districts, all state capitals and major cities. Mr Sam Pitroda, technology ad- viser to the Prime Minister and chief of the Centre for Development of Telema- tics, highlighted this aspect in his keyn- ote address at the 23rd annual conven- tion of the Computer Society of India at Madras on January 6. Mr Pitroda, who has got the cars' of the PM, also heads the five special technol- ogy missions announced by the govern- ment. When Mr Pitroda said there would not be any large scale import of equip- ment or technology for computers, he should be taken seriously. He stressed that self-reliance would be achieved even it was time consuming and took a generation to accomplish. Mr Pitroda has suggested to the Planning Commission that equal emphasis should be laid on telecommunications, comput- ers and energy. Prof H.N. Mahabala, president of the CSI, told the convention that India could also export hardware if the government policies encouraged volume production and local R and D. It was high time that the government supported the R and D in the private sector. By 1990. India will have 100,000 personal computers .and this would necessitate a national plan to provide locally produced, quality Mr Hemant Sonawala, vice-president of the CSI, said the convention was the first to have an interlinked electronic mail, an on-line query system and a special high- tech pavilion. Also, for the first time, the department of electronics announced an award for the best software package de- veloped by an Indian Company. India was negotiating with a big Ameri- can company a proposal to export 100,000 computer systems to the U.S. this year and the systems would be supplied with specific software packages developed in India, Dr N. Seshagiri, ad- ditional secretary in the department of electronics, announced at the CSI con- vention. Indian companies obtained orders worth Rs.20 crores to the US and Singapore in the last six months and the fact that the orders were for hardware indicated the potential for Indian hardware exports. Dr Seshagiri pointed out. Since IBM was getting out of the PC market as it de- veloped new types, the older types of PC ranges were open for countries like India to exploit. Indian firms could supply both the hardware and software in this The Indian government would support the fifth generation technology and R and D in a bid to catch up with the ad- vanced countries. Consequently, em- phasis would be laid on Artificial Intelli- gence and parallel processing systems, according to Mr K.I'.P. Nambiar, secret- ary to the department of electronics. Dr Nambiar said the government would set up a centre for advanced computing technology which would concentrate on new software and hardware procedures. Part of this effort could lead to the de- velopment of a supercomputer by India within three years. The supercomputer would initially work at 100 million float- ing point operations per second and would later be upgraded to one billion or giga operations per second. The depart- ment of electronics would also set up hardware design and tesling centres in collaboration with major manufacturers like the ECIL. BEL. ITI, Keltron and Uptron. DEC in Delhi Digital Equipment Corporation (DEC), one of the world’s largest computer firms, has entered into a joint venture with the Indian firm, Hinditron Comput- ers, to float a new company called Digi- tal Equipment (India) Ltd. DEC will make VAX-11 range of supermini com- puters in India and this may help in av- oiding the imports of the systems. DEC and Hinditron already share a software export facility at the Santacruz Elec- tronics Export Processing Zone, Bom- bay and a similar facility will be set up in Bangalore. The government has also approved a similar tie up between the Modi group and Italy’s Olivetti. Competition in the minicomputer mar- kets will increase with the entry of DEC. Though IBM does not have any official tie up with India, Unisys has an Indian subsidiary called Tata Unisys; Wang Labs Inc. has a tie up with Digitron Com- puters; Hewlett Packard has links with Blue Star; Texas Instruments have joined with Zenith and Apple with Raba Con tel Ltd. Control systems Advani-Oerlikon Ltd. has signed a memorandum of understanding with two British companies, Oceantech Systems Ltd., and Vosper Thornycraft Controls for transfer of technology in electronic control systems. The company will invest about Rs. 100 crores in the next five years in new areas of control systems for applications in off- shore and on shore oil drilling projects and the Indian Navy’s frigates and other vessels. ECIL Pact While we talk of collaborations between Indian companies and international gaints. for a change an Indian giant is having collaboration with another In- dian firm. The state-owned Electronics Corporation of India has a tie up with the DCM Data Products. The coming to- gether of a public sector and a private sector unit is significant. DCM Data Products will market the Medha scries of mainframe computer systems, manufactured by ECIL, on a value-added basis. It will provide service and maintenance support besides some specific software. IBC Awards The international Broadcasting Conven- tion has invited nominations of candi- dates for its 1988 award. Together with a cheque for 3000 pound sterling, the award is given in recognition of a signific- ant contribution over any period by a person or group of persons to all aspects of broadcasting technology and allied re- search, design, development, manufac- alsklor India march 1988 3.19 ELECTRONICS NEWS • ELECTRONICS N ture, operational practice and manage- Nominations should be submitted by May 31, 1988 to 1BC Award 1988, In- stitution of Electrical Engineers, Savoy Place, London WC2R OBL, U.K. The award will be presented during the Inter- national Broadcasting Convention to be held in Brighton^from September 23 to 27, 1988. World Semiconductor Market lat constant 1986 values & exchange rates) 1986 1987 US$ bn 30.7 32.9 % increase 1.2 7.1 Source: Benn Electronics Publications, Luton, UK World semiconductor market to expand by 11% A report from Benn Electronics, Profile of the Worldwide Semiconductor In- dustry 1987-88, forecasts that the in- dustry is set to expand at a rate of 11% in 1988. This increase will take the total value of the market to $36.6 billion, up from $32.9 at constant 1986 values and exchange rates. Growth will be highest in the USA (14%). followed by Europe (11%), and Japan (7%). For Japan, the improvement represents a recovery from the performance in 1986 and 1987, when the market lost 5% of its value in real terms. The report also highlights the fast- changing technological composition of the world market, with CMOS products expected to account for 44% of the IC sector value in 1991, compared with only 23.5% in 1986. In the discretes market, the changes are less dramatic, but Op- toelectronics and Power devices are both expected to gain overall market share over the 1986-91 period. Benn Electronics Publications Ltd • Chiltem House • 146 Midland Road • LUTON LU2 OBI. • Telephone (0582) 421981. TELECOMMUNICATION NEWS • TELECO An Exchange a day The department of telecommunications is embarking on a programme of expand- ing its network in rural areas and the aim of this programme is to instal “one di- gital rural exchange a day”. About Rs. 30 crores will be spent in 1988 for this mission. Initially, the exchanges would be small ones with a capacity of 128 ports or roughly 80 lines each and all the equip- ment would be manufactured within the country. The average cost of putting up an exchange had been worked out to be Rs. 10,000 to Rs. 15,000 per line. In 1988, 250 exchanges arc expected to be installed in different parts of the country. The location selected for setting up an exchange would have minimum popula- tion of 4000. A 15-member committee has been set up by the Planning Commission to examine the ways in which different sectors could pool their resources allocated for de- velopment of telecommunication so that duplication of efforts can be removed. 3.20 TELECOMMUNICATION NEWS • TELECO Mr Sam Pitroda, adviser to the Prime Minister, addressing members of the Confederation of Engineering Industry at Calcutta, opposed the scheme of mobile telephones or phones in cars as he felt that the efforts should be more on a national network. On parallel com- munication network for businessmen, Mr Pitroda said any such scheme should also serve the national interests. Import from different countries had resulted in lack of computability between various systems. While microprocessors and in- tegrated circuits could be imported, the designs and software could be made in India, according to Mr Pitroda. Car Phones The car phones project, opposed by many as a luxury and non-priority in the context, was shelved sometime ago but latest reports from abroad show that the project is not dead after all. During his recent visit to Stockholm, the Prime Minister, Mr Rajiv Gandhi, showed interest in the activities of the Swedish telecommunication firm, Ericsson. Mr Gandhi dialled Mr D.K. Sangal, telecommunications secretary in Delhi, using a mobile telephone man- ufactured by Ericsson from Stockholm. Two days after this episode, Financial Times, London, reported that Ericsson was close to winning a Rs. 100 million contract to supply a mobile phone sys- tem to India. The report said Ericsson, Motorola of the US and NEC of Japan have been short-listed to supply a mobile- telephone system in Bombay for 5000 subscribers. The entry of Ericsson in mobile tele- phones may pave for others to come to "the expanding” Indian market. New Delhi has plans to set up mobile tele- phone systems in 14 major systems, it is learnt, Incidentally, the mobile tele- phone system may require re-writing of the existing software in digital electronic exchanges. The changing perception on the advisa- bility of car telephones has obviously raised many controversial points. More than commercial interests and the legiti- mate urge to become "modem" over- night, induction of sophisticated technology should be preceded by sane and sensible evaluation. Award to TCIL The Telecommunication Consultants India Ltd. has bagged the 1987 corporate performance award given by “The Economic Times” and Harvard Business School Association of India. Within 10 years. TCIL achieved over- seas orders worth Rs. 350 crores, with its operations spreading across 22 countries of Asia and Africa. Recently, three de- veloped countries in the field of telecom- munication. the Netherlands, Sweden and the USA have sought the skills of TCIL in software development. TCIL's recent achievement was in the area of satellite based commnication net- work, engineered for the National Ther- mal Power Corporation. A defence organisation has entrusted the TCIL with the job of establishing an in- tegrated network for international com- munication services via a purpose de- signed satellite earth station. World Radio Conference The world Administrative Radio Con- ference for Mobile Services which met in Geneva towards the end of 1987 took a number of decisions which could signific- antly affect key aspects of mobile satel- lite communications. The conference brought together about 800 delegates from 108 countries. The most significant decision taken at the meet was regarding the Global Maritime Distress and Safety System. It specified that any equipment covered by the new chapter IX of the International Tejecommunications Union Radio Reg- ulations must be maintained on board ship by a qualified radio-cicctronic of- ficer. Existing regulatory provisions will con- tinue to be followed until adequate mea- sures have been taken to ensure safe communications. While some nations objected to the un- necessary burden imposed on the maritime community, some others felt that perpetuation of outmoded systems could lead to inadequate safety stan- Many countries like the US, UK, Canada. France, FRG, Norway, Liberia and Panama be.lieve that the route to im- proved safety lies in the installation of modem equipment which can be oper- ated as easily as a telex machine or a tele- phone. In the event of failure, the equip- ment have sufficient built-in diagnostic routes to help the ship personnel replace defective parts. This is the justification for doing away with certified radio offic- The conference also made several mod- ifications to L-band frequency alloca- tion. While the maritime community will continue to have access to the entire 1530-1544 MHz band, the first three MHz 1530-1533 will be shared on a co- primacy basis with land mobile services. Satellite Search: The satellite aided distress alert detec- tion and position location has emerged as a proven new earth bound application of satellite technology for humanitarian purposes. In this system, a series of satellites in low, near-polar orbits listen to the dis- tress signals and relay them to a network of dedicated ground stations. The ground station alerts the rescue coordi- nation centre to rush to the site of emergency . For providing distress alert transmission capability in the event of fire, explosion or sudden floundering of a vessel the float-free Emergency Position Indicat- ing Radio Beacon is regarded as a key element in the future Global Maritime Distress and Safety System (GMDSS) by the International Maritime Organisa- The first Indian ground station for re- ceiving distress signals will he ready at Bangalore by 1989. The agreement with various interna- tional parties for use has already been signed. The agreement envisages that the Bangalore local user terminal will re- ceive 243 MHz signals as well as 121,5 and 406 MHz signals. The search and rescue payloads will be incorporated on host satellites as well as on future Indian satellites, l he first two of the second generation Indian National Satellite system, INSAT-IIA and IIB will carry 406 MHz payloads for detec- tion of distress signals. The engineering model of this payload is under fabrica- In 1986, Indian Space Research Organi- sation and the National Aeronautics and Space Administration of the USA con- cluded an agreement for cooperation in the development of 406 MHz geo-statio- nary search and rescue experience. In August, 1987, the USSR expressed its interest in the establishment of a suitable terminal in the USSR to receive and pro- cess the 406 MHz distress signal relayed through INSAT-IIA and IIB. Titus, a strong Indian intcr-agcncv prog- ramme in satellite search and rescue programme is emerging. 3.21 INDUSTRY STANDARD MOVING TO CHMOS High CPU power and a very high level of integration have developed the Type 80186 and 80188 16-bit microprocessors into industry standards in the embedded control arena. Most systems in the automation and power engineering area, like CNC machines and robots, are based on the 80186/188 architecture. by Bernhard Meier, Dipl. Inform. (FH|* INTEL'S 80C186 is the newest member of the popular, high integrated 80186/ 188 microprocessor family. The chip provides full hardware and software compatibility with .its NMOS prede- cessor 80186 and gives the design engin- eer additional opportunities via an inte- grated DRAM refresh unit, special power-saving logic and the new asyn- chronous numerics coprocessor (NPX) interface. The 80086 is manufactured with IN- TEL’S CHMOS 111 process technology (the same process on which the 32-bit 80386 is based) and is specified for 10. 12.5, or 16 MHz operation. Two operating inodes The 80CI86 supports two operating modes: Compatible Mode and lin- hanced Mode. When running in Com- patible Mode, the chip is fully hardware and software compatible with the NMOS 80186, with identical pin-out, timings, instruction set and driving levels on the I/O pins. Fig. 1 shows the block diagram of the new CHMOS compo- nent. It is seen that all 80186 peripheral functions are present: • a clock generator • two independent, high speed DMA channels • one fully programmable interrupt controller • three programmable 16-bit timer/ counters • user programmable memory and peripheral chip-select-logic • a wail-state-generator • and the local bus controller. Enhanced Mode operation offers an even higher level of integration. Ad- ditional facilities are: • the DRAM refresh unit. It is added to the bus interface unit of the 80C186 and automatically generates the refresh bus cycles for the system DRAM-battks. Additional costs and design effort for a seperate refresh-controller now belong to history in 800 86-designs. • power-saving logic. This unit is placed before the clock oscillator circuitry and provides the facility of internally dividing the clock frequency of the 80086. Soft- ware determines the internal speed and power consumption of the total chip. Power savings of up to 94®™ can be achieved by this unique feature. • asynchronous numerics coprocessor interface. This asynchronous interface replaces the current synchronous 8087- interfacc. which is no longer sup- ported on the 80086. A 80287-type of numerics coprocessor can be inter- faced without any TTL-glue in be- tween. The current integrated bus controller (IHC) 82188 is no longer necessary either. A detailed description of these new features will be given after the following brief overview of the 80186/800 86 in- ternal architecture. 80186/80086 Base Architecture The 80086 CPU provides full object code compatibility with the other members of the 8086-family (8086/186/ 286/386), but offers twice the 8086-CPU performance by virtue of a couple of architectural enhancements. The regis- ter- and base instruction set, as well as the segmented memory organisation, follows the 8086-standard. The chip of- fers (like its predecessor the 80186) up to 15 standard peripherals, thus reducing overall system cost dramatically. Fig. 2 shows the high level of integration in a typical 80086 based CPU-board, where additional hardware is only necessary for EPROM. RAM and special I/O functions, like disk-, winchester- or I.AN-interfacing. The on-chip DMA controller has two channels which can each be shared by multiple devices. At a speed of 12.5 Mil/, each channel is capable of transferring data at up to 3.12 Mbytes per second. It offers the choice of byte and word transfers and can be pro- grammed to perform a burst transfer of a block of data, transfer data per speci- fied time interval, or transfer data per external request. The on-chip interrupt controller re- sponds to both external interrupts and interrupts requested by the on-chip peripherals such as the timers and the DMA channels. It can be configured to generate interrupt vector addresses in- ternally like the INTEL microcontrollers or externally like the popular 8259A in- terrupt controller. In addition to that, it can also be configured as a slave con- troller to an external interrupt controller (iRMX 86 mode) or as a master for one or two 8259As, which in turn may be masters for up to 8 more 8259As. When operating in this master mode, each channel can support up to 64 external in- terrupts giving a total of 128. The three 16-bit timers arc also inte- grated on the chip. Timer 0 and timer 1 can be programmed to be 16-bit counters able to count external events. If con- figured as timers, they can be started by software or by a specific external event. Timers 0 and 1 each contain a timer out- put pin. Transitions on these pins occur when the timers reach one of the two possible maximum counts, which is es- pecially helpful in real-time appli- cations, where external hardware has to be synchronized with internal timing events. Timer 2 can be used as a presealer for timers 0 and 1, and is able to generate DMA requests to the two on- chip DMA channels. Finally, the integrated clock generator, the wait state generator, and the chip sel- ect logic reduce the externa', logic necessary to build a processing PCB. Enhanced Mode As mentioned earlier, the 80086 is com patible with the NMOS-version 80186 when operating in Compatible Mode, With the exception of the 8087-support, so that no numerics coprocessing is possible in Compatible Mode. All the Enhanced Mode features are completely masked during operation in Compatible Mode. A write to any of the new control and status registers will have no effect, while a read will return irrelevant data. In order to bring the 80C186 into En- hanced Mode, the user has to supply a special level combination at the TEST#/BUSY input during and after RESET. If the processor secs a HIGH on the TEST# pin at the rising edge of the RESET signal and a LOW four clocks later, it will start working in Enhanced Mode. From a board layout point of view, this can easily be achieved by tying the RESETOUT signal from the 80C186 to the TEST#/BUSY input. Together with a numerics coprocessor, the CPU is working only and automatically in En- hanced Mode. DRAM Refresh Unit (DRU) Many hardware designs in the past 'have used one of the DMA channels for dynamic RAM refresh. This was very cost effective and easy to implement but left only one channel for real DMA. To offer a higher level of integration and free the DMA, the 80C186 uses a fully programmable DRAM refresh unit in the Enhanced Mode. The refresh request rate can be set from one to 512 phase 2 clocks and performs a dummy read with the correct chip select activated. It is im- portant to mention that the 80C186 deactivates a given HI. DA signal when- ever a refresh request is pending and reactivates the HLDA after the refresh bus cycle. The signal combination of HLDA going inactive while HOLD is still active is showing the system that a DRAM refresh has to be performed to maintain the data integrity. To program the DRU, the 80C186 peripheral control block (PCB) has been enlarged by the three registers MDRAM (offset EOH), C'DRAM (offset E2H) and EDRAM (offset E4II). The function of these registers is shown in Fig. 3. To avoid missing refresh requests, the value in the CDRAM register should always be at least 18 (12H). Therefore, the refresh request rate should be in the range of 18- 512, despite the fact that theoretically a minimum value of 1 is possible. Fig. 4 shows all the necessary logic to implement a 1 Mbyte (512K x 16) DRAM design together with the 80C186. The design can be effected with three 74LS157s as address multiplexers and only one 20-pin EPLD 5C032 to generate DRAM control signals PRE RAS#, RAS#, MUX#. CASO#, CAS1#. WEL# and WEH#. The necessary PAL/EPLD equations, together with the corresponding DRAM speed calculations, can be obtained by contacting the application group at your local INTEL sales office. By using a more flexible EPLD 5C060, one could remove one of the LS157s. Power-save logic To save power in CMOS designs, the 80C186 offers the opportunity to divide the internal clock by a programmable factor of 1, 4, 8 or 16. As shown in (he following tabic, typical power savings of up to 94% can be achieved with this unique feature. Divisor Power consumption 1 100% of full power 4 25% of full power 8 13% of full power 16 6% of full power Because the CPU is not stopped, only- slowed down, it may continue to execute tasks with low priority like scanning a keyboard or serving a serial channel. This power-saving mode is controlled via two bits in the new register PDCON, which has the offset FOH in the peripheral control block (see also Fig. 5). Important for the whole system is the fact that the divided internal clock is also available at the CLOCKOUT pin of the 80086. All internal logic, including the DRAM refresh unit and the timers, will have their clock slowed down by the dividing factor. To maintain a real-time count, or a fixed DRAM refresh rate, the user has to ensure that these peripherals dehor India march 1988 3.23 are re-programmed when entering and leaving the power-saving mode. The power-saving mode is exeited whenever an interrupt is processed or whenever the user clears the enable bit in the register PDCON. Asynchronous numerics coprocessor interface The 80086 is a general purpose 16-bit microprocessor, designed for a wide range of embedded control applications. Typically, these areas need fast, efficient data movem ..it and a very short inter- rupt response time combined with a very high level of integration. Traditionally, the arithmetic on data values in these ap- plications tended to be simple, so that the 80186/188 fulfilled these needs in a low-cost, effective manner. However, more and more automation equipment requires extremely fast and 3.24 eleklor India march 1988 complex mathematical functions, which arc not provided by the instruction set of 'a general purpose CPU. Such functions as square root, sine, cosine, and logarithms are not directly available in a general purpose processor like the 80086. Software routines to get high speed numerics are too slow, so that special numeric coprocessors (NPX), like 8087/287/387 have been designed as a hardware extension to the correspond- ing CPUs. For the NMOS 80186/188, numerics re- quirements can easily be fulfilled with the 8087 and the integrated bus con- troller (IBC) 82188. The 80086 does not support this synchronous coprocessor interface in either Compatible Mode or Enhanced Mode. As a replacement, in Enhanced Mode the 80086 has been equipped with an asynchronous nu- merics coprocessor interface, which is similar to the 80286/80287 interface and shows some advantage over a synchron- ous one. For example, the clock fre- quency of the NPX is not limited by the CPU-clock rate. To get maximum floating point performance, the NPX clock frequency can be higher than the 80086 system clock. Additionally, 80086 DRAM refresh bus cycles can in- terrupt NPX-data transfers, for example during the NPX-commands FRSTOR and FSAVE. The new asynchronous in- terface also allows the full use of the 80086 chip select, wait state generator and bus control logic for memory. The handshaking between the 80086 and the NPX is accomplished with four dedicated pins: NPS#, ERROR#, PEREQ and BUSY#. To keep the 80086 in the standard 68-pin form fac- tor and yet accommodate these pins, it has been necessary to redefine three of the mid-range memory chip select lines according to the following table: Compatible Mode MCSO# MCS1# MCS3# Enhanced Mode PEREQ ERROR# NPS# The pin PEREQ means Processor Ex- tension Request. This is used to signal to the CPU that numeric data transfers to and from the numerics processor have to be performed. The ERROR# pin is useful during ESCAPE instructions, where a low on this pin will vector to the INT 16 interrupt. Lastly, NPS# is the numerics coprocessor select line. For a 80CI86-NPX CPU board design it is im- portant not to use pins MCSO/l/3. An external decoder is recommended to re- place their functions. In addition to the four pins, four dedicated I/O port addresses are re- served for passing information between the 80C186 and the NPX: I/O address 00F8H OOFAH OOFCH OOFEH Read definition status/ control data reserved opcode Write definition opcode data CS:IP, DS:EA reserved Fig. 6 gives details of the asynchronous interface between the 80C186 and the numerics coprocessor (NPX). Note that there is no TTL-glue between the two chips. It should be mentioned at this point that the interface is not available with the 8-bit version 80C188. ONCE Mode and development tools The 80C186 has an additional feature which allows the user to electrically isolate the device from the PC-board when it is soldered through hole or sur- face mounted. This special test mode is called ONCE (ON Circuit Emulation) and provides an easy way of testing and inspecting devices that are fixed into a target system. During this mode, all 80C186 pins are placed in a high im- pedance state so that a board test can be accomplished without the need of removing the 80C186. The ONCE mode is selected by tying pins UCS# and LCS# low during RESET and is ter- minated by a normal RESET (UCS# and LCS# high). The success of new board designs is more and more dependent on the availability of efficient hardware and software development tools. These tools arc required to run on industry standard hosts. Because the 80C186 shows object code compatibility with the 8086-family, the current INTEL compilers, like C-86, FORTAN-86, PLM-86, PASCAL-86 and the standard 8086-Asscmbler, can be used. These software tools are available on a variety of hosts, including INTEL'S MDS I1I/IV, INTEL’S systems 310/320 and of course on the IBM PC XT/AT and its compatibles. For designs of up to 10 MHz in Compatible Mode, the I2ICE-186 is a comfortable hardware emulation vehicle also for the 80C186. To support new, true CMOS designs with the 80C186 and clock frequencies of up to 16 MHz, a new emulator, the ICE-186, has been developed. This new tool incorporates the 80086 bond-out chip, which provides full access to all the new features of Enhanced Mode. Summary The new features of the 80086, the ad- vantages of the CHMOS-process with speed selections of up to 16 MHz, and the availability of powerful hard- and software development tools, make this new processor the ideal solution for many new embedded control appli- cations. For current 80186-based prod- ucts the 80086 is a logical and efficient upgrade. All conditions are there for it to become the next embedded control mi- croprocessor standard. Literature: (1) 80CI86 Data Sheet, INTEL Corpor- ation, 1987. (2) 8088/8086/80188/80186 Hardware Reference Manual INTEL Corporation, 1986. (3) 8088/8086/80188/80186 Program- mers Ref. Manual INTEL Corporation, 1986. * Bernard Meier is with INTEL Semi- conductor GmbH, Munich VAM- video/audio modulator colour pictures and sound from your personal computer First of all, let us answer the question: What is a video modulator? This could be described as a kind of miniature TV transmitter which processes a video signal in such a way that it is suitable for application to the aerial input of a conventional TV set. It is an essential element in a TV games computer, for example, or a test pattern generator. It is also required by a Videotext decoder or TV terminal for a personal computer. Several video modulators have already been published in Elektor. However, the last design dates back to the October 1978 issue and is not suitable for colour applications. Moreover, it cannot be used for audio and the sound must be applied to a separate amplifier. This means that the sound section of the TV set remains silent, which is a pity. It is not an elegant solution from the technical point of view. These various factors prompted the design of a new circuit which is suitable for modu- lating both video and sound. The circuit is of such universal design that it can be used for a wide number of applications. Design The intention is for the user of the VAM to be able to convert the RGB signal gen- erated by this hobby computer, test pattern generator or other source into a video signal of his choice. This was a basic require- ment of the VAM in the development stage. The circuit was to be equipped with digital R(ed), G(reen), B(lue) inputs, a separate audio input, and a video output. After some reflection, the 'Teletext Decoder published in the November 1981 issue was LM1886N LM1889N 3.26 elektor India chosen as a suitable basis for our design. After minor modifications and a somewhat different arrangement, we achieved our objective - the VAM. The circuit chiefly consists of two special ICs whose internal block diagram is shown in figure 1. The LM 1889 N is the heart of the circuit. This IC contains a complete colour modulator which is capable of ‘composing’ a colour video signal from a brightness (luminance) signal Y (at pin 13) and the R-Y and B-Y signals. The LM 1889N also contains an oscillator for generating the sound carrier. This sound carrier is mixed with the video signal via pin 12. The LM 1886 N integrated circuit serves as a converter. In addition to a matrix for generating the Y, R-Y and B Y signals required by the LM 1889 N, this 1C has inputs for colour modulation according to the PAL system. Three digital inputs are provided per colour (Red, Green and Blue), corresponding to 9-bit colour data; this is adequate for all possible applications. The circuit Figure 2 shows the combination of the two ICs into a ‘miniature colour-TV power encoder'. 3.27 The different inputs can be seen on the left of the figure. The most important ones are the 9 RGB inputs, sync input and audio input. The VHF and video outputs are on the right of the figure. They can be optionally selected by means of SI. The LM 1886 N and LM 1889N are designated here as IC1 and IC2 respectively and interconnected via lines B-Y, R-Y, bias and Y. ICs 3, 4 and 5 are neede d to able to obtain the burst-anable (burst) and H/2 (for the PAL switch) signals required for generating a PAL video signal. Additionally, a blanking pulse (BL) is generated with these ICs; this suppresses the picture information during vertical synchronisation. However, the pulse is only required when no external BL signal is available. We shall examine this in more detail later. The audio modulator in the upper part of figure 2 is a simple circuit. A resonant circuit (LI, C4, C5) at the intercarrier frequency (6 MHz) is frequency modulated by means of varicap diode DIO. The audio signal serves as modulation signal. Since the circuit mentioned is a part of the os- cillator contained in IC2, the sound is also modulated in this way. Input sensitivity of the audio modulator is approximately 1 v rms- We shall now consider the signals in more detail. RGB Three inputs are provided for each of the red, green and blue signals. Eight levels can therefore be realised per colour, resulting inatotalof2 9 = 512differentcolourshades. The coding for the most common colours is listed in table 1. For simple applications the three R, G and B inputs can be interconnected, so that only one input is available per colour. One pull-up resistor (Rl, R4, R7) and one limiting diode (Dl, D4, D7) is utilised per group of three in this case. The selection is thus restricted to six colours plus black and white. This may not appear to be much, but it is satisfactory in most cases, e.g. for microcomputers with digital RGB outputs. Such microcomputers often supply an NTSC colour signal which is of little use in the UK and continental Europe. However, the VAM can be directly utilised as an ‘adapter’ between these computers and the aerial or video input of a PAL colour tele- vision set. In these cases problems are sometimes encountered with the vertical synchronisation (60 Hz for NTSC). In general, however, the TV set can easily be readjusted. One more comment: if the RGB inputs are driven by TTL, the pull-up resistors and limiting diodes can be omitted. Sync The sync signal must be applied to the circuit without fail. For this reason it is also provided by every video signal source. Pulses (logic zero) which can be directly used as a sync signal are those with a width of about 4 /is and a repetition frequency of 15625 Hz (64 ps). Additionally, the pulse train must contain an interval of approxi- mately 500 /is (7.5 x 64 (is, to be precise) every 20 ms for purposes of vertical synchronisation. During the interval, the synchronisation signals deliver a substitute signal which is inverted with respect to the original sync signal and which has twice the frequency. This doubled frequency is used in the VAM to suppress the burst pulse. We shall examine the BE (burst enable) signal later. Incidentally, a combined (horizontal plus vertical) sync signal is not always available. Injhis case the horizontal (H3 ) and vertica l (VS ) components must be combined into a sync signal. Figure 3 shows a simple circuit: an AND gate (3a) or two tri-state buffers (3b) form the desired sync signal from the HS and VS . BL = blanking The BL signal is not absolutely necessary. Its purpose is to suppress the input signals at the RGB inputs. In most cases this sup- pression already takes place in the computer or test pattern generator, thus making an external blanking signal superfluous. If necessary, the VAM can provide an external although ‘primitive 1 rasterblanking signal. This will be discussed in the description of the BE signal. When applying a BL signal, care should be taken to ensure that it is active during the logic zero periods. 'I 3 BE = burst enable The sync signal is immediately followed by a short pulse (approximately 9 periods), to synchronise the TV set with the colour demodulator. The task of the BE signal is to establish the instant at which this pulse is emitted. To prevent the TV set from ‘flip- ping out' during the raster-sync (vertical- sync) pulses, the BE signal is suppressed during this period. On the one hand, the PAL flip-flop IC3 is prevented from reacting to the double sync-frequency by means of IC4 (Ql - see figure 2); FF1 continues to follow the same rate. On the other hand, a blanking signal of approximately 600 ns in duration is generated as soon as IC4 signals this double frequency (when a new sync pulse appears within 40 ms). This signal can serve for raster blanking via wire link V-W, instead of an external BL signal. However, this blanking signal is mainly required to sup- press the BE pulse. Here are two more points. Firstly, it should be noted that when the VAM is used as a monochrome modulator the oscillator con- nected to pins 1,17 and 18 of IC2 becomes superfluous. In this case the BE signal is not required either, because it is normally employed to modulate the phase of this oscillator together with the RGB signals (converted to R-Y and B-Y). The second R1 . . . R9 ■ 5k6 RIO ° 22 k R11.R12- 15k R13 a 2k2 R14.R20 - 4k7 R15.R16 = 270 n R17 - 820 SI R18 - 82 n R21.R23.R24 - 1 k R22 - 3k3 R25 = 68 « PCBs & Set of COMPONENTS forprojeds ore normally avoilabte with precious * »>««>» 1 52 C Proctor Pood. BomBay-400 007 Phones: 367 459'369478 | R27 = 27 k R28- 18 k R29 - 8k2 Capacitors: Cl. . .C3,C7,C17,C19 = 100 n C4 = 33 p C5.C1 1 - 4 . . ,40p C6 = 39 p C8.C9 = 100 p C10= 10. . 60p C12 . . .C15- 18p C16.C21 = 10 n C20 = 47 /i/1 6 V C22 - 27 n C23 = 390 p C24 = 470 p 3.29 Practice Construction of the VAM should present no problems using the printed circuit board shown in figure 4. All inputs are arranged at one edge of the p.c.b. Located at the other edge are the VHF and video outputs and the terminals for switch SI, which is used to select one of the two outputs. The supply voltage terminals are at one of the longer edges of the p.c.b.. Two different supply voltages are required: +12 V and +5 V. The 12 V rail must be capable of supplying approximately 60 mA and the 5 V rail approximately 10 mA. Since no other special demands are made on the power supply for the VAM, it is possible to use the teletext power supply from the February 1982 issue, for example. When fitting the components to the p.c.b. it should be noted that a total of six wire links must be installed. Two of these wire links are alternatives: if an external BL signal is applied, wire link V-W is omitted. If an external BE signal is applied, link X-Y is omitted. Flesh tone Sky Blue Alignment Alignment is fairly simple. It is merely necessary to adjust three trimmer capacitors: C5, CIO and Cll. The oscillator circuit of the audio modulator is tuned to precisely 6 MHz by means of C5. This is easier than one might think. In practice the trimmer is set to minimum audible noise and maximum Cl 1 is used for fine adjustment of the colour carrier frequency. The range of adjustment is relativily narrow, because this is a crystal- controlled frequency. The colour TV set will display a good picture within a particular capacitance range of Cll. The trimmer should therefore be set to the midpoint of this range. Last but not least, CIO. The main purpose of this trimmer is to allow adjustment of the VHF output frequency. If switch SI is set to the ‘RF’ position, the output signal can be tuned to VHF channels 2, 3 and 4. Fine adjustment can be made using the appropriate potentiometer in the TV set. Readers fortunate enough to have a TV set with a video input should connect it to the corresponding output of the VAM. Picture quality will probably be somewhat better. 3.30 elektor India FLAT AERIAL FOR SATELLITE TV RECEPTION Matsushita Electric Works (MEW) have recently introduced a flat, easy-to-install, 12 GHz aerial developed by Comsat Corporation. The new product is available in seven versions. Simple to install, unobtrusive, and complete with a low-noise down converter, the flat aerial is an attractive alternative to the conventional parabolic or off-set dish. The flat aerial for satellite TV reception was developed by Comsat Corporation, known worldwide as one of the technical consultants of Intelsat and Inmarsat as regards microwave technology. Comsat’s research and development laboratories recently succeeded in designing a 12 GHz aerial which forms a radical departure from the parabolic concept used for dishes of diameter between 50 cm and 1 m. The signals to be beamed down by the direct broadcasting satellites TV-SAT1, TDF-I, Olympus. Tele-X, and others, are strong enough to be picked up by relatively small — and. therefore, easy to install— aerials, in combination with a low-noise block down converter (LNB or LNC). But even a so-called off-set dish of, say, 60 cm diameter may be difficult to install in built up areas. In many cases, a building permit is required before the aerial may be fitted onto the roof. Another import- ant point is the total depth of the dish aerial including the pointing system at the rear, and the the LNB mounting system in front. Compared to a depth of 30 cm or so for a modern dish of the off- set type, the aerial introduced by MEW is truly flat at only 20 mm. Multi-layer structure captures received power The operation of a dish aerial is based on reflection of the received microwave power to the focus, i.e., the feed horn or LNB input. This is in contrast to the flat aerial, which receives power direct on a multi-layer laminated structure as shown in Fig. 1. Power loss is minimized by vir- tue of the stacking system of radome, radiation plate, feed line plate and ground plate. The multi-layer laminated structure developed by Comsat is claimed to yield high efficiency (60—70^), and sufficient gain for DBS reception over a wide frequency band. The flat aerial is much easier to point at the satellite than the dish. This is because of the greater half power beam- width, which is typically 6-8° in the azimuth plane. With the exception of the "top of the range” model, the Type PA66-D, the flat aerials receive either right-hand or left-hand circularly polarized signals in the DBS band. The accompanying table shows the main technical characteristics of the available models. Note the use of the standardized LNB intermediate frequency (IF) of 950-1750 MHz, which ensures ready connection to most types of indoor unit 2 1 Simple mounting for roofs or gardens via an F connector and a downlead cable that carries the RF signal and the supply voltage for the LNB. The noise figure and LNB conversion gain are also fairly standard at 2.3 dB and 55 dB, respect- The ease of use, and a number of instal- lation options, of the new aerials is il- lustrated in Fig. 2. The smallest type has a size of 35 x 35 cm and weighs only 1.3 kg: it is, therefore, ideal for semi- portable applications. The flat aerial from MEW is among the most important of new components in- troduced in support of individual recep- tion of TV satellites. It is a rugged, easy to handle component that can even be mounted behind glass surfaces for ex- periments in the reception of audio pro- grammes transmitted in narrow band- width pulse code modulation (PCM). Matsushita Electric Works Limited International Trade Development Div- 1048 Kadoma-Shi • Osaka 571 • Japan Telephone: 06-906-1823 Telex: 529-3319 MEW J Fax: 06-909-7053 Fig. 2 . Various applications of the new fiat aerial for DBS reception. 3.32 elektor India march 1988 GENEVA CALLING: ISDN AND SATELLITES AT TELECOM 87 A brief look at some of the new technical concepts introduced at Telecom 87, the world's largest and most comprehensive telecommunications exhibition held in Geneva last October. The main technical topic at Telecom 87 was integrated services digital network- ing, ISDN. The underlying principle of this far-reaching technical concept is the total integration of all electronic com- munication equipment in a network that allows continuous data transfer in all directions, at the highest possible speed. Ideally, wait times are eradicated, and every communication unit, whether this is an electronic typewriter, a telex, a grade-4 facsimile machine, or a voice synthesizer in a telephone exchange, can communicate direct to every other unit in the network. Communication is, therefore, interactive at all levels. An ISDN structure can only handle digital data, so that all types of analogue messages, including voice, require digitizing. ISDN supports a multitude of com- munication services: telephone, videophone, telex, fax, videotext, slow- scan television, local area networks (LANs), videoconferencing systems, data terminals, personal computers, tele- phone exchanges, printers, payphones, and many more. It is all very well for communication units to be part of an efficiently operating network, but can we connect two or more ISDNs to form an even larger network? In other words, can we connect an ISDN to the outside world? Satellites and fibre optic cables provide the answer. Digital signals in ISDN channels travel at 64 kbit/s, and processor-controlled central units (con- centrators) regulate the multitude of data streams in accordance with the ca- pacity of the lines in the system. Ob- viously, the higher the bandwidth of the channels, the more traffic can be carried at a relatively high bit-rate. The increas- ing use of fibre-optic technology is cer- tain to bring the transmission of moving pictures in ISDNs within reach in the not too distant future. An important aspect of ISDN is that the routeing and buffer- ing of data in the system are completely invisible. This means that the user of, say, a personal micro can send out a data file to another computer user in the of- fice building without having to wait for access if the "receiver” is engaged in other work: the data is- automatically buffered and kept stored until the re- Example of an integrated digital systems network (ISDN). Data flow is regulated and opti- ceiver is ready to accept them. mized by processor-controlled exchanges, which are completely invisible to the users of com- Data from the ISDN in an office may be munication equipment connected ( courtesy Ptessey/GEC). elektor India march 1988 3.33 fed to a satellite uplink unit. It is then digitally transmitted to a geostationary transponder, which amplifies the signal, and beams it down to the receiving station, which may be thousands of miles away from the sending office. Both offices are equipped with transmit and receive equipment for access to a par- ticular satellite, or even a network of satellites, so that high quality full-duplex communication channels are continu- ously available. On the aerial grounds outside Telecom 87, a number of companies demon- strated new, transportable, satellite uplink equipment in various power ratings, geared to connection to an ISDN. Dish sizes varied from about 1.5 m to 10 m and more. Companies actively engaged in building ISDN equipment include NEC, Siemens, Hewlett Packard, the Northern Telecom consortium, Philips/AT&T (Sopho-S sys- tem), IBM and Olivetti. ISDN in practice: System X Plessey and GEC-Marconi are currently regarded as the leaders in the develop- ment of ISDN systems to CCITT stan- dards. Their joint product is called System X. Although System X equip- ment has been in use for a number of years in British Telecom’s main trunk ex- changes, recent improvements as regards the achievable speed on the internal and external data links have aroused the in- terest of many national PTTs planning and building new data and voice com- munication networks. Recently, the data transfer rate of System X has been upgraded from 80 to 144 kbit/s, with full compatibility between old and new systems guaranteed. At Telecom 87, Plessey/GEC demon- strated the versatility of the latest version of an ISDN compatible trunk exchange. The system installed on the stand was in System X live at Telecom 87: 1-ondon literally transferred to Geneva. With the co-operation of British Telecom, the Geneva based System X exchange from GEC/PI.essey operates as an integral part of the UK telephone net- work. Two other companies exhibiting at Telecom 87, Comsat and STC, had access to the "I-ondon" exchange and its ISDN ser- vices ( courtesy Plessey/GEC). 3.34 elektor India march 1388 continuous operation, functioning as part of a telephone exchange situated in London. Two-way satellite links between Geneva and London had been set up for the occasion of Telecom 87 to show that part of the traffic carried by a main London telephone exchange could be transferred to the system installed on the System X stand. In fact, the public was invited to contact London extensions direct from the stand, without having to prefix calls with STD code 01. The ISDN exchange occupied relatively little floor space, yet carried fax, telex, slow-scan, computer, LAN, voice and videophone services for 5 companies simultaneously. An interesting technical novelty devel- oped specifically for use in ISDN sys- tems is dynamic line inductance balanc- ing. A computer simulation on the Sys- tem X stand showed how an intelligent test and control system runs a fast and invisible check on the electrical charac- teristics of the telephone line. This takes place within a second or so after the line has been selected, and provides the basic settings for the active fork circuit that terminates the line at the ISDN side. The combined termination and source in- ductance of the fork is continuously ad- justed to achieve optimum suppression of noise, pulse ringing, and line echoes. These are often troublesome effects in data transmission, causing distortion and, of course, a reduced bit rate (data speed). In short, the active fork circuit makes the best of every line, irrespective of the length, or the equipment connec- ted to it. As such, it offers new ways to use existing telephone lines for high- speed modems. The new ISDN compatible videophone from Philips Communication Industries. The operator console coupled to an ISDN compatible exchange is a radical departure from the well-known ’’switch- board". The bulk of the work is now carried out automatically by a computer. A high-resolution screen gives an over- view of all current and pending connec- tions between internal and external ex- tensions. Internal extensions do not have numbers, but easy to memorize letter codes, which are all displayed on the screen, complete with extension status information. Extensions can be called up with a single command from the keyboard. Automatic redialling, call diversion, automatic reminders, priority level assignment, interrupting calls, group extension calling, conferencing ar- rangements, extension scans to locate called up persons, and fully automated dialling of emergency services are among the many features of the new operator console, which records the day’s ac- tivities on a printer. The speed at which the system works is unbeatable by even the most experienced and efficient of ex- change operators. TEST + MEASUREMENT Hewlett Packard proposes lo use ISDN structures for fast data throughput in complex automated test and measurement systems. Large transparant panels allowed a glance at some of the latest electronics technology fitted into racks that together form the digital and voice com- patible System X ISDN exchange. Plessey/GEC have relied mostly on their own expertise as regards the use of high density multi-layer PCBs, VLSI chips. SMA components, 8 Mbyte memory boards, multi-tasking processor systems, and fibre optic connections between modules, instead of complex and costly bus structures. The System X exchange is completely modular, and can be tailored and programmed to customer require- ments: it is, for example, possible to sel- ect a synthesized, male or female, voice, which upon request advises cost and duration of the call. Field technicians can also make use of the synthesized — but remarkably real — voice to obtain technical information on the line or ex- change section brought into service. An array of lead-acid batteries provides the memory back-up function, enabling the complete exchange to be brought into service again within 2 minutes after a mains failure. One of the most interesting demon- strations of the capabilities of ISDN was the full-duplex slow-scan link with one camera installed on the Plessey/GEC stand, and the other in an office in Man- chester. A high-speed fax message was sent to this office via the System X ex- change, and an office employee could be seen to collect it from his fax receiver. For reasons unknown, a demonstration of data file transfer to a UK-based bulletin board via the ISDN exchange was less successful. Satellites: competition and co-operation Much excitement, optimism and good cheer at the stands of EutelSat, Aero- spatiale, EuroSatellitc, ArianeSpacc, and many other companies and insti- tutions involved in the building, launch, and operation of the first European direct broadcasting satellite (DBS), TV SAT-1. At long last, and after much negative publicity caused by the Colum- bia disaster and the launch failures of 2 communication satellites, ArianeSpace was hopeful again: the countdown for TV SAT-1 was the topic of the day. Mr The Stornophone 6000 multilingual radio- telephone can prompt and instruct the user in 10 different languages. EUTELSAT I-F1 EUTELSAT I-F2 and following EUTELSAT II Stabilization 3 axis 3 axis 3 axis Mass at launch 1045 kg 1160 kg 1 700 kg ( 7 years) 1 800 kg (10 years) Mass in orbit •'! 510 kg 550 kg 866 kg Span (with solar panel deployed) 1180 m 1160 m 22.40 m Electrical power 01 MOW 900 W- 3 000 W Lifetime 7 years 7 years 7 to 10 years Frequency bands 14/11 GHz 14/11 and 14/12 GHz 14/11 and 14/12 GHz Number of transponders 12 14 16 Number of transponder for simultaneous use 10<« 10 16 Transmit power of each transponder Antennas: 20 W 20 w 50 W - receive/transmit 1 - receive only - transmit only 4 4 1 (1) at end of life - (2) 6 only in eclipse - (3) one antenna as a back-up for the other 880036 - T Comparison of the technical features of future Eutelsal Series-2 satellites to the "good old" Series 1 spacecraft Eutelsal 1 FI (LCS-ll and Lutclsa! 1 F2 (ECS-2). Not shown in the table is the recently launched Eutelsal 1 F4 (EC8-4; OP = 10° E), which is also a Series 1 type. EC'S-.' was lost in an unsuccessful launch ( courtesy Eutelsal ). Jean-Pierre Baudry of EuroSatellite re- ceived telexes straight from the ESA launch site at Kourou, French Guyana, and faithfully added a tick to a long list of check items related to the prep- arations for the launch of the Ariane 2 rocket to carry TV SAT-1 into geo- stationary orbit. Now, almost 4 months after Telecom 87, it has evolved that the launch was successful, but that TV SAT- 1 is unlikely to be be taken into service as scheduled owing to technical difficulties with telemetry equipment and one of the solar panels. This was the last thing the German electronics industry had ex- pected: a successful launch, but a defec- tive satellite. How does the American satellite in- dustry regard the European efforts at putting high power TV satellites in or- bit? Mrs Walda W Roseman, chief press officer of Intelsat, argued that the com- bined power of the European satellite in- dustry is not, or not yet, a serious com- petitor to her company, simply because ’’the technology lacks the experience". She then went on to show the huge tech- nical potential and the good Financial results achieved by Intelsat, an inter- national consortium renowned for its ex- perience in operating tens of geostation- ary satellites for data communications and TV services. The 4-channel German and French DB services, TV SAT and TDF, are so heavily sponsored by the respective governments as to be econ- omically unviable: in other words, they can not be, nor become, profitable simply because they have no channels available for leasing to commercial TV stations. In this context, it is interesting to note that SES of Luxemburg have signed a contract with RCA for the con- struction of Astra, a 16-channel medium power satellite to be launched later this Meanwhile, Eutelsat has started a program for the construction and launch of their Series-2 satellites in the early 1990s. These satellites will be con- siderably improved with respect to the current types in Series-1 (ECS-1, ECS-2, and, recently, ECS-4). Transmit power will be 50 W per transponder instead of 20 W. Again, it is interesting to note that Eutelsat has no intention whatsoever of building satellites with the power rating of the "heavy-weights” TV SAT, TDF or Olympus. Mr Michel Chabrol, oper- ational planning engineer of Eutelsat, said that 50 W would be adequate, even for direct (individual) reception, con- sidering the recent technical advances achieved in satellite receiver technology. Indeed, lowering the receiver’s noise fig- ure by about 0.5 dB is easier, and cer- tainly less costly, than increasing the sat- ellite transmit power by, say, 100 W. Telecommunications has developed spec- tacularly since Alexander Graham Bell's in- vention of the telephone in 1876 (courtesy ITU). Fuba's off-set parabolic dish aerial Type OAP120 for satellite TV reception (I'uliii press photograph ). Better luck lhan TV SAT1, we hope: engineers working on the French national DB satellite. TDF-1 (courtesi Aerospatiale). D2-MAC: already a skeleton in the cupboard? Nol a single West-German company on Telecom 87 was able to show a working, D2-MAC compatible, satellite TV re- ceiver for the consumer market. This was simply because ITT Semiconductors of Freiburg did not have the key compo- nent ready in time. Embarrassed press officers and engineers on the stands of Fuba, Hirschmann and Bosch had to ad- mit that receive systems for TV SAT-1 were still incomplete without the Type DMA2270 transcoder chip. Whether or not D2-MAC will succeed in becoming the new European TV stan- dard, the professional world is ready for it: Malra Communication of France and Fuba of West Germany showed working prototypes of D2-MAC to PAL/SECAM transcoders. These systems arc only in- tended for cable head-end stations, how- ever, and come as a number of racks fit- ted in a 19 inch enclosure. Plessey and Philips arc also reported to have commenced a joint programme for the development of a MAC transcoder chip, but details of this were not known at Telecom 87. The Japanese industry has simply skipped everything to do with MAC transcoders, and have come up with the far more powerful MUSE transmission standard, which is briefly discussed further on in this article. Inmarsat The International Maritime Satellite Or- ganisation (Inmarsat) had built an im- pressive and colourful stand. Inmarsat is totally dedicated to operating a network of geostationary satellites that carry data and voice communication between ships, shore stations, and, shortly, aeroplanes. The main topic was Inmarsats new in- itiative to extend their services with land- mobile and aeronautical communication systems. In the not too distant future. Geostationary satellites operated by Inmarsat can play an important role in the forming of a worldwide distress calling system for ships ( courtesy DFVLR). Motorcycle top box with Slorno's "Silent Messenger" radio installed in a shock absor- bent enclosure. airlines will be able to offer passengers world-wide telephone and data trans- mission facilities. Before long, the businessman on board an aeroplane will be seen sending reports prepared on his lap-top computer to the head-office. Inmarsat currently operates communi- cations capacity on 9 satellites in geo- stationary orbit around the world. These are the Marccs A and B2 satellites, three MariSat spacecraft, and transpon- ders leased on four Intelsat series-5 satel- lites. Inmarsat expects to satisfy the ever increasing demand for more communi- cation capacity at higher speed by means of three Inmarsat-2 satellites currently being constructed by an international consortium headed by British Aero- space. Inmarsat will own, rather than lease, these new satellites. STC, one of the companies that supply Inmarsat approved communications equipment for use on ships, demon- strated a new mechanically steered dish aerial that uses an electronic gyroscope to keep itself pointed at the satellite with an accuracy of tenths of a degree. Oriental power Twenty-six Japanese organizations and tclccommuncations manufacturers par- ticipated in Telecom 87. Their collective stand was the third largest on the exhi- bition, following the United States and France. Japan Radio, Hitachi, Fujitsu, NEC, Sony, Panasonic, Matsushita, NHK (The Japanese broadcasting cor- poration), Canon, Ricoh, OKI and KDD made their presence as the most import- ant companies. One of the most interesting technical novelties on display was the HDTV (high definition television) equipment devel- oped by NHK. This TV standard is based on 1,125 lines and a horizontal-to- verticai picture aspect ratio of 9:16, and is expected to revolutionize TV watch- ing. Colour pictures of unparallellcd brightness and resolution are displayed on 32 or 40 inch monitors, and the ac- companying sound is to CD standards. Since the Hi-vision picture contains about 5 times the information of a con- ventional PAL picture, NHK set out to develop the MUSE transmission system for use on satellites. MUSE means Multiple Sub Niquist Sampling En- coding. Studio equipment has been developed to compress the HDTV band- width of more than 20 MHz to about 8 MHz, the standard uplink baseband, without reducing picture quality. NHK have already conducted many ex- periments in broadcasting Hi-Vision signals via the Japanese satellite BS-2B. The aim of NHK is to increase the number of lines in the TV raster to 2,200, while 3-dimensional television is also being studied. A HDTV video cassette recorder is already available, and was demonstrated successfully. Further interesting new items on the Japanese stand were Ricoh's and Canon's fast, ISDN compatible G4 fac- simile machines. The Canon fax Type 14003 is complete with a desk-top publishing system, a vertical A4 moni- tor, and a medium-resolution laser printer. At the speed of 64 kbits/s, the machine transmits a document in just 3 seconds. Who needs telex any longer? Hitachi presented its new HMAP-D system, which is a complete workstation for the design, storage and retrieval of map information. The system was demonstrated live on Telecom, using a satellite link to receive information from a central storage computer in Tokyo. Real estate listings and detailed maps complete with street names and traffic information were available almost in- stantly on a 58-inch high resolution colour display, and a colour printer. Colour coding, magnifying, reducing or scrolling of maps are among the many technical features of this powerful lllrd WORLD BOOK AND AUDIOVISUAL FAIR ON TELECOMMUNICATIONS AND ELECTRONICS DIPLOMA EUktor Electronic* No way can the telecommunications industry go round informative books and magazines on the subject! OPTIC FIBRE COMMUNICATION The development of the self-supporting aerial fibre optic cables Fibrcspan and Translite has opened up enormous possibilities for improving and expanding communications systems at considerably less cost and effort by relying on existing electrical grid and railway networks. The technology of fibre optics generally has been making rapid inroads into various areas of control and communi- cations, replacing or supplementing tra- ditional metal conductors and other methods. In the aircraft industry when hydraulic and mechanical linkages were replaced by electric control cables, the technology was hailed as "fly-by-wire”. With the in- troduction of fibre optic cables into air- craft, the term “fly-by-light” was coined. One can only wonder how earth- bound aerial optical fibre cables will be described. The laying of subterranean trunk com- munication cables is an expensive under- taking and that of optical fibre cables is no exception. Despite their relatively low weight and ease of handling, they still have to be laid in ducting or other pro- tective materials. The routeing of the cables and the construction work, with all the related problems, constitutes a difficult and time-consuming task. Ready-made distribution network However, in most countries, there are existing distribution systems with the potential for enhancement to provide comprehensive trunk communications at considerably less cost and effort. These are the electrical grid and railway net- works which have established routes and carry their electrical power or signalling circuits, for the most part, via poles or These systems naturally serve the major centres of population and industry, and embrace the secondary ones. Communi- cations planners have, no doubt, con- sidered for some time the possibility of using metallic cables on the electric pylons across the countryside, but the strong electromagnetic fields associated with high voltages have precluded their effective use as communications car- When, in recent years, the development of lasers and fibre optic cables provided communication by light circuits unaf- fected by magnetic fields, a reappraisal of routeing them together with electrical distribution became inevitable. However, the design of a self-supporting cable suitable for long spans and capable of withstanding a wide range of climatic conditions presented problems. by Bill Presdee, BSc, CEng, MIEE The first method to meet these re- quirements sought to use the electrical conductors as a bearer for the fibre optic communications. A composite cable was developed where the earth wire con- tained a core of fibre optics and, later, another type in which they were wrapped around the conductor. But the dependence of the communi- cations on the electrics was a hindrance. To maintain the fibre optics, an electrical circuit had to be de-energized and to rcstring electrical conductors, the com- munications link had to be broken. These restrictions led Standard Tele- phone and Cables (STC) to develop Fibrespan as a self-supporting aerial fibre optic cable which could be strung between pylons, operated and main- tained quite independently of electrical conductors and without interruption of electrical supplies. It has since been sub- jected to exhaustive tests at the Central Electricity Generating Board’s labora- tories at Leatherhead. Its appearance on the market has been followed recently by the announcement of Translite as a fibre optic aerial cable of generally similar capability. This is manufactured by Telephone Cables Ltd (TCL) a subsidiary of the General Elec- tric Company — which has undergone tests with England's East Midland Elec- tricity Board. Fibrespan and Translite cable features The cable design is based on a single rod of glass reinforced plastic (GRP) with a tensile strength of 65 kN, which is three times the design maximum for operation of 22.5 kN. The GRP rod has a longi- tudinal slot in which ribbons containing up to 24 fibres are laid in a thixotropic gel to cushion them against distortion of the rod through strains and stresses. The slot is covered by a polythene slot cap which restores the circular profile and the whole is covered by a binder yarn and outer sheath. The single mode fibres used in the cable operate at 1300 nm with 0.5 dB/km attenuation or better and a pulse dis- persion factor of not more than 3.5 ps/nm/km. The cable with an outer diameter of 13mm weights 220 kg/km and has an operating temperature of -40°C to 70°C. TCL offers two types of Translite cable self-supported by GRP rod: a 250 kg/km long span circular section cable, of 15.7 mm external diameter for installation on towers with spans up to 1000 m, and a 240 kg/km short span fig- ure of eight cable of 12 mm x 22 mm, suitable for mounting on pole routes with spans up to 100 m. The long span type has a working tension of 25 kN, while that for the short span cable is 5 kN. In the long span type, up to 24 optical fibres are carried in polymer tubes laid up with symmetrically disposed load bearing GRP rods, while for the short span a single GRP rod supports the op- tical fibres in their tubes. Attenuation of less than 0.5 dB/km at 1J00 nm and dispersion of less than 6 ps/nm/km arc quoted for single mode optical fibres. The standard drum lenght for both Fibrespan and Tfanslitc is 2 km but 4 km drums can be provided. The maxi- mum span for Fibrespan cable on nor- mal pylons in temperate climates would be 550 m, assuming the worst climatic condition to be 12.5 mm of radial ice and concurrent 88 km/h winds, although this could be extended to 720 m for a river or canyon crossing. In tropical climates with no ice hazard but a maximum anticipated wind speed of 135 km/h, a normal span would be up to 800 m, extending to 1000 m for a river or canyon crossing. The location of the optical cable on the suspension towers is of course critical. It must en- sure adequate ground clearance at mid- span while avoiding any clash with the electrical conductors under worst weather conditions. Arc fusion welding A low cable site is preferred, centrally on the lower near the level of the bottom cross arm, or for asymmetric cross arms half way between the two bottom pfase conductors. This enables installation to be carried out under live grid conditions while allowing a minimum ground clear- ance of 5.6 m. A method of tension stringing appro- priate to the new cable has been devel- oped by STC and provides rapid instal- lation with minimum interference to crops and activities on the ground. A full kit of installation devices including terminal clamps, suspension clamps, vi- bration dampers and joint housings, is available. The fibres are jointed on the ground using arc fusion welding and this is fol- lowed by a test of each joint by an op- tical time domain reflectometer, which provides a visual display of the optical attenuation through the splice. In a cable section of, say, 40 km, about 15 cable joint housings would be needed. The fre- quency of optical repeater stations would depend on the length of the trunk route and the type of optical line system employed. For a 565 Mbit/s single mode system, for instance, the spacing of stations could be up to 50 km apart. With the relentless increase in the bit rate for optical line systems it would be inap- propriate to designate a particular system for use with Fibrespan or Translite cable. The choice of system would depend, apart from the project budget, on current and projected traffic well into the future, especially as the life expectancy of the cable is over 25 years. One STC 565 Mbit system operating over two single mode fibres has the capacity of 7,680 telephone circuits each of 64 kbits (or a combination of telephone, television, and sound programme chan- nels, or data up to 546,992 kbits). With Fibrespan and Translite offering up to 24 single mode fibres per cable, the poten- tial traffic adds up to a considerable number of kbits along the pylons. COMPUTER AND TELECOMMUNICATIONS REVOLUTION WILL BRING ITS LEGAL PROBLEMS By John McQueen Since the early 1970’s the development of computer and telecommunications technology has been taking place at a breathtaking rate. A world-wide revol- ution has taken place in the transmission of data within countries and between them. In particular financial institutions of every type and variety have taken hold of the new developments in a very big way. It would be no exaggeration to say that the world banking system is now totally dependent on the new technology in order to go about its business. And the banking systems within most countries in the Western World are equally dependent upon the new tech- nology. These changes have taken place almost overnight against a background of deregulation for financial dealings generally. Foreign financial transactions which used to be very strictly governed now have very few restrictions. And the recent ’’Big Bang” has brought about large scale deregulation of all types of financial transactions within the UK. We are now in a position where massive flows of money are being transmitted around the world and within countries without any kind of restrictions — a situation that would have been regarded as irresponsible just a decade ago. The problems are already beginning to show through. Many experts have blamed the recent world-wide crash of the stock markets on unrestricted inter- national transactions completed through the push button electronic communi- cations network that now links all the world’s stock markets. If these argu- ments are true then the unrestricted use of communications systems can be said to have precipitated a world-wide crisis. There are those who would argue that the cause of the collapse was due to fac- tors other than instantaneous computer dealings — even so it cannot be denied that these dealings were an important factor in what happened. But whatever the truth behind the stock market collapse there can be little argu- ment that there are major risks involved in the application of computer and tele- communications technology in the financial field. The amount of money being transmitted around the world and within countries can be measured in billions of pounds a day. The figures and the risks involved are frightening. The financial field is the biggest and most obvious example of the impact of the new technology. But masses of other information is also being transmitted. Interpol, for example, now have a huge capacity to exchange information about criminals and suspects. Multi-National companies also have their own networks to transmit masses of commercial infor- mation. And many government departments are becoming rapidly computerised. In the UK, Customs and Excise already have a sophisticated set up. The Inland Revenue are currently honing up a huge computer network that will eventually churn out tax forms and demands automatically. Yet against this background of incredible rapid development there is virtually no international law in place to deal with the problems that may, and which must one day arise. What, for example, is the legal position if a deal involving many millions of pounds goes wrong between two financial institutions in different countries? How would any agreement be sorted out if the deal has been set up by the transmission of electronic messages? How would the problem be sorted out? More importantly, which country would have jurisdiction to sort the matter out? The answers at the moment are that there arc no answers. If some gigantic financial accident happens then there are no international laws in force that can bring about a solution. And, if as usually happens in the nature of things, a series of accidents occurs then chaos on the financial markets could result. These big nightmares are real enough, yet on the national front there are many domestic issues to cause concern. The transmission and storage of electronic data within the UK is now of gigantic proportions. Yet the laws that regulates this field are only in their infancy. The relevant Acts in the UK are the Data Protection Act 1984 and the Telecom- munications Act 1984. Both are rela- tively new Acts with the former barely implemented so most of the provisions remain untested in the courts. The Telecommunications Act concerns itself more with the considerable techni- cal and legal problems that face the in- dustry in the day to day business of run- ning a communication system estab- ' lishing rights of access and so on to land and equipment. A complex Act, it deals with the nitty gritty of everyday prac- ticalities. But it does not really address itself to the important issues of the regulation of the transmission of huge amounts of infor- mation. It is left to the Data Protection Act to provide the necessary protections in this regard. There are several main elements to the Data Protection Act. It contains the pro- vision that anyone holding personal data on a computer must register their precise uses of their equipment with the new Data Protection Registrar, Eric Hove. Failure to register can bring about unlimited fines on those involved. Few people still realise that the provision applies to every computer user however limited their use of computers for per- sonal data storage might be. Some companies have still not registered and they face severe penalties if they are caught. Most companies have, however, now registered for every possible type of use from a list of options to be on the safe side. And though discussion surrounding the Data Protection Act has largely centred on the question of privacy because of the sensitive implications, it is important to point out that the Act is also intended to ensure the physical security of infor- mation from possible destruction from fire, flood and terrorism. In general terms there is a right of access to information held on a computer about any individual person who has a right to be supplied by any data user with a copy of any information held on that individual, so long as that request is made in writing. If the information held is shown to be incorrect then compensation can be claimed as a result of any distress or damage caused by the holding of inac- curate information. However, it will be a defence for the data user to show they had taken all reasonable steps to store in- formation they believed to be accurate. However, a large section of the Act gives itself over to exceptions. Most important government departments are excluded from the requirements to provide infor- mation and there are a whole host of other exceptions which are already giv- ing rise to some considerable confusion about just what sort of information is covered by the Act. It is clear however that only a limited amount of infor- mation can be obtained. The UK has been very slow to legislate in this field and the new Act has only come about because of a ruling by the EEC’s Coun- cil of Europe that such an Act must be brought into force in all Member countries. But at the very least the Data Protection Act, however limited its provisions, opened up the debate on the important subject of the issues involved in all this electronic transmission of information. Professional engineers and all those in- volved in the communications business arc going to have to give more thought to the practical problems involved in pro- viding for the proper security of sensitive equipment. Society generally is now be- ginning to wake up to the wider impli- cations of this amazing new technology, and it is important that those actively in- volved in work in this field are also aware of the wider ramifications to their work. The current electronic revolution has been equated in the scope of its impli- cations with the industrial revolution of the eighteenth and nineteenth centuries. That revolution brought with it huge social, economic and political changes that transformed the world. The real fear of the present electronic revolution is that it is proceeding at such an incredible pace that the social and legal structures are unable to keep up with it. And now that so many import- ant financial and other institutions are so dependent on the new technology it may prove impossible to regulate and control its growth. Certainly there is a general feeling about that some terrible disaster will occur in this field. Otherwise it is impossible to square the fact that the Data Protection Act only applies to data stored on elec- tronic files and does not apply to manual files. It seems odd in logic that such a distinction should be made. But it is also an indicator of the very real fears beginning to open up in the minds of people about the uses that may be put to the transmission of all this information and of all the possible damages. During December 1985 a congressional sub-committee in the United Stales learned that computer problems of the Bank of New York led to it accumulating an overdraft of 20 billion dollars in the course of a day. Without the interven- tion of The Federal Reserve there could have been disastrous implications for the whole domestic and international finan- cial system. Incidents like this not unnaturally make people worry about the dangers involved in computerising virtually all important information in government and society generally. Certainly this whole area is a fertile legal field that is bound to see major developments in the future. PRESCALER FOR MULTI- FUNCTION FREQUENCY METER An add-on board that extends the usable frequency range of the instrument introduced 2 months ago from 10 MHz to well over 1.2 GHz. The prescaler described here is intended as an optional extension of the multi- function frequency meter introduced in reference There are various ways of adding a prescaler to an existing frequency meter. The simplest of these is based on the assumption that the instrument is mainly intended for measuring relatively low frequencies, indicated on a kilohertz (kHz) scale. Fitting a prescaler with a divisor of 1,000 to the input of such a frequency meter effectively changes the kHz scale into a MHz scale, obviating the need for changing the position of the decimal point. The main disadvantage of the above method is the reduction by 1,000 of the meter’s resolution. A better approach entails increasing the gate time of the counter by a factor 1,000. This results in more count pulses fed to the counter circuits, and hence re- tains the formerly available resolution. The gate time of a frequency meter is de- termined primarily by the output fre- quency of the central clock oscillator, which is quartz-controlled in most cases. The oscillator frequency is scaled down internally to obtain the required gate time. Inserting, for instance, a binary scaler between the clock output and the internal divider cascade results in a doubling of the gate time, so that the measured signal must be passed through a -r2 divider also. These applications are often thought to be restricted to the use of decade scalers, while in practice any other divisor works equally well. Block diagram The present prescalcr was designed for ready connection to the multi-function frequency meter without compromising its usability in other, similar, instru- ments. With reference to the block diagram of Fig. 1, electronic switches ES5, ES<. and ES’ select between 10 MHz, 2.5 MHz and 78.125 kHz at point e. The switches are controlled by signal detectors on the input channels. The existing 10 MHz in- put on the multi-function frequency meter is retained along with the 2 prescaler inputs, so that the complete in- strument has 3 frequency ranges in all. A separate 10. . .40 MHz input is used in view of the reduced sensitivity of the -^64 prescaler in this frequency range. The sensitivity of the -f64 prescaler is highest at around 250 MHz. The use of the 10. .40 MHz input is also advan- tageous because it enables the use of relatively short gate periods. With the greatest divisor, 128, the available gate periods are in the range from 0.14 to 140 s. Detector controlled switches ESi and ES 2 arrange the cor- rect selection or disconnection of prcscalcr outputs on the 10 MHz input of the main frequency meter. ESj func- tions as an inverter, while ESs takes care of the ’’mode” settings, and the shifting of the decimal point. The switch configurations for the 3 fre- quency ranges of the meter are as follows: ,±~& - 0 — 0-4 .± 040 — Fig. 1. Block diagram of the 1.2 GHz prescaler. Preparing for the extension A few simple modifications are required on the main frequency meter board before the prescaler extension can be used. With reference to Fig. 2, power for the prescaler is available from terminals + and _L at the output of the regulated 5 V supply on the frequency meter board. The AC coupled input of channel A on the frequency meter, point f, accepts the prescaler output signal. The divided or undivided clock signal from the pre- scaler board is connected to the extxjsc input of IC.i (point e). Points x and y are connected by a wire link as shown. Configuration switch S’ is replaced by a wire link. Remove St and Ss, since their functions are taken over by ESs on the prescaler board. Connect the anodes of Dt and D» to create point d. Point c in the presealer circuit is connected to junc- tion R9-AD7. The 10 MHz crystal may be removed for rc-use in the oscillator on the prescaler board. Figure 3 shows the locations of the various points and con- nections on the frequency meter board. Circuit description of the prescaler The main functional blocks in the prescaler discussed under Block diagram arc readily found back in the circuit diagram of Fig. 4. Crystal oscillator and buffer Ti-Tj ensures the required stab- ility of the 10 MHz digital signal applied to counter ICi and electronic switch ESs. Binary ripple outputs Q2 (-r2 ! =4) and Q7 (-r-2 7 = 128) of ICi carry the 2.5 MHz and 78.125 kHz clock signal, respectively. Fig. 3. Location of links and terminals to be fitted on the main frequency 1988 3.43 Signals applied to the 10. . .40 MHz in- put are amplified in fast opamp IC2, and divided by 4 in bistables FFi (-r2) and FF2 <-r2). Preset Pi enables accurate setting of the bistable’s switching threshold to 2.5 V . The rectifier (signal detector) for controlling the electronic switches as discussed is formed by diodes D.i, D4 and Dt, together with R- C combination R9-C12. Signals in the frequency range of 40... 1250 MHz are applied direct to -i-64 prescaler ICj, a Type U664B from AEG-Telefunken. Bistable FFi divides by 2, so that the total divisor on this channel is 128. The function of the recti- fier and the threshold preset is similar to that of the corresponding circuits in the 10. . .40 MHz channel. The dashed lines in the circuit diagram denote metal screens fitted to prevent stray radiation and erroneous meter readings caused by digital interference. Construction of the prescaler The first components to be fitted on the prescaler board arc Icadlcss ceramic capacitors Cu and Cm. Both disc and rectangular versions may be used in these positions. Cut the required slots in the PCB, push-fit the capacitors, and carefully solder the pretinned sides to the relevant copper areas. Solder fast and accurately: leadless ceramic capacitors are relatively brittle compo- nents. The next somewhat unusual part is presealer ICj. Use precision pliers to carefully bend the 8 pins of this IC over 180°, and mount the chip at the track side of the board, observing the orien- tation indicated on the component over- Fig. 4. Circuit diagram of Ihe 1.2 GHz presealer for the Elektnr Electronics multi-function frequency meter. The dashed lines denote metal lay. If bending the pins is considered risky, ii is also possible to mount the 1C at the component side of the PCB, pro- vided a suitable clearance is cut. What- ever mounting method is adopted, the connections to the prescaler pins should be as short as possible. The fitting of the remaining components on the presealer board is straightfor- ward. It is recommended to use sockets for the 6 ICs. The screens at the compo- nent side of the PCB arc made of 15 mm high brass or tin metal sheet, bent to shape and secured with the aid of soldering pins— see Fig. 6. The screen- ing of the VHF/UHF prescaler is ’’con- tinued” at the track side of the PCB as shown in Fig. 7. The connections be- tween the BNC sockets and the prescaler inputs are made in thin (03 mm) coaxial cable, c.g. Type RG174/U. Keep the con- nection of the centre cores to the prescaler inputs as short as possible. The shielding braid of the 40. . . 1250 MHz input cable is soldered direct to the screening plate at the track side. Use copper foil to shield the connections of the BNC sockets to the coax cables. It is recommended to make the connections between the prescaler and the main fre- quency meter board in coaxial cable, with the exception of the supply wires. The completed prescaler board is fitted vertically behind the main frequency meter board as shown in the introduc- tory photograph of this article. Finally, make sure that the mains adap- tor can handle the additional current drain of the prescaler board. Fig. 5. Track layout and component mounting plan for the prescaler PCB. READ THE TEXT BEFORE FITTING 1C., Cu AND Cu. elektor India march 1988 3.45 Setting up The setting up of the extended frequency meter is fairly simple if a signal source of 10... 40 MHz and 40... 1250 MHz is available. To begin with, set the clock os- cillator to 10.000 MHz precisely with the aid of a second, calibrated, frequency meter. Apply a test signal at a frequency higher than 40 MHz to prescaler input A, and reduce the generator output until the read-out becomes unstable. Adjust P2 to restore the correct read-out, reduce the input signal, rc-adjust P2, and so on, until the optimum threshold setting is achieved. The sensitivity of the prescaler’s B input is set likewise. A carefully aligned prototype of the fre- quency meter achieved a sensitivity of about 400 mV™. at 1190 MHz. B Reference: 111 Multi-function frequency meter. Elektor India, January 1988. Fig. 7. Close-up photograph showing the screen around the VHF/IJHF input at the track side of the board. percolator switch Most of the timer ICs which are commonly available provide only relatively short timing intervals. If longer delays, of say, from several minutes up to a few hours, are required then one is faced with something of a problem. The following circuit, which can be used in any number of possible applications (e.g. as a time switch for cookers, heaters, alarms, house lighting, etc.), permits delay times of up to approximately four hours. The circuit was originally designed to automatically switch off a coffee perco- lator after a certain time, and as such has been functioning satisfactorily for quite a while here at the Elektor offices. The operating principle is simple: After pressing the start button (SI), capacitor C2 is charged up to almost the full supply voltage, and the non- inverting input (pin 3) of IC1 is taken positive of the inverting input (pin 2), the latter being held low via the voltage divider R2/PI/R3. The output of 1C 1 therefore turns on Tl. which in turn triggers triac Tril. LED D3 will light up to indicate that the device in question (Rl) is switched on. As soon as the button SI is released, C2 begins to discharge via the non-inverting input of IC1. After a certain interval, the length of which is determined by the value of C2 and R6 as well as the position of PI, the voltage across C2 will drop to below that at the inverting input (this being set by PI). The output of IC1 therefore drops to almost zero, turning off both Tl and Tril, and the LED is extinguished, thereby indicating that the load device has been switched off. If one wishes to switch off the device earlier than was originally intended, this can be done simply by pressing the stop button S2, which causes C2 to be dis- charged rapidly via R4. Since C2 cannot have too high a value (it must be a low-leakage capacitor and therefore not an electrolytic), very long timing intervals can only be achieved by giving R6 an extremely high value. Although this is not a major problem, it is slightly inconvenient, since such high value resistors cannot be obtained individually and one is forced to use a number of smaller resistors connected With the value of C2 as given in the cir- cuit diagram ( 2 ^ 2 ), the maximum poss- ible value for R6 is 40 M. This gives a maximum timing interval (which is set by PI) of 4 hours. It should be men- tioned that the exact delay time will depend upon the tolerances of some of the components. If very long times are in fact required, it may be necessary to choose a slightly higher value for C2. Times of up to 1 hour are possible when 3.46 component values shown in the circuit diagram are used. The printed circuit board is designed to accomodate a CA 3094 in a mini-DIP package (a TO- version could also be used), whilst either a bridge rectifier or four discrete diodes may be used for B I . The skull and crossbones beside the cir- cuit diagram should be a clear enough indication that the circuit operates at dangerously high voltages, and there- fore great care should be taken during construction. The circuit should be mounted in a fully insulating (plastic) case. If however a metal enclosure is used, then it should be connected to mains earth via a three core cable, and the circuit itself insulated from the box. To further eliminate the possibility of electric shock, the pushbutton switches should be of a good quality type, suit- able for mains use. Selecting a triac The selection of the triac will depend on the intended application. To avoid exceeding the PIV rating (peak inverse voltage) of the triac, a 400 V unit should be used. The current rating will depend upon the load which is to be switched. For loads such as lamps and heating elements, the switch-on ‘surge current' is usually quite a bit larger than the steady operating current. Therefore, if a 2 A device is being switched, it is advisable to tise a 100% (or more) over-rated triac (4 A). In this connection, it is interesting to note that there is often very little difference in price between triac's with a low current rating and those with a high rating. For this reason, it is wise to purchase one with a large current rating, say 8 or 10 A, and not have to worry about accidently ‘blowing up’ an under-rated slightly cheaper triac. M 1988 3.47 TEST & MEASURING EQUIPMENT The 3rd part of Julian Nolan’s review of dual trace oscilloscopes looks at the Philips PM3050 and the Kenwood CS1045 instruments. Philips PM 3050 The Philips PM3050 is one of a range of high grade oscilloscopes ranging from the 15 MHz PM3206 at £320 to. for example, the new range of 400 MHz scopes. Other instruments manufactured bij Philips include logic analyzers, mul- timeters, pulse generators, chart re- corders and a comprehensive range of waveform analysers. Philips has a long standing reputation for the reliability of its instruments. The PM3050, which was launched in 1986, is no exception to this, selling in its first year to a wide range of both universities and companies such as GEC. The modern styling and unconventional appearance of the PM3055 are brought about mainly by its use of a LCD panel and the use of ’softkeys’ for the set- ting of most of the operating par- ameters. An Autoset key is also pro- vided, allowing automatic setting of am- plitude, timebase and triggering func- tions. These characteristics are com- bined with a Y-amplifier bandwidth of 50 MHz (-3dB), a 16 kV tube and a IEEE option for £845 (3055) or £795 for the single timebase PM3050. Auloset and ‘softkey’ functions These two features distinguish the PM3050 from other 50 MHz scopes and are unique in its price range, being aimed at providing ease of operation along with increased reliability. The ’softkeys’ consist of a group of 21 keys, which con- trol all oscilloscope functions with the exception of those which need to be con- tinuously variable such as the trace pos- ition, triggering level and hold off con- trols. The state of these, some of which combine up to 5 functions, is continu- ously displayed on the LCD panel along with the range settings of the three up/down switches, controlling timebase and Y-amplifier coefficients. The ‘soft- keys’ replace all the usual rotary or slider switches which are to be found on com- parable scopes. On the whole, I found that operation in term of time taken was 3.48 elektor India march 1988 Part I: dual-trace oscilloscopes (C) t ig. 13. The Philips PM3050 oscilloscope on a par with that taken in more conven- tional scopes. In some cases, however, such as when changing the triggering (or X, when in X-Y mode) source, the time taken to, for example, change from trig- gering on CH B to CH A can be con- siderably longer than on most conven- tional scopes. This is largely because CH B is one of five different triggering source options available, so that to change back to triggering on the A chan- nel a total of 3 key presses are required. The LCD provides a clear alphanumeric readout of all settings and is also back- lit for operation in low ambient lighting conditions. This is particularly advan- tageous for timebase, delayed sweep and Y-amplifier readouts, providing a very clear and unambiguous display. Its rel- evance is increased for the timebase sweep time when in the xlO deflection magnification mode, showing the actual sweep time (down to 5ns/div) instead of the user having to manually multiply the sweep speed by 10, thereby eliminating any possible scaling error. An asterisk is also shown on the LCD when in xlO mode. Unfortunately, a non-volatile memory is not used to store the front panel settings and as consequence they are reset to their default value should the instrument be turned off. This is lV/div for the vertical deflection coefficient and lms/div for the timebase. Although there can be little doubt that the ‘soft- key’ system is easier to use and less am- biguous in most cases than its analogue counterpart, this cannot be said of the speed of operation for the up/down range keys, which can be significantly Fig. 14. Internal construction of the PM3050 15 h Fig. 15. Front view of the PM3050 with the trace and LCD shown enlarged slower, especially on the deflection coef- In addition to this, the microcontroller ficient settings when in manual mode, also incorporates other functions, in- For example, to change from a timebase eluding a menu facility in which the speed of 0.5 s/div to 50 ns/div takes ap- functions of any one of the 'softkeys’ proximately 5 seconds using softkeys, can be displayed in a step-through func- while speeds of typically under 1 second tion sequence, without affecting any of can be obtained with a standard rotary the operating parameters that have been control. In practice, this may not be so previously set. A test routine is also pro- noticeable as it is unlikely that such large vided, which provides a 6 step visual test changes in the deflection coefficients of Y amplifier, triggering and timebase will be required, but the time required functions, may still be longer than that in its rotary counterpart. v The use of a single chip microcontroller * 'amplifiers enables not only ‘softkey’ control, but The maximum bandwidth of 50 MHz also a full Autoset facility. This function (-3dB) is only usable at sensitivities is increasingly being introduced into a above 20 mV/div; below these a maxi- range of oscilloscopes, although at pres- mum bandwidth of 35 MHz can be ob- ent the Philips PM3050 and 3055 arc the served. This lack of sensitivity at higher only units to incorporate it in their class, frequencies is rather disappointing for i.e. 50 MHz and under £1000. The Auto- an oscilloscope in its range: some of its test function allows the automatic set- direct competitors maintain the full ting of both Y-amplifiers, timebases and 50 MHz bandwidth down to 5 mV/div, the triggering source. The total time re- although admittedly they- do not have quired for one ‘setting’ is approximately the advanced level of control of the 3 seconds, so continuous assessment and PM3050, nor several of its other setting of the required and necessary facilities. Deflection coefficients range parameters is not possible. Obviously, all from 2 mV to 10 V per division, the ver- continuously variable controls, includ- nier control decreasing the minimum ing trigger holdoff remain unaffected. sensitivity to 25 V/div. Uncalibrated op- 1988 3.49 Delav Timebase Multiplier Resolution 1:10.000 Error limit total 4%(* 10 magn.l Delay time litter 1: >20, 000 Triggering IDTB1 Starts. A, B, Composite (A. B). Ext IDC or AC), TVL Other oscilloscopes available at under El 500 Rack mounted versions of PM3050 and PM 3055. at £995. VAT and El 045. VAT PM32060ual channel 15MH2 bandwidth. 2 100 ns/dtv to 200 ms/dlv: £*350 * VAT PM32 17-50 MHz dual trace, 2 mV sensitivity to full 50 MHz I - 3dB), dual timebase and delayed sweep, automatic p-p triggering, trigger holdoff. 10 kV CRT: El 325. VAT Table 9. Specification cration is indicated by a flashing *>’ sign on the LCD. Provision is also made for automatic x 10 probe sensing when used with the recommended PM8936/09 xl/xlO switchable probes which come at £95+VAT per pair. This enables the scaling on the LCD to be automatically divided by 10, minimizing any possible reading errors. Both Y-ampiifiers per- formed reasonably well for a scope in this price range, possessing a dynamic range covering the full vertical deflection capability of 8 cm at 50 MHz. Both the risetime and base line jump were also within the specified limits at 7 ns (down to 20 mV/div) and 1 small division (vari- able) respectively. Overshoot, ringing and rounding were restricted to approxi- mately 1.4 small divisions p-p for an in- put pulse of amplitude 5 divisions centred around the screen centre. One slightly odd cause of trace shift is the graticule illumination control, which has the effect of causing approximately 1/3 small division shift if the graticule il- lumination is varied from zero to maxi- mum. In Autoset mode, vertical deflec- tion coefficient selection is usually ac- curate, typically being set for a deflec- tion of 4 cm. One inconvenient but in- evitable result of this is the need to set the input coupling to AC, as obviously only the user can decide whether it is necessary to view any DC offset which may be present. The ‘softkeys' con- trolling the Y-amplifiers are neatly and logically grouped together opposite the appropriate section of the LCD, and in- clude the usual alternate/chopped, add/ invert functions. In common with some other scopes in this price range, only CH B can be inverted, which, although not restricting the range of possible algebraic functions, could entail the swapping of the CH A and CH B input leads. 3.50 elektor india march 1988 Table 10. Performance summary Triggering The PM3050 is equipped with a wide range of triggering features which in- clude peak to peak and composite, or alternate sourcing facilities. The trigger- ing functions are, like the Y-amplifiers and timebase, under the control of the microcontroller when in Autoset mode. Perhaps not surprisingly, no great benefit appears to have come of this, however, as far as the automatic setting of the trigger coupling, mode and slope is concerned. These settings are largely user-dependent and inevitably set to their default values of p-p, auto and rising edge respectively when the Autoset key is pressed. The Autoset function has an effect on the triggering source in selecting either CH A or CH B, but not on the external input which might have been useful. The LCD gives an indi- cation of whether the scope is triggered or armed in single shot mode. All other triggering functions, such as triggering slope, trigger coupling and mode are also displayed. When both Y-amplifiers are grounded, an automatic bright line is displayed irrespective of the operating mode in which the scope is set, i.e. single shot, triggered or auto. Triggering per- formance was good; signals of over 100 MHz were displayed stably, while the delayed holdoff control was effective against most complex pulse trains. When in peak to peak mode, the level control thresholds are automatically set for the peak values of the waveform, enabling both the triggering stability of a normal p-p automatic triggering circuit and ver- satility of the more usual auto mode to be combined. One noticeable absence from the facilities available is that of HF and LF filtering. Timebase The timebase can also be set automati- cally by the Autosct control, with speeds ranging from 0.5 s to 50 ns, providing a total of 22 ranges. A clear indication of the speed is provided by the LCD, which also takes into account the x 10 increases in deflection speed which is brought about if the xlO magnifier is operated. In Autoset mode, typically three cycles of the waveform are displayed where possible. The minimum timebase speed automatically set in this mode appears to be 20 ms/div. Sweep speed accuracy was well within the specified 39/0, or 4170 with the xlO magnifier in operation. Linearity is also good. X-Y operation benefits from a versatile range of available sources: CH A, CH B and external, all of which can be in- dependently selected and displayed in any combination. CRT The PM3050 is equipped with a 16 kV CRT which enables it to give a good level of brightness even at its maximum deflection speed of 5 ns/div. The high level of intensity also allows easily definable traces to be obtained at the same deflection speeds in bright of am- bient light. The focusing could have been slightly sharper, although it is per- fectly acceptable, especially at higher intensity levels. A small amount of defocusing occurs if the intensity is altered by a large coefficient, necessitating an adjustment in the focus- ing potential. Tube geometry was par- ticularly good with the minimum of bar- relling and pincushioning over the whole of its area. Overall, the CRT’s perform- ance was very good for a scope in the ’under £1000’ price bracket, especially in the brightness sector of its performance characteristics. A graticule illumination facility is also provided, although due to its very low level of illumination it is only really effective in correspondingly low levels of ambient lighting, or for photographic uses. Construction The construction is perhaps the most revolutionary part of the PM3050: it is completely and drastically different from the more conventional oscillo- scopes, which up to the PM3050's launch dominated the 50 MHz market. A one-piece moulded plastic chassis is the basis of the PM3050, housing all components, including the CRT and PCBs. This appears to be reasonably rugged, and in use should be as robust as the more usually encountered alu- minium. Two of the oscilloscope’s total of four screws are used to keep the two steel covers in place, which are free of ventilation slots. The PCBs, CRT and other components are secured by a system of customized plastic clips and slots. This system of snap in components enables quick servicing, while appar- ently not affecting the robustness of the instrument. The CRT and Y-amplifier shielding are practically the only pieces of metal in the scope; the extensive use of plastic mouldings keeps the number of mechanical components to an absol- ute minimum and should increase MTBF. The instrument itself is constructed around 7 PCBs, all of which are double sided, enabling a clear an uncluttered layout. The microcontroller, an 8052, and associated circuitry are mounted directly onto the front panel PCB, which also houses the ‘softkey’ switches, all of which are independently mounted and fig. 16. The Kenwood CS-1045 should further help reliability. Obvi- ously, many of the ICs are custom de- signed, making the return to Philips of a faulty board essential. For this reason, none of the boards is silk screened. The PM3050 has been designed, however, with ease of servicing very much in mind: each PCB is easily accessible for the minimum of down time. A switch mode power supply is also a feature of the PM3050, resulting in a weight of only 7.5 kg and enabling a non-switched line voltage range of 100 to 240 VAC at 50 to 400 Hz to be specified. Short IDC terminated ribbon cables provide the vast majority of internal connections, further improving the ease of servicing. Typical assembly time of the PM3050 is 20 minutes compared to 10 hours for a conventional scope. Interface facilities The PM3050 is unique in its price range in that an IEEE interface is available as an optional extra. This is external to the scope, and is fitted by means of the 9-pin ’D’ type connector provided at the rear of the scope. The external nature of the interface, which is priced at £349 +VAT allows it to be used with a large number of other instruments where required, at a great saving in cost. The IEEE inter- face is capable of controlling all scope functions remotely, with the exception of the potentiometer settings. This makes its use valid for a wide range of appli- cations, such as ATE and production line QC environments. Other interfaces available include front panel memory backup, the PM 8998 at £54+VAT. A number of output options such as Y-amplifier signal out are also available. Manual The manual contains information on setting the scope up, performance characteristics and preventative mainten- ance. All of these are covered in some depth, but areas such as applications arc not included, which, given the sector of the market the scope is aimed at, may not be surprising. A service manual con- taining circuit diagrams etc is available free of charge upon request. Conclusion The Philips PM3050 represents a radical new approach to the design of an oscillo- scope in its class. Only time will tell whether or not this new approach will increase the reliability of the instrument, but on the face of it, one must expect it to. Ease of use is greatly simplified by the use of ‘softkeys’ and the LCD, but this may be limiting so far as the speed of operation is concerned, which is worth bearing in mind if large range changes have to be made in situations where it would be innappropriate to use the Autoset function. This in itself can help to save a great deal of time com- pared to a conventional analogue os- cilloscope, although it rarely sets the ideal setting in terms of input and trigger coupling. Despite this, it should still be of a value, even if in some situations it is restricted to an intelligent beam finder. As a 50 MHz oscilloscope, the PM3050 performs well, the high brightness tube being of particular benefit at higher fre- quencies. The PM3050 should fit a large range of applications, from ATE to educational environments and this has been proved by the fact that its users so far range from building societies to calibration laboratories. Its particular strengths lie in its ease of use, price/performance ratio and construction characteristics. It does have one or two minor failings, such as its 20 mV maximum sensitivity at the full 50 MHz (-3dB) bandwidth, but on the whole its performance equates with what can be expected from a 50 MHz scope in its class. If the ease of use and additional features, including Autoset, are then added to this, together with the IEEE capability, the instrument becomes a good choice, whether its in- elektor India ™,ch ,988 3.51 tended use is for the latest 007 film (the PM3050 was used in ‘The Living Day- lights’), or a servicing application. PM3055 The PM3055 incorporates a dual timebase and delayed sweep facilities, as well as trigger view. Both timebascs have independent trigger level controls. The 16 kV tube allows high levels of magnifi- cation while maintaining a reasonable trace intensity. Highly accurate setting of the delay time multiplier is possible because of the incorporation of the LCD. Overall, the PM3055’s additional features should be well worth the extra £50 for most users. The Philips PM3050 was supplied by Pye Unicam Ltd, York Street, Cam- bridge. CBI 2PX. Telephone (0223) 358866. Konwootl CS-1045 Trio, or Kenwood as it is now called, is a long-established Japanese company renowned for its products in the elec- tronics sector, particularly communi- cation receivers and oscilloscopes. The Kenwood CS-1045 is one of a new series of oscilloscopes, ranging in price from a competitive £319 (20 MHz) to £1695 for the top-of-lhe-rangc 150 MHz scope. The CS-1045 is a 40 MHz, 3-trace, delayed-sweep, dual-timebase oscillo- scope retailing at £695+ VAT. Two high- quality xl/xlO switchable probes are supplied with the CS-1045, as well as a set of spare fuses, covering the different line voltage options that are available on the instrument. The CS-1045 is a relatively small unit, measuring 319 mm (W) x 132 mm (H) x 380 mm (D), although what it loses in size is made up in weight, which is 9.2 kg. A robust multiposition stand is fitted, which also has the appropriate fixing holes for an optional soft vinyl probe pouch. These two features should prove extremely useful if portability is re- quired. Mains connection is by a stan- dard IEC style socket; the line voltage is externally selectable from 100 VAC to 240 VAC. The CS-1045 has several features which, although uncommon even on ‘top-of- the-range’ units a few years ago, are becoming increasingly popular, es- pecially on medium-price oscilloscopes. In this case, they include 3 input chan- nels, comprehensive TV triggering on both timebases and trigger holdoff fa- cility. In common with several other ranges of oscilloscopes, a CH 1 output is provided along with the more standard Z-axis input, both of which are situated on the back panel. The mounting of these connections on the back panel is virtually common to all scopes, includ- ing the CS-1045. I feel that this is a pity 3.52 elettor indie march 1988 ELECTRICAL CHARACTERISTICS Line voltage; 100. 120. 220. 240 VAC ±10%, externally adjustable. Power 61 Watts. Line frequency: 50-60 Hz SWEEP Type: A; A Sweep; Alt; A sweep (intensified for duration of B sweep) and B sweep (delayed sweep) alternating: B; delayed MECHANICAL CONSTRUCTION Dimensions: W 319 mm. H 132 mm. D 380 mm Housing; steel sheet Weight approx. 9.2 kg Y AMPLIFIER ETC. Operating modes: CH 1 alone or CH 2 alone Inversion capability on CH 2 only. Dual: CH 1 and CH 2 (alternate or chopped (250 kHzl) Triple; CH 1. CH 2 and CH 3 (alternate or chopped) CH 1 + CH 2 Frequency response: 0 ... 40 MHz ( - 3 dB); 15 MHz 1 mV and 2 mV/div Risetime <8.8 ns. 123.4 ns 1 mV/div to 2 mV/div) Deflection factor 1 2 steps: 1 mV/div 5 V/div ±3%, vernier control adjusts min sensitivity on 5 V/div range to approx 17 V/div (fully cw)-CH 1 and 2 only. Input coupling: AC, DC or Gnd. Input impedance: 1 MQ/20 pF;msx input voltage 250 (DC + peak AC) Signal delay time: approx 20 ns on CRT CH 3 only specifications Sensitivity: 0.5 V/div ±3%; input impedance 1 MQ/20pF. Frequency response: 40 MHz; risetime 8.8 ns Max input: 50 VIDC + AC peak) X-Y MODE CH 1 Y-axis. CH 2 X-axis; X bandwidth DC to 1 MHz ( -3dB); X-Y phase difference <3° at 100 kHz A sweep time 0.1 s/div to 0.5 s/div, ±3% in 21 ranges. 1-2-5 sequence. Vernier control slows sweep down by up to 3: 1 ; B sweep 0.1 s/div to 50 ms/div, ±3% in 18 ranges. 1-2-5 sequence. Sweep magnification x 10 ±5% (±8% on 0.1 s/div to 0.2 s/div range) Hold off; variable upto 10:1 Delay modes: continuous delay. Trigger Delay (Trig), Trigger Delay (TV line), delay = zero Delay jitter: 1/20000 TRIGGERING Trigger modes: Auto (bright line). Normal. Fixed (automatic triggering), single-reset. Trigger coupling: AC, DC, HF reject. TV frame and line. Trigger sources: CH 1.CH 2. Line, Ext. or CH 3. Vertical (alternate) Triggering sensitivity: Internal <1 div at 40 MHz, External <0.5 Vp-p at 40 MHz, Normal mode MISCELLANEOUS CRT-make Trio-Kenwood, measuring area 80 x 100 mm, accelerating voltage 12 kV, Domed-mesh type. Compensation signal for divider probe, ampli- tude aprox. 1 Vp-p (±3%), frequency 1 kHz. Z modulation Sensitivity 5 V (complete blanking) Vertical CH 1 output approx 50 mV/div into 50 O: frequency response 1 00 Hz to 40 MHz except on 1 mV/div and 2 mV/div ranges (100 Hz to 15 MHz) Table 11. Specification Table 12. Performance summan since in some siluations these connectors become almost inaccessible. The CS-1045 has a comprehensive set of functions, as can be seen from Fig. 17. As already mentioned, the CS-1045 pos- sesses 3 input channels, 2 of which are variable, while the third is fixed at a con- venient 0.5 V/div. The two main chan- nels have a maximum sensitivity of 1 mV/div, which is, however, only usable to a bandwidth of maximum 15 MHz (— 3dB). A sensitivity of 5 mV/div can be sustained across the full 40 MHz ( — 3dB) bandwidth. Input impedance is 1MQ at 20pF and should be of con- siderable help in observing signals from very high impedance sources, especially if a x 10 probe is used. The performance of the Y-amps was good: the 1 mV/div and 2 mV/div ranges have a good re- sponse up to 25 MHz, while still main- taining a reasonable frequency depen- dent attenuation of just over -3dB. This kind of performance was repeated across the rest of the range: the attenu- ation at 40 MHz (5mV/div) was inside the quoted - 3dB range. The triggering range of the unit extends well beyond the 40 MHz Y-amplificr bandwidth, and it is possible to stably trigger the main timebase with signals approaching 100 MHz. Both Y-amps have a continu- ously variable control, which can in- crease the maximum deflection ampli- tude, from the calibrated 5 V/div to ap- proximately 15 V/div. To prevent any further cramping of the front panel layout, only one channel is invertable. The third channel’s usefulness is limited by its fixed deflection factor of 0.5 V/div, but this can be increased to 5 V/div by the use of a x 10 probe, mak- ing it useful for digital measurements. It can also be used, for example, as a marker channel for both digital and analogue applications, when the band- width extends to the full 40 MHz band- width ( — 3dB). The third channel's input impedance is matched to channels 1 and 2, so that swapping of xlO or X100 probes across all three channels causes the minimum of trace distortion. No provisions are made for an internal trig- ger view, which would have been helpful in some instances. On the review model, it was noticeable that the DC balance on both channels was slightly out, necessi- tating the need for a readjustment of the horizontal position of the Y amps on the most sensitive ranges. A trace shift of approximately 3-5 mm occurred during the warm-up period of about 10 min- utes, making accurate measurements within that period difficult. The third channel can only be displayed in the tri-trace mode and not in- dependently, but when the nature of channel is taken into account, this should hardly be important. In the tri- or dual-trace modes the channels can either be displayed in chopped (f=250 kHz) or alternate mode, although only CH 1 and CH 2 can be added or subtracted. The CS has a wide range of trigger func- tions, typical of an oscilloscope in its class. These include a fix mode, where the unit is automatically triggered from the centre of the waveform, and an alter- nate channel triggering mode (or vertical mode), Which is vital for stable display of non-synchronized waveforms. Other features include TV line triggering on the second timebase (B), enabling the A timebase to be triggered on the frame frequency, and perhaps displaying one frame, while the B timebase is triggering on line frequency, perhaps displaying one line of information. This section, shown on the A timebase sweep by a bright spot, is selected by the delay time multiplier. When the correct section, such as a single line, has been selected, the B timebase sweep can be displayed on its own, centred on the original A trace. Other features of the second timebase include the more common after-delay and zero-delay functions. Performance on the trigger side was on the whole good, triggering reliably on the vast majority of waveforms. The holdoff control contributed significantly to this, enabling irregular waveforms, which otherwise may have been a prob- lem, to be stably triggered. An HF reject trigger coupling facility is provided, but there is a notable absence of any such LF function. I found, however, that this did not seriously affect the unit’s triggering performance, as it is sometimes possible to compensate this function by very careful adjustment of the triggering threshold. There is usually no delay when locking onto a waveform in fix mode, although on signals of approxi- mately '/: div amplitude, delays of up to about 10 seconds can be observed in cer- tain circumstances. This can usually be corrected by increasing the vertical deflection to roughly 1 div. A single sweep facility is also available for non- repetitive waveforms etc. Timebase A on the CS-1045 covers from 0.5 s/div to 0.1 ps/div, while the second timebase, B, covers from a faster 50 ms/div to the same o.l ps/div. Both these speeds are extendable to 10 ns/div deflection speed by the use of a xlO magnifier control. The error over the deflection speed range of 10 ns to 20 ns is surprisingly specified as ± 8%, although on the review model these speeds appeared to be within the more normal ±5% limit. Only timebase A has a continuously variable sweep time/div control. Incidentally, neither the Y- amplifiers nor the A timebase have un- calibrated indicators to show when these controls are in use. I found that this in- itially led to one or two measurement er- rors where these controls had been used for a previous reading. Horizontal modes cover the timebase sweeps being displayed separately or alternately and there is also the usual X-Y mode. These, coupled with the B timebase mode func- tions, cover a comprehensive range of in- put possibilities from the standard delayed sweep and magnified sweep to a triggered B sweep. An external accessible intensity control for the B trace would have been helpful in delayed sweep mode, especially at the higher sweep rates. The trace separation control only allows the separation of the B sweep in the downward position and, while this helps to avoid any confusion over which trace is which, it is also slightly limiting in that often the A trace has to be repos- itioned to accommodate the positioning of the B trace below it. The delay time itself is controlled by a continuously variable, fully calibrated, 10-turn control over 0.2 to 10 times the A timebase speed. The action of this is very smooth and consequently allows readings to be taken very accurately, for example, over 3.53 a pulse width measurement. Calibration accuracy is good, and there is the mini- mum of jitter. In most cases, the results obtained with the delayed sweep (± a few digits) typically corresponded to those obtained from a digital counter/ timer. The timebase performance is very good, but it would have benifited from a maximum timebase speed of 50 ns/div, given the 40 MHz Y-amp bandwidth and the wide bandwidth of the triggering system. The Trio Kenwood CRT is of the 12 kV, domed-mesh variety, and produces a very clear and well focused trace, as can be expected from a tube with a reasonably high accelerating potential. The brightness is also good, although, when used in dual timebase mode, magnification rations of over 200 can be difficult to observe on the B sweep in average bright light. When, however, the unit is used in artificial light of fairly poor brightness, it is possible to observe ratios of over 1000 limes. Front panel controls for astigmatism and also for the scale illumination are provided on the CS-1045. The graticule, which is fully marked with the appropriate risetime graduations, lights to a highly visible amber colour on maximum illumi- nation, making measurements in sub- dued lighting conditions an easy task. A very sensitive Z-modulation input is provided at the back panel; it has a typical sensitivity of +3 V for complete blanking to - 5 V for a large increase in trace intensity. The CH 1 output is AC coupled, providing a 50 mV/div output and a reasonable degree of calibration accuracy, enabling it to be used for voltage or frequency measurements, etc. The output is also consistent over the en- tire deflection range, in contrast to similar outputs provided by some other manufacturers, where clipping occurs if the total deflection exceeds approxi- mately 6 divisions. A signal delay line is also fitted, enabling the viewing of the triggering edge of most waveforms. Internal construction is centred around four main PCBs, all of which are silk screened and single sided. The compo- nent side is screened with the track layout and this should prove a great help if any servicing is necessary. The number of boards and external connections necessitates a large number of wire links, but I am satisfied that these will in no way affect the reliability of the instru- ment, although servicing may be rather time-consuming. The PCBs and other components are mounted on a steel frame, from which the external casing is also constructed. This should enable the scope to be used successfully in a variety of environments. All components and presets appear to be of a good quality, especially the mode and triggering selec- tion switches which have a light, yet very positive, action, providing easy oper- ation of the instrument. Front panel layout is good and allows the unit’s range of functions to be quickly oper- ated. One minor point is, however, that some of the controls extend a good distance from the front panel, and may, therefore, be easily damaged. The 31-page manual is good, providing particdlar emphasis on dual timebase operation, with shorther descriptions of the more standard operating modes. De- tailed sections arc included on a large number of dual timebase applications which also include the appropriate examples. No circuit diagram, or de- scription is given, but a service manual is available separately. Conclusion Overall, the CS-1045 is a highly specified instrument, and should meet most users’ present requirements, as well as their future ones. The delayed sweep facility is particularly good, and has some useful, if perhaps specialized functions such as independent TV line triggering. Trigger performance is also good over and beyond the stated Y-amp bandwidth. The CRT provides a fairly high standard of performance, giving a well focused trace at the vast majority of timebase speeds and magnification ratios com- bined with a reasonable brightness range. One or two features, such as inter- nal trigger view or comprehensive chan- nel selection, are not included, and this is worth considering. To sum up, the CS- 1045 gives a good allround performance and is well worth considering. The Kenwood CS-1045 was supplied by Thurlby Electronics Ltd, New Road, St. Ives, Huntington, Cambs. PE17 4BG. Tel. (0480) 63570 Other scopes available under £1500 in the Kenwood range Dual trace, 20 MHz bandwidth, 1 mV/div to 10 MHz, 50 ns/div max sweep, alternate triggering, 2 kV CRT: £319+VAT CS-1025 Similar to CS-1021 + 6 kV CRT, 20 ns/div maximum sweep, scale illumi- nation. CS-1044 Similar to CS-1025 + 40 MHz band- width, variable holdoff: £575+ VAT CS-1045 Covered in review: £695+ VAT CS-1065 Similar to CS-1045 + 60 MHz band- width, 5 ns/div maximum sweep + wider bandwidth probes supplied: £795+ VAT CS-1100A Similar to CS-1065 + 100 MHz band- width, 16 kV CRT, different physical ap- pearance: £11 95+ VAT CS-2110 Similar to CS-1100A + independent triggering of second timebase, il- luminated push-button switches, 4 chan- nel capability, 20 kV CRT: £1395+VAT CS-8010 10 MHz sampling cursor measurement DSO, 2k memory (8-bit), full pen recorder facilities— will be covered in a later review: £1I95+VAT 3.54 selex-32 A common baby phone used tor supervising the sleep of an infant or child, allows only for one way communication. Also, it can be used for monitoring the general during the day. The circuit presented here, however, allows for two way communication. It is not exactly an Intercom, but quite near to it. Figure 1 : Switch S2 determines the mode of operetion. SI and S3 are push to on Key Switches, with their locking mechanism removed. S2 in B position is the standby mode, whereas S/H position gives the intercom mode, or baby phone-hear mode. It allows also for one way secondary station to the master station. The master can decide whether to switch over to two way communication. The circuit is thus a combination of a normal baby phone and an intercom. The Circuit As described earlier, the circuit provides for both, one way as well as two way communication. The mode selection is possible through switch SI, S3, and the change over switch S2. These are shown in figure 1. Switch SI and S2 belong to the master station (Al and S3 belongs to the secondary, or slave, station (B). The unit works as a baby phone with one way communication, when SI and S3 are in released position and S2 is in the S/H position. With the switch S2 in B position, the circuit functions as an intercom, and is ready for speak from the master station, S2 must be switched over to S/H position and SI must be kept pressed while speaking. After speaking is over, SI can be released and an answer from the slave station can be received. At 3.55 selex be switched over to B position again. Whene S2 is in S/H and SI is in released position, there is one way communication from slave It is also possible for the slave station to request a communication with the master station. This is possible with S2 in B position (Stand by mode). When the switch S3 is pressed at the slave station, a call signal is master station. It is then ampli and fed to the power amplifie which in turn sends it over to loudspeaker LS2 in the maste In the intercom mode, when t master station wants to speak the slave station the switch m be in S position. This connect the loudspeaker in master stat as a microphone and feeds th The pre-amplifier amplifies it i ed feeds the power amplifier C. It is C. then further passed on to the he slave station F. If during the standby mode, the slave station wants to e communicate with the master to station, the call tone generator E ust is activated by switch S3 (see figure 3). In the standby mode on the switch in the master station is in H position, and thus enables the power amplifier C to amplify nd and pass on the call tone to loudspeaker in the master The block D functions as an AVC (Automatic Volume Control). It volume throughout the operation. This is achieved by a lamps and an LDR. If the sound level is too large, the lamp glows brightly and the LOR resistance is reduced. This drop in the resistance is used to reduce the gain of the preamplifier block B. There must be someone present the call by putting the switch S2 2 1 Figure 2: The entire circuit is divided into in S/H position. The actual circuit diagram is shown in figure 3, and is divided functionally into 6 blocks. The block diagram is shown in figure 2 and is easy to understand. aP-nru six functional parts. Power Supply (A), Pre-amplifier (B), Power amplifier (C), Autometic Volume Control (D) and the Call tone generator E. The slave unit is (F). make the power supply for both the stations. The circuit uses two loudspeakers and has no microphones. The loudspeakers themselves function as microphones. In the baby phone “H3 The 6 functional flocks of figure 2 can be easily recognised here with their internal working details. mode, the audio signal coming from the slave station F is given 3.56 selex This avoids the overload of the power amplifier C and keeps the volume at a constant level. Figure 3 shows all these functional blocks in greater detail inside the dotted lines, and can be easily identified as the functional blocks described above. The power supply is designed to give about 10V output. This can be achieved by using a step-down transformer of 230 : 8 V ratio. The preamplifier consists of an op amp 741. The circuit of the preamplifier is designed in such a way that the LOR affects the gain between 2 and 10Q0. The resistors R4, R5 and R7 are fixed value resistors which decide the R6. C2 is used to limit the high frequency signals. R2 and D9 take care of the split voltage level required. Pin 6 of 741 thus lies on aproximately 5 V DC. The capacitor Cl is used for suppressing the noise. The power amplifier also uses a 741 Op amp. It also uses two transistors T1 and T2 to deliver the audio signal to the loudspeaker. The gain of this stage is decided by resistors R8. R9 and RIO, and is aproximately 400. 04 is used to limit the low frequencies and C6 is used to limit the higher frequencies. The audio output signal is rectified by D7, and is fed to the AVC section consisting of T3 and T4. C8 works as a filter capacitor The DC voltage fed to the combination of PI. P2 and D8 is thus directly proportional to the audio output. Potentiometer PI decides the sensitivity of the AVC circuit. C8 bypasses the short duration peaks and smoothens the action of the AVC circuit. The sensitivity is also affected by adjusting P2. A break in the continuity at x - x makes the AVC ineffective. When S2 is in B position, the unit is in standby mode. If switch S3 is closed during the standby mode, point 1 in the slave unit gets connected to R1 and as the other end of R1 is connected to the connection point C of the call tone generator circuit, the voltage is connected through R20 to the 555 1C. The 1C generates a square wave signal at pin 3 which is fed over C7 and R1 1 to the output stage in master unit. The signal is reproduced through loud speaker LS2 and Communication can be established by the master station by changing over switch S2 in S/H position on hearing the call Construction Component layout of the main section of the circuit is shown in figure 4. This covers the master station of the circuit except the switches, power supply and the loudspeaker. The Slave Section consists of Loudspeaker LSI, Capacitor Cl 3. resistor R1 and switch S3. These are to be wired separately. As usual, the assembly should start with the jumper wires, then the resistors, potentiometers, diodes, capacitors and so on. The polarity for diodes and capacitors must be observed correctly. LED D8 also must be soldered with correct polarity. This LED shows when the AVC circuit is in the front panel of the enclosure. Component list R1. R20, R21 - 10011 R2 - 15 Kit R3 = 8.2 K!1 R4, R5, R8, R9 1 Kil R6 - LDR R7. R11, R17 - 1 Mil R10 - 820 K!1 R12. R13 = 1.2 Kil R14, R15 - 1.2 H R16 - 47 O R18 = 10 Kit PI - 1 MI! (Preset) P2 - 250 Kl! (Preset) P3 = 10 Ki! (Preset) Cl, CIO = 47 uF/16V C2. C6 220 pF C3 = lOOnF C4, C5 = 220 nF C7 = 10nF C8 = 10 UF/16V C9 = 47 nF C11 = 1000 uF/16V C12, C13 = 220 UF/16V D1, D2, D3, D4 = 1 N 4001 D5. D6, D7 = 1 N 4148 D8 = LED (Red) D9 - Zener 5.6 V/400 mW T1 = BD 135 (or BD 139) T2 = BD 136 (or BD 140) T3, T4 = BC 547B IC1. IC2 = 741 IC3 = 555 Other parts: 1 Standard SELEX PCB. Size 2, (80 x 100 mm) 1 Transformer 230 V/8 V (500 mA| 1 Fuse (100 mA) 1 Fuse holder LS1.LS2 - 811/1 W loud SI. S2, S3 Push button switches. La 1 - 6V/50 mA lamp. 3.57 selex The pin details of the transistors also must be followed correctly. The thick black line shown in the layout diagram is the heat sink fin of the transistors. The ICS are to be soldered in the end. Be careful to solder the LOR in such a way that the light sensitive side of the LOR faces correctly in the direction of the lamp. The lamp is to be soldered directly without using a socket. Also important is the requirement that the LDR should be protected from external light, so that external light conditions do not affect the operation of the AVC circuit. After the soldering work is over, a black insulation tape can be wrapped around the combination of Lamp and LDR to protect them from external light. After wiring the PCB, all the external parts must be connected. These are the transformer, the switches and the loud speakers. The testing should be done first without the I Cs fitted into sockets. Keep PI in middle position and the sliding contact of P2 in the earth position. As soon as the power is applied, D8 must glow. The voltages at various test points should be as follows. 2 = 5.6 V approx. 5 = 5 V approx. The voltage at pin 7 of the connectors for IC1 and IC2 must be around 10 V. Now temporarily connect point B to point C and see the voltages at the pin 8 and pin 4 of socket for IC3. They must bbe about 5V. If they are OK, then remove the connection- between B and C. and switch off the power. Now the ICs can be inserted if everything has gone all right upto this stage. The pin 1 marking on the ICs must be correctly followed. If you switch on the power once again, after inserting the ICs, the voltages at point 3 and 4 must be now 5V. P3 connected accross the pins 1 and 5 of IC2 prevents a clicking sound coming from the loudspeaker, whenever any switch is pressed. Adjust P3 till the voltage between points A and B goes to a minimum. Finally, disconnect the power again and install the capacitor Cl 2 with Loud Speaker LS2. Also, connect B to C temporarily and then switch on power. A ringing tone must come from the loud Now disconnect B-C. the capacitor, loud speaker again. The fitting inside the enclosures can now be started. SI and S2 are similar push button switches, but the locking mechanism must be removed from SI, so that it does not remain locked after releasing the push button. S3 is just a simplr push to on type key switch. SI and S2 connections are as shown in figure 5. Flexible hook up wire must be used for the interconnections, wherever necessary the loudspeakers are installed last inside the enclosures. The slave station is relatively easy to construct. The components are directly mounted on the loud speaker. The key switch S3 is to be installed on the enclosure front panel. If a suitable key switch with only one pair of contacts is difficult to obtain, uses same switch as SI but use only one pair of contacts. Don't forget to remove the locking mechanism. Use a two core shielded wire to connect the Master Station to the slave station. Figures: The connection details for the switches. The locking mechanism must be removed from switch SI . 3.58 .le NEW PRODUCTS • NEW PRODUCTS • N Timer Spradecom Elec.ro Controls offers a range of Industr al Digital Timers for on Delay/Off Delay and Sequencial opera- tions. The elapsed time of the digital tim- ers are displayed on four digit Vi” LED display, which can be set with the help of thumb wheel switch. These timers are available in standard 48H x 96W x 12 OD mm DIN size. SPRADECOM ELECTRO CON- TROLS, • 40, Bajson Industrial Estate, • Chakala, Andheri (E), • Bombay 400 099. Thermometer RADIX ELECTROSYSTEMS offers a pocket sized digital thermometer DI- GIRAD 2000. The standard model is calibrated for Chromel/Alumel ther mocouple and covers a range of -100°C to + 1200°C. The measured temperature is indicated on a 3 Vi digit LCD display. DIGIRAD 2000 operates off a single 9 volt Eveready 216 battery. The instru- ment measures 75(W) x 125 (H) x 20 (D) mm. M/S. RADIX ELECTROSYSTEMS. A/22, Bonanza Industrial Estate, • Kan- divli (East), • Bombay 400 101. Wirewound Resistors CHESIRE RESISTRONICS PVT. LTD., manufacture “CHESIRE'' Brand Wirewound Resistors in Axial. Radial and Direct PCB Mounting Types. The Resistors are available silicon coated. Ceramic encased or Vitreous Enamel- led. These are available in Inductive & Non Inductive types. The Resistance range is from 0.01 to 750 K Ohms in 0.5 W to 500 W with a standard Tolerance of ± 5% & ± 10% . On request Tolerance upto ±0.1% can also be provided. The Dielectric Strength is more than 700 V AC tp 1000 V AC and power rating is at 25 °C and 40 ° C, derated at 0 to 300 °C and 350 °C depending on the type of Re- sistors. Higher Dielectric strength can be provided on request. Smaller size of Re- sistors in Berryllium oxide cores & Tubes are available. These Resistors are specially packed in Blisters packing for safety and easy handling. CHESIRE RESISTRONICS PVT. LTD., • 210. Nahar & Seth Estate, • Cardinal Gracious Road, • Chakala, An- dheri (E), • Bombay 400 093. • Tele- phone: 634 42 48. • TLX No.: 11-72395 CHES IN Terminal Blocks •Nelster Welcon' offers Barrier Terminal Blocks in 5. 10 & 20 A ratings upto 22 ways in various terminal configuration with accessories to suit your require- ments. Phenolic insulators are moulded in-house. Contacts are plated brass to ensure smooth contact and solderability. Screws are nickel plated brass. M/S. NELSTER WELCON • 6, Laxmi Woollen Mills Compound, • Shakti Mills lane, • Off. Dr. E. Moses Road. • Mahalaxmi. Bombay 400 01 1 . Ding Dong Bell The Rider range of electronic Fan Reg- ulators. Light Dimmers and Musical Door Bell occupy number one position in the market today. Ideally suited for modern homes and of- fices, the Rider Range is manufactured using carefully selected components and strict quality control tests. Rider offers the largest choice of designs and colours with elegant, strong reinforced plastic housing or attractive metallish finish. The Rider Ding Dong Bell is the latest of a string of electrifying ideas from H.V. Industrial Electronics. Elegant and mod- ern in design, it's special alloy steel plates gives a pleasing, melodious and resounding peal. It has a thicker copper coil for high durability. They are availa- ble in a choice of attractive designs and colours. Rider also manufactures Fan Reg- ulators, Light Dimmers, Musical Door Bells, Light Chasers, Voltage Stabiliz- ers, Energy Lights, Disco Lights, Strobe Lights, Musical Car Reverse Horns and Musical two and three-wheeler Horns. The products are available widely throughout India at all electrical stores and automobile accessories retail stores. • H.V. Industrial Electronics Pvt. Ltd. • 223, Vyapar Bhavan • 49, P. D’Mello Road, • Bombay -400 009 • Tel 346022/ 379868 NEW PRODUCTS • NEW PRODUCTS • N Z8 Microcomputer Has On- Board Eprom ARGATE BZ-APRIL 1987-SGS has extended the popular Z8 microcomputer family with the introduction of the Z86E11, a complete single-chip mic- rocomputer containing a powerful CPU, RAM, serial and parallel l/o ports, two counter/timers and a 4K UV EPROM. The Z86E11 can be configured as a stand-alone microcomputer, as a tradi- tional microprocessor that manages up to 120 k bytes of external memory or as a processor element in parallel processing systems. The Z86E11 contains a 144-byte RAM. organised as four I/O port registers, 16 control and status registers directly or in- directly via an 8-bit address field. In ad- dition. the register file can be considered as nine 16-register workspaces and indi- vidual registers within the selected work- space can be addressed via a short 4-bit addressing mode. The workspace or- ganisation leads to compact programs and also simplifies context switching dur- ing interrupt and subroutine calls. The 4 K x 8 on-board EPROM can be programmed in three different ways, first using a conventional EPROM prog- ramming procedure, second using the self-programming mode that allows single bytes to be altered during normal program execution, and in addition an autoloading operation using a simple board. An important feature of the Z86E11 is the programmable readout protection facility which allows users to inhibit ex- teral access to proprietarty program code. Readout protection is activated by programming two non-volatile transis- tors. Once set these security locks can be reset only by erasing the entire EPROM array. M/S. SGS SEMICONDUCTORS (PTE) LTD., • 29, Ang Ko kio Industrial Park 2, • Singapore 2056. Clock Module ION clock module F-Cl k/M6 is primar- ily meant for automobiles. F-Clk/M6 also finds application in UPS systems, emergency lights, battery panels etc. The display used is 6mm vacuum fluores- cent type with green glow. For variety, a transparent acrylic filter of amber, yel- low, green, blue or violet can be used to change the display colour to individual taste. Time is shown in hours and mi- nutes in the 12 hours format. An addi- tional feature is the display of month & date in the calender mode. The module measures 45(H) x 81 (W) x 14 (D) mm. Four push button switches and a casing are required to complete the clock. Wiring and operat- ing instructions are provided with every piece. To save the car battery from cur- rent drain, the display is connected through the ignition switch so that it glows only when the car engine is on. PROMOTION, • Blk # 4, Fir # I, • 10. Subash Cross Lane, • Bombay 400 057. Push Buttons & Indicators Efficient Engineering have developed the Series 34 Lighted Push Buttons and indicators with rectangular bazel to DIN Standard 48 x 24 mm. Two independent lamp circuits and one or two pole SPDT Self cleaning and snap acting microswitches, momentary or maintained action or any combination, offer 100% redundancy and a com- prehensive functional range as shown. Such comprehensive range, aesthetic look and ample provision for engraving on front face make these Lighted Push Buttons and Indicators ideally suitable for process Control Instrumentation, Supervisory remote Control Systems, Data Acquisition and Control Systems. Sequencing Logic Controls, Hierarchy Controls and Turn key Instrumentation. M/s. SAI ELECTRONICS, A Div. of Starch & Allied Industries) • Thakor Estate, Kurla Kirol road, • Vidvavihar(West), • Bombay 400086. • Phone : 5136601/5131219. Voltmeters Etc. MECO manufactures a range of Porta- ble Instruments for measuring various Electrical Parameters like Amps, Volts, Watts, Power Factor, Frequency, etc., Instruments are made in Moving Iron type. Moving Coil type. Moving Coil type. Moving Coil Transducer type & Electrodynamimeter type. The com- plete body is moulded from bakelite and the movement is placed in a separate compartment making it completely dust proof. Instrument conforms to BSS & ISS specification and is available in both Industrial Grade Accuracy & Precision Grade Accuracy. MECO INSTRUMENTS PVT. LTD. • Bharat Industrial Estate, • T.J. Road, Sewree, • Bombay 400 015. • Phone: 4137423, 4132435. 4137253, • Telex: 11 7101 MECO IN. 3.62 RN No 39 '58 1/83 Ilf M..9I Right Conn eclion ••• Champion £l££trani£s IM Ltd