CQ-T V No. 160 November 1992 I ' f (' o u V dm, OZ ire. a V C , slA,9 El L~~ AiH .HV M H NH_ S AiV• fi D L P - .221 0 .6 PI X, 3 ID ON N3, a o 4 `LN LX • 6 r JN O K ~3r R 2 X20 F %1 FMS •FTV 0E ~ 60 80 90 00 10 20 3.. 4o so 70 _ PEAN ATV EATE ifs NETTW r K MAP SUPPLIED BY AGA F BRITISH AMATEUR TELEVISION CLU B The BATC at the Dagenham Town Show circa 1958/5 9 Courtesy of Ted Stiles GOBHT CONTENTS 9 A Synclock Unit for the BBC Home Computer Hans Wessels PA2HW G 17 Lighting AT V Norman Ash G7AS H 21 A NICAM Decode r Rob Krijgsman PEICH Y 34 Digitalkers Revisited Steve Pocock GOCPV 36 Fade to Black, with A/B Mixer Peter Carliell 38 Tidal Propogation D .J.Bradford G8KB C 41 70cm TVI Filte r John Stockley G8MNY 42 The Middlesex Sho w John Stockley G8MNY 43 Camtech TXV4000 PLL Video Transmitter Review Mike Wooding G6IQM 51 Beyond TT L Trevor Brown G8CJS 56 BSB on 3cm ! ! Bob Platts G8OZ P 58 More on BSB Receivers Trevor Brown G8CJS 59 13cm ATV - It's as easy as this ! ! Bob Plattes GSOZ P 64 Expanding the Pace SS6000 Satellite Receiver Trevor Brown G8CJ S 66 Satellite TV News Paul Holland G3TZ O 73 BATC Contest Championship League Tabl e 74 Contest New s Richard Guttridge G4YT V 76 Contest Calendar 77 TV on the Air Andy Emmerson G8PT H 84 SSTV - A New British Scan Convertor in Kit Form Review Roland Humphries G4UKL CLOSE FOR PRESS FOR THE NEXT ISSUE 20th DECEMBER 1992 CQ-TV is produced on a 386 PC computer system, using the PROTEXT wor d processing package and the TIMEWORKS desktop publishing package . The camera-ready artwork is produced on an OKI OL400 Laser printer . The magazine is printed and bound by APEX PRINTERS of Rugby. CQ-TV 160 1 *.TGA and * .HRZ formats . It allows POST easy access to all drives and directories . It seems to be to SSTV what hydro - carbons were to steam ! It lacks tw o functions soon to be rectified - frame WANTED !! ! grabbing and graphics . Wanted adverts normally appear in the N9AMR has amended his Hi-Res pro - Market Place section, but this one is s o gramme for the 1200C Robot to encom- so well, so odd! to pass PASOKON TV under the new name warrant inclusion at the head of the of Hi-Res 32, a copy of which should be magazine: in my computer during October. This WANTED : Loan of two 12000 foot version will add the comprehensive mountains for 3cm DX working, or loan graphics facilities enjoyed by 1200c user s of similar! Bob `Gun Diode' Platts (wh o to the PC. Further, a low-cost frame- else!) . Tel: 0283 40742. grabber is imminent which, together with provision for input from a camera, wil l make PASOKON TV almost as compre- SSTV NEWS UPDAT E hensive as the highly expensive commer- cial scan-convertors. It doesn't need a Dear Mike, separate monitor interface-board, high The missing footnote to the review of stability oscillator, PSU or EPROM, al l ViewPort in the last CQ-TV has brough t that is required is contained on the PC down the wrath of the designer and plug-in expansion board and included several users on my head, they though t software . The system will run on all PCs , my review was incomplete because I had even XT machines, but in fairness it is based it on the early version of the best on a 386 with a 32K colour graphics software. I did think my footnote on th e board and 500K of free ram . updated software was inside the press - I have a limited supply of informatio n . We shall survive date . leaflets which I will send to members Two weeks ago I received the PCB and needing more information (S .A .E. components for the PASOKON TV please) . I have been on the air with thi s SSTV system for PC computers . It took system in all modes with highly satisfac- four hours to assemble, 10 minutes to tory results, for hams with PCs wanting install and set-up and is an almos t low-cost fully compatible colour SSTV , complete SSTV system, running in all then this is designed for just that purpose . current modes, displaying in 256 VGA The more ambitious will be be interested colours or 32K colours with a graphic s to know of a low-cost 1200C clone fro m board using Sierra Ram-dac L.S.I. Th e Felipe Rojas AB4QC . The DFM-120 0 quality is excellent, the mouse drive n USA costs $300 for the PCB boards and menus give armchair operation, it load s front panel . One of the PCBs is partly and saves pictures in * .GIF, *.PCX, wired, and tested and it is claimed tha t 2 CQ-TV 160 components for the rest of the project people who are interested in railways will will cost another $200 or so . At present show there latest train videos but with rates of exchange this would cost around people who just want a chat all you will £270 for a complete 1200C clone. Details see is their mug shots and pictures of the of the main PCB and layout (A3 ) shack . If what you are watching is no t together with front panel enclosure con- interesting to you then you don't jus t struction are to hand . I need more switch off. Because ATV is interactive information on this clone to be able t o you can tell the transmitting station what comment on its compatibility with the you do want to see or even better sen d PAL system, a development board is in something more interesting yourself. hand to effect full interchangeabilit y No other mode tries to polish up it s between NTSC and PAL . content before going on the air . For Pasokon TV is available from the UK example, have you ever heard of prize s and European Distributors: KM Publica- for the best short story on the packe t tions, 5 Ware Orchard, Barby, Nr .Rugby, network or best technical lecture on CV23 8UF, U .K. Tel: 0788 890365 . Fax: phone . If all phone contacts had to be 0788 891833 . witty, entertaining or informative then th e Roland Humphries G4UK L HF bands would be deserted. Most contacts that I've had on HF consist of a signal report, of dubious accuracy, ANOTHER RESPONSE TO and a weather report . This is hardly ANDY'S `WHAT'S WRON G competition for the BBC but it is still th e WITH ATV? ' most popular route into amateur radio . My point is that the popularity of the H F Dear Mike bands comes form the the fact that ther e In reply to the article What's Wron g is always some one there rather than th e With ATV in CQ-TV 158 I have written entertainment value of each contact . I down my own thoughts on the subject. believe that this is also true for ATV . I believe that Bill WA6ITF has missed I believe that the way to get more people the point of ATV . It would be nice to be interested in ATV is to get more signal s able to sit down and watch a programme on the air. A bit chicken and egg I realis e dedicated to amateur radio on ATV but but who would get a station on the air i f this is not what ATV is about . The there is no one else there to exchange difference between ATV and what you contacts with. can watch on the other box is that ATV I have noticed that it is not just ATV that is interactive. is suffering a decline in operators but The pleasure of operating ATV is similar most of the bands and modes are becom- to any other mode in that the content o f ing less active as the numbers in amateur the transmission is directly dependant o n radio decline and the bands and modes the people in contact . For example, two available increase . CQ-TV 160 3 As for the apathy that was commented o n listening is the gateway to amateur radio . I am as guilty as the rest but in m y I have a couple of suggestions which defence it comes back to the activit y may help bring the activity back to ATV . levels. the first is a national activity night. It When I started in ATV about 10 year s would be just like contests in concentrat- ago there were about a dozen active ing the activity to a particular time slo t stations in the Derby area and this mean t but would allow for the long exchange s that there was someone on the air mos t which are part of the fun of ATV . Maybe nights . I have seen it decline to level s the first day of each month which i s where it is difficult to get any local something easy to remember and pass on . contacts. I even started entering contest s The second suggestion is the televising o f to try and find more activity but the GB2RS. Again this would mean that numbers on those nights has also de- people would know when a signal is o n clined over the years.