Satgen 252 Satellite Spotters Part 1 by GM4IHJ 22nd Jan 94 BID of this msg is SGEN252 Please use this BID if you retransmit the msg Packet mail at GM4IHJ has recently included a number of enquiries from operators who hear an unusual signal , and want to know if it is a satellite. So perhaps this is a good time to produce a DIY ( Do It Yourself ) guide to satellite spotting. The following questions are the ones you should try to answer WHEN you are actually listening to the strange signal. Do not try to sort out your answers later, but, do make a tape record of the signal if you can. 1. What is the signal frequency ? 2. What is the signal mode (Carrier, Morse, RTTY, Digi, Voice,Wefax etc)? 3. Is the signal frequency dopplering - slowly/quickly getting lower ? 4. How long do you hear it for ? 5. Is there a slow or fast fading pattern on the signal ? 6. Is the azimuth or elevation bearing of the signal source changing ? 7. Do you hear any callsigns ,or recognisable speech/language ? 8. What time of day UTC, did the signal appear, did it reappear later ? 9. Is there similar signal on a harmonic (frequency x2 or x3 or x1/2) ? 10 Is there any visual target sat in your sky concurrent with the signal ? Make sure you get as many of these questions answered as you can. Then after the signal has gone, leave your receiver tuned to its frequency to see if it reappears , if it does, repeat the above checks. Once the signal has gone you can begin to sort out what it might have been by using the following guide. 1. Frequency. Satellites are supposed to use specific frequency bands allocated to them . There are some satellites outside recognised bands from countries which do not agree to the general plan ( France and the USA make the most use of the get out clause ). But generally you will find satellites in the following bands :- 19.900 to 20.008 MHz Russian HF beacons, Photoreconsats and Military 29.350 to 29.510 MHz Amateur Radio sats notably mode K and A downlinks 135 to 138 MHz Civil experiments , Wefax, etc ( mostly 136 to 138) 145.8 to 146 MHz Radio amateur sats Around 150 MHz Russian and American Doppler Navigation sats CW/RTTY Around 153 MHz Russian Electronic Intelligence 3/4 harmonic of 204 Around 160 MHz Russian low earth orbit telemetry Around 204 MHz Russian Electronic Intelligence , harmonic with 153 216 to 280 MHz Military communications from geosats and LEO sats 324 to 407 MHz Military comms geosats and low earth orbit LEO sats Around 400 MHz Russian and American Doppler Navsats harmonic of 150 432 to 440 MHz France and USA use this amateur band for non amsats 435 to 437 MHz Radio Amateur sats 1227 to 1250 MHz Navsats GPS 1500 to 1600 MHz Geosats for Comms, Marine and Aircraft usage. 1575.42 MHz USA GPS Navsats all this frequency spread spectrum 1603.5 MHz Russian Glosnass navsats group round this frequency To be continued in Pt2. Apologies to all being bothered by triplicate receipt of some satgen bulls Problem is retransmission N Ireland to G/GM of bulls downloaded ex Uosat. Am trying to get it stopped. 73 de John GM4IHJ @ GB7SAN