Satgen 483 Satellite Listening by GM4IHJ (BID SGEN483) 1998-06-27 Any day of the week, the satellite listener can tune around the bands and hear satellites which just do not sound right. Some of this is caused by propagation , such as Sporadic E, or Aurora , but quite often the problem is on the satellite itself. It pays therefore, to perhaps once a month, take a listen around. You may be surprised what you hear. At this moment starting on 137 MHz with the Wefax low earth orbiters. Noaa12 is nominal , Noaa14 is noisy to the north, while Noaa15 has improved greatly over its post launch performance but is still not quite right. Russian Meteor 3-5 disappeared a few weeks ago and a few days later Meteor 2-21 which had been orbiting silently for years , was switched on. Unfortunately after a week or two of relatively poor noisy pictures, it has now had a major change and lost all clear picture modulation and sync. It sometimes returns for a day or so but then reverts to this almost pure noise signal. On the Amsat front, RS10 and 16 seem to deaf to ground control and are not producing any thing useful, but RS12 and 15 are nominal and sometimes have lots of users. Fo20 and F029 are both presently mode JA, with 29 producing useful telemetry , whereas 20 is sending unmodulated carrier only . Neither satellite has been heard transponding user signals. Meanwhile Oscar 10 is sending a clear unmodulated beacon signal with no FMing, and it usually has several users getting reasonable conversation quality QSOs. So thats the survey, but how can we tell what is normal and what is not ? Noaa12 and 15 follow similar orbits at very roughly the same time of day. Comparing the two sats is therefore easy. 12 is quite good whereas 15 can be poor on some bearings. Which fits in with NOAA saying that while the VHF antenna has opened out quite a way since launch , it is not quite fully extended. Noaa 14 is in quite a different orbit coming over at different times of day and it has been particularly susceptible to the almosty daily Sporadic E, seeming to be markedly affected as it comes north over the Western Mediterranean . But its performance drop cannot be all due to poor propagation as FFTDSP trace comparisons with orbits a few months ago show reduced performance even when no SpE is present. Meteor 2-21 is much more of a puzzle. Its performance is very bad at times and it is to be hoped that the Russian controllers have a new bird to put up soon, or GM4IHJ will have to abandon his favourite sport of counting icebergs in Davis Strait. Indeed trying to image Devon Island to see the 20 km diameter meteor crater presently being used by NASA scientist to mimic conditions likely to be encountered on Mars - low temperature arctic conditions where there are sedimentary deposits but there is no vegetation . Has been fruitless , no sign of Devon Island never mind the much smaller crater. Because even when 2-21 had a clear signal note , QRM from Paging transmitters roughly 100Khz higher in frequency regularly breaks up the picture, and even the wide band Orbcom satellite signals around 137.7 MHz can cause difficulties for the already weak signal from Meteor 2-21, where 3-5 a few months ago produced excellent signals. More on Listening next week