Satgen 510 Sat Fingerprints Pt5 by GM4IHJ (BID SGEN510) 1999-01-01 The procedure for using satellite fingerprint material is similar to that used by police forces to identify criminals . As with police records , the procedure works best when you have amassed cosiderable library material. But it also has some interesting features not seen in police work, for unlike human finger prints, satellite fingerprints can show changes with time. Changes related to the satellites health, orbit and stability. Oscar Ten has provided the fullest range of these variations. Over a long period, it has gradually lost most of its transmission frequencies, and it suffers in a somewhat random manner , whereby it experiences weeks or months with no communication what so ever, punctuated by periods of slightly less than perfect but none the less very useful intervals of mode B operation. Periods when it is the only Amsat still providing long range communication. All its various modes - the on and off periods and those important periods in between when it is showing signs of shifting from On to Off or Off to On , being discernable in fingerprints taken at regular intervals. In a totally different sense, fingerprinting has proved most useful with new satellites. Firstly because old fingerprint material of other satellites going to similar orbits and /or using similar modulation techniques , or similar transmission frequencies , can be used as templates, predicting what the new arrival may look like. Secondly , when the new satellite begins to perform on task, any sign of performance outside of specification can be identified and investigated . As was the case when Oscar Ten and Ariane 502 went to orbits rather different than the ones they were designated for, or when Arsene and Sarah began to exhibit transmission anomalies/ failures. Knowing what should have appeared on the fingerprint as against what did, can be very helpful in identifying problems, and is sometimes the only way to be sure you are tracking the right satellite when most of the signal characteristics you are looking, for turn up in the wrong orbit. Sometimes , as with several Russian or ESA multiple launches, the original NORAD keplerian elements do not produce the right fingerprint, and the only way to spot just which satellite fits which set of Keps, is by refering to their fingerprints. In a different sense , as multiple launches become increasingly frequent as we get more and more LEO constellations. They start off as a " bunch" . Then as their controllers gradually nudge them into a regular formation, it is sometimes possible to use individual satellite characteristics to follow each bird as it moves into formation. Orbcom sats were particularly easy in this sense as they used "marshalling frequencies" , only reverting to operational frequencies when they were in position. Last but not least, The big advantage of fingerprints occurs with the "unknown" satellite". You hear it maybe for a minute or less . But you get a permanent .gif or jpg printout which you can study at your leisure.