[amsat-bb] AO-7 UHF beacon received!
Auke de Jong, VE6PWN
sparkycivic at shaw.ca
Mon Nov 26 19:24:37 PST 2007
I haven't seen anyone ever say that they heard the beacon on 435.1 lately, so I thought I'd give it a try...
I read somewhere that this beacon should be active while the satellite is in mode-a. a quick check of the ao-7 log site showed that the most recent contacts via her were on mode-b as of about 2am UTC, and knowing that her 24 hour timer is working deadly-acurate given continuous sunlight, I knew that by this time it should be in mode-A. I didn't hear anyone on the downlink in mode-a, but I decided to tune for the uhf beacon anyway, and after very faintly hearing something before it was overhead, i finally managed to latch-on as she fell to the horizon in the north. By this time my 7 el beam antenna was blinded by my house, so I changed to the horiz omni 0dB antenna, and then observed, for a few minutes, the doppler-shift-curve of a definite beacon from space. I have taken a screen-capture showing all the pertinent data, and the signal itself on the spectrum display! I think that it's a good thing I hooked up my pre-amp otherwise i might have missed it! after the screen-cap was taken, I observed the signal to "level-off" and then fade-out exactly as predicted LOS via my Orbitron program.
Maybe next time I'll be able to point my better antenna at it, and hear what information the beacon might be sending!
I read online that it is not a CW message like the VHF one, but rather an FSK modulated one... It's also known to have suffered low output on this beacon intermittently, or perhaps permanently. In that case, I might need a whole lot more antenna just to get a good copy anyway! someone else might be able to do a better job than I with this in mind...
I'll post a link to the image which I'll host on my local provider's gratuitous server... it might not live long there however, since I might need the space for something else in the future, so I encourage those interested to save a copy of it on your own computers for later reference.
Edmonton, AB DO33
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