[amsat-bb] Re: Po-63
rwmcgwier at gmail.com
Sat Nov 10 16:56:57 PST 2007
Auke de Jong, VE6PWN wrote:
> I would like to draw attention to a unique occurance that I have noticed today and last night...
> I was sitting on 144.200.0 usb with spectran running on the compy for no good reason, when suddenly i noticed a carrier sweeping down through my scope. By itself, this would be nothing special, BUT I recognized a pattern: the sweep rate was not linear, but resembled that of doppler-shift from a passing LEO satellite! it started out at one rate, then got faster as it passed through my IF, and past zero-beat. I retuned down, and continued to observe it become slower, finally fading-out rather abruptly while still sweeping down at a slower rate.
> I could not find any reason why any terrestrial signal might do this, so I looked through my list of sats on Orbitron, to see if there was any hardware that had passed recently. I noticed that "PEHUENSAT-1[+]" had JUST LOS my horizon on it's ascending orbit, and had been almost directly overhead a few minutes before. I made a mental note, and decided to check again on a future pass to see if it happened again, just to rule-out other possibilities.
> Sure enough, this morning on orbit # 4414, I was again, monitoring 144.200.0 usb and doing other tasks when I looked over at the PC and saw the same pattern. A check of Orbitron, showed that PO-63 just SO happens to be almost LOS decending from overhead.
> This brings a question which begs to be answered: How can this signal seem to be coming from this satellite? As far I as I can tell by searching google, the satellite is no longer functioning. could it be a reflection of a terrestrial signal, or could it be generated somehow by a malfunctioning onboard transmitter?
> I would like to hear from others about comparable observations or other insight.
> Auke, VE6PWN
Pehuensat had an unfortunate design as I pointed out shortly after its
launch. It had a stable spin axis that would almost assure that its
solar panels would go through long periods of not being illuminated and
then later turn when the sun angle shifted to illuminating the panels
again as the seasons went by because of the design of the panels on the
In my mind, what you have seen is not only reasonable, if the orbital
elements continue to agree with this, it is probable that we are simply
seeing the panels return to sufficient illumination to wake it up.
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
“An optimist may see a light where there is none, but why
must the pessimist always run to blow it out?” Descartes
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