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.
Thanks, Auke, VE6PWN DO33
Hi Auke,
I'm sure - that's not PEHUENSAT. There is only an alkaline battery on board and transmission stops end of January.
73, Mike DK3WN
-----Ursprüngliche Nachricht----- Von: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] Im Auftrag von Auke de Jong, VE6PWN Gesendet: Samstag, 10. November 2007 19:05 An: AMSAT-BB Betreff: [amsat-bb] Po-63
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.
Thanks, Auke, VE6PWN DO33 _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
____________ Virus checked by G DATA AntiVirusKit Version: AVK 18.447 from 09.11.2007 Virus news: www.antiviruslab.com
I will checkout this interesting possibility too. The batteries maybe dead but the solar panels may be supplying just enough energy to start turning on some of the electronics on board. Some local oscillator circuits can start generating RF with just afew volts of DC but will also have considerable frequency drift since the PLL's may not lock the oscillators on the correct frequency.
On noticed recently when I got my 2304 MHz EME system up and running, I was hearing quite afew signals drifting across the band just as you described here. This band is loaded with satellites active and declared dead as well. XM satellite radio operates right around our HAM band, I just found out, at around 2320 MHz, the EU EME segment of the band !!
Auke, was the satellite seeing sunlight on your program when you ran those times ?
K7XQ Jeff Atwater,CA. Grid: CM97qi EME CW and JT-65 modes
50 MHz: 2 X M2 7 ele 13 dBd 1 kW pending 2 X 3-500Z 144 MHz: 4 X M2 2MPX28 w/polarity rot 21.5 dBd 1.5 kw single GS35b 222 MHz: 1 X M2 5 W.L. no polarity rot 15 dBd 400 watts 432 MHz: 4 X M2 9 W.L. 23.3 dBd 1.5 kW single GS-35b 1296 MHz: 3 meter dish 27 dBd 350 watts single water cooled GS-15 2304 MHz: 3 meter dish 32 dBd 180 watts SS Spectrain Amplifier 10 GHz: 3 meter dish 45 dBd 18 watt TWTA Still under construction !
K7XQ Webpage: http://www.elite.net/~k7xq/k7xq.html
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Mike Rupprecht Sent: Saturday, November 10, 2007 1:55 PM To: 'Auke de Jong, VE6PWN'; 'AMSAT-BB' Subject: [amsat-bb] Re: Po-63
Hi Auke,
I'm sure - that's not PEHUENSAT. There is only an alkaline battery on board and transmission stops end of January.
73, Mike DK3WN
-----Ursprüngliche Nachricht----- Von: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] Im Auftrag von Auke de Jong, VE6PWN Gesendet: Samstag, 10. November 2007 19:05 An: AMSAT-BB Betreff: [amsat-bb] Po-63
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.
Thanks, Auke, VE6PWN DO33 _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
____________ Virus checked by G DATA AntiVirusKit Version: AVK 18.447 from 09.11.2007 Virus news: www.antiviruslab.com
_______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
I wish I had a better record, buy my memory says that the second pass that I wrote about was definitely in sunlight, and the first one I wrote about had just emerged from eclipse after passing overhead my QTH on the ascending node during the evening of the 9th.
Auke, VE6PWN DO33
----- Original Message ----- From: "K7XQ" k7xq@elite.net To: "'AMSAT-BB'" amsat-bb@amsat.org Sent: Saturday, November 10, 2007 6:31 PM Subject: [amsat-bb] Re: Po-63
Auke, was the satellite seeing sunlight on your program when you ran those times ?
K7XQ Jeff Atwater,CA. Grid: CM97qi EME CW and JT-65 modes
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.
Thanks, Auke, VE6PWN DO33
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 spacecraft.
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.
Bob
participants (4)
-
Auke de Jong, VE6PWN -
K7XQ -
Mike Rupprecht -
Robert McGwier