[amsat-bb] Re: really strange RX
Mark L. Hammond
n8mh at embarqmail.com
Sun Feb 17 17:57:10 PST 2008
You may very well be hearing IO-26, ITAMSAT.
IO-26 is currently in MBL mode transmitting PSK at 435.790 MHz +/- Doppler, so it's quite a bit lower than the published/launch frequency of 435.822. It has drifted a good bit!
If you share a footprint with my station, you might very well be hearing some MBL telemetry and/or packets coming from IO-26. Keep tuned for more information in the coming weeks :)
>Well, I got a chance to listen again and there it was again! I took some
>better notes this time and even got a recording. There didn't seem to be
>any telemetry frames transmitted, just the steady AFSK carriers. I picked
>it up about 1/2 way through the pass.
>I am 90% sure that these signals are coming from IO-26. the LOS occured
>precisely at 21:05:39UTC Just as IO-26 met my horizon here in DO-33, and the
>signal was strongest with my antenna pointed in the direction of that
>satellite. All this is according to my Orbitron display. The only problem
>is that the frequency is NOT on any list. I worked out the transmitter
>frequency to be 435.790MHz, where it was 435.7825 when it disappeared.
>FO-12 was also in view at the time, just as it was the first time I heard
>this, but it was in the opposite direction from me. LOS happened to occur
>at about the same time too, hence my less than 100% sure-ness. FO-12 also
>happens to have it's beacon set to a more believable 435.795, but again, the
>signal was stronger in the opposite direction from there. One last thing of
>note about the reception is that I noticed pronounced fading as if the sat
>was spinning, which seemed to mirror how AO-16 fades both in severity, and
>rotational frequency. the fades occur about every 10 seconds, for about 1
>second, as observed on my 7 element Sinclair Yagi fixed at horizontal pol
>and fixed elevation of 20 Deg.
>Can anyone here offer any help for me to understand these observations? Is
>it even possible for a satellite to drift this far off-frequency? Can
>anyone else confirm or dis-prove that these are coming from, or very near
>IO-26's closest downlink frequency is listed as "Downlink 435.8670 MHz AFSK
>as seen here on AMSAT's page:
>Auke de Jong
>From: "Auke de Jong, VE6PWN" <sparkycivic at shaw.ca>
>To: "AMSAT-BB" <amsat-bb at amsat.org>
>Sent: Sunday, February 03, 2008 2:28 PM
>Subject: [amsat-bb] really strange RX
>>I cannot identify what it was that I just heard:
>> at 20:55, i was bringing my dial up to try and hear IO-26, but I was
>> startled when I came accross another signal several hundred KHz below my
>> destination! I stopped to see if it was juse local noise, and found that
>> it was indeed LEO in origin. I picked it up at about 435.801MHz while
>> rotating the beam from the north to my east. As far as I can tell, there
>> is no satellite using a frequency in that range, on the list found on the
>> AMSAT website under "Satellite Frequencies". The signal seemed to be
>> strongest in the direction of IO26/KO25. judging by the rate of
>> doppler-shift it must probably be either one of those satellites. It also
>> faded out just before IO26/KO25 were near my horizon, given the inaccuracy
>> of my PC clock, they might have been exactly at the horizon. It's been a
>> week since I synchronised my clock, it was 4 seconds behind.
>> The signal sounded exactly like AO-16 MBL mode before they put it in voice
>> mode. I think I even heard a packet or some form of data transmitted once
>> during this pass.
>> Is it just a typo where IO26 is actually lower in frequency by about
>> 60KHz? Might it somehow have drifted that far down? Or is it another
>> satellite altogether?
>> Auke de Jong
>> Edmonton, AB
Mark L. Hammond [N8MH]
More information about the AMSAT-BB