[amsat-bb] Re: really strange RX
Auke de Jong, VE6PWN
sparkycivic at shaw.ca
Sun Feb 17 14:19:27 PST 2008
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
----- Original Message -----
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
> Sent via AMSAT-BB at 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
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.516 / Virus Database: 269.19.19/1256 - Release Date: 2/2/2008
> 1:50 PM
More information about the AMSAT-BB