[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 
1200 BPS"
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
> DO33go
> Edmonton, AB
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