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Re: ISS: 143.625 downlink 2x (also by D700 ??):



Hi Kenneth !

Sorry I did not express myself very clear - apologies.

What I think I heared were two (2) signals from ISS at the same time (both at 143.625):
1) the Russian VHF system (voice)
2) a second radio onboard the ISS, I guessed the D700 (constand carrier)

Reason for posting:
I hear often 1) and feel familiar with type of comm's on that channel.
However, I assume that IF the second signal came from ISS, that it would
have been the D700 - and that the D700 would not be expected to transmit
on that frequency (also assuming the SSTV VOX circuit was the cause of
the silent carrier to be transmitted)

That's all :-)
Henk


> Sounds like the Russian VHF comm. system which has a multi polarity antenna array. They may have locked the PTT in
> anticipation of a ground pass over Moscow and you were hearing background noise from within the ISS.
>
>
> Kenneth - N5VHO
>
> -----Original Message-----
> From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Henk, PA3GUO
> Sent: Thursday, October 16, 2008 6:02 AM
> To: amsat-bb@amsat.org
> Subject: [amsat-bb] ISS: 143.625 downlink 2x (also by D700 ??):
>
> To whom this may concern (Kenneth N5VHO ?):
>
> Thursday 10:45utc pass over Europe:
>
> With the very latest keps I monitored both 145.800 and 143.625.
> Late in the pass, a carrier appeared on 143.625.
> Also I heared now and then voice from another source (distorted) through that.
> Initially I believed this was a local station transmitting on 143.625.
>
> But: switching between HOR/VER/LHCP/RHCP gave exactly the same
> ratio of that carrier versus the voice/other signal... they must
> have identical polarization: too much coincidence to me.
>
> Then: the carrier faded down fast in the last 2 degrees elevation, like the ISS 145.800 also always does: the
> carrier must have come
> from ISS: I guess the D700 also has 143.625 programmed ?
>
> Conclusion:
> I suspect that maybe the Kenwood D700 onboard was transmitting
> on 143.625 and at the same time the astronauts tried via the other radio to reach Moscow (like they do every day).
> Most likely Moscow also could not hear the 2nd radio, as the carrier was strongest.
>
> Henk, PA3GUO
> The Netherlands
>
>
>
>
> _______________________________________________
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