[amsat-bb] AO-85 "reset" during pass
n0jy at amsat.org
Sun Nov 8 19:55:53 UTC 2015
A few thoughts on this.
First, Burns mentioned "the hang timer on the transponder timing out not
having detected a 67Hz tone in a couple minutes".
He mis-spoke accidentally, the timing is one minute not a couple of
minutes. So the hang timer will drop one minute after IHU ceases
detecting a valid CTCSS.
Regarding the CTCSS detection, with the receive sensitivity issue we
believe that this couples with a "tight" tone detection that we
implemented for power budget reasons that I will elaborate on after we
commission AO-85. The short story is that it makes it harder for AO-85
to hear and therefore find the tone. The tone detect requires the
presence of the tone for 1.5-2 seconds to consider it valid therefore
any fading, loss of signal, a stronger station capturing the receiver
and perhaps being off frequency or low elevation so that their tone was
not heard to continue that two seconds, or perhaps the strongest station
was not using a tone - a number of factors might make it such that IHU
just didn't hear a tone that it considers valid, for 60 seconds, so the
hang timer times out. The tone is detected again, the hang timer is
The description of the situation indicates the lack of tone detect and
hang timer timeout based my experience testing Fox-1A.
Yes, tone detect is being addressed in Fox-1Cliff/D/B. :-)
Thanks for the reports. Hopefully this will help you understand what is
probably happening, so that you might recognize it if it happens again
and more importantly recognize if it is NOT what happened in a future
situation that you report to us.
Jerry Buxton, NØJY
On 11/8/2015 12:43, Daniel Estévez wrote:
> I'm a bit doubtful on the no 67Hz on input theory. There were several
> stations trying to hit the satellite, including me. I was using only 5W,
> so perhaps the satellite won't lock to my 67Hz tone except in good
> conditions, but the other stations were probably using more power.
> El 08/11/15 a las 18:19, David G0MRF escribió:
>> I think that just means there was no 67Hz on the input to start the 1
>> minute timer.
>> However, there were some mails about testing another mode yesterday, so
>> the answer may be there.
>> -----Original Message-----
>> From: Daniel Estévez <daniel at destevez.net>
>> To: amsat-bb <amsat-bb at amsat.org>
>> Sent: Sun, 8 Nov 2015 14:37
>> Subject: [amsat-bb] AO-85 "reset" during pass
>> Hi all, An unusual thing happened during AO-85 last pass over Europe, at
>> about 14:20 UTC or so. The transponder stopped working and the satellite
>> went silent for about a minute. Then came the voice announcement in the
>> lines of "Hi! This is radio amateur satellite Fox 1", and some seconds
>> later the transponder started working again. I'm sorry that I have no
>> telemetry recording of the pass to try to see what happened. 73, Dani
>> M0HXM/EA4GPZ. _______________________________________________ Sent via
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