[amsat-bb] AO-85 "reset" during pass
daniel at destevez.net
Sun Nov 8 20:18:26 UTC 2015
Many thanks for the in-depth explanation. Perhaps it's also possible
that several stations are transmitting at the same time, each of them
slightly off-frequency, so that the sat doesn't hear the 1.5-2 seconds
of tone from any one of these stations because they keep transmitting on
top of each other all the time, and some are weak and some are way off
frequency... This seems very plausible from what I was hearing on the
El 08/11/15 a las 19:55, Jerry Buxton escribió:
> 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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