[amsat-bb] FM signal on FO-29?

[Robert Bruninga]

Zach

On Sun, Nov 8, 2015 at 5:54 PM, Zach Leffke <zleffke at vt.edu> wrote:

> well.. when I say students, I meant graduate students at VT that happened
> to be in the lab when I was doing the experiment.  They work with me and
> Bob, so a few crude words here and there aren't uncommon to them.
>
> But good point, probably not the best thing for a public demo if your
> audience is a bit younger.
>
> Actually, I've seen so much FM activity (basically every time I've
> monitored FO-29 since we first came online in late september) that I've
> been toying with the idea of trying to locate where the source emitters
> actually are located based on doppler shift data.  We know the doppler
> between the receiving ground station and FO-29, so we can back that out.
> We know the transponder mapping, so we can work through that to determine
> what the center frequency is as the signal enters the transponder uplink
> receiver.  What we don't know is the uplink doppler, because we don't know
> where the emitter is and we don't know what exact center frequency they are
> on (but I bet you its in 5kHz steps, maybe 2.5kHz).  So we have two
> unknowns.  I'm betting there's a way to work through it though, and with
> enough observations and by watching the rate of change of the doppler, I
> bet there's a way to make an educated guess on what their center freq and
> location are.
>
> Or if someone listening knows Spanish and/or Portugese, maybe we could get
> lucky and hear what cross streets the taxi is going to (if it is in fact a
> taxi).
>
> -Zach, KJ4QLP
>
> On 11/08/2015 05:30 PM, Clayton W5PFG wrote:
>
>> I wouldn't recommend playing the FM audio heard via FO-29 to a group of
>> children. Normally it's not English.  It's most likely NOT a religious
>> broadcast based on their choice of crude words.
>>
>> 73
>> Clayton
>> W5PFG
>>
>> On 11/8/2015 16:13, Zach Leffke wrote:
>>
>>> So yes, in the last couple weeks I've seen a LOT of FM activity on
>>> FO-29.  And based on my experience with Friday's pass, which was
>>> ascending, I'm leading towards the Central/South America QRM theory.
>>> Lots of strong FM activity as the pass started and the satellite was
>>> over the lower latitudes, but as FO-29 ascended over higher latitudes
>>> towards the north pole, the FM activity died down.
>>>
>>> -Zach, KJ4QLP
>>>
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>
> _______________________________________________
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