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

[Zach Leffke]

That makes sense Hector.  I've seen the FM activity kind of all over the 
transponder. More so than I would expect if it was the same transmitter 
each time on the same frequency and the different pass geometries 
causing a bit of swing due to doppler.


-Zach, KJ4QLP

On 11/08/2015 06:34 PM, Hector W5CBF/CO6CBF wrote:
> Hi Zach and group
>
> I think, the main problem is they are not always the same stations. I have
> heard several different stations in terrestrial QSOs QRMing  FO-29; majority
> of them speaking Spanish and without any kind of ID. I have not heard them
> recently, though.
>
> 73!
>
> Hector, CO6CBF/W5CBF
>
> -----Mensaje original-----
> De: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] En nombre de Zach Leffke
> Enviado el: Sunday, November 08, 2015 4:54 PM
> Para: amsat-bb at amsat.org
> Asunto: Re: [amsat-bb] FM signal on FO-29?
>
> 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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