[amsat-bb] Re: AO-73 QSOs on the beacon?

[n0jy]

Yep I'm definitely hearing stations again tonight, even with the preamp 
off.  It may be an image, I can see the same QSO up higher on the 
spectrum display at about the same offset from the center frequency 
145945 so that would make it about 145957 or so (give or take late night 
calculating) and that is in the transponder window. Stations appear much 
stronger on the spectrum display than the rest of the bumps.

Jerry
N0JY

On 12/6/2013 10:37 AM, Darren Long wrote:
> I also observed something like this the other day.  I wondered about its
> cause, but as I was actually doing something else at the time, I
> completely forgot about it.
>
> There were, as you note, strong SSB signals around the beacon freq
> during the AO-73 pass.
>
> Cheers,
>
> Darren, G0HWW
>
> On 06/12/13 15:47, n0jy wrote:
>> Good thought, David.  I do have the settings FCD Centre Frequency set
>> for 145945.  But I also have the auto tune range limited to 34599-44854
>> kHz which should only let the auto tune catch approximately 145931 to
>> 145941 kHz.  So it should not be (nor do I observer it to) tuning any of
>> the transponder portion.  It is always locked on the beacon as
>> identified by the hump and beep "spikes" as I watch it.
>> I do not hear FMing on the beacon.  It sounds like it should, but it is
>> covered by a stronger SSB signal, basically.  And it appears that the
>> combined doppler shift of the beacon and the signal make them move
>> across each other such that the QSO eventually passes by but then
>> another can come up and do the same.
>> Overloading the FCD maybe?  I do have a preamp on, maybe I'll try it
>> tonight without the preamp.  The reason I use the preamp is that when I
>> initially set up, I could not get a solid spectrograph (it blinked on
>> and off) unless I had the preamp on.  I believe that was related to the
>> version of Dashboard I had at that time as observed by a friend who had
>> seen the same thing when he just got his FCD Pro + the other day, but it
>> disappeared when he upgraded his Dashboard. Preamp is off now, I will
>> see what happens this morning and tonight.
>>
>> 73
>> Jerry
>> N0JY
>>
>> On 12/6/2013 2:47 AM, g0mrf at aol.com wrote:
>>> That's an interesting observation Jerry.   Not something we saw during
>>> commissioning the satellite.
>>>    A possible cause would be image response of the dongle.  Do you have
>>> the 'zero frequency' somewhere between the beacon and the transponder
>>> passband? e.g. 145.945 or off to one side e.g. 145.920?
>>>
>>> Other possibility is a large signal in the transponder passband
>>> causing the beacon to FM.    Is the modulation 'FM' or does it decode
>>> as SSB?
>>>    Thanks
>>>    David G0MRF
>>>
>>>
>>> -----Original Message-----
>>> From: n0jy <n0jy at n0jy.org>
>>> To: AMSAT-BB <amsat-bb at amsat.org>
>>> Sent: Fri, 6 Dec 2013 4:40
>>> Subject: [amsat-bb] AO-73 QSOs on the beacon?
>>>
>>>
>>> During the eclipse passes while copying telemetry with my Funcube Dongle
>>> Pro + I am hearing SSB QSOs on the beacon frequency.
>>> They usually "walk" across it but what puzzles me is that the website
>>> info indicates that the transponder passband is well away from the
>>> beacon frequency.
>>> Am I experiencing some weird stuff with my Dongle or is it possible for
>>> stations to work on an uplink that puts their downlink on the beacon
>>> frequency?
>>>
>>> Thanks,
>>> Jerry
>>> N0JY
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