[amsat-bb] HF Satellite Transponder

[Robert Bruninga]

I find that RS12/13 had 8 watt transponders.  WOW!  That's for 40 kHz
bandwidth.

Or if one user was in the passband, then he got all 8 watts!?  That coiuld
be a very loud signal?  What was Mode A and KT downlinks like?  Were they
armchair copy or pull them out of the noise contacts?

To get down to say the 2 watt level for a cubesat, then this suggests only
a 10 kHz wide transponder.  And with 3 kHz signals, that could only be 3
signals.  AND, what is it like near the edges of a super narrow filter?
Does the steep phase changes on the edge of the filter then distort SSB?


Bob, WB4APR

On Thu, May 26, 2016 at 1:49 PM, Paul Stoetzer <n8hm at arrl.net> wrote:

> A 15 to 10 Mode K satellite would be fun. 12 meters is allocated to the
> Amateur Satellite Service, of course, but the limited bandwidth of the band
> might cause conflicts if the satellite continues to function when the solar
> cycle starts to perk up again. 15 meters, on the other hand, has plenty of
> room, especially if you put the uplink somewhere above 21.400.
>
> 73,
>
> Paul, N8HM
>
> On Thu, May 26, 2016 at 1:45 PM, Robert Bruninga <bruninga at usna.edu>
> wrote:
>
>> I may have a launch opportunity for an HF=HF transponder for a possible
>> cubesat idea.  Probably something like 12m up and 10m down?
>>
>> Is this worth doing (re-doing) at this point of technology?  Enough
>> bandwidth to support a few voice channels?
>>
>> Any volunteers to build the translator board?
>>
>> How is 24 MHz band used?  The entire SSB portion of the band is only 60
>> kHz, so using say 15 kHz for a linear translator to 10m would be quite a
>> slice.  But then the downlink at 10m would be OK since it does have an
>> exclusive satellite band and so any inadvertent QSO's would be coming down
>> in a non-competing downlink
>>
>> Just some open ended thinking after Dayton.
>>
>> Bob, WB4aPR
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>
>