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Re: Re: PCSat2 PSK 31 operation



>>> "Michael R.Owen" <nlsa@nlsa.com> 4/6/05 11:00:29 AM >>>
>> Downlink will have no Doppler
>>because its a single FM signal that anyone can receive
>>with a UHF FM rig stright to their sound card.
>  
>Say what?   A satellite signal with no Doppler shift?  
>Maybe Bob means  "no significant Doppler."

Sorry, yes. No significant Doppler (meaning "none"
in the audio tones")

The usual +/- 3 KHz of Doppler will occur on the FM
2 meter downlink, but because of the low deviation
of the downlink transmittter, this should remain in the
passband of most FM receivers and so users will
"experience no Doppler".

However, NOTICE that this description was actually
for the 10m to 2m PSK-31 experiment on our RAFT
satellite which does have the downlink on 2m .

But I was WRONG about the downlink on PCSAT2.
Its downlink is on 70cm, and so the Doppler WILL
cause the signal to move outside of an FM passband,
so users will have to retune their FM receivers in
about four 5 KHz steps to maintain continuity in the
receovered PSK-31 audio.  Though the locations of
each singal in the audio package will not change
(significantly) due to Doppler.

The effect of Doppler on the audio tones themselvess
will be less than a fraction of a Hz

Hope that clarifies it.  Im working 3 satelites that have
to finish in a month and a 4th that  launches at the
same time, and so I sometimes confuse them...

de Wb4APR, Bob


W9IP

-- 
Michael R. Owen, Ph.D.                      Dept. of Geology
Northern Lights Software Associates         St. Lawrence University
http://www.nlsa.com                         mowen@stlawu.edu 
----
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