[amsat-bb] UO-11 beacon and Full Doppler Control

[Jerry Pixton <jpixton@xxxxxxxxxxx>]

Hello,

Friday I re-did an experiment that I ran several years ago as I was 
developing my W6IHG Radio Tuner application.

I tracked the S-Band beacon signal of UO-11 on an over-head (max El about 
60 degrees) pass WITHOUT touching the radio dials. I was using Full Doppler 
Tracking with my W6IHG Radio Tuner controlling the Doppler correction for 
my FT847.  The Doppler range was over 100 Khz in a 12 minute pass! This is 
much different than we have experienced with AO-40. Even though the Doppler 
range for AO-40 is as great, the change is over hours and manual tuning of 
the radio dials works (but even then we can not hold a constant frequency 
at the satellite).

As we look forward to Echo and using the L-Band uplink and the S-Band 
downlink, it seems to me that we are going to need computer assistance to 
correct for the radid Doppler shifts we will experience. Many of our radios 
DO have computer control and I think we are going to want to improve our 
stations to the point where we can use Full Doppler Control. Leaving the 
Transmit frequency (the lower frequency) fixed is not going to cut it on 
the L/S-band channel in a low earth orbit.

There are many solutions available to use in this improvement of our 
stations. See the URL in my signature block for my inexpensive W6IHG Radio 
Tuner.

Jerry, W6IHG


---------------

 >UO-11 S-Band still sounds good, but wow sure is alot of doppler.
 >copied at 21:45 utc 2-19-04


 >UO-11also has a 2401.5 MHz beacon, although hearing the 2.4 GHz signal
 >could present a challenge.

_______


------------------------------------------
Dr. Jerry R. Pixton, PIXOS Designs LLC
http://www.pixos.com/designs/RadioTuner/
jpixton@shentel.net
------------------------------------------


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