[amsat-bb] Some doppler observations/questions
Mark Lunday, WD4ELG
mlunday at nc.rr.com
Sat Nov 15 20:57:33 PST 2008
I am using HRD with Sat tracker module (thanks, Simon!)
I notice that for the non-FM birds I am working (AO7, FO29, VO52) the
Doppler is never quite exact. Or I guess I should say there seems to be a
constant *offset* that needs to be included in the Doppler calc. Tonight on
AO7 mode B pass, my actual downlink frequency seemed to be about 4 kHz lower
than what it should be according to the Doppler. As the bird passed by, I
followed the "one true rule" and only adjusted the higher freq (uplink in
this case). It was consistently about 4 kHz lower.
On FO29 pass, there seemed to be about a 2 kHz offset. When the bird passed
overhead, the Doppler "flipped" quickly and I had to find my signal again.
How can I consistently determine this offset so I can include it in with the
Doppler correction? Or is it on a case-by-case basis?
PS Thanks, Frank, K9CIS, for the nice CW rag chew on FO29 tonight.
wd4elg at arrl.net
More information about the AMSAT-BB