[amsat-bb] Re: Should I abandon full doppler correction?

KM9U arskm9u at gmail.com
Sun Jul 24 15:12:19 PDT 2011

I am new to the linear birds and am having the same problem, Tom. It seems 
to be kind of a "D*(%#@ if you do and D*(%#@ if you don't" type of thing 
with computer doppler control. I have a FT-897 that I have used half-duplex 
with CAT control via SATPC32. I have also tried full-duplex using my TH-F6a 
as a receiver which, of course has to be manually tuned. Either way, it is 
not smooth going. Maybe this is why they call the FM birds "Easy 
Sats"...'cuz, so far, the linear birds ain't!

Chuck, KM9U

----- Original Message ----- 
From: "Tom Schaefer, NY4I" <ny4i at arrl.net>
To: "Amsat BB" <amsat-bb at amsat.org>
Sent: Sunday, July 24, 2011 17:17
Subject: [amsat-bb] Should I abandon full doppler correction?

Hi all,

I just tried a nice pass on FO-29. I heard K9CIS on CW and W5BK from Texas. 
In both cases, while I am using full doppler correction with my 9100 and 
MacDoppler, I suspect they are leaving the transmit frequency fixed as they 
both changed frequency. K9CIS on CW was quite extreme in the Doppler shift. 
I know that this is a by-product of me using full doppler to listen to 
stations that are not, but it seems that the majority of the stations I hear 
are NOT using flu doppler. I have asked this question before, but it seems 
to be happening more frequently.

Should I abandon full doppler correction? Another less black-and-white step 
is that if I hear a station moving to adjust my settings so I am not doing 
full doppler.

Has anyone ever taken a survey to see how many satellite users actually use 
full doppler. Am I assuming more guys use computers and anyone of the 
multiple ways to do computer control that have ben available for years? Does 
anyone ever talk about this in AMSAT circles? Sort of like the encouragement 
one gives to people afraid of LOTW to try it? "Computers in the 
shack…NEVER!" I exaggerate but it seems that way. Then again, being a 
computer person and having computer capable rigs I realize I am skewed in my 
expectations. I know there are guys working with old 271/471 pairs or even 
the old FT726 out there. Great radios and a simple way to do it, but even 
they have ways to do full doppler control and they have been out for 20 


Tom Schaefer, NY4I
ny4i at arrl.net
Monitoring EchoLink node KJ4FEC-L 489389
DSTAR Capable  APRS: NY4I-15

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