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

Sun Jul 24 15:27:21 PDT 2011


There was an article in the Journal a few issues back on why the various
manual techniques are only approximations, sometimes surprisingly bad ones.
I think the author's call was WA4SCA.  So it does get talked about. With an
accurate clock, and current Keps it is possible to work a full pass and
scarcely touch the dial.  It definitely makes it easier to conduct a round
table.  If the transponder uses either modes L and/or S, you really don't
have much choice.  The change rate is just too fast for practical manual
running, though VE3NPC does an amazing job.  Even FM, which is very
forgiving is a challenge for manual tuning at those frequencies.  

My default is for full Doppler correction.  If the other station is using
it, fine.  We can concentrate on communicating.  If not, I switch off and do
it the traditional way.  It does provide some gentle encouragement to try a
new method, and gives you an opportunity to spread the word.  I am
embarrassed at how long I stuck with paper logs amid all this technology.  I
experienced a lot of nostalgia when I transferred all my old satellite
contacts to electronic format, but I have never looked back.

Hang in there.  As time goes by, you will see more stations using it, as
they won't have to unlearn years of experience.  Just remember that it is a
hobby, and there are many for whom tuning and pointing are an integral part
of satellite operations.  Have fun!


-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Tom Schaefer, NY4I
Sent: Sunday, July 24, 2011 4:17 PM
To: Amsat BB
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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