[amsat-bb] Re: Doppler Tuning Convention Question

Tue Jun 1 06:43:50 PDT 2010

Joe,

I have used both manual tuning over the years and automated Doppler tuning since last year using SatPC. As Tim N3TL mentioned, I was on a recent Dxpedition working portable satellite from KH6 using an FT857D for transmit and an FT817 for receive. I used the automated tracking on the linear and FM satellites with complete success. This allowed me to concentrate on logging and manually tuning the antenna on my tripod during each pass. I am very happy with SatPC and it works like a charm as designed. I and many other users have had great support by the author.

What program are using? What radios are you using? Do your radios have CAT interfaces? I can help you with getting the settings properly set so you can make Doppler tracking work properly with minimal effort. I know there is a little bit of a leaning curve with SatPC, but once you have it up and running it works like a charm. I can attest to that having used it in the field in half duplex and full duplex mode during my DXpeditions. I usually just give the receive knob a small nudge once in a while to be on downlink frequency.

Let me and the group know if you would like some assistance to make it work for you. Collectively we can provide lots of feedback.

73,
Adrian AA5UK

________________________________
From: "Gary "Joe" Mayfield" <gary_mayfield at hotmail.com>
To: amsat-bb at amsat.org
Sent: Mon, May 31, 2010 9:05:09 PM
Subject: [amsat-bb] Re: Doppler Tuning Convention Question

Tim,

     Speak for yourself :-)  In the 20+ years I have been a satellite
operator, I have never gotten computer doppler control to work right on the
linear birds.  It works great on FM, but I always wind up fighting it on the
linear birds.  As soon as I tune the other guy in the computer moves me off
frequency.  It's so much easier to just listen and adjust on the fly.

    Maybe there is some secret, but I have yet to be clued in...  If
someone wants to write a "Dummies Guide" for this I would be willing to be
your test subject.

73,
Joe kk0sd

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Tim - N3TL
Sent: Monday, May 31, 2010 8:42 PM
To: APBIDDLE at mailaps.org; 'John Belstner'; amsat-bb at amsat.org
Subject: [amsat-bb] Re: Doppler Tuning Convention Question

Alan, John and all,

There is no question that computer-controlled Doppler tuning makes working
the linear satellites easier. That being said, I am glad that my lack of a
computer to dedicate to ham radio forced me to learn and use manual tuning
by following the one true rule of always tuning the higher frequency.

These days, I often use SatPC 32 for computer control when I use my two
FT-817 QRP rigs for the satellites. But last year, right after Field Day,
the CAT plug on my FT-857D stopped working. Because of the choices I've made
about my station setup (i.e., a totally portable station that I can set up
and operate anywhere at any time), I need to use the 857 as a transmit radio
in order to work the DX into Europe and Africa that I have on AO-7 Mode B.
And without its higher power on 2 meters, I would not have gotten Hawaii
into the log earlier this year on FO-29 from Adrian, AA5UK/KH6. Since the
CAT plug died on the 857, I have been manually tuning on every pass during
which I use that radio. 

I really like being able to do it, even if I don't have to. I hope new
satellite operators will take the time to at least develop the basic ability
to effectively use manual tuning. But then - dinosaur that I am - I also
wish more amateurs in general would at least learn Morse Code at slow speeds
... hihi.

And since we're on the topic ... has anyone else noticed that the latest
edition of "The ARRL Satellite Handbook" uses VO-52 as the example for
Doppler tuning - and that it suggests that newcomers who are manually tuning
for Doppler park their transmit frequency on the UHF uplink and tune the VHF
downlink (i.e., the exact opposite of the One True Rule)? That is really
mystifying and disappointing.

Alan, I have no doubt that you're right about the necessity for Doppler
control above Mode B satellites. Having always preferred the KISS approach
whenever possible, I suppose that's why I haven't been able to get myself
very excited for L- and S-band opportunities. I definitely enjoy the
benefits of computer control for Doppler. I just don't much care for having
no choice in using it (or not) to effectively work a satellite.

73 to all,

Tim - N3TL

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Alan P. Biddle
Sent: Monday, May 31, 2010 6:07 PM
To: 'John Belstner'; amsat-bb at amsat.org
Subject: [amsat-bb] Re: Doppler Tuning Convention Question

John,

MacDoppler, SATPC32, Ham Radio Deluxe, and other programs all support what
has been called the One True Rule.  The usual name for the implementation is
Full Doppler Tuning.  You are doing it right.  When everyone does this, it
provides a very pleasant opportunity to talk instead of tune.  It also keeps
from drifting all over another QSO, though the transponders are seldom full
these days.

However, that is not to say that people not using this are doing it wrong,
exactly.  There are still many rigs in use which do not have the capability
for computer frequency control.  In the old days, the rule was to tune the
highest frequency, whether uplink or downlink, since this is where the
Doppler shift is greatest.  Take a look at KB5MU's original article and
updates here:

http://www.amsat.org/amsat/features/one_true_rule.html

My suggestion is to use full tuning until you find that the other operator
isn't.  Then adapt, usually by turning off the updating for the lower
frequency.  It isn't worth getting doctrinaire about it.  However, by using
the One True Rule as the default, you set a good example and encourage the
movement of other operators in this direction.  As you will find, it is
truly painful to do it the manual way after getting used to automagic
tuning.  As we move above 70 cms, full tuning truly becomes necessary.

Alan
WA4SCA

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of John Belstner
Sent: Monday, May 31, 2010 3:36 PM
To: amsat-bb at amsat.org
Subject: [amsat-bb] Doppler Tuning Convention Question

I know there is a lot of discussion on this subject in the AMSAT archives,
but I've recently read a few posts to the BB that have me confused.

Just this weekend I got my Sat station on the air (FT-736R w/MacDoppler) and
I noticed that the MacDoppler program I use adjusts both the TX and RX
frequencies during the satellite pass.  I'm assuming this is to keep my
signal located in the same place in the transponder.  The program seemed to
work quite well.  I was able to copy several QSO's on VO-52 and made a
couple contacts as well.

One thing I noticed is that about half the QSO's I copied did not require
any manual tuning on my part (MacDoppler adjusted the RX correctly) while
the other half did.  According to MacDoppler, those that did require manual
tuning were moving around within the transponder passband.

I've read a few posts (one as recent as today) that suggested the convention
is to keep the RX frequency fixed and manually adjusting the TX frequency
while monitoring the downlink.  Looking through the AMSAT archives this is
the old convention prior to the popularity of tracking software and CAT
control.  So my question is, are there two conventions? or do I not have my
software configured correctly?

Sorry for what might seem like a stupid question, but I'm a newbie to this
facet of Ham Radio.  BTW, I'm having a blast!

Cheers,

John Belstner
w9en at arrl.net

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