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Re: One true rule in 2004...



Freeman wrote:

How many folks today are using computer controlled doppler adjustments
with their radios?

If computer control is not universal yet.  How many folks are following
the alternative outlined by KB5MU to tune the radio with the highest
frequency?

I noticed on SO-50, FO-20, and FO-29 that QSOs seem to drift up and down
which would suggest that folks are still doing manual adjustments but
following different rules for making those adjustments.

Wayne replies:

I use computer-controlled uplink/downlink Doppler tuning (SatPC32), but it
seems like the majority of people on the satellites don't.  It's a shame
because there are several programs that allow one to get automatic Doppler
tuning essentially for free (for the cost of a serial cable).

Some satellite operators use old radios that don't have a computer
interface, or have a "write only" computer interface which is not suitable
for "transparent Doppler tuning".  And some satellite operators use multiple
radios which are somewhat more difficult to equip for Doppler tuning.  But
it seems to me that the majority of satellite operators do use radios that
support computer-controlled Doppler tuning, but they just don't use it.

I find Doppler tuning to be very helpful when operating FO-29.  It greatly
simplifies the task of "finding" my downlink, especially when I also hear
harmonics that are coming from my transmitter instead of from the satellite.
Automatic Doppler tuning is helpful, but not essential, on the FM satellites
to keep the signal as clear as possible.  On FM satellites it's difficult to
determine whether or not somebody is using automatic Doppler tuning.  You
don't hear the pitch drifting like you do on a linear transponder such as
FO-29.  Sometimes a weak or distorted signal is caused by frequency error,
but sometimes it is caused by polarization mismatch at the antenna(s).

When tuning manually, I think the majority of satellite operators tune the
highest frequency.  But not everybody.

Wayne Estes W9AE
Mundelein, IL, USA






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