[amsat-bb] Re: FT 847 and Doppler for Delfi
stefan_wagener at hotmail.com
Sun May 4 06:20:23 PDT 2008
Here is a quote from Wouter Jan Ubbels PE4WJ (Delfi Team):
" Tuning can sometimes be difficult, in the presence of Doppler shift,
fading due to polarization changes, frequency offset due to temperature of
the spacecraft oscillators and there is the possibility that the Costas Loop
indicates a false sync because of lock on one of the signal's sidebands. If
possible, you can use a waterfall display in software like MixW running
parallel to RASCAL which will give you an indication of the center
During transmission of AX.25 flags, the actual carrier frequency is the
highest peak in the spectrum, with a couple of sidebands exactly 150Hz
apart, looks like a comb. Now, using the waterfall display, tune such that
this highest peak corresponds to 1600Hz +/-100Hz, in order to achieve sync.
...As you can see the last part is very important. The highest peak is the
one that you will center around 1600Hz. You do that by tuning your radio.
Once you have it centered the Doppler control will keep it there (more or
less) and only minor adjustments are necessary afterwards (depend also which
Keppler data you are using).
I have attached pictures of my screen from last night and two days ago. You
can see it on "Spectran". I have that program running on top of Rascal. Try
it, it is fun and don't get frustrated.
73, Stefan VE4NSA
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of john heath
Sent: May-04-08 3:11 AM
To: Jeroen Vreeken
Subject: [amsat-bb] Re: FT 847 and Doppler for Delfi
Try a hard reset, the software in the 817 may have become corrupted.
Try running with the software COMMANDER I find it works realy well, and it
gives you some more features on the 817. It was written by the authjor of
Ham Radio Deluxe.
73 John G7HIA
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