[amsat-bb] Re: Offset Correction for CW Beacons in SatPC32

Erich Eichmann erich.eichmann at t-online.de
Sat Dec 2 03:03:28 PST 2006

1. to calibrate your  2 data lines for each SSB sat  for SSB and CW do
the following (separately for the SSB and CW entry):

While the satellite is audible calibrate the uplink frequency until you hear
your own voice or CW signal with the best audio pitch. To fine tune the
uplink frequency use the "Upl. Calibr." controls in menu CAT (these controls
leave the downlink frequency unchanged, so, they change the offset between
downlink and uplink frequency).

Then click the button "Change/Store Data File". In the menu that opens click
on "Store ...Uplink Calibration". This function saves the new offset and at
next program start you should hear your own signal with the right audio
pitch or very close to it.

Recently there was a discussion whether to use the button "Change/Store
.. TX/RX frequency data" to save the calibration. The purpose of that
function is another one, however, see below.

The calibration  procedure should be done with each SSB satellite, because
there are hardware depending frequency deviations between the single radios.
So, the frequencies that come with the program can't be optimized for each
radio. Between my IC-821H and IC-910H, i.e., is a deviation of  about 1 KHz.

The mode entry in Doppler.SQF (USB, LSB, CW) can be changed only manually
with Notepad, of course.

To start CAT tuning immediately on the beacon frequency of a satellite, i.e.
FO-29, do the following (after you executed the procedure above 1):

While the satellite is audible tune the radio to the satellite's beacon
signal. That can be done with the VFO knob.

In menu "CAT" click the button "Change/Store Data File" and in the menu that
opens click on "Change/Store RX/TX  Freq. Data".

That will save the new uplink AND downlink frequencies (after eliminating
the actual Doppler shifts, of course) but leaves the offset unchanged. To
operate over the satellite you only need to tune off the beacon frequency to
an unused frequency.

(This feature was very helpful with the AO-40 S-band beacon. It allowed to
easily find the own downlink signal inspite of the daily temperature changes
of the outdoor  downconverter L.O.)

3.There is a detailed description of these functions in the manual in the
section regarding menu CAT.

73s, Erich, DK1TB

----- Original Message ----- 
From: "Dean Shutt" <al7cr at amsat.org>
To: <erich.eichmann at t-online.de>
Cc: <amsat-bb at amsat.org>
Sent: Friday, December 01, 2006 8:56 PM
Subject: [amsat-bb] Offset Correction for CW Beacons in SatPC32

> Erich,
> Further to a recent question, it appears that I must change the
> doppler.sqf file to calibrate a cw beacon rather than use the
> "change/store data file" button.  Is this correct?  I have a seperate
> line for each SSB sat that tunes the beacon frequency in CW mode and was
> attempting to adjust for the offsets in my system.
> Thanks for the help.
> 73 de Dean, AL7CR
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