[amsat-bb] SSB, SatPC32 and Doppler (was Two Questions)

Stephen E. Belter seb at wintek.com
Fri Sep 23 04:41:36 PDT 2011

This e-mail is my feeble attempt to provide a helpful response to how to set-up SatPC32 for Doppler correction when operating SSB.  I'm not an expert, but I just went through this process because I'm migrating from Nova to SatPC32.  

Since I'm out-of-town, I don't have access to my satellite station, so I'm doing this from memory.  I also deleted your original post, as I was hopeful that an expert would step forward to help you.

Your station is fine, with the Kenwood TS-2000 (?) and SatPC32.  Your success operating the FM satellites is a good proving ground.

Here is the approach I took:

(1)  Install SatPC32, update the Keplarian elements, and synchronize the PC clock to a national standard like WWV/NIST.

(2)  Get your radio and SatPC32 communicating, and verify the operation (including Doppler correction) using the FM satellites (AO-27, SO-50, and AO-51).

(3)  Wait for a good pass of VO-52, for example 60+ degrees maximum elevation.  I suggest VO-52 because it is the newest (compared to AO-7 and FO-29), it is more tolerant of using too much transmit power, and it has the smallest transponder correction.

(4)  Open the "CAT" window.  You can move the Window so that it doesn't block access to the main SatPC32 window.  Tune the radio above the center of the satellite passband to reduce the QRM to other users.  Make sure you are in SSB mode on the radio ("C-" on SatPC32).

(5)  Using your call and "Test 1-2-3", listen for yourself while you are transmitting.  You probably won't hear yourself at all, at least I didn't.  Using the +100 and -100 buttons in the Transmit Correction part of the CAT window, try to find yourself.  For VO-52, you should hear yourself within +/- 1500 hertz.  (I think I was about +800, but that is from memory.)

(6)  Once you hear yourself using the +/-100 buttons, fine tune using the +/-10 buttons.

(7)  You can improve the tuning of your uplink/downlink using CW mode ("C+" on SatPC32).  Zero-beat the Kenwood's CW sidetone with your received signal.

(8)  *Save* the result by using the "Save" button in the CAT window.  When given the choice, save the transmitter correction.

(9)  Verify that things are working by working a few VO-52 QSOs.  

(10)  Repeat using FO-29 and AO-7, in that order.  You may need to search over a wider frequency range (+/-3000 hertz).

(11)  One other important change when moving from FM to SSB.  Your power output is important!  Learn how to reduce your power and use the minimum power needed to hear yourself on the satellite.  If you use too much power, you'll trash other conversations on the satellite and your transmissions will be badly distorted!

Good luck!

73, Steve N9IP

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