Bernie,

The centers of the uplink and downlink are the easiest starting points. SatPC32 uses commas as delimiters to separate the various values in the configuration files. The trailing comma allows for an optional comment in Doppler.Sqf. So you want that there, even without a comment.

As to why the tracking isn't working well. First, the Doppler.sqf values are nominal, which is good enough for most FM satellites. FM has many vices, but it is relatively insensitive to small frequency devations. In reality, the actually satellite calibrations will be close, but vary due to things like aging, temperature shifts, power supplie voltage, etc. Likewise, your rig will probably not be exactly on frequency. So once you get the nominal values in, you will need to tweak the actual values. See 4. 'CAT' menu in the manual for details on why and how.

Another cause of drifting is your computer clock. It needs to be accurate within a couple of seconds, preferably better, for the Doppler calculation to be correct. A good quick check is to go to https://time.is/ which does a remarkably good job. If you are significantly off, you will need to address that.

Finally, some satellites drift more than others. AO-73, for reasons of component cost and availability when launched, drifts enough that Doppler control is not normally used. AO-7 also drifts a bit, and has seasonal variations. The SatPC32 manual discusses how to make one off tuning in these cases.

73,

Alan WA4SCA

<-----Original Message----- <From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Bernie and Cheryl <via AMSAT-BB <Sent: Saturday, October 31, 2020 12:57 AM <To: amsat-bb@amsat.org <Subject: [amsat-bb] Doppler.Sqf files in SatPC32 < <Dear Folks: < <I have two questions. < <First, I am having trouble figuring out CAT for the linear satellites <(not as critical as FM birds, but my CAT works for those just fine). <When I create the Doppler.Sqf file for SatPC32, do I used the center <frequency for the passband as the entry into the file, or should I use <some other frequency? When I try and use CAT for the linear birds, it <really doesn't work (the downlink and uplink frequencies rarely match up <and I end up adjusting for doppler manually after turning CAT off). < <Second, I initially typed up my Sqf files by hand after reading the <instructions. However, I checked out the Sqf file generator on the <AMSAT and notice that the file generated always ends with a ",". Since <I hadn't included that when I manually typed the files (I've since added <it) is it possible that that could be part of the problem on the linear <birds? < <Thanks for any help you can give me and 73 de Bernie, KF0QS < < <_______________________________________________ <Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available <to all interested persons worldwide without requiring membership. Opinions expressed <are solely those of the author, and do not reflect the official views of AMSAT-NA. <Not an AMSAT-NA member? Join now to support the amateur satellite program! <Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb