[amsat-bb] Re: Question about tuning for doppler and SatPC32

Jim K0SBH k0sbhjim at sbcglobal.net
Mon Nov 20 17:21:17 PST 2006

Hi Ed,
  I do agree with your resolve on using pc-32 to tune the uplink freq. This will in fact keep you very close to the original receive freq. You start out on, and not slide down/up on others using the bird. Not discounting how others might be tuning. hi hi
  As an old , AO-10 and AO-13 guy, I could always be found on the DX freq. that we "DXer's" so called, used. The uplink freq. was the only one that was ever corrected during a QSO. This worked out best on a crowded transponder.
  A system that needs to be implemented for the LEO's is up to the majority of users. This has been bantered about over the years. The aforementioned system of only changing the uplink freq. is my choice and not that I should try and impose it on others, but it does work. 
  A nice thing about using the birds is that there is a most courteous group and I am not sure of the explanation why? But it is a very helpful group. Unlike 75/80 meter where the self appointed Freq. police are always lurking. hi hi
  Friendship Through Ham Radio,
  Jim, K0SBH
  Satellite-DXCC,WAS,WAC, one short of WAZ
  Former Oscar Satellite Report, OSR, DX Editor
ehekman at cox.net wrote:
  I have found it much easier to maintain QSOs when both stations use computer controlled Doppler correction on both links. The downlink frequency errors are easily tracked with the receiver RIT control. 

It seems to me that the best practice out of courtesy to others is to always use Doppler correction on the uplink. If that is done then the uplink and downlinks frequencies stay nearly constant at the satellite and the receiving station can follow the signal with computer control and very minor RIT adjustments. If uplink Doppler correction is not used then receiving stations must manually track the downlink frequency.

Since I have found it easy to implement and it makes QSOs much easier to maintain I am curious why computer controlled Doppler correction is not used by all stations. Are there some radios still in use that do not have the capability for computer control?

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