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Re: Doppler programming question - more



iPhil:

I'm in the process of rewriting the user interface for my
custom rotator/radio control box. The controller runs Java
and sits on the Ethernet. The user interface is being done
in Java so it will "run anywhere", and talks over Ethernet
both to NOVA and the control box. Of course, the control of
the radio is via a serial interface from the controller.

I get tracking info from NOVA using a TCP connection. I
worked with Michael to get that feature added. It's now in
the current version of NOVA. Later on, I plan on adding
predict as a tracking server.

I already have one interface running in Visual Basic, and as
you stated, it corrects both the transmitter and receiver
for doppler. Otherwise, as doppler changes, the transmit
frequency as seen in the downlink passband would drift
up/down. The Java version will do the same.

Art
N3OY

P.S. FYI for those who write their own software. As of
Visual Basic.net, Microsoft has dropped support for DDE.
That's why I convinced Mike Owen to support a TCP connection
In NOVA to obtain the same tracking info put out over DDE.

He's got it set up to accept a TCP connection on a port you
specify, either from any machine, or only from a specific
host. (Security, you know.) Then, every time you send
"SUMMARY" over that connection, NOVA responds with the
tracking data string.


Phil wrote:
> 
> Thank you all for the replies. I have a lot to read and will digest them
> offline.
> 
> A couple of points so far:
> 
> 1. I don't need to calculate the Doppler shifts; I'm getting those from
> Predict running in server mode. So I'm confident that at least that part is
> correct.
> 
> 2. I am trying to correct both the up and downlink frequencies at the same
> time. I'm told that I shouldn't do this. Isn't that the aim of "the one true
> Doppler rule"?
> 
> 3. If I correct just the downlink then the beacon stays fairly well in tune
> for say ten minutes or so on FO-29. However, my uplink drifts and that's why
> I started on uplink correction.
> 
> I've tried to get enlightenment from other tracking programs, including Itrack
> for Windows, but it isn't easy trying to understand undocumented code.
> 
> I'll think about this some more, during the night when I should be asleep no
> doubt.
> 
> By the way, I'm pleased to have added two more countries to my growing list of
> contacts made on AO-40, none from the US yet.
> 
> --
> Regards,
> Phil.
> 
> ----
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