[amsat-bb] Dish position pulse counter

Phil phillor at telstra.com
Thu Apr 24 16:46:52 PDT 2008

Thank you for reading this.

While looking for something to do recently, I came across a project that I was 
working on four years ago. It's the basis of a PIC controller for a home-built 
satellite dish rotator.

It's taken me the better part of a week to figure out what it's all about and I 
now remember one of the problems that slowed the pace of the project. I'm 
wondering if it's worth the effort of continuing.

The PIC was counting pulses reasonably well from the elevation jack but was not 
always accurate because of noise pulses from the motor. I expect the larger 
azimuth rotator motor will produce even more hash. An accurate pulse count is 
important so as not to accumulate a large error towards the end of a satellite 
pass. Constant stopping and starting would probably add extra pulses too.

Do home TV dish pointers use shielded cable to take the position pulses back to 
the controller? It's not something that I can test myself because my satellite 
gear is in storage more that 1100km from where I live.

I'm having second thoughts about the pulse counting scheme and I'm beginning to 
think that the tried and proven ten-turn pot method might be more fool proof.

Has anyone else had any success, or otherwise, with pulse counting? It's an 
interesting project but it might be impractical.


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