I've done this very thing! I published details in OSCAR News 184, December 2008, page
It uses a very cheap PICAXE 08M chip, which interfaces via the COM port on the main computer. The program on the PICAXE is trivial. The difficult part of the project was to interface the COM port with SatExploer tracking program. I've no idea what would be involved with other tracking programs.
A temporary package containing the source codes for both parts are on my website www.g3cwv.co.uk/doppler.htm
I can e-mail a copy of the original article & circuits if needed.
BTW I've got a related question about doppler tracking which I'll raise in a separate thread.
73 Clive G3CWV
Hitchin, North Hertfordshire, UK
Ryan Caron wrote:
Anybody ever rig up automatic doppler tuning to a FT-726? Without a CI-V interface (or equivalent) the best idea I can think of is splicing a microcontroller in to push the up, down, and maybe the fast buttons on the microphone during a pass.
Then I'd just have to dial in the initial frequency before the pass starts.
73, Ryan KB1LKI AMSAT #37207