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| The main circuit of the DOG Tracker. |
OBSERVATIONS FROM NORWAY . 05-05-07.
A FULLY AUTOMATED SATELLITE STATION USING 25 YEAR OLD RADIOS.
So ... you have 25 year old radios without CAT interfaces ... you're bone idle!
and want to operate a fully automated amateur satellite station? ... what do you
do? ...
You use The DOG Tracker.
The DOG Tracker is a "lunchbox" that allows you to operate your satellite
station fully automated, that is to say, even with rigs that only have mic push
button controls it will automatically compensate for doppler as well as turn
your rotors to track a satellite ... so that you can just sit back, relax and
bellow "ARRRRRRRRRRGGHHHHHH!!!!" into the microphone ... (preferably on top of
somebody else who's already using that frequency) ... full duplex? ... ugh ??
... what's that !!!! got to do with satellite operating.
The DOG Tracker will do everything for you ... providing you hook it up to
InstantTRACK's ITUNE software and the NOVA satellite tracking program.
I wish somebody would write some tracking software that performed *ALL* the
necessary tracking and tuning functions for people like me who don't have two
pennies to rub together but unfortunately, they don't. I'm a bit long in the
tooth these days and can't follow the the "cutting edge" technology either brain
wise or economy wise ... (I assume I'm not alone) ... therefore ... like the
actress said to the bishop ... IMPROVISE !!!.
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| The main circuit of the DOG Tracker. |
The PIC software used for this system came from the site at FODTrack Software on Geocities and due acknowledgement is given. It can handle both AZ and EL with a single microcontroller. Two potentiometers measure the difference in AZ and EL between wanted and actual angles and the software attempts to converge the readings to zero error. The PIC of course runs on a regulated 5V supply. The 7805 is overkill for this job so if you have a low power 100ma version 78LO5, use that instead.
The "guts" of the system uses a PIC16F877 and the NOVA tracking software to control the rotors and status LEDs. The automatic doppler tuning is taken care of by the Instant-TUNE software and a couple of transistors and relays. In my case, the circuit is built into a plastic lunchbox (!) ... (because it was available).
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| When in doubt...... Improvise! |
The circuit diagrams should be self explanatory. The necessary software can be
downloaded from the Amsat-NA website.
Some points worth noting. Instant-TUNE "knows" when you change frequency so
whenever you tune your TX VFO, the RX frequency will follow and will always!! be
correctly compensated for for Doppler-wise.
THE FLY IN THE OINTMENT.
Be aware that Instant-TUNE can *ONLY* function as *EITHER* a transmit or a
receive system so to be 100% fully automated you need 2 interfaces ... (one for
TX and one for RX) ... as well as two computers to control them.
Stop complaining !!! ... this is a system for those who can't !!!! afford the
latest "all singing, all dancing" dedicated satellite radios. I'm sure you can
find a couple of old "throw-away" 386 computers somewhere!!.
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| Simple AZ-only DEMO version of the DOG Tracker. |
Why call this "lunchbox" The DOG Tracker? ... well, the "Observations" website
started out with the satellite book for potential with the working title
SATELLITES FOR DOGS. You can figure the rest out for yourself.
Post Scrotum.
"MANUAL" doppler tuning and tracking is *MUCH* more fun and educational.
73 John. <la2qaa@amsat.org>