Auto Tracking Antenna?

[Tristar500]

anybody have any info on setting up an auto tracking antenna? We have a GPS onboard and a radio modem sending the data to the ground.

Now, if we could just get an interface to run a couple of stepper motors or servos that would keep the antenna aimed at the plane using the GPS data.

Any ideas?


Lawrence

[Quacker]

I've considered building one several times. What kind of antenna gain and beamwidth are you thinking about?

[ockie]

My take on this problem: you have GPS on the aircraft, thus its position is known at all times. If a secondary GPS unit is kept at your base/ground station near the directional antenna (ideally the ground based GPS receiver could have an external antenna mounted on the same mast as your directional comms antenna), that precise location is known as well. Having both these coordinates (and a fixed frame of reference, ofcourse) it is down to simple trignometry to calculated where your antenna must point. Because lattitude, longitude and elevation may not be precise (or the fact that your GPS update rate might be too slow -- although COTS 4Hz systems should be MORE than adequate) you could possibly factor the RSSI (signal strength) ouput of your ground station radio modem into the control loop for the antenna actuators. This might even compensate for the directional antenna's possible non perfect radiation pattern.

Now, to implement all this will take an evening or two -- should be well worth the effort though! ;-)

[lvspark]

Been done many times before...

Check out the balloon guys and thier software.. I believe Baltrack for windows has tracking built in... Uses ARPS data with a TNC.. Doesn't work with soundcard packet..
http://www.eoss.org/balsoft.htm

Hams also use it so search some of those HAM sites..