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DIY radio tracking system? Answered

i need to track my dog, and i would like to do it with a radio tracking system, but since im a DIY guy i dont care to buy it, (only to examin it if necessary ;)) and i would like it to have a needle indicator, is that possible? have used the last motnh searching the net for at tips and inspiration for the tracking system.



Of course it is! What I'll describe only shows direction, not distance. Transmitter gets stuck on dog. Grab a directional antenna (search up "cantenna") and connect to receiver circuit tuned to transmitter frequency. Turn around 360 until you find the signal (you can make the transmitter transmit your favorite music or morse code or just plain static). You know you found the signal when the signal is strongest. That's the simplest I can give you. If you wanna find distance, you're gonna have to go trigonometry and give a hand for the art of triangulation (I would solder myself a calculator to calculate in the field but that's something different). The needle indicator is something I wouldn't consider if you were looking for something simple, and just let your mind do the number crunching. Just make sure the transmitter isn't strong enough to jam commercial radio stations (different frequency perhaps?).

I found a project (not the simple German School kid one). http://www.patents.com/us-5170172.html
A little more sophisticated, but along the same lines.
The one I liked used an A.M. pulse of x frequency, when received by second board, initiates pulse of y frequency, when received crunches the speed of sound equation. A simple four digit display gives you meters. Not direction.

This is for direction. A little more complex. http://clearrx.tripod.com/RDFUNIT.HTM

Hope this helps.

Google "ham radio fox hunting" and "ham radio direction finding".  You'll get all the info you need.

Ham licenses are easy to get now and that will let you legally use more power at the transmitter assuring you that you won't loose track of your dog.

Direction finding is based on finding the direction of the strongest signal coming from the trans.  Most systems are hand held and you wave a directional antenna around looking for the peaks.

There are a few systems that use 3 or 4 antennas then analyze the signal from those antennas to give you a pointer or indicator on a dial that shows you the direction to go.  Those are going to be much more expensive since they need some kind of computer controller and software to analyze the signals.  It can be done without the computer but it's much less accurate.

thats some good information thank you iy=t helped me out too... i have a couple more questions and i was hoping that you might be able to answer them, i am new to all this and know next to nothing about ham radios... i can however make something from a schematic. would you please clarify what sort of radio transmitter i would need and the approx. size of both the transmitter and receiver and maybe any other information that might be useful to a newbie?

Why not build a bleeper and attach to the dogs collar. 

You could then make it dependent on a short range radio signal from a transmitter you keep (receivers are smaller so put on the dog) when it goes out of range it starts to BEEP.  This is probably easier and more effective than direction finding a radio collar.

On the other hand train the dog to come to you when you call it!.

Some sort of simple, small, FM transmitter fed with an audio tone should be easy to do.  Picking up the signal, a good Yagi antenna will have the directionality you need.

You'll find you can get better directionality using the returned tone (which you'd pick up with a standard FM radio) and a pair of headphones. Human hearing is incredibly good at hearing changes in signal level, but eyes are not good at seeing small changes in meter position.