# Triagulating radio frequencies

1. May 27, 2008

### bassplayer142

I was just thinking the other day about how they triangulate on radio frequencies. Imagine an illegal fm broadcast they are trying to find. From thought (not necessarily right), they would have 3 vehicles with receivers that would form a triangle and depending on angles and the time it takes for the signal to reach each vehicle. Using some simultaneous equations they can figure out where it is from. I'm not asking anyone to do the math here as I don't know where to start. Is there any website out there or anything that anyone could lead me to. Thanks.

2. May 28, 2008

### FernBarc

I think they would need just two vehicles.
(the enough to get two lines)

3. May 28, 2008

### bassplayer142

Funny thing, I couldn't help but try this myself partly from boredom and it is just a great application and math practice. I did end up solving it just a minute ago and I only did need two vehicles. Is this how they do it because It seems logical and I don't know any other way. If anyone is interested in the answer let me know.

4. May 28, 2008

### maze

No need to measure signal strength. Just cover the radio up with metal foil in all but one direction, and rotate the radio/foil to determine which direction the radio signal is coming from.

5. May 28, 2008

### FernBarc

Do it twice, at different places, and you will get the "2 lines" stated in post #2.

6. May 28, 2008

### bassplayer142

My attempt was not to measure signal strength but the time for the signal to reach the separate vehicles. Using the difference you can find the distances. The foil approach sounds like a good idea. Does anyone know how agencies actually do this?

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