signal tracing

I 'd like to design a receiver that can trace the signal was emitted by the transimitter.
If I put a transimitter in a mobil stuff(like people or car), and transimitter emits the signal regularly.
The receiver can trace the signal from transimitter, and estiminates the distance and direction.
This stuff is really cool, that can trace someone or some stuff.
Does anyone know any relative product that has exist in the marketing?

Using one mobile transmitter and one receiver you can find only the direction of the transmitter.
http://userweb.springnet1.com/sparro...n-finding.html
To find direction and distance (actually to find the position of the transmitter) you need at least 3 synchronized receivers.
If the mobile transmitter is synchronized with the receiver (that is hard to implement) you can do also this job, calculating the distance from the delay between TX to RX.