Measure distance in meters with radio

[dragospd]

Hi, I need an advice about the possibility to build a device (actually two) able to measure the distance between two points by using radio. So, basically there are two electronic devices, one is able to send a radio message to the other and the other will reply back. By multiplying the speed of light with the time needed by the radiowave to travel (measured by the device) we can find the distance.

I'm not so naive to believe that is a simple task, I don't know even if it is possible with the current technology; what I know is that it is possible to measure distances in kilometers.What I need is meters (10 meters would be the minimum)

By using an 1GHZ oscillator, in 1 ns a ray of light travels aprox 0.3 m. That means for one meter we have 3 cycles. It is possible to measure three cycles? What is the minimum?

Thanks for your opinions

 

[Harald Kapp]

Look up radar, it works similarly but uses only one combined transceiver and the reflections from the distant object.
You can buy radar modules fully assembled.