How to find distance between usrp and the object reflcting its rf wave using 2901 and labview 2014

[Tawahaa38]

I am making a long range metal detector that can detect a metal from a maximum of 30 meters.

and i know about this clock problem but i am trying to implement a proof of concept of long range metal detector with bad precision.
now i am thinking of finding the flight of signal by using bpsk modulation.

[DuncanW.]

That's an interesting project. BPSK could help you preserve the quality of your signal, but I don't believe it will allow you to get around the clock problem. Is there a reason you need to know the flight of the signal in order to detect a metal? It seems to me that you can just threshold the magnitude of the return signal.

If you don't care that your flight time will be heavily quantized, then you can use a counter that is hardware-triggered to start counting by the sent signal and hardware-triggered to stop counting by the received signal.