The USRP is an Software Defined Radio created by Ettus Research. I have one with a WBX daughterboard.

For various notes and experimental results concerning the USRP, please have a look at the dedicated page on my wiki.

Performing an XO drift test on the USRP (just behind the laptop's screen).
The WBX is connected to an HP 8640B signal generator (on the left under the CRO).

The WBX can receive signals from a broad frequency range, for example 2G and 3G mobile networks:

A waterfall display of the spectrum around 948MHz (2G GSM) using GNU Radio.

If you wish to see various technical images concerning GSM, please visit the page on my wiki.