GNU Radio is an open source software tool kit that enables
building of a Software Defined Radio. The prime advantage
obtained by GNU Radio is by creating different radio devices
on a single USRP board. Different functionalities like modulation,
demodulation, filtering, encoding, decoding, source
coding, channel coding etc. are provided as software codes
[9]. The advantage of implementing functionalities as software
modules is that it provides a high degree and ease of reconfigurability
property to SDR. One of the helpful attributes
accepted by GNU Radio is the spectrum analyzing tool which
can be useful in detecting the carrier frequency of a BTS.
Also in conjunction with Airprobe tool, collective broadcast
messages from the BTS can be acquired.