In the third article of the series we will try to find GSM signal.
First of all, we need to design a signal processing algorithm. The GNU Radio package contains a frontend graphical interface designated for design signal processing flow graphs that may ease our work. It could be found in Application Center with GRC name, which means GNU Radio Companion. GRC automatically creates python programs for the required SDR blocks.
Let’s start with adding of USRP Source from UHD tab to the workspace of GRC. USRP Source is the abstraction layer that allows communication with a hardware. It produces digital signal which will be consumed by the next blocks in our flow graph. The source block tells our SDR to turn on receive mode.