FM Receiver in GNU Radio

2015 FM Receiver Using GNU Radio and USRP

Author: Rakesh Rakesh Email id: [email protected]

#9/3,Shree Lakshmi complex,2 nd Floor,Opp,To Vivekananda Park,Girinagar,Bangalore-560085 Park,Girinagar,Bangalore-560085.www.tenettech.com

What is GNU Radio? Radio? GNU Radio is a software library, which can be used to develop complete applications applications What is Univers Universal al Software Radio Radio Peripherial(USRP)? Peripherial(USRP)? The USRP is an integrated board which incorporates analog-to-digital converters (ADC) and digital-to-analog converters (DAC), some forms of RF front end, and an FPGA which does some important but computat computationally ionally expensive pre-processing of the input signal. GNU Radio along with the USRP makes the complete Software Defined Radio Introduction to Universal Software Radio Peripheral The Universal Software Radio Peripheral (USRP) enables engineers to rapidly design and implement powerful, flexible software radio systems. The intuitive USRP design helps you to get your software software radio up and running quickly. quickly. Simply download GNU Radio, a complete open source software radio and signal processing package, and the USRP is ready to use. Once you install the software and plug the USRP into a host computer, it is ready to transmit and receive a virtually limitless variety of signals . Features of USRP 

Four 64 MS/s 12-bit analog to digital Converters

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Four128 MS/s 14-bit digital to analog Converters

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Four digital downconverters with programmable decimation rates

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Two digital upconverters with programmable interpolation interpolatio n rates

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High-speed USB 2.0 interface (480 Mb/s)

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Capable of processing signals up to 16 MHz wide

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Modular architecture architecture supports wide variety of RF daughterboards


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Auxiliary analog analog and digital I/O support complex complex radio controls controls such as RSSI RSSI and AGC

Blocks for building FM receiver

The USRP Source block initiates the flow graph in the GNU Radio that allows the interfacing with the hardware (USRP).The important parameter to be noticed is the output port which is blue in color, which means that signals are received in complex (16bit) format and there are other parameters to be mentioned in the block like shown in the figure

The band pass filter is used to filter out the unwanted high frequency components and to tune to all the FM stations available. The band pass filter has a decimation factor in order to reduce the incoming samples.

The wideband FM receiver is used to demodulate the received signal. The Quadrature rate parameter indicates, at what rate the demodulated signals are passed out. The input received is complex and the output is in float format.


The Rational Resampler block is meant for resampling the signals. In other way, it performs both interpolation and decimation process in order to adjust the sampling rate that is suitable to the output sink. Ratio = (input sampling rate*interpolation)/dec rate*interpolation)/decimation imation

The audio sink block terminates the flow graph in GNU Radio. It is used to listen to the tuned FM stations at 96kilo samples/sec.

The FFT sink is used to view frequency domain representation of the output.


The final flow graph of the FM receiver

USRP SETUP


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Connect the usb2.0 cable to communicate communicate with the host PC. The wbx daughter board is mounted at the given slot on the motherboard motherboard which is capable capable of receiving the signal signal from 50MHZ to 2.2GHZ.

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Connect the vert200 antenna for the reception of the FM

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Finally supply the power to switch on the board .


FM Receiver in GNU Radio

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