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GNU Radio for Tech Enthusiasts

GNU Radio is an open-source software development toolkit that provides signal processing blocks to implement software-defined radios and signal-processing systems. It uses a flow graph-based programming model where signal processing blocks are connected to build applications. The blocks are implemented in C++ and the flow graphs are written in Python. GNU Radio works with low-cost external RF hardware like the Universal Software Radio Peripheral for analog signal processing. It supports software radio architectures from tier 1 to tier 3.

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520 views34 pages

GNU Radio for Tech Enthusiasts

GNU Radio is an open-source software development toolkit that provides signal processing blocks to implement software-defined radios and signal-processing systems. It uses a flow graph-based programming model where signal processing blocks are connected to build applications. The blocks are implemented in C++ and the flow graphs are written in Python. GNU Radio works with low-cost external RF hardware like the Universal Software Radio Peripheral for analog signal processing. It supports software radio architectures from tier 1 to tier 3.

Uploaded by

Islam Osama
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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An Introduction to Gnu Radio

Kuntal Ray

Outline
Introduction
Software Radio What is GNU Radio?

GNU Radio Architecture


Hardware Architecture Software Architecture

Programming the GNU Radio


GNU Radio "Hello World" GNU Radio Companion

References

Outline
Introduction
Software Radio

Software Radio
An implementation technology A technique for moving digital signal processing into software Software Radio definition
Replacing Rigid Hardware... with flexible software based solutions

A software (defined) radio is a radio that includes a transmitter in which the operating parameters of the transmitter, including the frequency range, modulation type or maximum radiated or conducted output power can be altered by making a change in software without making any hardware changes.

Defining Software Radio using Tiers


Tier 0: The Hardware Radio
The radio is implemented using hardware components only and cannot be modified except through physical intervention

Tier 1: Software Controlled Radio(SCR)


Multiple hardware transceivers are required to support several protocols. Software controls are used to choose which transceiver to activate. An example will be a dual-mode mobile phone implementing GSM and code division multiple access (CDMA).

Defining Software Radio using Tiers


Tier 2: Software Defined Radio
It employs software to control various modulation techniques, wideband and narrowband operation, security. Example : GNU Radio and USRP2.

Tier 3: Ideal Software Radio


It includes all the features of Tier 2, but eliminates the analog amplification or heterodyne mixing prior to digital-to-analog conversion. Analog conversions taking place at the antenna.

Outline
Introduction
What is GNU Radio?

GNU Radio
An open source software toolkit
Supports, Linux, Mac OS and Windows Creating signal processing applications Defining waveforms in software Processing waveforms in software

A hardware platform USRP, Universal software radio peripheral, low cost HW platform for preprocessing
ADC &DAC FPGA Ethernet Interface to Host PC

A framework for building software radio transceivers

GNU Radio
Using the GNU radio is cross disciplinary
Requiring know-how in the fields of
Computer programming Communications systems Digital signal processing Analog as well as digital hardware
Hardware is also open source Schematics are available

Outline

GNU Radio Architecture


Hardware Architecture

GNU Radio Block Schematic

GNU Radio block schematic in more detail

Features of USRP2
100 MS/s 14-bit dual (IQ) ADCs
~80 MHz instantaneous RF bandwidth

400 MS/s 16-bit dual (IQ) DACs Gigabit Ethernet interface


3-6x improvement over US Allows for 25 MHz of RF BW each way @16bits Wide enough for WiFi!

Features of USRP2
Bigger FPGA w/Multipliers (Spartan 3) 1 MB high-speed on-board SRAM High speed serial expansion interface Configured by flash
Can operate without host computer

Outline

GNU Radio Architecture


Software Architecture

A 3 Tier Architecture
Python scripting language used for creating "signal flow graphs" C++ used for creating signal processing blocks
An already existing library of signaling blocks OFDM functionality is currently being added tested and will be added to the library.

Python Application development, creating flow graphs

C++ Signal processing modules


Scheduler Controlling flow graphs

The scheduler is using Pythons built-in module threading, to control the starting, stopping or waiting operations of the signal flow graph.

Software development on GNU Radio


The application of Python
It is a high Level scripting language Select sources , sinks & signal processing blocks Set parameters for the various blocks Using Python for creating flow graphs Connects the Signal processing blocks

Signal processing blocks in C++


Built as shared libraries dynamically loaded using python import feature SWIG "Simplified Wrapper and Interface Generator" used for glue code allowing python import. Components needed in writing a C++ block
.h & .cc file for class declaration .i file defining how SWIG generate glue code binding the C++ class into Python

Outline

Programming the GNU Radio


GNU Radio "Hello World"

Sine generator (350Hz)

GNU Radio Hello World application


#!/usr/bin/env python

from gnuradio import gr from gnuradio import audio def build_graph (): sampling_freq = 48000 ampl = 0.1
fg = gr.flow_graph () src0 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 350, ampl) src1 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 440, ampl) dst = audio.sink (sampling_freq) fg.connect ((src0, 0), (dst, 0)) fg.connect ((src1, 0), (dst, 1))

Sine generator (350Hz)


return fg if __name__ == __main__: fg = build_graph () fg.start () raw_input (Press Enter to quit: ) fg.stop ()

Audio Sink Sine generator (450Hz)

Hello world step-by-step


#!/usr/bin/env python `

Makes the python code executable by executing $ chmod +x filename.py"

Sine generator (350Hz) Audio Sink Sine generator (450Hz)

Hello world step-by-step


#!/usr/bin/env python

from gnuradio import gr from gnuradio import audio


`

Importing Necessary Modules, modules from GNU library

Sine generator (350Hz) Audio Sink Sine generator (450Hz)

Hello world step-by-step


#!/usr/bin/env python

from gnuradio import gr from gnuradio import audio def build_graph (): sampling_freq = 48000 ampl = 0.1
`

Setting up fo signal flow graph Sampling Freq and Amplitude on Sound Card

Sine generator (350Hz) Audio Sink Sine generator (450Hz)

Hello world step-by-step


#!/usr/bin/env python

from gnuradio import gr from gnuradio import audio def build_graph (): sampling_freq = 48000 ampl = 0.1

Setting up sine waves at 350 and 440 Hz

fg = gr.flow_graph () src0 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 350, ampl) src1 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 440, ampl)

Sine generator (350Hz) Audio Sink Sine generator (450Hz)

Hello world step-by-step


#!/usr/bin/env python

from gnuradio import gr from gnuradio import audio def build_graph (): sampling_freq = 48000 ampl = 0.1

defining destination to be soundcard

fg = gr.flow_graph () src0 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 350, ampl) src1 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 440, ampl) dst = audio.sink (sampling_freq) `

Sine generator (350Hz) Audio Sink Sine generator (450Hz)

Hello world step-by-step


#!/usr/bin/env python

from gnuradio import gr from gnuradio import audio def build_graph (): sampling_freq = 48000 ampl = 0.1

connecting source and destinations

fg = gr.flow_graph () src0 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 350, ampl) src1 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 440, ampl) dst = audio.sink (sampling_freq) fg.connect ((src0, 0), (dst, 0)) fg.connect ((src1, 0), (dst, 1))

Sine generator (350Hz)


`

Audio Sink Sine generator (450Hz)

Hello world step-by-step


#!/usr/bin/env python

from gnuradio import gr from gnuradio import audio def build_graph (): sampling_freq = 48000 ampl = 0.1

returning created flow graph

fg = gr.flow_graph () src0 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 350, ampl) src1 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 440, ampl) dst = audio.sink (sampling_freq) fg.connect ((src0, 0), (dst, 0)) fg.connect ((src1, 0), (dst, 1))

Sine generator (350Hz)


return fg

Audio Sink Sine generator (450Hz)

Hello world step-by-step


#!/usr/bin/env python

from gnuradio import gr from gnuradio import audio def build_graph (): sampling_freq = 48000 ampl = 0.1

Create code to execute the flowgraph

fg = gr.flow_graph () src0 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 350, ampl) src1 = gr.sig_source_f (sampling_freq, gr.GR_SIN_WAVE, 440, ampl) dst = audio.sink (sampling_freq) fg.connect ((src0, 0), (dst, 0)) fg.connect ((src1, 0), (dst, 1))

Sine generator (350Hz)


return fg

if __name__ == __main__: fg = build_graph () fg.start () raw_input (Press Enter to quit: ) fg.stop ()

Audio Sink Sine generator (450Hz)

Outline

GNU Radio Companion

GNU Radio Companion(GRC)


GRC is bundled with the GNU radio source. Graphical user Interface of GNU Radio Drag and drop feature. Flow can be created merely by connecting the block by mouse click GRC can generate source code as per the block connections.

Outline

References

References
GNU Radio website
http://www.gnu.org/software/gnuradio/

GNU Radio tutorials


http://www.nd.edu/ jnl/sdr/

How to Write a Signal Processing Block


http://www.gnu.org/software/gnuradio/doc/how to-write-a-block.html

Exploring GNU Radio


http://www.gnu.org/software/gnuradio/doc/expl oring-gnuradio.html

THANK YOU
ANY QUESTIONS??

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