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An introduction to RALF

D 16 December 2017    

RAdio Logicielle pour la Formation (RALF): an educational software defined radio platform at the University of Toulouse.

Project summary

The RALF project has been carried out by the University of Toulouse/ISAE-Supaero (since 2014) in order to promote Software Defined Radio (SDR) techniques in several engineering trainings. One can define a SDR transceiver as a generic hardware device (typically wideband with high sampling rate) where all application-related signal processing is performed in the digital domain thanks to a host computer or an embedded controller. It results in a highly flexible architecture, generally made of high-level software building blocks allowing to move from an application/standard to another within a tenth of second.

From an educational point of view, SDR offers several advantages:

  • cross-curricular approach involving digital communications, beamforming, computer science, networks, radio frequency electronics, embedded electronics;
  • fully functional applications based on well-known standards and presented with an appropriate abstraction level;
  • well suited to new teaching methods (e.g. project based, active, flipped teaching...);
  • possible connection with research topics (from a simulator to a demonstrator);
  • source code oriented project management, more and more used in the industry (e.g. agile, eXtreme programming).

For all those reasons, we believe that SDR can be a valuable professionalizing approach to bridge the gap between theory and practice in the field of telecommunications and signal processing.

Examples of applications

The wide frequency range covered by our transceivers enables a large set of potential applications:

  • aeronautic (ACARS, VDL mode 2, ADS-B, HFDL...);
  • satellite (NOAA APT, DVB-S...);
  • cellular (GSM, UMTS, LTE, POCSAG...);
  • home automation (CCIR tones...);
  • amateur radio (SSB, APRS, PSK31...);
  • audio and video broadcast (FM, DVB-T, DRM...);
  • direction finding (AOA, TOA...);
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An USRP B200 station
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A FM receiver flowgraph with GNURadio Companion
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Waterfall plot in the GSM band
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A QPSK modulation observed with GNURadio
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A typical RALF workbench
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An USRP N210 transceiver


The project has been funded by the University of Toulouse (23 k€) and ISAE-Supaero (13 k€). It includes several members: ENAC, ENSEEIHT, INSA, UPS. RALF also benefits from the experience and hardware resources from several partners such as GIPSA-lab, National Instruments and The MathWorks. More information is given on the team page.

The project will be composed of two parts:

  • hardware available for loan (mainly SDR transceivers);
  • a fully equipped platform hosted at ISAE-Supaero (rooftop antennas, signal analyzers and synthesizers, desktop computers..);

A collaboration platform is provided to support RALF’s projects and centralize documentation and teaching resources (programs, lab subjects...). Every member/partner is encouraged to use it.


For further information, you can contact D. Roque (associate professor at ISAE-Supaero).