Modular Software Radio

The idea of this project is quite old, and different people tried to hack things together. The main characteristics of this implementation are the following:

  • Real-time operation using RTLinux
  • MIMO Tx/Rx with a bandwith of 5MHz @ 2.4-2.48GHz
  • Modular design
  • Graphical interface

Our Definition of Software Radio

We talk about Software Radio when the map between the data (sending and receiving) and the data-carrying antenna signal are completely (within hardware limits) specified by the software. Any map that conforms with the hardware limitations (power, bandwith, hardware imperfections) may be implemented by means of an appropriate code.

Bixio Rimoldi, 2003


Of course, the documentation is not complete yet, and I hope it will never be,as this is an ongoing project. Either go to the HTML-version of the documentation, or download the PS-file of the documentation. After reading this, you can make up your mind whether it's worth to continue looking at this project.


We have now a running 4x4 antenna system using custom-designed cards from Radio Innovation together with some high-quality A/D and D/A cards from ICS-LTD. Because of the limit of the PCI-bus we currently only get a bandwith of about 2MHz.


Click on image for bigger view

Here is our setup. Too many cables, I know ;) To the left and right you see four cards each, where each card handles one antenna in Tx- and Rx-direction.

Each card has an IF-in, IF-out, LO-in and RF-in/out connection. Furthermore there are some digital control lines in order to ajdust the gains and change the carrier-frequency of the transmission. There is also a line to switch between reception and transmission.

Below each group of four cards is a Dell Poweredge dual-Xeon server. Two years back they were quite fast at 2.4GHz. For long signal aquisitions we have 2GBytes of RAM in these.


  • 2004-06-01: we have now a working 4x4 LDPC-implementation over the air!
  • 2004-04-14: updated the manual-links
  • 2004-03-31: new release: sradio-1.0, changelog


These are some links relative to this software-radio: Logo