Software Radio Testbed
Our software radio testbed has been implemented as a set of components
written in C and C++. These components can be assembled to form a
communications system. We have implemented the following receivers using
- AM Receiver
- Narrowband FM Receiver
- Broadcast FM Receiver with stereo recovery
- FSK data (A BIM compatible receiver)
- BPSK, QPSK, etc (nearly there!)
Our receiver hardware consists of a minimal radio front-end receiver,
an IF amplifier and a high speed A/D converter.
The A/D converter digitises a 10.7MHz IF and performs all remaining processing
in real-time on a PC. Although a RTOS is not being used, real-time processing targets for this receiver are achieved
Our transmitter system is under development. This consists of a high speed D/A
converter and with an up-conversion module that can generate signals in
multiple bands of interest.
We have implemented our system on Windows 2000. Our system consists of a set of
software radio components built from optimised signal processing libraries.
These components can be assembled dynamically
to create the desired receiver. We have also implemented some components
that allow the analysis and recording of data about the software radio system.
This has proved an invaluable resource when developing and testing new modulation schemes.
The following screenshot shows a real-time power spectrum display of a demodulated FM signal.
This picture outlines the different components of the FM signal.
This spectrum display component can be inserted anywhere in the communications system
to monitor the frequency content of signals at this point. For example, this screenshot
shows the frequency content of the signal when it is inserted after audio filtering of
the mono component of the signal.
This screenshot shows the spectrum of the digitised 10.7 MHz IF.
Click here to listen to a sample of demodulated broadcast FM.
Mackenzie, P., Doyle, L., O'Mahony, D.& Nolan, K.,
Software Radio on General-Purpose Processors, in Proceedings of
the First Joint IEI/IEE Symposium on Telecommunications Systems Research, Dublin, November 27th, 2001
Mail me if you have any questions or comments.
Last modified: 12th December 2001