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Welcome to the fixed and mobile communications research website.

Satellite transmission

Satellite transmission

Received image

Received image

Iterative decoder after 5 iterations

Iterative decoder after 5 iterations

Final output of iterative decoder

Final output of iterative decoder

The above images show the benefit of error correction coding in satellite communications.

The main activities of the group are split into two areas:

Latest Research Areas

Analogue error correction

It has been recently realised that the classical BCH codes may be applied to analogue sampled waveforms using the discrete Fourier transform to produce codewords capable of correcting errors resulting from storage or transmission. This is the subject of a recent patent filing by the group: "Error correction system using the discrete Fourier transform" , M. Tomlinson, C. Tjhai, M. Ambroze and M. Ahmed, US patent application 12,057,781.

Received Audio samples Decoder Decoded audio samples
 
input to decoder (with errors)
  
output of decoder (all errors corrected)

 

Future music error correction

 

Personal Radio Station

This is a new patented concept(Patent Applications 0813074.2 and 0816312.3) that could make the use of DAB radio obsolete within the home. The idea is to set up your own personal broadcast transmitter within the home and the transmitter relays information from a radio station feed on the Internet or received by a communications satellite to one or more portable domestic (modified) transistor radios around the house or garden. The transmission format used is robust (free from noise or interference), high quality (better than FM) and provides instant reception upon switching on of any of the radios. Battery consumption of the modified transistor radios is minimal. A transmitter is provided within the radios so that the required station may be heard. Other information such as weather reports, sports results or breaking news may also be selected. We are seeking manufacturers of the technology and it is hoped to make this new product available to consumers within 12 months.

Prototype of new domestic radio Base station Another view of the prototype

This is featured on ITV West Country news on 23rd October 2008.

"Green Radio": incremental redundancy for wireless links

The idea is to use modern coding techniques to reduce the energy required to communicate each bit of information. In this way the transmitted power may be reduced, limiting energy consumption, extending battery life for mobile applications and generally reducing the health risks from the totality of all electromagnetic radiation.

A practical very low power "green radio" system is being evaluated using chains of extended BCH codes and CRC-less error detection in a hybrid ARQ arrangement. The theoretical basis for this is described here and also a subject of a recent patent filing: "Incremental Redundancy Coding System”, M. Tomlinson and C.J. Tjhai, US Patent Application 11/751313.

RF transceiver at 433MHz Transmitted RF spectrum Link performance analysis
Green radio transceiver at 433MHz
Transmitted RF spectrum
Link performance analysis

 

Train detection with greater safety margins

Typically error correcting codes are used in space communications. By ensuring that all transmitted waveforms have to be codewords, unwanted interference and noise will be rejected by the receiver and very reliable communication is achieved. Working with a leading company specialising in train signalling systems, the research group have successfully applied a new coding technique to next generation train signalling systems, which will result in increased safety for rail travellers.

Rail track Train

 

 

Latest Research Areas (additional information)

For further information on any of these topics, please contact Prof. Martin Tomlinson.