ERA's Electronic Systems business was contracted by Chelton Ltd to deliver the next generation of RF interference cancellation system. ERA produced a miniaturised version of Chelton's successful INCAN^TM (INterference CANcellation) product, named mINCAN^TM.

RF interference cancellation is important when wideband RF transmitters and receivers are co-located in close proximity. This is becoming increasingly common in many modern RF communication installations and a mINCANTM system is used to protect one or more RF receivers from interference caused by one or more of the co-sited RF transmitters. A RF cancellation system works much in the same way as a proprietary acoustic noise cancellation system. These acoustic systems are typically headphones where the ambient acoustic noise levels outside the headphone are monitored and an exact anti-phase version of the ambient noise is injected into the headphone speaker to achieve cancellation. Although perfect for enjoying CD music while travelling on a commercial airliner, implementation of the technique to achieve the same effect with modern frequency-hopping RF communication systems is considerably more complex.

In a mINCAN^TM system, a sample of each interfering RF signal is fed into the unit, adjusted in magnitude and phase, and the resultant signal injected into the feed line between the receiver antenna the each receiver. Cancellation is achieved by monitoring the residual composite signal, which enters a control loop, to effectively phase out or cancel the interfering signal.

The advantage of the design that ERA has developed for Chelton is that it provides filtering and co-site improvement particularly for in-band coupled signals as well as wideband cancellation in a compact, miniaturised package. The technology also cancels the 'big-bang' RF phenomenon and ensures that receiver desensitization does not occur.

ERA's Electronic Systems group has considerable expertise in RF interference cancellation techniques and this project is another successful demonstration of ERA's world-class design consultancy services for electronics, sensors and wireless communications.

For further information, please contact steve.nightingale@era.co.uk or visit www.chelton.com