The field of private mobile radio systems (taxis, police, emergency services, dispatch
systems etc.) is undergoing accelerated change and deregulation. More users,
demanding more services with better quality, are squeezed into the same bandwidth.
However, noise and impulsive noise levels on the radio path are increasing and this
reduces quality. This project seeks to use advanced signal processing to develop a
generic noise blanking technique suitable for a new generation of mobile radio
equipment to be developed by Motorola Australia.
The project involves an analysis of impulsive noise sources (car ignitions, overhead
powerlines etc), a review of existing noise blanking techniques, which will then lead
to the development of an appropriate noise blanking technique suitable for the
impending deregulated environment. The method chosen used a surface acoustic
wave delay filter (SAW) and a balanced blanker switch. It outperformed the pervious
noise blanker in both bench and field tests. The shape of the blanking pulse was found
to be critical for good blanker performance.