Gec Avery Limited

Jonathan Paul Evans

A system for sensing the value of a physical property (such as force, temperature or movement) and having a plurality of sensors used in combination, for example a weighing system where a plurality of load cells are employed to sense the magnitude of a load placed on a weighing platform, has a first analogue to digital (A/D) converter and a second A/D converter, capable of faster operation than said first A/D converter; wherein said first A/D converter produces a signal representative of the average of the physical property and said second A/D converter produces a signal representative of the distribution of sensor output signal amplitudes amongst the sensors, thereby overcoming the problems associated with the prior art in producing a high resolution, high accuracy result but without requiring a high speed, high resolution A/D converter.

Sensing system

Difficulty is experienced where filters are required to provide a high level of noise reduction and a fast step response in systems where a large input step in comparison to the final resolution may occur. A suitable filter comprises a variable length averaging filter, an averaging sample counter, the count of which is reduced by a predetermined factor when the count reaches a maximum value, and a spike counter, the count of which is incremented when the difference between an input sample and the current filter output exceeds a predetermined value, the sample count being reset to 1 when the spike count reaches a predetermined value, the filter output being otherwise maintained at the previous output.

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Warley, United Kingdom

Jonathan Paul Evans