Elsag International N.v.

Tourang Birangi

Joseph C Nemer

Pierre C Bertrand

A method and apparatus for increasing the resolution of a pulse width modulated signal representative of a measured parameter such as the pressure measured by a pressure cell. The analog signal from the pressure cell is converted to a digital signal using a predetermined clock frequency. The digital signal is scaled to 2.sup.N (N is an integer greater than or equal to one) times the clock frequency and the N lowest order bits are checked to determine if they are a one or a zero. A one is added to the least significant bit of the scaled digital signal in a predetermined manner in the next N consecutive cycles of the scaled digital signal dependent upon the which of the N lowest order bits are a one.

Method and apparatus for increasing the resolution of a digital to

A method for compensating for the differences in temperature across a cell used to sense pressure. A microprocessor calculates a dynamic temperature factor signal by multiplying a signal representative of temperature change across the cell by a coefficient based on measurements made of the effect of temperature change on the cell. The dynamic temperature factor signal is then subtracted from the signal representative of the differential pressure sensed by the cell to thereby provide the dynamic temperature compensation.

Dynamic temperature compensation for a pressure cell

A method for filtering digital signals in a pressure transmitter. The transmitter includes a microprocessor. In each operating cycle of the microprocessor included in the transmitter, the method determines if there are any noise spikes in the signal at the input to the microprocessor representative of pressure and provides rejection for such spikes. The method also provides for a faster response to a step change in pressure than is provided by conventional filtering methods and also dampens small fluctuations in the filtered output signal.

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Eastlake, OH, United States of America

Tourang Birangi