Siemens Milltronics Process Instruments, Inc.

Graham Wall

A method for converting an N-bit digital value into an analog value is provided. N-M most significant bits of the digital value are converted into a first PWM signal whose period is a multiple of a base time period. M least significant bits of the digital value are converted into a second PWM signal whose period is a &#xbd;fraction of the period of the first PWM signal. A third PWM signal is generated by inserting, during the pulse pause of the first PWM signal, the pulse of a selected single period of the second PWM signal into the first PWM signal. Further, the third PWM signal is low-pass filtered.

Method and circuit for converting an N-bit digital value into an analog value

A method for processing echoes in a time-of-flight ranging system or level measurement system. The method comprises applying an entropy filter to the echo profile. The entropy filter comprises determining the information content in the echo profile. The entropy filter determines the occurrences of a pattern in the bit stream representing magnitudes in the echo profile. Repeated occurrences of the pattern are used to characterize the echo signal as having low randomness (i.e. higher information content) indicative of a potential echo pulse or as having high randomness (i.e. lower information content) indicative of noise.

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Peterborough, Canada

Graham Wall