Wide range, high resolution frequency monitor

摘要

A frequency monitor provides high resolution frequency monitoring over a range of input signal frequencies by measuring the time period of the signal to produce a raw frequency value and then filtering the raw frequency value with a low pass filter to remove an error component caused by quantization effects at high input signal frequencies. The system automatically accommodates changes in the input frequency eliminating a need for manual adjustment of the system based on anticipated measured frequencies.

主权项

1. A frequency monitor comprising:
an input for receiving a signal to be measured; a signal feature extractor identifying a regular feature of the signal related to the signal's period; a timer system including a clock providing a periodic clock signal communicating with a counter counting the periodic clock signal between detection signals from the signal feature extractor identifying a regular feature of the signal, the timer system communicating with the signal feature extractor to provide an output being a function of the period of the signal; an inverter receiving the output and converting the period of the signal to a frequency to provide a measured frequency output; a low pass filter receiving the measured frequency output to reduce high frequency fluctuations in the measured frequency output to provide a corrected frequency output for monitoring frequency of the signal, wherein the low pass filter is in communication with the clock to sample the measured frequency output at the same rate as the clock, and wherein the low pass filter includes an input for adjusting a corner frequency of the low pass filter.