Frequency-to-digital value converter

Claim 1

A converter to convert an incoming variable data frequency which lies in a low frequency range whose upper limit is about 2,000 Hz to a corresponding digital value, the converter comprising: (A) a digital computer; (B) an electronic UP counter having an enabling input and a count input; (C) means controlled by the computer to derive from the incoming data frequency a data signal whose frequency is a selected sub-multiple of the data frequency; (D) an electronic clock operating at a constant frequency which exceeds 10,000 Hz; (E) means controlled by the computer to derive from the clock frequency a clock signal having periodic pulses whose repetition rate is a selected sub-multiple of the clock frequency; (F) means to apply the data signal to the enabling input of the UP counter to enable the counter for an enabling period equal to a half cycle of the applied data signal; (G) means to apply the clock signal to the count input of the UP counter whereby the count accumulated therein is determined by the number of pulses in the clock signal which appear during the enabling period; and (H) means to enter the accumulated count in the computer which, on the basis of the data signal and the clock signal selected by the computer, then functions to calculate the time period (P) of the data frequency (F), from which it then calculates and provides a digital output corresponding to the incoming data frequency based on the equation F=1/P.