Apparatus for generating a d.c. signal proportional to an input frequency
AssigneeJoseph Lucas (Industries) Limited
InventorAnthony Brian Plant
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Abstract
An apparatus for generating a d.c. output signal which is proportional to the frequency of an alternating input signal, includes a pulse generator and a counter arranged to count pulses from the generator for a time which is dependent on the input signal frequency. A digital to analog converter is responsive to the count in the counter and also to the d.c. output signal to provide an intermediate d.c. signal which is compared with a d.c. reference signal. The difference between the intermediate and reference signals is integrated to provide the output signal. The arrangement is such that the d.c. output signal is directly proportional to the input signal frequency.
Claims8
An apparatus for generating a d.c. output signal whose magnitude is proportional to the frequency of an electrical input signal, comprising means for generating a train of substantially equispaced electrical pulses, a pulse counter, gating means responsive to said input signal for gating said pulses to said counter for a time interval which is dependent on the frequency of said input signal, a digital to analog converter for providing a d.c. signal dependent on the count in said counter at the end of said time interval, a summing junction responsive to said d.c. signal and to an electrical reference signal to generate a control signal proportional to the difference between said d.c. signal and said reference signal, and an integrating circuit responsive to said control signal to generate said output signal, said digital to analog converter also being responsive to said output signal so that said d.c. signal is proportional to the product of said count and said output signal, and a feedback arrangement provided such that variations in said d.c. signal are opposed by corresponding changes in said output signal.
Dependencies are inferred from the claim text.