US 4,308,501 AGranted

Digital peak sensor

AssigneeThe United States of America as represented by the Secretary of the Army

InventorsThomas E. Tuccinardi, Michael Conner

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Abstract

A digital circuit for sensing peaks exceeding a predetermined threshold in nalog signals employs clock and control oscillators arranged such that their frequencies vary in opposite senses in response to changes in the sensed signal. The clock oscillator frequency is counted during sample intervals of durations which vary inversely with the control oscillator frequency. A count increase (or decrease) of predetermined amount from one sample interval to the next, followed by a count decrease (or increase) from another sample interval to the next, results in an output signal. In a preferred embodiment, the clock frequency is counted in an up/down counter which, for each sample interval, is counted up and down for equal numbers of control oscillator cycles. The net count at the end of a sample interval is therefore an indication of the magnitude and polarity of changes in the sensed signal. In a particular utilization the circuit serves in a mine fuze and senses the peak of a magnetic field signal such as is associated with a tank or other vehicle.

Claims10

Dependent claims

Digital apparatus for sensing a peak condition in an analog-varying parameter comprising:

a clock oscillator arranged to provide a cyclic-clock signal at a first nominal frequency;
a control oscillator arranged to provide a cyclic control signal at a second nominal frequency;
sensing means responsive to said analog-varying parameter for varying the frequencies of said oscillators in opposite senses as said parameter varies;
actuable clock counter means for counting clock signal cycles when actuated;
control counter means for counting control signal cycles and actuating said clock counter means during repetitive sample intervals containing a predetermined number of control signal cycles;
threshold detection means for detecting when the count in said clock counter differs in one sense from a reference count by a predetermined threshold amount, said threshold detection means including means for storing an indication that the threshold amount has been exceeded;
means for resetting said clock counter means in response to a threshold detection by said threshold detection means;
and
over-the-peak detecting means, responsive to said indication stored in said bistable means, for detecting when the count in said clock counter means differs from said reference count in an opposite sense to said one sense.

6 more elements

Dependencies are inferred from the claim text.