Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Frequency of cyclic current or voltage
Patent
1982-09-28
1985-01-15
Levy, Stewart J.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Frequency of cyclic current or voltage
324 78D, 324 78F, 324 78R, 324 83D, 328133, G01R 2314
Patent
active
044940670
ABSTRACT:
Disclosed is a high resolution frequency measuring system which uses a frequency counter for a coarse reading and a frequency to voltage converter for a vernier reading, which readings are combined. Two types of converters are disclosed. One embodiment comprises an input terminal for receiving an input signal frequency and a pulse shaper for converting the input signal to a first train of pulses. The pulses are applied to a delay means to produce a second train of pulses delayed with respect to the first train of pulses and the first and second trains of pulses are applied to first and second inputs of a phase detector, e.g. a flip-flop. In another embodiment, delayed and undelayed versions of the input signal are fed to separate pulse shapers and then to the inputs of the phase detector. The phase detector has an output connected to operate a switch between two voltage levels to produce a third train of pulses having a duty ratio depending on the phase difference between the first and second trains of pulses. The third train of pulses is time averaged to produce an output voltage, the output voltage being proportional to the phase difference between the first and second trains of pulses and varying with changes in the frequency of the input signal. An analog to digital converter converts the output voltage to a digital reading for combining with the output of the frequency counter. The invention provides a unique, fast frequency measuring system allowing high resolution, not obtainable with a counter.
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Canadian Patents & Development Limited
Levy Stewart J.
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