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Method of Phase Detection

IP.com Disclosure Number: IPCOM000075897D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Herbert, CN: AUTHOR

Abstract

This circuit provides rapid, accurate detection of input frequency signals. By the use of unique pulse preparation circuitry, the detection of the phase difference of two incoming signals is no longer dependent on the amplitude of either incoming signal. Additional advantages are increased processing speed, since the detection devices are isolated from input noise and increased output/input isolation because of output frequency down shifting.

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Method of Phase Detection

This circuit provides rapid, accurate detection of input frequency signals. By the use of unique pulse preparation circuitry, the detection of the phase difference of two incoming signals is no longer dependent on the amplitude of either incoming signal. Additional advantages are increased processing speed, since the detection devices are isolated from input noise and increased output/input isolation because of output frequency down shifting.

The signal designated F1 is applied to buffers 1 and 2 wherein the signal is shaped. A single-phase signal is fed to a buffer and gate 3. The buffers also serve to increase the slope of the zero crossings, which increases the accuracy of the phase measurement. The signals from the buffers are gated in the frequency dividers 4 and 5 to produce an output frequency. The output frequency is equal to Fi/N where Fi is the input frequency and N is an even integer equal or greater than 2. The circuit arrangement within the frequency dividers increases the output/input isolation and it compresses information by allowing the phase detector 10 to read (360 degrees) (N). The outputs from the frequency dividers are fed through conventional amplifiers 6 and 7 into filters 8 and 9. The outputs are then combined in the phase detector 10, which is comprised of two balanced mixers with input signals 90 degrees out of phase.

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