Phase responsive frequency detector
First Claim
1. A detector for detecting the presence of selected frequency components of an input signal comprising:
- two separate signal paths each delivering an output signal;
an input circuit operative to receive the input signal and to deliver similar signal components into each of said signal paths;
frequency responsive means in at least one of the signal paths, the frequency responsive means having a cross-over point in its frequency characteristic, the frequency responsive means being operative to deliver output such that for input signal components having frequencies on one side of the cross-over point the output of the frequency responsive means in said one path will comprise output frequency components which are substantially in phase with the output signal components of the other path, but for input signal components having frequencies on the other side of the cross-over point the output of the frequency responsive means in said one path will comprise output frequency components which are substantially out of phase with the output signal components of the other path; and
a coincidence circuit having two inputs respectively connected to receive the output signal components of said separate paths, the coincidence circuit being operative to compare the instantaneous phases of the output components and to generate output at a first level when said output signals components have coincident phase and to generate output at a second different level when said output signals components have non-coincident phase.
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Abstract
A detector for detecting the presence of selected frequency components of an input signal and operative to deliver output responsive thereto by providing two separate signal paths in the detector, at least one path including filter circuitry having a distinct cross-over point operative to pass frequencies on one side of the cross-over point with one phase relative to the input and to pass frequencies on the other side of the cross-over point substantially 180° out of phase relative to the input, and the detector further including a coincidence circuit receiving the signals from the two paths and generating one level of output for signals which are substantially in phase and generating another lower level of output for signals substantially out of phase. The coincidence circuit may have provisions for establishing an input threshold level which the signals must overcome.
19 Citations
13 Claims
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1. A detector for detecting the presence of selected frequency components of an input signal comprising:
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two separate signal paths each delivering an output signal; an input circuit operative to receive the input signal and to deliver similar signal components into each of said signal paths; frequency responsive means in at least one of the signal paths, the frequency responsive means having a cross-over point in its frequency characteristic, the frequency responsive means being operative to deliver output such that for input signal components having frequencies on one side of the cross-over point the output of the frequency responsive means in said one path will comprise output frequency components which are substantially in phase with the output signal components of the other path, but for input signal components having frequencies on the other side of the cross-over point the output of the frequency responsive means in said one path will comprise output frequency components which are substantially out of phase with the output signal components of the other path; and a coincidence circuit having two inputs respectively connected to receive the output signal components of said separate paths, the coincidence circuit being operative to compare the instantaneous phases of the output components and to generate output at a first level when said output signals components have coincident phase and to generate output at a second different level when said output signals components have non-coincident phase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification