Real-time cross-correlation signal processor
First Claim
1. In a real time signal processing system of the cross-correlation type for selecting input signals depending upon the instantaneous degree of similarity of the input signal to a locally generated reference signal, the combination of:
- first means for generating a reference signal;
second means for generating a control signal which is a real time measure of the instantaneous degree of similarity of an input signal to said reference signal;
third means for selecting said input signal as a function of said control signal, and providing the selected signal as the output;
means for connecting said input signal to said second means and to said third means; and
means for connecting said reference signal to said second means.
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Abstract
Apparatus for improving the signal to noise ratio in an electrical signal. A signal enhancement processor operating in real time and selecting signals based upon the similarity of the incoming signal to a locally generated reference and which does not require that signals be filterable in the frequency domain, that external reference signals be supplied, or that signal amplitude criteria be employed. A system for providing input signal attenuation or rejection as a function of the frequency or phase of the input signal, with attenuation at a maximum for an undesired signal and at a minimum for a desired signal.
72 Citations
40 Claims
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1. In a real time signal processing system of the cross-correlation type for selecting input signals depending upon the instantaneous degree of similarity of the input signal to a locally generated reference signal, the combination of:
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first means for generating a reference signal; second means for generating a control signal which is a real time measure of the instantaneous degree of similarity of an input signal to said reference signal; third means for selecting said input signal as a function of said control signal, and providing the selected signal as the output; means for connecting said input signal to said second means and to said third means; and means for connecting said reference signal to said second means. - View Dependent Claims (2, 3, 4)
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5. In a real time signal processing system of the cross-correlation type for selecting input signals depending upon the instantaneous degree of similarity of the input signal to a locally generated reference signal, the combination of:
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means for generating a real time measure of the instantaneous degree of similarity of the input signal to said reference signal; means for using said measure of input signal similarity such that input signals are selected in accordance with said measure of similarity; means for connecting said input signal to said means for generating the measure of similarity and to said means for using input signals; means for connecting said reference signal to said means for generating the measure of similarity; and means for providing selected signals as an output. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. In a real-time signal processing system of the cross-correlation type, the combination of:
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a phase shifter providing a phase shifted output; a reference oscillator providing a reference output; first and second frequency multipliers having said phase shifted output and said reference output as inputs, respectively, and providing first and second local outputs; a first channel having said phase shifted output as an input; a second channel having said reference output as an input; each of said channels comprising a cascaded multiplier having the first and second local outputs alternately as multiplier mixer inputs, providing a plurality of cascaded outputs, a summing unit for said plurality of cascaded outputs, and a detector for the summing unit outputs; and a comparator having the output of the detectors of said first and second channels as inputs and providing an output varying as a function of the relative magnitudes of the two inputs. - View Dependent Claims (25)
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26. In a real time signal processing system of the cross correlation type, the combination of:
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a signal-to-noise processor providing an output varying as a function of the degree of similarity of the frequency of the first and second inputs thereto; a signal attenuator having a signal input, a control input, and an output, and providing the signal input as the output varying as a function of the control input; means for connection an input signal to said processor first input and to said attenuator as the signal input; means for connecting to said processor second input a reference signal which represents the frequency of input signals to be accepted; and means for connecting said processor output to said attenuator control input to provide a large attenuator output when the frequency of the input signal matches the frequency represented by the reference signal and to provide a small output for other input signal frequencies. - View Dependent Claims (27, 28)
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29. In a real time signal processing system of the cross correlation type, the combination of:
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a signal attenuator having a signal input, a control input, and an output, and providing the signal input as the output varying as a function of the control input; a signal-to-noise processor providing an output varying as a function of the degree of similarity of the phases of first and second inputs thereto; means for connecting an input signal to said processor first input and to said attenuator as the signal input; means for connecting to said processor second input reference signals which represent the phase of input signals to be accepted; and means for connecting said processor output to said attenuator control input to provide a large attenuator output when the phase of the input signal matches the phase represented by the reference signals and to provide a small attenuator output for other input signal phase. - View Dependent Claims (30)
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31. In a real time signal processing system of the cross correlation type for first and second input signals of the same frequency and varying in phase, the combination of:
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a signal attenuator having a signal input, a control input, and an output and providing the signal input as an output varying as a function of the control input; means for connecting one of said input signals to said attenuator signal input; first and second limiters for said first and second input signals respectively; a 90°
phase shifter for the output of one of said limiters;first and second phase detectors for the output of said phase shifter and the output of the other of said limiters respectively; a comparitor having the outputs of said phase detectors and a reference voltage as inputs and providing an output varying as a function of the differences of the voltages of the inputs thereto; and a low pass filter having the comparitor output as input and providing an output to the control input of said signal attenuator.
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32. In a real time signal processing system of the cross correlation type, the combination of:
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a frequency multiplier providing an output varying in amplitude in accordance with the input thereto and varying in frequency as a multiple of the frequency variations of the input thereto; a frequency multiplexer comprising a plurality of parallel connected channels each having a pass band with a different center frequency; and means for connecting an input signal to said multiplier and for connecting said multiplier and said multiplexer in series. - View Dependent Claims (33, 34, 35)
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36. In a real time signal processing system of the cross correlation type for first and second input signals of the same frequency, similar amplitudes, and varying in phase, the combination of:
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first and second channels each having one of said input signals as input and providing a local output and a plurality of cascaded outputs; and a summing unit for the first and second cascaded outputs; each of said channels comprising a band pass filter and a frequency multiplier for the input signal providing the local output at 2-times the input signal frequency, and a cascade of series connected frequency multiplier stages having the bandpass filter output as input and having the first and second local outputs alternately as multiplier inputs with the first multiplier having the local output of the other channel as input, and providing the plurality of cascaded outputs. - View Dependent Claims (37, 38, 39, 40)
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Specification