Signal processing system
First Claim
1. A system for detecting the presence of a desired signal frequency in a multi-signal environment, comprising:
- spectrum analyzer means adapted to sample the multi-signal environment for providing digital information indicative of real and imaginary magnitude components of the desired signal frequency;
phase determinator means connected to receive the digital information from said spectrum analyzer means for producing a first digital signal indicative of the instantaneous phase of the desired signal frequency;
phase precession means connected to said phase determinator means for producing a second digital signal representative of a statistical estimate of phase variation of the desired signal frequency;
a first fixed storage device adapted to provide a plurality of third digital signals representative of distinct phase reference values between 0° and
360°
;
an adder connected to said phase precession means and said first fixed storage device for summing the second digital signal with each of the plurality of third digital signals thereby producing a plurality of fourth digital signals representative of revised phase reference values;
cosine integrator means connected to said phase determinator means and said adder for producing a plurality of fifth digital signals representative of relative signal strength for each of the phase reference values;
a second fixed storage device adapted to provide a sixth digital signal representative of a threshold signal value; and
a comparator connected to said cosine integrator means and said second fixed storage device for indicating the presence of the desired signal frequency when any of the plurality of fifth digital signals exceeds the sixth digital signal.
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Accused Products
Abstract
A signal processing system and technique is disclosed for detecting the pence of a desired frequency signal particularly that of a sine wave, in a noisy environment. The signal mixed with noise is received and analyzed by a Fast Fourier Transform spectrum analyzer the output of which is indicative of instantaneous signal phase. The output of the spectrum analyzer is digitally processed to produce a series of average instantaneous signal values based upon the instantaneous signal phase and a statistical estimate of its rate of change, the values being representative of the relative signal strengths for a progression of phase reference values between 0° and 360°. The desired signal is detected when an average instantaneous signal value exceeds a threshold value determined empirically based upon a certain probability of detection and false alarm rate.
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Citations
11 Claims
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1. A system for detecting the presence of a desired signal frequency in a multi-signal environment, comprising:
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spectrum analyzer means adapted to sample the multi-signal environment for providing digital information indicative of real and imaginary magnitude components of the desired signal frequency; phase determinator means connected to receive the digital information from said spectrum analyzer means for producing a first digital signal indicative of the instantaneous phase of the desired signal frequency; phase precession means connected to said phase determinator means for producing a second digital signal representative of a statistical estimate of phase variation of the desired signal frequency; a first fixed storage device adapted to provide a plurality of third digital signals representative of distinct phase reference values between 0° and
360°
;an adder connected to said phase precession means and said first fixed storage device for summing the second digital signal with each of the plurality of third digital signals thereby producing a plurality of fourth digital signals representative of revised phase reference values; cosine integrator means connected to said phase determinator means and said adder for producing a plurality of fifth digital signals representative of relative signal strength for each of the phase reference values; a second fixed storage device adapted to provide a sixth digital signal representative of a threshold signal value; and a comparator connected to said cosine integrator means and said second fixed storage device for indicating the presence of the desired signal frequency when any of the plurality of fifth digital signals exceeds the sixth digital signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A signal processor for detecting the presence of a desired signal frequency in a multi-signal environment sampled by a Fast Fourier Transform spectrum analyzer, comprising:
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phase determinator means connected to the spectrum analyzer for producing a first digital signal indicative of the instantaneous phase of the desired signal frequency; phase precession means connected to said phase determinator means for producing a second digital signal representative of a statistical estimate of phase variation of the desired signal frequency; a first fixed storage device adapted to provide a plurality of third digital signals representative of distinct phase reference values between 0° and
360°
;an adder connected to said phase precession means and said first fixed storage device for summing the second digital signal with each of the plurality of third digital signals thereby producing a plurality of fourth digital signals representative of revised phase reference values; cosine integrator means connected to said adder for producing a plurality of fifth digital signals representative of relative signal strength for each of the phase reference values; a second fixed storage device adapted to provide a sixth digital signal representative of a threshold signal value; and a comparator connected to said cosine integrator means and said second fixed storage device for indicating the presence of the desired signal frequency when any of the plurality of fifth digital signals exceeds the sixth digital signal. - View Dependent Claims (8, 9, 10, 11)
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Specification