US3602826A — Adaptive signal detection system

Claim 1

Independent Claim 159 words

Apparatus for detecting information signal level variations in the presence of noise level variations, said apparatus comprising: an array of sensing elements responsive to energy of a form which may consist of both information and environmental background, for generating electrical signals functionally related to the respective levels of said energy, means for generating a train of timing pulses at a selectively variable repetition rate, means responsive to said timing pulses for sequentially sampling the signals generated by the sensing elements of said array, means selectively responsive, in accordance with said timing pulses, to the samples appearing in said sequence for deriving therefrom amplitude representations of the level variations occurring in a predetermined minimum time interval and a predetermined maximum time interval over which information signal level variations are expected to occur, and means responsive to said amplitude representations over said time intervals for comparison thereof as an indication of whether they are derived from information signal or background noise.

Claim 2

Dependent Claim 159 words

Apparatus for detecting information signal level variations in the presence of noise level variations, said apparatus comprising: an array of sensing elements responsive to energy of a form which may consist of both information and environmental background, for generating electrical signals functionally related to the respective levels of said energy, means for generating a train of timing pulses at a selectively variable repetition rate, means responsive to said timing pulses for sequentially sampling the signals generated by the sensing elements of said array, means selectively responsive, in accordance with said timing pulses, to the samples appearing in said sequence for deriving therefrom amplitude representations of the level variations occurring in a predetermined minimum time interval and a predetermined maximum time interval over which information signal level variations are expected to occur, and means responsive to said amplitude representations over said time intervals for comparison thereof as an indication of whether they are derived from information signal or background noise.

Claim 3

Dependent Claim 50 words

The invention according to claim 1 wherein said means for deriving representations includes means for converting the representations to logarithmic form, and wherein said comparison means includes means for detecting the difference in amplitude of respective logarithmic variations derived for said time intervals, as a ratio of the original representations.

Claim 4

Dependent Claim 152 words

The invention according to claim 1 wherein said means for deriving representations includes first and second integrator means in respective parallel channels for processing the signal samples from a selected sensing element, one of said integrator means having a substantially longer time constant of integration than the other of said integrator means, the time constants of said first and second integrator means corresponding to the extremes in time over which information signal is expected to occur, whereby differences in the results of integration by said first and second integrator means are obtained for information signal level variations as a consequence of the difference in the number of signal samples averaged by the integrations performed by the two integrator means, while background noise level variations sensed by said selected sensing element and processed by the two integRator means have substantially the same average values regardless of said difference in time constants of integration.

Claim 5

Dependent Claim 51 words

The invention according to claim 3 further including means responsive to the sequential signal samples for retention of the level of each sample applied thereto from application of that sample to application of the next consecutive sample thereto, as the sample levels to be applied to said means for deriving representations.

Claim 6

Dependent Claim 73 words

The invention according to claim 4 wherein said means for deriving representations includes distinct and different sets of said parallel channels for each of said sensing elements of said array, each set of parallel channels having first and second of said integrator means, and switch means responsive to said timing pulses for supplying the sample levels attributable to each sensing element to the corresponding set of parallel channels, during scanning of said elements.

Claim 7

Dependent Claim 107 words

The invention according to claim 5 wherein the outputs of each set of parallel channels are commutated in a sequence of parallel channels corresponding to the scanning sequence of the elements in said array, to said comparison means, and wherein said comparison means includes differencing means responsive to the outputs of each single set of parallel channels for deriving the difference in level thereof, and means responsive to each said difference in level derived by said differencing means for reference respectively against a predetermined threshold level below which information signal is deemed to be absent from the sensed energy which resulted in the respective difference in level.

Claim 8

Dependent Claim 48 words

The invention according to claim 6 wherein said comparison means further includes means responsive to the number of differences in level exceeding said threshold level, as detected by said referencing means in a predetermined time interval, as the basis of a decision on whether information signal is present.

Claim 9

Independent Claim 175 words

A system for extracting information from a train of pulses, comprising a plurality of channels connected for parallel reception of pulses in said train, means synchronized with the timing of the pulses in said train for selectively completing a circuit path in each of said channels for passage of pulses therethrough, said plurality of channels being paired, and each channel of a pair including means for sensing energy in a pulse applied thereto and for retaining a signal level representative of that energy, means responsive to signal levels retained by said retaining means in both channels of a pair of channels for detecting the difference in levels therebetween at times based on said timing of said pulses, means responsive to each difference in level detected by said detecting means for conversion of each difference level to a value representative of its significance relative to a predetermined reference level, and means for accumulating said conversion values in accordance with said timing of said pulses, as an indication of the information content in said train of pulses.

Claim 10

Independent Claim 175 words

A system for extracting information from a train of pulses, comprising a plurality of channels connected for parallel reception of pulses in said train, means synchronized with the timing of the pulses in said train for selectively completing a circuit path in each of said channels for passage of pulses therethrough, said plurality of channels being paired, and each channel of a pair including means for sensing energy in a pulse applied thereto and for retaining a signal level representative of that energy, means responsive to signal levels retained by said retaining means in both channels of a pair of channels for detecting the difference in levels therebetween at times based on said timing of said pulses, means responsive to each difference in level detected by said detecting means for conversion of each difference level to a value representative of its significance relative to a predetermined reference level, and means for accumulating said conversion values in accordance with said timing of said pulses, as an indication of the information content in said train of pulses.

Claim 11

Dependent Claim 86 words

The system of claim 8 wherein said circuit path completing means completes circuit paths simultaneously in both channels of each pair of channels, to pass pulses to be processed by a predetermined pair of channels concurrently to both of said retaining means thereof, and wherein each of said retaining means comprises integrating means for averaging the level of incoming pulses over a time interval depending upon the respective time constant of the integrating means, said integrating means of both of said channels having different time constants.

Claim 12

Dependent Claim 68 words

The system of claim 9 wherein the time constant of one of said integrating means is related to the minimum time over which information is expected to be present in a predetermined set of said pulses, and the time constant of the other of said integrating means is related to the maximum time over which information is expected to be present in a predetermined set of said pulses.

Claim 13

Dependent Claim 80 words

The system of claim 10 wherein said train of pulses is obtained from repeated scanning of the outputs of a plurality of energy detectors, and wherein a separate and distinct pair of channels is provided for pulses derived from each respective energy detector, said circuit completing means completing circuit paths in a given pair of channels only during the interval in which the pulses derived from the energy detector associated with that pair of channels occur in said pulse train.

Claim 14

Dependent Claim 55 words

The system of claim 11 wherein said conversion means comprises means for comparing the difference in level detected by said detecting means with a selectively variable threshold level constituting said predetermined reference level, and for generating an output if and only if the difference in level detected in a timing interval exceeds said threshold level.

Claim 15

Dependent Claim 58 words

The system of claim 12 wherein said accumulating means comprises means responsive to the number of outputs generated by said comparing means over a preselected number of scans of said energy detectors for indicating the presence or absence of information on the basis of whether said number of outputs is respectively greater or less than a predetermined number.

Claim 16

Dependent Claim 31 words

The system of claim 13 wherein said number of outputs is responded to by said means for indicating presence of information, only if said outputs are derived from consecutive energy detectors.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1974-08-30	1975-03-01	1975-08-31	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1978-08-30	1979-03-01	1979-08-31	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1982-08-30	1983-03-01	1983-08-31	$7700.00	Window Closed / Lapsed

Adaptive signal detection system

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