US3925650A
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Method and apparatus for detecting a repetitive signal in a noisy background
Assignee: Leidos Holdings Inc
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Filing: 1974-02-15
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Granted: 1975-12-09
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Expires: 1994-02-15
Abstract
Abstract A method and apparatus is disclosed for detecting and enhancing a repetitive pulse echo signal in a noisy background. Periodic acoustic pulses are generated and reflected from a target object. The return signal, having a preselected period, is converted into a plurality of binary signals, one for each of a plurality of time increments in each repetition interval. The magnitude of the signal in each time increment is subtracted from the magnitude of the signal in the succeeding time increment. The resulting difference signals are sequentially stored in a first register until the return signal interval has been completed. The difference signals for a plurality of such return signal intervals are stored in a plurality of shift registers. The magnitude of the difference signals in each of the corresponding discrete time increments of a plurality of repetition intervals are added together and an average signal strength is derived for each of the discrete time increments in the repetitive signal. In addition, the magnitude of the difference signal in a discrete time increment for each of the repetition intervals is multiplied by the magnitude of the signal in the corresponding time increment in the next succeeding repetition interval. These product signals are then summed to provide an autocorrelated signal. This multiplication continues until the signals in each of the corresponding discrete time increments in each of the repetition intervals has been multiplied by the signal in the corresponding increment in the next succeeding repetition interval. The sum and auto correlated signals are then added together and displayed at an output to provide a double independent correlation of the input repetitive pulse echo signal.
Inventors
- 👤 Buck C Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:50
CPC Classifications
G; G06; G06F; G06F17/00; G06F17/10; G06F17/15; G06F17/18
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
195 words
An apparatus for detecting repetitive and similar input information signals in a noisy background wherein the information signals exist for only a short time relative to a complete repetitive interval and wherein the noise background exists for the complete repetition interval, comprising means for generating a plurality of digital signals, one for each of a plurality of time increments in each repetition interval, said digital signals having a value corresponding to the amplitude of the input signal at each time increment, means for subtracting the value of the digital signal in each time increment from the value of the digital signal in the next succeeding time interval to derive a plurality of difference signals, means for sequentially storing each of said difference signals, means for sequentially storing the difference signals of a plurality of said repetition intervals, and means for summing the values of each of the difference signals in a predetermined time increment of each of said plurality of repetition intervals, wherein the difference signals in corresponding time intervals of said plurality of repetition intervals are summed to form a cumulative difference signal for the predetermined time increment over the plurality of repetition intervals.
Claim 2
Independent Claim
195 words
An apparatus for detecting repetitive and similar input information signals in a noisy background wherein the information signals exist for only a short time relative to a complete repetitive interval and wherein the noise background exists for the complete repetition interval, comprising means for generating a plurality of digital signals, one for each of a plurality of time increments in each repetition interval, said digital signals having a value corresponding to the amplitude of the input signal at each time increment, means for subtracting the value of the digital signal in each time increment from the value of the digital signal in the next succeeding time interval to derive a plurality of difference signals, means for sequentially storing each of said difference signals, means for sequentially storing the difference signals of a plurality of said repetition intervals, and means for summing the values of each of the difference signals in a predetermined time increment of each of said plurality of repetition intervals, wherein the difference signals in corresponding time intervals of said plurality of repetition intervals are summed to form a cumulative difference signal for the predetermined time increment over the plurality of repetition intervals.
Claim 3
Dependent Claim
49 words
The apparatus of claim 1 wherein said summing means additionally sums the values of a difference signal in each of said repetition intervals wherein the difference signals summed in each repetition interval is in the correspondingly adjacent time increment of the time increment in the next succeeding repetition interval.
Claim 4
Independent Claim
211 words
A apparatus for detecting repetitive and similar input information signals in a noisy background wherein the information signals exist for only a short time relative to the complete repetition interval and wherein the noise background exists for the complete repetition interval, comprising an analog to digital converter, said converter generating a plurality of digital signals, one for each of a plurality of time increments in each repetition interval, said digital signals having a value corresponding to the amplitude of the input signal at each time increment, a subtractor circuit connected to the output of said analog to digital converter for subtracting the value of the digital signal in each time increment from the value of the digital signal in a next succeeding time increment to derive a plurality of difference signals, a data register connected to the output of said subtractor for sequentially storing each of said difference signals, a plurality of memory registers serially connected to one another and to the output of said data register for storing the difference signals of a plurality of said repetition intervals, and an arithmetic circuit connected to said memory registers for summing the values of each of the difference signals in a predetermined time increment of each of said plurality of repetition intervals.
Claim 5
Independent Claim
211 words
A apparatus for detecting repetitive and similar input information signals in a noisy background wherein the information signals exist for only a short time relative to the complete repetition interval and wherein the noise background exists for the complete repetition interval, comprising an analog to digital converter, said converter generating a plurality of digital signals, one for each of a plurality of time increments in each repetition interval, said digital signals having a value corresponding to the amplitude of the input signal at each time increment, a subtractor circuit connected to the output of said analog to digital converter for subtracting the value of the digital signal in each time increment from the value of the digital signal in a next succeeding time increment to derive a plurality of difference signals, a data register connected to the output of said subtractor for sequentially storing each of said difference signals, a plurality of memory registers serially connected to one another and to the output of said data register for storing the difference signals of a plurality of said repetition intervals, and an arithmetic circuit connected to said memory registers for summing the values of each of the difference signals in a predetermined time increment of each of said plurality of repetition intervals.
Claim 6
Dependent Claim
98 words
The apparatus of claim 3 further comprising a variable delay line having a plurality of outputs connected to the shift inputs of said plurality of memory registers and means for applying a clock signal to said variable delay line, said variable delay line providing delayed clock pulse outputs to each of said memory registers in accordance with the rate of movement of said information signal from increment to increment within each repetition interval, said arithmetic summing circuit thereby summing the difference signals in correspondingly adjacent time increments relative to the time increment in a next succeeding repetition interval.
Claim 7
Dependent Claim
75 words
The apparatus of claim 3 wherein said arithmetic circuit further multiplies the value of the difference signal in a preselected time increment by the value of the difference signal in a corresponding time increment in the Next succeeding repetition interval to derive a plurality of product signals, the multiplication occurring over a plurality of repetition intervals, and said arithmetic circuit further sums said product signals to derive an autocorrelated signal for said selected time increment.
Claim 8
Independent Claim
223 words
An apparatus for detecting repetitive and similar input information signals in a noisy background wherein the information signals exist for only a short time relative to a complete repetition interval and wherein the noise background exists for the complete repetion interval, comprising means for generating a plurality of digital signals, one for each of a plurality of time increments in each repetition interval, said digital signals having a value corresponding to the amplitude of the input signal at each time increment, means for subtracting the value of the digital signal in each time increment from the value of the digital signal in the next succeeding time increment to derive a plurality of difference signals, means for sequentially storing each of said difference signals, means for storing the difference signals of a plurality of said repetition intervals, means for summing the values of each of the difference signals in a predetermined time increment of each of said plurality of repetition intervals, for multiplying the value of a difference signal in a preselected time increment by the value of the difference signal in a corresponding time increment in the next succeeding repetition interval to derive a plurality of product signals, said multiplication occurring over a plurality of repetition intervals, and for summing said product signals to derive an autocorrelated signal for said selected time increment.
Claim 9
Independent Claim
223 words
An apparatus for detecting repetitive and similar input information signals in a noisy background wherein the information signals exist for only a short time relative to a complete repetition interval and wherein the noise background exists for the complete repetion interval, comprising means for generating a plurality of digital signals, one for each of a plurality of time increments in each repetition interval, said digital signals having a value corresponding to the amplitude of the input signal at each time increment, means for subtracting the value of the digital signal in each time increment from the value of the digital signal in the next succeeding time increment to derive a plurality of difference signals, means for sequentially storing each of said difference signals, means for storing the difference signals of a plurality of said repetition intervals, means for summing the values of each of the difference signals in a predetermined time increment of each of said plurality of repetition intervals, for multiplying the value of a difference signal in a preselected time increment by the value of the difference signal in a corresponding time increment in the next succeeding repetition interval to derive a plurality of product signals, said multiplication occurring over a plurality of repetition intervals, and for summing said product signals to derive an autocorrelated signal for said selected time increment.
Claim 10
Dependent Claim
34 words
The apparatus of claim 6 wherein said means for summing, multiplying and summing said product signals further sums the autocorrelated signals and the summed difference signals for each of a plurality of time increments.
Claim 11
Dependent Claim
32 words
The apparatus of claim 6 wherein said means for summing, multiplying and summing said product signals normalizes said correlated signals and said summed difference signals over the number of repetition intervals considered.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-08 | 1979-06-09 | 1979-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-08 | 1983-06-09 | 1983-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-08 | 1987-06-09 | 1987-12-09 | $7700.00 | Window Closed / Lapsed |