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US4166980A Expired / Lapsed US ⏱️ 0.0 years remaining

Method and apparatus for signal recognition

Assignee: Lockheed Martin Corp
•
Filing: 1977-08-25
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Granted: 1979-09-04
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Expires: 1997-08-25
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Abstract

Abstract A method and apparatus are provided for sorting signals from compressive receivers in accordance with the type of modulation on the signal, so as to be able to establish the identity of the signal short of fully demodulating it. It has been found that signals from a compressive receiver which are insufficiently sampled for complete demodulation can be identified by "histograms" in which each designated condition, such as the number of consecutive 1's or 0's is graphed against the number of occurrences of this designated condition over a period of time, designated a "data collection interval." The result is a pattern or diagram which is characteristic of the modulation type, such that FSK, DFSK, PSK, hand morse, machine morse, anomolous morse, AM, SSB, and multitones can be distinguished one from another. Moreover, it is possible to recognize two-way voice communication.

Inventors

  • 👤 John T. Apostolos
  • 👤 Robert P. Boland

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-25 10:11
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/0012

Claims Analysis

Total Claims: 40
Claim 1
Independent Claim 60 words
A method of establishing the type of modulation impressed on a signal insufficiently sampled for complete demodulation comprising the steps of: detecting a designated modulation-related condition of said signal, correlating said designated condition with the amount of time said designated condition exists over a predetermined time period and, determining the modulation type based on the results of said correlation step.
Claim 2
Independent Claim 60 words
A method of establishing the type of modulation impressed on a signal insufficiently sampled for complete demodulation comprising the steps of: detecting a designated modulation-related condition of said signal, correlating said designated condition with the amount of time said designated condition exists over a predetermined time period and, determining the modulation type based on the results of said correlation step.
Claim 3
Dependent Claim 35 words
The method of claim 1 wherein said modulation includes modulation state changes and wherein said predetermined time period is sufficiently long to allow a relatively large number of said modulation state changes to have occurred.
Claim 4
Dependent Claim 34 words
The method of claim 1 wherein said correlation step includes the step of visually portraying said designated condition on one axis and the amount of time said designated condition exists on a different axis.
Claim 5
Dependent Claim 47 words
The method of claim 1 wherein said steps include detecting more than one designated condition and correlating each of said designated conditions with the number of times the corresponding designated condition occurs over a predetermined time period, whereby the different correlations when taken together indicate modulation type.
Claim 6
Dependent Claim 21 words
The method of claim 4 wherein said designated conditions include consecutive 1's, consecutive 0's, frequency and amplitude singly or in combination.
Claim 7
Independent Claim 64 words
A method of establishing the type of modulation impressed on a signal comprising the steps of: repetitively sampling said signal, detecting a designated modulation-related condition of each sample; correlating said designated condition against the number of times said designated condition occurs over a predetermined time period during the repetitive sampling process and determining the modulation type based on the results of said correlation step.
Claim 8
Independent Claim 64 words
A method of establishing the type of modulation impressed on a signal comprising the steps of: repetitively sampling said signal, detecting a designated modulation-related condition of each sample; correlating said designated condition against the number of times said designated condition occurs over a predetermined time period during the repetitive sampling process and determining the modulation type based on the results of said correlation step.
Claim 9
Dependent Claim 35 words
The method of claim 6 wherein said modulation includes modulation state changes and wherein said predetermined time period is sufficiently long to allow a relatively large number of said modulation state changes to have occurred.
Claim 10
Dependent Claim 34 words
The method of claim 6 wherein said correlation step includes the step of visually portraying said designated condition on one axis and said number of times said designated condition occurs on a different axis.
Claim 11
Dependent Claim 49 words
The method of claim 6 wherein said steps include simultaneously detecting more than one designated condition and simultaneously correlating each of said designated conditions with the number of times the corresponding designated condition occurs over a predetermined time period, whereby the different correlations when taken together indicate modulation type.
Claim 12
Independent Claim 63 words
A method of establishing the type of modulation impressed on a signal which is insufficiently sampled for complete demodulation comprising: detecting a designated modulation-related condition of the samples taken of said signal, and, correlating said designated condition with the number of times said designated condition occurs within a predetermined time period determining the modulation type based on the results of said correlation step.
Claim 13
Independent Claim 63 words
A method of establishing the type of modulation impressed on a signal which is insufficiently sampled for complete demodulation comprising: detecting a designated modulation-related condition of the samples taken of said signal, and, correlating said designated condition with the number of times said designated condition occurs within a predetermined time period determining the modulation type based on the results of said correlation step.
Claim 14
Dependent Claim 35 words
The method of claim 10 wherein said modulation includes modulation state changes and wherein said predetermined time period is sufficiently long to allow a relatively large number of said modulation state changes to have occurred.
Claim 15
Dependent Claim 34 words
The method of claim 10 wherein said correlation step includes the step of visually portraying said designated condition on one axis and said number of times said designated condition occurs on a different axis.
Claim 16
Dependent Claim 49 words
The method of claim 10 wherein said steps include simultaneously detecting more than one designated condition and simultaneously correlating each of said designated conditions with the number of times the corresponding designated condition occurs over a predetermined time period, whereby the different correlations when taken together indicate modulation type.
Claim 17
Dependent Claim 31 words
The method of claim 10 wherein said modulation includes modulation state changes and wherein said predetermined time period is long with respect to the time between changes of said modulation state.
Claim 18
Independent Claim 65 words
A method of establishing the type of modulation impressed on a signal detected by a compressive receiver comprising the steps of: detecting a designated modulation-related condition of the output signal from said compressive receiver, correlating said designated condition with the number of times said designated condition occurs within a predetermined time period and, determining the modulation type based on the results of said correlation step.
Claim 19
Independent Claim 65 words
A method of establishing the type of modulation impressed on a signal detected by a compressive receiver comprising the steps of: detecting a designated modulation-related condition of the output signal from said compressive receiver, correlating said designated condition with the number of times said designated condition occurs within a predetermined time period and, determining the modulation type based on the results of said correlation step.
Claim 20
Dependent Claim 35 words
The method of claim 15 wherein said modulation includes modulation state changes and wherein said predetermined time period is sufficiently long to allow a relatively large number of said modulation state changes to have occurred.
Claim 21
Dependent Claim 34 words
The method of claim 15 wherein said correlation step includes the step of visually portraying said designated condition on one axis and said number of times said designated condition occurs on a different axis.
Claim 22
Dependent Claim 49 words
The method of claim 15 wherein said step include simultaneously detecting more than one designated condition and simultaneously correlating each of said designated conditions with the number of times the corresponding designated condition occurs over a predetermined time period, whereby the different correlations when taken together indicate modulation type.
Claim 23
Dependent Claim 58 words
Apparatus for establishing the type of modulation impressed on a signal comprising: means for detecting a designated modulation-related condition of said signal, means for correlating said designated condition with the amount of time said designated condition exists over a predetermined time period and, means for determining the modulation type based on the correlation established by said correlating means.
Claim 24
Dependent Claim 58 words
Apparatus for establishing the type of modulation impressed on a signal comprising: means for detecting a designated modulation-related condition of said signal, means for correlating said designated condition with the amount of time said designated condition exists over a predetermined time period and, means for determining the modulation type based on the correlation established by said correlating means.
Claim 25
Dependent Claim 35 words
The apparatus of claim 19 wherein said modulation includes modulation state changes and wherein said predetermined time period is sufficiently long to allow a relatively large number of said modulation state changes to have occurred.
Claim 26
Dependent Claim 33 words
The apparatus of claim 19 wherein said correlation means includes means for visually portraying said designated condition on one axis and the amount of time said designated condition exists on a different axis.
Claim 27
Dependent Claim 49 words
The apparatus of claim 19 and further including means for detecting more than one designated condition and for correlating each of said designated conditions with the number of times the corresponding designated condition occurs over a predetermined time period, whereby the different correlations when taken together indicate modulation type.
Claim 28
Dependent Claim 69 words
Apparatus for establishing the type of modulation impressed on a signal comprising: means for repetitively sampling said signal, means for detecting a designated modulation-related condition of each sample; means for correlating said designated condition against the number of times said designated condition occurs over a predetermined time period during the repetitive sampling process; and, means for determining the modulation type based on the correlation established by said correlating means.
Claim 29
Dependent Claim 69 words
Apparatus for establishing the type of modulation impressed on a signal comprising: means for repetitively sampling said signal, means for detecting a designated modulation-related condition of each sample; means for correlating said designated condition against the number of times said designated condition occurs over a predetermined time period during the repetitive sampling process; and, means for determining the modulation type based on the correlation established by said correlating means.
Claim 30
Dependent Claim 14 words
The apparatus of claim 23 wherein said repetitive sampling means includes a compressive receiver.
Claim 31
Dependent Claim 57 words
In combination, a frequency swept compressive receiver; means for detecting a designated modulation-related condition of the signal from said compressive receiver; means for correlating said designated condition with the number of times said designated condition occurs over a predetermined data collection interval; and, means for determining modulation type based on the correlation established by said correlating means.
Claim 32
Dependent Claim 57 words
In combination, a frequency swept compressive receiver; means for detecting a designated modulation-related condition of the signal from said compressive receiver; means for correlating said designated condition with the number of times said designated condition occurs over a predetermined data collection interval; and, means for determining modulation type based on the correlation established by said correlating means.
Claim 33
Dependent Claim 122 words
The combination of claim 25 wherein said detecting means includes means for transforming the occurrence of said designated condition into an address for a random access memory, and wherein said correlating means includes a random access memory normally operative in a READ mode, means for adding 1 to the contents of the register in said memory corresponding to the address of the incoming signal applied thereto whenever said incoming signal is present and said memory is in a WRITE mode, and means for placing said memory in a WRITE mode when, said receiver is tuned to a predetermined frequency, whereby after a number of sweeps of said receiver, the number in said register reflects the number of occurrences of said designated condition.
Claim 34
Dependent Claim 26 words
The combination of claim 25 wherein said detecting means includes means for detecting the frequency of the signal from said compressive receiver as said designated condition.
Claim 35
Dependent Claim 43 words
The combination of claim 27 wherein said frequency detecting means includes means for generating a signal envelope from the signals from said compressive receiver and means for generating a pulse having a time-position corresponding to the time-position of the peak of said envelope.
Claim 36
Dependent Claim 26 words
The combination of claim 25 wherein said detecting means includes means for detecting the amplitude of the signal from said compressive receiver as said designated condition.
Claim 37
Dependent Claim 30 words
The combination of claim 25 wherein said detecting means includes means for detecting the consecutive 1's or 0's condition of the signal from said compressive receiver as said designated condition.
Claim 38
Dependent Claim 264 words
The combination of claim 30 wherein said 1's or 0's detection means includes: a threshold detector for producing a logic level "1" signal when an input signal thereto is above a predetermined threshold and a logic level "0" signal when said input signal is below said predetermined threshold; means for detecting a change in the output of said threshold detector, thereby to detect a change in modulation state from a "1" to a "0" or visa versa; a counter/latch circuit having a clock input terminal, a reset input terminal, and a latch input terminal; a two input terminal AND gate; means for connecting the output of said change detecting means to said latch and reset input terminals and to one input terminal of said AND gate; means for generating a clock pulse when in the sweep of said compressive receiver, said receiver is tuned to a predetermined frequency; means for applying said clock pulse to the other input terminal of said AND gate and to said clock input terminal, whereby when no modulation state change occurs said counter circuit increases its count with each clock pulse, and whereby whenever a modulation state change occurs, upon the next clock pulse said AND gate produces a signal suitable to place a random access memory, which is normally in a READ mode, in a WRITE mode, said latch circuit is latched, the contents of said counter are dumped to indicate the number of consecutive 1's or 0's and said counter is reset, such that the counter contents may be written into said memory as an address therefor.
Claim 39
Dependent Claim 121 words
The combination of claim 31 wherein said change detection means includes a two input terminal exclusive OR gate, with one input terminal connected directly to the output of said threshold detector; means for delaying the signal from said threshold detector by the time it takes for said compressive receiver to revisit said predetermined frequency, and means for applying the output of said delay means to the other input terminal of said exclusive OR gate and to the output of said counter/latch circuit such that the output of said delay means forms the most significant bit of the output from said counter/latch circuit, whereby the output of said counter/latch circuit indicates whether the counter contents relates to consecutive 1's or consecutive 0's.
Claim 40
Dependent Claim 101 words
The combination of claim 31 wherein said correlating means includes a random access memory normally operative in a READ mode, means for connecting said memory to the output of said counter/latch circuit and to the output of said AND gate, and means for adding 1 to the contents of the register in said memory corresponding to the address of the incoming signal applied thereto whenever said incoming signal is present and said memory is in a WRITE mode, whereby after a number of sweeps of said receiver, the number in said register reflects the number of occurrences of said designated condition.

References Cited (Backward Citations)

US2779869A Cited
US3465247A Cited
US3568054A Cited
US3560852A Cited
US3743942A Cited
US3820025A Cited
US3880147A Cited
US3982101A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1982-09-03 1983-03-05 1983-09-04 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1986-09-03 1987-03-05 1987-09-04 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1990-09-03 1991-03-05 1991-09-04 $7700.00 Window Closed / Lapsed

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