Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
653 words
In an acoustic echo ranging system for detection of the presence of a target submarine and of the type which transmits a twin pulse echo ranging search signal consisting of first and second pulses having a predetermined interval of time separation therebetween; and in which the input signal received during a listening period is fed through a dual channel delay network for splitting a signal into two parallel channels and introducing a relative delay therebetween, said dual channel delay network comprising first and second parallel channels with the second channel adapted to provide a fixed delay in the transmission of the input signal therethrough which exceeds the time for transmission of the input signal through said first channel by said predetermined interval of separation between the first and second pulses of the twin pulse echo ranging search signal; and in which the outputs of said first and second parallel channels are compared to detect coincidence of target reflection of the second of the twin pulses from a target in the output of the first channel with reflection of the first of the twin pulses from the same target in the output of the second channel; said echo ranging system being operative to repetitively transmit the twin pulse search signal at regular time intervals of the order of 1-2 seconds; the improvements in combination comprising: 1. means for generating a twin pulse modulation signal for application to the modulator of the echo ranging system transmitter, said twin pulse modulating signal consisting of first and second pulses having a predetermined interval of separation therebetween, said first and second pulses both being of the same predetermined pulse duration, having a value of an order of 1-2 milliseconds, said interval of separation between the first and second pulses being substantially equal to the maximum expected duration of pulse reflection signal from a target submarine which may appear in said system input signal, said maximum expected duration of pulse reflection signal being determined by the time it takes an individual pulse of the twin pulse search signal to transverse the length of a target submarine oriented substantially longitudinally along the line-of-sight from the echo ranging system, the magnitude of the maximum expected duration of pulse reflection being of an order including the value 70 milliseconds, 2. a transmitter and an associated modulator, said transmitter and modulator being operable to transmit a single frequency acoustic signal in response to said twin pulse modulation signal applied to a modulator, whereby said twin pulse modulation signal causes the system to transmit a single frequency acoustic energy twin pulse echo ranging search signal having its first and second pulses of a single frequency of acoustic energy and having pulse duration and interval of time separation characteristics corresponding to those of the modulation signal, and 3. means for demodulating the input signal operative to provide the amplitude modulation envelope of the input signal at the outputs of both the first and second channels of the dual channel delay network, 4. reflection by a target submarine of said single frequency acoustic energy twin pulse echo ranging search signal producing an input signal amplitude modulation envelope containing a sequential pair of target echo signature signals separated by said predetermined time, the individual target echo signals of said sequential pair being correlated relative to one another to a high degree in both time and amplitude of component perturbation as the result of the reflection mechanism of the twin pulses of a single frequency of acoustic energy, said high degree of correlation having a magnitude of correlation coefficient R, of an order including the range of values 0.8 to 0.9, whereby system selectivity in detection of coincidence of the first of the sequential pair of target echo signature signals at the output of the first channel with the second of the sequential pair of target echo signature signals at the output of the second channel is enhanced.
Claim 2
Dependent Claim
653 words
In an acoustic echo ranging system for detection of the presence of a target submarine and of the type which transmits a twin pulse echo ranging search signal consisting of first and second pulses having a predetermined interval of time separation therebetween; and in which the input signal received during a listening period is fed through a dual channel delay network for splitting a signal into two parallel channels and introducing a relative delay therebetween, said dual channel delay network comprising first and second parallel channels with the second channel adapted to provide a fixed delay in the transmission of the input signal therethrough which exceeds the time for transmission of the input signal through said first channel by said predetermined interval of separation between the first and second pulses of the twin pulse echo ranging search signal; and in which the outputs of said first and second parallel channels are compared to detect coincidence of target reflection of the second of the twin pulses from a target in the output of the first channel with reflection of the first of the twin pulses from the same target in the output of the second channel; said echo ranging system being operative to repetitively transmit the twin pulse search signal at regular time intervals of the order of 1-2 seconds; the improvements in combination comprising: 1. means for generating a twin pulse modulation signal for application to the modulator of the echo ranging system transmitter, said twin pulse modulating signal consisting of first and second pulses having a predetermined interval of separation therebetween, said first and second pulses both being of the same predetermined pulse duration, having a value of an order of 1-2 milliseconds, said interval of separation between the first and second pulses being substantially equal to the maximum expected duration of pulse reflection signal from a target submarine which may appear in said system input signal, said maximum expected duration of pulse reflection signal being determined by the time it takes an individual pulse of the twin pulse search signal to transverse the length of a target submarine oriented substantially longitudinally along the line-of-sight from the echo ranging system, the magnitude of the maximum expected duration of pulse reflection being of an order including the value 70 milliseconds, 2. a transmitter and an associated modulator, said transmitter and modulator being operable to transmit a single frequency acoustic signal in response to said twin pulse modulation signal applied to a modulator, whereby said twin pulse modulation signal causes the system to transmit a single frequency acoustic energy twin pulse echo ranging search signal having its first and second pulses of a single frequency of acoustic energy and having pulse duration and interval of time separation characteristics corresponding to those of the modulation signal, and 3. means for demodulating the input signal operative to provide the amplitude modulation envelope of the input signal at the outputs of both the first and second channels of the dual channel delay network, 4. reflection by a target submarine of said single frequency acoustic energy twin pulse echo ranging search signal producing an input signal amplitude modulation envelope containing a sequential pair of target echo signature signals separated by said predetermined time, the individual target echo signals of said sequential pair being correlated relative to one another to a high degree in both time and amplitude of component perturbation as the result of the reflection mechanism of the twin pulses of a single frequency of acoustic energy, said high degree of correlation having a magnitude of correlation coefficient R, of an order including the range of values 0.8 to 0.9, whereby system selectivity in detection of coincidence of the first of the sequential pair of target echo signature signals at the output of the first channel with the second of the sequential pair of target echo signature signals at the output of the second channel is enhanced.
Claim 3
Dependent Claim
84 words
a transmitter and an associated modulator, said transmitter and modulator being operable to transmit a single frequency acoustic signal in response to said twin pulse modulation signal applied to a modulator, whereby said twin pulse modulation signal causes the system to transmit a single frequency acoustic energy twin pulse echo ranging search signal having its first and second pulses of a single frequency of acoustic energy and having pulse duration and interval of time separation characteristics corresponding to those of the modulation signal, and
Claim 4
Dependent Claim
84 words
a transmitter and an associated modulator, said transmitter and modulator being operable to transmit a single frequency acoustic signal in response to said twin pulse modulation signal applied to a modulator, whereby said twin pulse modulation signal causes the system to transmit a single frequency acoustic energy twin pulse echo ranging search signal having its first and second pulses of a single frequency of acoustic energy and having pulse duration and interval of time separation characteristics corresponding to those of the modulation signal, and
Claim 5
Dependent Claim
11 words
A system in accordance with claim 1, the improvements further comprising:
Claim 6
Dependent Claim
33 words
means for demodulating the input signal operative to provide the amplitude modulation envelope of the input signal at the outputs of both the first and second channels of the dual channel delay network,
Claim 7
Dependent Claim
33 words
means for demodulating the input signal operative to provide the amplitude modulation envelope of the input signal at the outputs of both the first and second channels of the dual channel delay network,
Claim 8
Dependent Claim
153 words
reflection by a target submarine of said single frequency acoustic energy twin pulse echo ranging search signal producing an input signal amplitude modulation envelope containing a sequential pair of target echo signature signals separated by said predetermined time, the individual target echo signals of said sequential pair being correlated relative to one another to a high degree in both time and amplitude of component perturbation as the result of the reflection mechanism of the twin pulses of a single frequency of acoustic energy, said high degree of correlation having a magnitude of correlation coefficient R, of an order including the range of values 0.8 to 0.9, whereby system selectivity in detection of coincidence of the first of the sequential pair of target echo signature signals at the output of the first channel with the second of the sequential pair of target echo signature signals at the output of the second channel is enhanced.
Claim 9
Dependent Claim
153 words
reflection by a target submarine of said single frequency acoustic energy twin pulse echo ranging search signal producing an input signal amplitude modulation envelope containing a sequential pair of target echo signature signals separated by said predetermined time, the individual target echo signals of said sequential pair being correlated relative to one another to a high degree in both time and amplitude of component perturbation as the result of the reflection mechanism of the twin pulses of a single frequency of acoustic energy, said high degree of correlation having a magnitude of correlation coefficient R, of an order including the range of values 0.8 to 0.9, whereby system selectivity in detection of coincidence of the first of the sequential pair of target echo signature signals at the output of the first channel with the second of the sequential pair of target echo signature signals at the output of the second channel is enhanced.
Claim 10
Dependent Claim
93 words
means for displaying the output of the first and second parallel channels of the dual channel delay network as adjacent traces of their respective time varying amplitudes and for displaying same in a manner in which the portions of the respective channel output signals which are in time coincidence at the output ends of the channels are in juxtaposed relationship in the adjacent traces, whereby presence of a target signature echo may be detected by a visual recognition of a high degree of amplitude symmetry in coextensive linear sections of the adjacent traces.
Claim 11
Dependent Claim
93 words
means for displaying the output of the first and second parallel channels of the dual channel delay network as adjacent traces of their respective time varying amplitudes and for displaying same in a manner in which the portions of the respective channel output signals which are in time coincidence at the output ends of the channels are in juxtaposed relationship in the adjacent traces, whereby presence of a target signature echo may be detected by a visual recognition of a high degree of amplitude symmetry in coextensive linear sections of the adjacent traces.