Sonar transceiver system and method
First Claim
1. A sonar transceiver system including transducer means for transmiting and receiving sonar signals in the water, including means for generating chirp-like electrical signals connected to said transducer, means to convert said electrical signals to acoustic transmitted signals and means for receiving echo signals including said transducer means and a correlator for correlating the received signals with the transmitted signals and which responds to a recognized correlation by producing an output signal, characterized in that said system includes:
- (a) means including said transducer means for generating and transmitting sonar signals consisting of a plurality of n ultrasonic tones closely spaced in frequency and consecutive such as to form a pseudo chirp pulse,(b) means for receiving and detecting echo signals including said transducer means, and a receiver including hard limiting means for converting said received signals into binary signals,(c) a shift register for receiving said binary signals,(d) clock means connected to said shift register for processing samples of said binary signals through said register for a predetermined number of counts at a rate corresponding to the frequency of the first of said tones,(e) storage means for storing a binary wave pattern corresponding to said transmitted tones as limited,(f) correlation means comprising said received binary signals with said stored pattern and producing an output signal when said shift register binary signal and said stored pattern reach a desired correlation,(g) means responsive to the occurence of said output signal to reset said clock to change the rate of sampling said received binary signals in said shift register to correspond to the frequency of the second of said tones, said correlation means then comparing said received binary signals with said stored pattern and producing a second output signal when said shift register binary signal and said stored pattern reach a desired correlation,(h) means responsive to the completion of the number of counts of said clock means at each of said second and subsequent output signals to the nth output signals for successively resetting said clock to change the rate of processing said binary signals in said shift register to correspond to the frequencies of said second and successive tones to the nth tone, said correlation means producing an output signals each time said shift register binary signal and said stored pattern reach a desired correlation,(i) circuit means determining whether said output signals represent the reception of said tones in the proper order as transmitted, and(j) majority test means responsive to the occurence of a desired majority of said "n" tones and providing an output if said desired majority of tones is present.
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Accused Products
Abstract
A sonar transceiver system and method includes an oscillator and programmable divider which are arranged to cause a transmitting transducer to transmit a plurality of four consecutive closely spaced tones in the manner of a pseudo-chirp. The receiver includes hard limiting means for converting received echo signals to binary signals and tone correlation and detection means including a shift register which compares samples of the binary received signal with a sample of a sine wave as hard limited which is carried on a storage register. A series of exclusive-OR comparator circuits effect the comparison and produce output signals of a desired magnitude when correlations are found. Switching means responsive to detection of the first of the transmitted tones causes the programming means to vary the divisors of the programmable divider to produce clock pulses of varying frequency to the shift register for the time and in the order of the transmitted tones.
20 Citations
14 Claims
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1. A sonar transceiver system including transducer means for transmiting and receiving sonar signals in the water, including means for generating chirp-like electrical signals connected to said transducer, means to convert said electrical signals to acoustic transmitted signals and means for receiving echo signals including said transducer means and a correlator for correlating the received signals with the transmitted signals and which responds to a recognized correlation by producing an output signal, characterized in that said system includes:
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(a) means including said transducer means for generating and transmitting sonar signals consisting of a plurality of n ultrasonic tones closely spaced in frequency and consecutive such as to form a pseudo chirp pulse, (b) means for receiving and detecting echo signals including said transducer means, and a receiver including hard limiting means for converting said received signals into binary signals, (c) a shift register for receiving said binary signals, (d) clock means connected to said shift register for processing samples of said binary signals through said register for a predetermined number of counts at a rate corresponding to the frequency of the first of said tones, (e) storage means for storing a binary wave pattern corresponding to said transmitted tones as limited, (f) correlation means comprising said received binary signals with said stored pattern and producing an output signal when said shift register binary signal and said stored pattern reach a desired correlation, (g) means responsive to the occurence of said output signal to reset said clock to change the rate of sampling said received binary signals in said shift register to correspond to the frequency of the second of said tones, said correlation means then comparing said received binary signals with said stored pattern and producing a second output signal when said shift register binary signal and said stored pattern reach a desired correlation, (h) means responsive to the completion of the number of counts of said clock means at each of said second and subsequent output signals to the nth output signals for successively resetting said clock to change the rate of processing said binary signals in said shift register to correspond to the frequencies of said second and successive tones to the nth tone, said correlation means producing an output signals each time said shift register binary signal and said stored pattern reach a desired correlation, (i) circuit means determining whether said output signals represent the reception of said tones in the proper order as transmitted, and (j) majority test means responsive to the occurence of a desired majority of said "n" tones and providing an output if said desired majority of tones is present.
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2. A system of correlating a series of received acoustic signals with a plurality or uniform closely spaced transmitted tones comprising receiving means for receiving said acoustic signals, converting said acoustic signals to electrical alternating current signals and hard limiting said electrical signals to produce a corresponding series of binary signals:
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a shift register connected to said receiving means and a programmable clock for clocking samples of said series of binary signals through said shift register, a storage register storing a pattern of binary signals corresponding to the pattern of a sine wave as hard limited, means programming said clock to produce clock pulses at the frequencies and in the order of said transmitted tones to cause samples of said series of received binary signals to be clocked through said shift register at said frequencies and in the order transmitted, comparator circuit and summing means connected to said shift register and said storage register for continuously comparing the binary signals thereon and for producing an output of a desired magnitude upon the occurrence of a desired correlation between said shift register and said storage register signals. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9)
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10. A system for correlating a series of uniform alternating current signals closely spaced in frequency and consisting of first through nth tones with unknown alternating current signals believed to contain said tones comprising,
means hard limiting said unknown alternating current signals to produce a series of binary signals, a shift register including a clock terminal for clocking samples of said binary signals therethrough, a storage register for storing a pattern of binary signals corresponding to the pattern of a sine wave as hard limited, programmable counter means connected to said clock terminal for providing variable frequency clock pulses to said shift register, the frequencies of said clock pulses corresponding to the order of said first through nth tones, comparator circuit and summing means connected to said shift register and said storage register for continuously comparing the binary signals thereon and for producing output signals of a desired magnitude upon the occurence of correlations between said binary signals,
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12. A method of processing sonar signals using chirp-like tones including the steps of:
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(a) transmitting a plurality of n ultrasonic tones closely spaced in frequency and consecutive such as to form a pseudo chirp pulse, (b) receiving echo signals including said tones and hard limiting said received signals to produce binary signals representative of said received signals, (c) storing a binary pattern corresponding to a sine wave as hard limited, (d) processing samples of said binary received signals through a shift register at a clock rate corresponding to the frequency of the first of said tones, (e) comparing said received binary signals with said stored binary pattern and producing an output signal when said binary received signals and said binary pattern reach a desired correlation, (f) varying said clock rate in response to said output signal to correspond to the frequency of the second of said tones, repeating step (e) and producing a second output signal if a correlation is found, (g) successively varying said clock rate to correspond to the frequency of the third and subsequent tones up to the nth tone, repeating step (e) each time and producing third and subsequent output signals up to the nth output signal, and (h) testing said output signals to determine if a desired majority of said "n" tones is represented and providing an output if said desired majority of tones is present.
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13. A method of correlating a series of one through n closely spaced uniform alternating current tones having an essentially sine wave characteristic and constituting a pseudo-chirp with an unknown alternating current signal, comprising the steps of:
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(a) storing on a storage register a binary pattern corresponding to a sine wave as hard limited, (b) hard limiting said unknown alternating current signal to produce a series of binary signals and connecting said signals to a shift register, (c) providing a series of clock pulses corresponding to the frequency of the first of said tones and clocking samples of said series of binary signals through said shift register at said frequency, (d) continually comparing said series of binary signals with said binary pattern and producing an output signal when said signals reach a desired correlation, (e) responding to said output signal to change the frequency of said clock pulses to that of the second of said tones and continuing said clock frequency for the period of the second of said tones, while repeating step (d) and producing a second output signal if a correlation is found, (f) responding to completion of the period of the second of said tones to change the frequency of said clock pulses to that of the third tone, again repeating step (d) and producing a third output signal if a correlation is found, (g) continuing to change the frequency of said clock pulses to that of said subsequent tones to said nth tone, each time repeating step (d) and producing an output signal when a correlation is found. - View Dependent Claims (14)
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Specification