Correlation sonar system
First Claim
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1. A method of determining the relative velocity between a correlation sonar system and a reflective surface, comprising the steps of:
- providing a transmitting transducer for emitting acoustic energy onto the reflective surface;
generating a single pulse of electrical energy to the transmitting transducer;
providing a plurality of receiving transducers for receiving a single return echo pulse from the reflecting surface after transmission of the single pulse from the transmitting transducer;
providing a plurality of demodulators, wherein each one of the demodulators is connected to a corresponding one of the receiving transducers, and wherein each of the demodulators generates a set of values;
cross-correlating the set of values for each receiving transducer at a predetermined time lag less than the width of the single return echo pulse; and
estimating the relative velocity between the sonar system and the reflective surface using the cross-correlated set of values.
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Abstract
In a correlation device, a system and method for measuring velocities using a single coded pulse generator. The correlation device may also include maximum likelihood estimation techniques for processing the echo signals received from a plurality of transducers. The presently preferred embodiment of the device is as a current profiler having a bottom tracking capability for providing vessel velocity.
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Citations
17 Claims
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1. A method of determining the relative velocity between a correlation sonar system and a reflective surface, comprising the steps of:
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providing a transmitting transducer for emitting acoustic energy onto the reflective surface; generating a single pulse of electrical energy to the transmitting transducer; providing a plurality of receiving transducers for receiving a single return echo pulse from the reflecting surface after transmission of the single pulse from the transmitting transducer; providing a plurality of demodulators, wherein each one of the demodulators is connected to a corresponding one of the receiving transducers, and wherein each of the demodulators generates a set of values; cross-correlating the set of values for each receiving transducer at a predetermined time lag less than the width of the single return echo pulse; and estimating the relative velocity between the sonar system and the reflective surface using the cross-correlated set of values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 16, 17)
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8. In a computer, a method for generating an optimized coded monopulse signal comprising a plurality of coded pulse elements to improve noise averaging, comprising the steps of:
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specifying a length for a coded monopulse signal; specifying a time lag for an autocorrelation peak of the autocorrelation function corresponding to the coded monopulse signal; generating an initial pseudo-random code of the specified length using a code-finding program in the computer, said code indicative of the coded monopulse signal; calculating an autocorrelation function for the initial pseudo-random code having the specified time lag; calculating a current best figure of merit based upon the autocorrelation function; and searching among a plurality of candidate codes, each one of said codes having a calculable figure of merit, for a best coded monopulse signal, said search beginning with the initial pseudo-random code and being responsive to the current best and calculable figures of merit. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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Specification