Digital beamsteering for a parametric scanning sonar system
First Claim
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1. A parametric scanning sonar system which generates a desired pattern of ensonification in a fluid medium comprising:
- transducer means for producing sonar waves,means for driving the transducer means, said driving means comprising;
a source of continuous wave energy comprising a selected modulation waveform generator and a carrier waveform generator, andmeans, connected to the source, for appropriately switching the energy from the source on and off, said switching means comprising a comparator means for receiving waveforms from the modulation waveform generator and the carrier waveform generator as inputs and for producing a pulse duration modulation composite transducer drive output when the magnitude of the carrier waveform exceeds the magnitude of the modulation waveform, andmeans for thereafter entering the composite transducer drive output waveform into the transducer means which transforms the composite transducer drive output into a sonar beam.
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Abstract
Digital beamsteering for a parametric scanning sonar steers a nonlinear, ulated signal of a single high frequency by appropriately delaying and/or varying the phase of the signal as it enters each of a plurality of elements in an array. The sonar beam can be steered electronically over a wide range of angles.
21 Citations
24 Claims
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1. A parametric scanning sonar system which generates a desired pattern of ensonification in a fluid medium comprising:
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transducer means for producing sonar waves, means for driving the transducer means, said driving means comprising; a source of continuous wave energy comprising a selected modulation waveform generator and a carrier waveform generator, and means, connected to the source, for appropriately switching the energy from the source on and off, said switching means comprising a comparator means for receiving waveforms from the modulation waveform generator and the carrier waveform generator as inputs and for producing a pulse duration modulation composite transducer drive output when the magnitude of the carrier waveform exceeds the magnitude of the modulation waveform, and means for thereafter entering the composite transducer drive output waveform into the transducer means which transforms the composite transducer drive output into a sonar beam. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for digitally steering a sonar beam, by means of a transducer array comprised of a plurality of elements, comprising the steps of:
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generating a transducer drive output signal; entering the generated transducer drive output signal into a first plurality of shift register strings arranged as an ordered sequence of strings, where each string comprises an equal number η
of shift registers connected in series,producing the transducer drive output signal at the output of the η
th shift register of the first string after (y)×
(p) clock pulses at frequency F1 and (y) ×
(η
-p) clock pulses at frequency F2, y representing bits per shift register, andproducing the transducer drive output signal at the η
th shift register of successive strings in the sequence after an appropriate number of clock pulses at frequency F1 and at frequency F2, andfeeding the transducer drive output signal at the output of the η
th shift register of each string in the sequence to corresponding elements in the transducer array. - View Dependent Claims (20, 21, 22, 23, 24)
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19. A method for digitally steering a sonar beam as in clain 18, further comprising the steps of:
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generating a basic clock frequency F, and extracting clocks at frequencies F1 and F2 from the basic clock frequency F such that F1+F2=F.
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Specification