Virtually steerable parametric acoustic array
First Claim
1. A sonar system of the type wherein a carrier signal is modulated by an envelope signal and the modulated carrier signal is returned from an echo source as a reflected signal, the improvement comprising:
- means for converting the reflected signal to a digital reflected signal;
a first digital integrator for digitally integrating the digital reflected signal and producing a digital integrated signal;
a digital filter having a response matched to the envelope signal for digitally filtering the digital integrated signal thereby producing a digital filtered signal;
means for autoregressive modelling the digital filtered signal as the impulse response of a filter having a complex s-plane pole thereby providing a digital complex pole location; and
means for converting the digital complex pole location to a digital bearing signal proportional to the bearing of the echo source.
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Accused Products
Abstract
The invention concerns an application of linear system parameter estimation techniques to finite amplitude sonar devices, to extract fine grained angular position information about echo sources. The invention makes use of the fact that the waveform return by a reflecting object within the sonar'"'"'s beam varies according to its relative angular position from the receiver, and a discovery that this variation may be fit to a linear system model using autoregressive estimation theory to extract the nature of the variation. In all cases, the information is extracted without the mechanical or electrical steering of the sonar transmitting beam.
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Citations
12 Claims
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1. A sonar system of the type wherein a carrier signal is modulated by an envelope signal and the modulated carrier signal is returned from an echo source as a reflected signal, the improvement comprising:
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means for converting the reflected signal to a digital reflected signal; a first digital integrator for digitally integrating the digital reflected signal and producing a digital integrated signal; a digital filter having a response matched to the envelope signal for digitally filtering the digital integrated signal thereby producing a digital filtered signal; means for autoregressive modelling the digital filtered signal as the impulse response of a filter having a complex s-plane pole thereby providing a digital complex pole location; and means for converting the digital complex pole location to a digital bearing signal proportional to the bearing of the echo source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for finding the position of a reflecting object in an acoustic medium, in which a carrier signal is modulated by an envelope signal, and the modulated carrier signal is returned by the object as a reflected signal, the improvement comprising the steps of:
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(a) converting the reflected signal to a digital reflected signal; (b) integrating the digital reflected signal to provide a digital integrated signal; (c) filtering the digital integrated signal by a digital filter having a response method to the envelope signal, to provide a digital filtered signal; (d) autoregressively modelling the digital filtered signal as the response of a filter having a complex pole, to provide a digital complex pole location; and (e) converting the digital complex pole location to a bearing angle. - View Dependent Claims (11, 12)
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Specification