A Modulation Method of Recursive Filtering for Transient Broadband Excitation Signal of Parametric Array Sonar

Abstract

The invention relates to a recursive filtering modulating method of a transient broadband excitation signal of parametric array sonar. The method comprises the following steps: performing recursive filtering for a signal to be processed through a recursive filtering device to obtain X(n+1); obtaining an envelope E(n+1); performing up-sampling for the envelope E(n+1) through an interpolation filter; performing double-sideband amplitude modulation together with a digital carrier signal; performing D / A conversion to obtain an analog signal, and thus obtaining the excitation signal of a parametric emitting system. The method applies to both parametric array sonar and an air acoustical parametric array system; the application scope of acoustical parametric array is widely expanded, and a predictable huge potential market value is brought.

Description

technical field [0001] The invention relates to a recursive filtering modulation method of a parametric array sonar transient broadband excitation signal. Background technique [0002] Under the nonlinear effect of water (or air) medium, parametric array sonar will generate secondary waves, which have the advantage of high directivity, so parametric arrays have been widely used in sonar technology at first. In the parametric array system, signal processing is the key technology in the parametric array system, and the signal processing generally includes two parts: preprocessing and modulation. The signal processing of the earliest parametric array (or called audio frequency directional system) is to use the signal as an envelope and carry out double-sided band amplitude modulation [1], and then transmit it as an excitation signal through the parametric array system. This method is simple to implement but is not suitable for broadband The distortion of the signal is relative...

AI Technical Summary

Problems solved by technology

The signal processing of the earliest parametric array (or called audio frequency directional system) is to use the signal as an envelope and carry out double-sided band amplitude modulation [1], and then transmit it as an excitation signal through the parametric array system. This method is simple to implement but is not suitable for broadband The signal distortion is relatively serious

The square root modulation method [2] performs pre-square root processing on the signal, and then performs double-sided band amplitude modulation with the carrier. This method significantly reduces the distortion of the secondary wave. If the compensation filter of 12dB / oct is performed before the amplitude modulation , then this method satisfies the no-distortion condition, but for transient broadband signals (especially in the case of unknown signal parameters), a good 12dB / oct compensation filter is not easy to implement and the implementation process is not flexible enough, which is not conducive to real-time implementation

Although single sideband modulation [3] reduces the bandwidth limit of the transducer compared with double sideband modulation, it has intermodulation distortion for broadband signals

The double-integral pre-square extraction method [4-5] is strictly in line with the Berktay far-field solution without distortion conditions, but when this method is applied in engineering practice, due to the influence of the initial value and other factors in the process of double-integrating the signal, , the integration results are often 'divergent'

Other modulation methods [6-9] require iterative calculations. Although they can be close to distortion-free after processing, the large amount of calculation is not conducive to real-time implementation

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