Amplitude correction method of signals measured by hydrophone based on FIR filter design

Abstract

[Objectives] Due to the limitation of the existing fabrication technology, the sensitivity of hydrophones at different frequency is not exactly the same. Most of the acquisition equipment can only convert acoustic waves to electrical signals by setting up a fixed reference sensitivity,which will lead to the deviation between measured signal and actual signal,so it is necessary to improve the accuracy of the measured signal by amplitude correction. An amplitude correction method of signals measured by hydrophone based on filter design was proposed in this paper to convert the amplitude correction into Finite Impulse Response(FIR)filter design problem.[Methods] Firstly,the filter coefficients that meet the amplitude correction characteristics were designed by the second-order cone programming method. Then, the measured signal is filtered in time domain to achieve amplitude correction.[Results] The processing results show that the relative error of corrected signals decreases with the length of the filter. When the length of the filter is 257,the relative error of the corrected signal is only 0.3%.[Conclusions] The method overcomes the defect of time accumulation required by block processing of Fast Fourier Transform (FFT),and obtains continuous and accurate corrected signals only by using time-domain filter,which has the advantages of good real-time capability,small relative error and low computational cost.

Keywords

• broadband signal amplitude correction
• fir filter design
• second-order cone programming
• hydrophone