Research On Weak Signal Processing Method Of MHD Angular Rate Sensor

The Magnetohydrodynamics(MHD)angular rate sensor has the advantages of wide frequency band,low noise and small volume,so it is suitable for the measurement of micro-angle vibration of spatial structures.The MHD angular rate sensor is used to measure small angular vibrations.One of the most important performance indicators is equivalent noise.At present,the research of MHD angular rate sensor focuses on improving its low-frequency signal-to-noise ratio to improve low-frequency performance and further reduce the passband noise to obtain higher resolution.Therefore,the weak signal extraction and processing of MHD angular rate sensor is a key issue to achieve the above research objectives..In this paper,we study the processing method of weak signal of MHD angular rate sensor,and study the algorithm of signal frequency and amplitude estimation under low SNR.First,this paper studies the noise characteristics of the MHD angular rate sensor.The noise floor of the sensor is collected,and the noise power spectral density curve and the noise signal probability density curve of the sensor are obtained,and it is determined that the MHD angular rate sensor noise belongs to Gaussian colored noise.Secondly,this paper studies the wavelet denoising algorithm and power spectrum estimation algorithm for the parameter estimation of MHD angular rate sensor.The wavelet denoising algorithm is used to denoise the simulated signal and MHD angular rate sensor signals in different frequency bands and different SNR conditions,compare the performance of different denoising algorithms,and finally select the threshold denoising algorithm to process the sensor signals.Then,this paper studies the classical spectrum and modern spectrum estimation algorithm,estimates the frequency and amplitude of the signal,analyzes the frequency and amplitude estimation performance of each power spectrum estimation algorithm,and selects the periodic diagram method to process the sensor signal.Finally,the wavelet threshold denoising algorithm and the periodogram method are combined to estimate the frequency and amplitude of the MHD angular rate sensor.Finally,this paper adopts the high-order spectral method combining fourth-order cumulant with modern cross-spectrum,including: mutual fourth-order spectrum,mutual fourth-order spectrum MUSIC,mutual fourth-order Esprit-Tls and mutual fourth-order SVD algorithm.Under different frequency bands and signal-to-noise ratio conditions,the frequency and amplitude of the simulated signal and the sensor signal are estimated,and the improvement of the signal-to-noise ratio of the signal is analyzed.The results show that the mutual fourth-order spectrum estimation algorithm has a good ability to suppress the Gaussian colored noise of the MHD angular rate sensor.The frequency estimation resolution is < 1 Hz and the signal-to-noise ratio is improved by 7-11 dB.