Beat frequency extraction method of high speed and high noise Doppler signal based on double correction

Abstract

When detecting ultrahigh speed micro targets, because the photon Doppler signal will be seriously interfered with by high-frequency noise, it is difficult to accurately extract the beat frequency information, resulting in serious speed demodulation error. Therefore, we propose a beat frequency extraction method for high-speed and high-noise Doppler signals based on double correction, which can accurately correct the beat frequency signals of high-frequency noise interference. First, the ratio correction method is used for the first spectrum correction to screen out the normalized spectrum of high-frequency noise interference; then, according to the degree of noise interference, the energy barycenter correction method or linear interpolation method is used for the second spectrum correction. Numerical simulation results show that this method can reduce the spectral error by 1.6% to 2.1%. We used this method to process the Doppler signal from the detonation small flyer experiment in Initiating explosive device testing. The results show that it can reduce the beat frequency error by 1.83 times at most under high-frequency noise interfered, equivalent to the instantaneous velocity error of 1955 m/s can be decreased after velocity demodulation. Therefore, the beat frequency extraction method based on double correction has good noise resistance and reliability. We corrected the different regions’ frequency spectrums according to the noise interference intensity, which provides an idea for the beat frequency extraction of high-speed and high-noise Doppler signals.