Velocity measurement signal processing method for Doppler velocimeter

Abstract

The invention discloses a velocity measurement signal processing method for a Doppler velocimeter, comprising the following steps of: (A) preprocessing a received velocity measurement signal by using a filter; (B) carrying out Fourier analysis on the frequency of the signal obtained in the step (A) to obtain a reference velocity; (C) respectively solving the sine and a plurality of peak frequencies of the reference velocity obtained in the step (B) to respectively obtain a sine velocity curve and a peak velocity curve; and (D) comparing the reference velocity obtained in the step (B) with the sine velocity curve and the peak velocity curve obtained in the step (C) to obtain a corrected velocity curve. Three solving methods including a frequency Fourier analysis method, a sine solving method and a multi-peak frequency solving method are used in the velocity measurement signal processing method, so that the signal processing method is suitable for all the speed ranges, and the problem that the current velocity measurement method is difficult in velocity measurement in a region with low velocity smaller than 1000m / s, and particularly a region with the velocity close to 100m / s, is solved.

Description

technical field [0001] The invention relates to a signal processing method, in particular to a speed measuring signal processing method suitable for a Doppler speed measuring instrument. Background technique [0002] The Doppler Velocimeter is a velocity measuring device based on the optical Doppler effect and heterodyne method. It has the advantages of continuous monitoring of displacement and velocity, non-contact measurement and high testing accuracy. The basic principle of the device is that a laser emits laser light and divides it into two beams, which are reference light and signal light. The reference light is directly incident on the detector, and the signal light is emitted to the surface of the moving object. The surface of the object reflects the beam of light, and couples with the reference light to be incident on the detector. According to the Doppler effect, the frequency of light reflected by the surface of a moving object will change according to the speed o...

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Problems solved by technology

Since the wavelength of the laser used in the Doppler velocimeter is generally 1550 nm, according to formula (1), when the moving speed of the object is 100 m / s, the frequency of the interference signal is 1.29×10 8 , since the commonly used oscilloscope sampling rate in the test is 1×10 10 Above, according to the principle of discrete Fourier transform, the final frequency value obtained in the transform is Integer multiples of is the data sampling rate, is the number of Fourier analysis window points, when When the value is small, due to the limitation of the value range, the analysis of low-speed signals often shows a phase-like frequency signal curve, but when When taking a larger value, due to excessive smoothing, it will not be able to reflect the local changes of the speed curve. At the same time, because the speed will increase significantly during the entire speed measurement process of the experiment, in order to ensure the accuracy of the high-speed section measurement, the sampling rate of the oscilloscope cannot be reduced. , so the current speed measurement signal processing method of Doppler speedometer limits its application in low speed measurement

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