A Method for Measuring the Center Velocity of the Echo Beam of Surface Target

Abstract

The invention discloses an area target echo beam center velocity measurement method. Firstly, echoes are subjected to acceleration compensation; secondly, whether a velocity filtering value is in a near-zone measurement pattern or a far-zone measurement pattern is judged, if the velocity filtering value is in the near-zone measurement pattern, after a frequency spectrum of the echoes is obtained through FFT operation, the Chirp-Z method is used for thinning spectral lines nearby the Doppler velocity to obtain an echo frequency spectrum, and if the velocity filtering value is in the far-zone measurement pattern, the echo frequency spectrum is obtained through the FFT operation, and finally the echo frequency spectrum is subjected to smoothing and envelop interception to obtain a frequency value corresponding to a beam center, so that the velocity value is calculated; finally, the Kalman filtering method is adopted to track the velocity, and the velocity, acceleration and other information at the next moment are predicted. By means of the area target echo beam center velocity measurement method, the requirements for a large dynamic range and high accuracy are met, and measurement accuracy is improved.

Description

Technical field [0001] The invention relates to a method for measuring the center velocity of an echo beam, in particular to a method for measuring the center velocity of a continuous wave Doppler radar high-precision surface target echo beam, and belongs to the technical field of space microwave remote sensing. Background technique [0002] Continuous wave speed radar is a key single unit in the lunar deep space exploration and landing project. It provides accurate satellite speed information for satellite guidance, navigation and control systems, thereby ensuring the safety of landing. The continuous wave velocity measurement radar has high measurement accuracy. It adopts a single method of obtaining the Doppler beam center of the echo from a high-precision surface target, and calculates the Doppler frequency of the beam center from the Doppler spectrum of the surface target. In addition, continuous wave speed radar has broad application prospects in missile guidance and the ta...

AI Technical Summary

Problems solved by technology

[0003] The electromagnetic wave emitted by the antenna is a beam with a certain width. The radial components of the velocity in each component direction in the beam are different, which corresponds to different Doppler frequency shifts. Therefore, the echo signal received by the antenna is composed of multiple components with different frequencies. Due to the acceleration of the lander, the Doppler bandwidth will be broadened, and at the same time, due to the influence of scattering and other factors, the position of the peak component in the echo signal will be shifted

[0004] In order to improve the measurement accuracy of the Doppler signal, it is necessary to eliminate the influence of the Doppler spectrum broadening caused by the acceleration of the lander's motion, so it is necessary to estimate and compensate the acceleration. At present, the existing literature is all about the movement of the point target under the condition of maneuvering For compensation, the maximum likelihood method, the time-frequency analysis method, and the de-chirp method based on the acceleration template can be used to estimate the target acceleration. These methods require too much computation, which is not conducive to real-time processing; the second-order polynomial phase transformation (DPT ) is a method of estimating the acceleration with a small amount of calculation, but for the acceleration estimation of the surface target, its accuracy will be greatly reduced

In addition, for the detection of the Doppler frequency of the surface target, the frontier detection, energy center of gravity method or geometric center method are used in the existing literature, but these methods have poor estimation errors for obtaining the Doppler frequency corresponding to the center of the antenna beam

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