A radar intermediate frequency signal adaptive control system and method

Abstract

The invention discloses a radar intermediate frequency signal adaptive control system and method. The system includes an analog switch filter adjustment module, a gain adjustment module and a control module. The output end of the analog switch filter adjustment module is connected to the input of the gain adjustment module. The input end of the control module is connected with the output end of the gain adjustment module, and the output end of the control module is connected with the control end of the analog switch filter adjustment module and the gain adjustment module; the control module is used The filter frequency curve of the analog switch filter adjustment module or / and the gain multiple of the gain adjustment module are adjusted according to the output signal of the gain adjustment module. The invention can realize the self-adaptive control of the radar intermediate frequency signal, and greatly reduce the design difficulty and debugging difficulty of the operational amplifier of the intermediate frequency signal.

Description

technical field [0001] The invention mainly relates to the technical field of radar signal processing, in particular to a radar intermediate frequency signal self-adaptive control system and method. Background technique [0002] There has been a lack of effective in-depth research on the processing of relatively low-frequency intermediate frequency signals after radar mixing. The usual practice is to use operational amplifiers to build primary / secondary gain modules, use DC blocking capacitors as high-pass filters at the front end, and use RC as low-pass filters at the rear end. device. The high-pass filter is mainly used to suppress the radar low-frequency signal. The low-frequency signal is mainly generated by the AM leakage. By suppressing the low-frequency signal, the AM leakage signal will not saturate the op amp. The low-pass filter is mainly used to suppress high-frequency signals that are not needed for radar detection, so as to prevent high-frequency signals from a...

AI Technical Summary

Problems solved by technology

The gain multiple of the op amp module and the cut-off frequency of the filter are determined by the feedback resistor or the series resistor, which cannot be adjusted during the operation of the radar, and the electromagnetic waves emitted by the radar encounter obstacles and reflect back to the radar. RCS, and the distance between the object and the radar is constantly changing. The larger the RCS, the closer the object is to the detection radar, and the stronger the intermediate frequency energy after the radar is mixed.

[0003] If the gain multiple of the intermediate frequency operational amplifier module is set relatively low, the signal after the operational amplifier gain cannot fully meet the sampling amplitude requirements of the ADC, reducing the effective number of bits used by the ADC and reducing the long-distance detection performance of the radar; on the contrary, if the intermediate frequency operational amplifier The gain multiple of the module is set relatively high. Reflectors with large RCS such as cars or close-range targets are likely to cause op amp saturation. The harm caused by saturation is more obvious. A single-frequency sine wave becomes a rectangle after saturation and clipping. wave, and the spectrum expansion of the rectangular wave is not a single frequency point, the harmonic component increases, and multiple false target points appear

[0004] The existing intermediate frequency signal modules generally have two forms: fixed gain amplifier; AGC software controllable gain amplifier, fixed gain amplifier means that the gain of the intermediate frequency is determined by the welding feedback resistor, the gain cannot be adjusted during the radar working process, AGC is the voltage control Gain, during the working process of the radar, the radar can control the gain by controlling the voltage of the AGC module through software. Both of these forms cannot dynamically adjust the amplitude-frequency characteristics of the intermediate frequency signal processing module, and can only simply amplify / reduce all echoes within the bandwidth. The frequency signal cannot fully utilize the operational amplifier to improve the signal-to-noise ratio of targets at different distances and different RCS targets. It cannot be used as an independent individual to judge the impact of amplification / reduction gain, especially the amplification. When the amplification is excessive, the radar detection area will be damaged. The echo signal of the strong reflector and near reflector in the interior is very easy to cause the saturation of the op amp. Saturation of the op amp is a very bad phenomenon in the whole system of the radar. When the electromagnetic wave of the radar hits the target, the echo signal should be a single frequency When the op amp is saturated, the sine wave will be clipped into a rectangular wave, and the Fourier expansion of the spectrum of the rectangular wave will contain multiple harmonics, and a large number of false targets will appear.

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