Non-linear target harmonic detection method based on noise frequency modulation technology

Abstract

The invention provides a non-linear target harmonic detection method based on a noise frequency modulation technology. The non-linear target harmonic detection method comprises the steps that a noisesequence is generated; the noise sequence is subjected to frequency modulation to generate a harmonic radar transmission signal, and the harmonic radar transmission signal is sent through a transmitting antenna; the signal is received by a receiving antenna, band-pass filtering is conducted on the signal at frequency bands corresponding to the doubled and triple frequencies to improve the signal-to-noise ratio of the received signal, and actual measurement signals of the doubled and triple frequencies are obtained; the noise sequence is subjected to doubled frequency modulation and triple frequency modulation to generate harmonic radar original copy signals, namely the doubled and triple frequency production signals; the doubled and triple frequency production signals and the actual measurement signals of the doubled and triple frequencies are separately subjected to matching filtration; non-linear target detection is conducted. In the method, the noise frequency modulation technology,the Doppler compensation technology and the transmit-receive signal matching filtration technology are adopted, the formed harmonic radar has the performance of resisting electromagnetic interferenceand resisting Doppler frequency shift, the detection sensitivity is high, and the applicable field is wider.

Description

technical field [0001] The invention relates to a method for detecting a short-distance nonlinear target harmonic, in particular to a method for detecting a nonlinear target harmonic based on noise frequency modulation technology. Background technique [0002] Different from ordinary fundamental wave radar, the frequency of harmonic radar receiving signal is the second or third harmonic of its transmitting signal frequency. Therefore, for harmonic radar, nonlinear targets with harmonic radiation characteristics are effective targets. Wave radar transmits a carrier signal. If there is an electronic device within the detection range, it can receive the second harmonic of the target signal (the frequency of the received signal is twice the frequency of the transmitted signal); if there is a metal target, it can receive the target signal. The third harmonic of the received signal (the frequency of the received signal is three times the frequency of the transmitted signal); if th...

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Problems solved by technology

[0003] The existing harmonic radar technology mainly uses single-frequency signals or the superposition of multiple single-frequency signals. This type of signal has narrow-band characteristics, and its anti-electromagnetic interference performance is poor. If there are electromagnetic interference signals close to the frequency of the transmitted signal in the detection area , the device will have a false alarm (misjudgment that there is no target as a target), which will limit the application environment of the device; and when the measured target moves, the received signal will undergo Doppler frequency shift, so that the received signal cannot get enough The time gain of the target will cause the target detection threshold to fail, and the device will miss the alarm (the target will be misjudged as no target), resulting in the detection of the target motion state of the device being limited.

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