Low SNR signal parameter extraction method based on pulse cutting

Abstract

The invention discloses a low SNR (signal noise ratio) signal parameter extraction method based on pulse cutting, and a problem that parameters of a discrete frequency coded signal are difficult to extract under the condition of a low SNR in the prior art mainly is solved. The implementation scheme comprises a step of intercepting one section of digital pulse signals received by a radar to be a reference signal and performing short-time Fourier transform on the reference signal to obtain a time-frequency diagram, a step of obtaining a pulse repetition time estimation value of the radar pulse signal and the number of frequency codes by using the time-frequency diagram, and a step of grouping the digital pulse signals by the pulse repetition time, and sequentially performing pulsed alignmentcorrection, phase compensation and coherent accumulation on the grouped signals to obtain accumulated signals with a high SNR, and obtaining estimated results of pulse width, bandwidth, carrier frequency and frequency code of a radar pulse signal. According to the method, the parameters of a discrete frequency coded signal can be effectively extracted under the condition of the low SNR, the parameter precision is high, and the method can be used for processing and analyzing a discrete frequency code pulse signal.

Description

technical field [0001] The invention belongs to the technical field of radar, in particular to a signal parameter extraction method with low signal-to-noise ratio, which is suitable for processing and analyzing discrete frequency coded pulse signals. Background technique [0002] The ground base station radar receives the direct wave pulse signal emitted by the opponent's radar, and the signal passes through the radar receiver, and is converted into a baseband signal by down-conversion processing. The signal amplitude is amplified by an operational amplifier, and then converted into a digital pulse signal through AD conversion. The signal threshold is defined for pulse detection, and then a series of parameter extraction operations are performed on the detected pulse signal. [0003] However, in actual work, the signal received by the ground base station radar is generally the signal emitted by the beam sidelobe of the opponent's radar, and the pulse signal level obtained af...

AI Technical Summary

Problems solved by technology

In general, when the pulse signal level and the noise level are clearly separable, a fixed noise threshold can be set to detect the signal. The level-limited part is the noise part of the signal, and the pulse repetition time PRT of the detected pulse signal is used to accurately group the signal, but under the condition of low signal-to-noise ratio, the acquired pulse signal itself is submerged in the noise In the signal, it is difficult to use the traditional algorithm of threshold detection to distinguish the signal from the noise, and it becomes very difficult to accurately group the pulse signal, which will inevitably affect the accuracy of subsequent parameter extraction

[0006] Chinese patent CN 106877901A proposes a method for detecting signals under low signal-to-noise ratio conditions by detecting signal power spectrum and performing band-pass filtering; Chinese patent CN 105072067B proposes to use the cepstrum of the signal power spectrum, take its maximum value for smoothing, and use the K-means clustering algorithm to classify and judge the signal and noise to distinguish the signal from the noise, but these two methods are not suitable for subsequent signal analysis. group computing

However, this method is only aimed at LFM linear frequency modulation signal, and only detects the signal, and does not further analyze other characteristic parameters of the signal

[0007] Chinese patent CN 108415013A proposes a method for extracting parameters of low signal-to-noise ratio signals based on frequency modulation slope fine search, which can effectively detect the carrier of LFM linear frequency modulation signal Frequency, bandwidth, pulse width and other parameter information, but this method is only limited to LFM type signals, and cannot be used for parameter extraction and analysis of discrete frequency coded signals

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