Passive radar low-altitude object detection method

Abstract

The invention provides a passive radar low-altitude object detection method. The distance between an object and an array is detected by installing a circular passive receiving radar antenna array, receiving OFDM communication signals reflected by a low-altitude slow-speed object and performing pulse compression, then a weak object under a low signal-to-noise ratio and strong interference is detected through a constant false alarm detection module, and finally, determination and advanced early warning of a low-altitude object with a potential threat are carried out through extracting the speed of the detected weak object. The method provided by the invention decreases the cost under the condition that the coverage scope is ensured by use of OFDM wireless communication signals through a passive radar system, and compared to a conventional OFDM phase-coded radar, is greatly simplified in terms of system; and the method is suitable for application in key areas which are covered by the OFDM wireless communication signals and require monitoring of low-altitude safety by use of such features of high utilization rate of an OFDM signal spectrum, good anti-multipath performance, high-distance resolution with broadband, adaptability of narrowband to a low noise-to-signal ratio and the like.

Description

technical field [0001] The invention belongs to the field of radar data and signal processing, in particular to a passive radar low-altitude target detection method. Background technique [0002] With the gradual opening of low-altitude control, low-altitude aircraft such as helicopters and drones are becoming more and more popular in cities, which has brought huge security risks to key areas. It is reported that the White House in the United States has been invaded by toy drones . [0003] At present, low-altitude targets are mostly detected by active radar, but active detection is costly and the coverage is limited. At present, base stations have basically achieved full coverage in cities, so the system of passive radar receiving wireless communication signals can have a wider detection range and lower research and development costs. [0004] Based on this idea, Bai Jianxiong, a scholar at Xidian University, proposed a method for detecting weak target trajectories under ...

AI Technical Summary

Problems solved by technology

[0006] First, for the detection of weak targets, most of the existing research focuses on high-speed targets, using the Doppler frequency shift brought by the target's high-speed movement to complete the recognition, and there are few systematic methods for slow targets (Mach number less than 1);

[0007] Second, regarding the influence of array parameters (number of array elements, circular array radius) setting on digital beamforming, there is currently no public information for research in this area;

[0008] Third, the existing constant false alarm detection methods, such as CA-CFAR, SO-CFAR, GO-CAFR, etc. have their own advantages and disadvantages. For example, although the threshold calculation of CA-CFAR is not affected by the target itself, it is used in a clean environment. It can get a high target detection probability and effectively control the false alarm rate, but if there are multiple targets or strong interference in the reference unit, the threshold will be raised, and its detection performance will be greatly reduced; SO-CFAR solves the problem of CA-CFAR It is not suitable for the problem of multiple targets or interference in the samples on both sides of the measured unit, but the detection of clutter areas will also lead to an increase in the false alarm rate, so SO-CFAR is suitable for multiple targets and strong interference in the reference unit in a clean environment When GO-CFAR is used for target detection in clutter environment, it can well control the increase of false alarm rate caused by clutter, but when it is used for clean environment detection, the constant false alarm loss is greater than CA-CFAR, Therefore, GO-CFAR is suitable for detection in clutter areas; in summary, a new constant false alarm detection method is needed that can integrate the advantages of the three to better detect slow and weak targets

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