Leaky Cable Intrusion Detection Method Based on Frequency Selective Coding Multicarrier Modulation

Abstract

The invention provides a leakage cable intrusion detection method based on the frequency selective coding multi-carrier modulation technology. The method comprises the following steps: step 1: performing constellation modulation on a pseudo-random coding sequence according to a desired modulation signal, performing frequency selective coding and symbol mapping according to a frequency spectrum detection and interference estimation vector, then performing inverse Fourier transform, and feeding a transmission signal to a transmission leakage cable input end after filtering and amplifying the same; and step 2: performing parallel cross-correlation operation on receiving signals and the transmission signals with uniform delay input from a receiving leakage cable, and performing moving target indication, threshold detection and delay estimation on the signal after the correlation operation in each parallel processing unit.

Description

technical field [0001] The invention relates to the technical field of leaky cable detection, in particular to a broadband leaky cable intrusion detection method using frequency selective coding multi-carrier modulation technology. Background technique [0002] Most of the existing leaky cable intrusion detection devices adopt a single-frequency signal system. By transmitting a single-frequency signal, high-frequency energy is generated and fed into the transmitting leaky cable, and part of the energy radiates to the surrounding space through the gap, forming a joint with the receiving leaky cable. Spatial three-dimensional electromagnetic field warning area. When an intruder enters the area, it will disturb the electromagnetic field and form a Doppler frequency shift. The receiver circuit realizes the purpose of intrusion detection by detecting the energy of the Doppler frequency shift. This technology is used throughout the There is no positioning and partition sensitivity...

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Problems solved by technology

[0002] Most of the existing leaky cable intrusion detection devices adopt a single-frequency signal system. By transmitting a single-frequency signal, high-frequency energy is generated and fed into the transmitting leaky cable, and part of the energy radiates to the surrounding space through the gap, forming a joint with the receiving leaky cable. Spatial three-dimensional electromagnetic field warning area. When an intruder enters the area, it will disturb the electromagnetic field and form a Doppler frequency shift. The receiver circuit realizes the purpose of intrusion detection by detecting the energy of the Doppler frequency shift. This technology is used throughout the There is no positioning and partition sensitivity setting capabilities in the detection area, and the detection sensitivity is low. When encountering short-term co-frequency signal interference, the working conditions will be completely destroyed, resulting in serious false alarms

A small number of leakage cable intrusion detection devices use pseudo-random phase coding to modulate broadband signals to detect and locate intrusion targets. They have high detection sensitivity and partition sensitivity setting functions, but when encountering random in-band interference, the system will experience a decrease in sensitivity , Serious false alarms or even complete inability to work

When the electromagnetic coverage environment becomes more complex, the existing leaky cable detection technology is less able to ensure that the system can work normally when there is in-band random interference, and the detection sensitivity is basically not reduced, which seriously affects the complex distribution of leaky cable detection technology in the electromagnetic environment. The scope of application in the environment

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