关键词: 周界入侵探测系统, 零中频接收机, 正交解调, 漏泄电缆, LC功分器, LC正交耦合器

Abstract:

Recently, the perimeter intrusion detection system based on leaky cable has attracted much attention of researchers and markets in security field because of its good security concealment, terrain fitting installation, omnibearing vigilance and all-weather work ability. In this paper, a new design method of zero-IF quadrature demodulation receiver was proposed. This method transformed high frequency signal into baseband signal for processing, which avoided the high cost of ultra-high speed AD devices used in the conventional design, and improved the performance of leaky cable intrusion detection system. ADS simulation results suggested that the receiver had 2.8 dB noise figure and 69 dB link gain in the 80120 MHz working frequency band. The test results showed that the receiver had 3.2 dB noise figure and 67 dB link gain in the same working frequency band, and the measured results were in good agreement with the simulation results. The system test revealed that the positioning accuracy of the perimeter intrusion detection system constructed with this receiver was better than 10 m, the false alarm rate and missed alarm rate were better than 5%.

Key words: perimeter intrusion detection system, zero-IF receiver, quadrature demodulation, leaky cable, LC power divider, LC quadrature coupler