Research On Coherent Detecting Technology And Method Of Perimeter Intruder Multifrequency Signals

The perimeter intruder location detecting equipment is a security precaution system that plays important role in the effective protection to the outdoor important situations. The perimeter intruder detecting system is one of the important research aspect in safety and defence field. The detecting sensor of the perimeter intruder location detecting system is the leaky coaxial cable. The leaky coaxial cable has some special characteristic, such as good concealment property, immune to environment, adapting any topographical condition and so on.Though it solved the leaking alarm problem, the misinformation hasn't been ultimately improved.The coherent detecting technology was introduced into signal monitoring treatment system in the thesis. And the Key technology of Digital locked-frequency, in-phase pilot and so on, were also introduced. The circuit could receive the ultra narrowband signal, so the rate of noise signal jamming to system would reduce. At last a new solvable scheme to reduce leaking alarm and false alarm rate was recommended.Adopted the theoretical calculation, the circuit simulation and the circuit experiment in this paper, the hardware circuits of the electromagnetic radiation unit, the signal receiver and coherent detecting process unit, phase locking and pilot unit in the perimeter intruder location detecting system were designed. Then the performance of hardware circuits were analysised. Firstly, the work principle and the performance of leaky coaxial cable were studied, as well as the digital phase locking was emphatically researched. Considered the demand of the perimeter intruder location detecting system, the performance parameters of the electromagnetic radiation unit were determined. The hardware schemes have been accomplished. Researches on the coherent detecting process technology have been accomplished. Then the signal receiver and coherent detecting process unit were developed. The circuit simulation and the circuit experiment both of non-intrusive and intrusive were done, and the receival signal analyzing and processing have been completed. The electromagnetic radiation unit and the receive unit were locked to the same oscillator, after researches on the pilot circuit done. At last each circuits performance experiment of the perimeter intruder location detecting system were carried out.The experimental results showed that the electromagnetic radiation unit and the receive unit locked to the same clock, the electromagnetic radiation unit in the definitive frequency range of 40 MHz~55 MHz , the frequency stability better than 10-5. After applied the signal receiver unit circuit, intruder signal would be detected precisely, and noise signal jamming to detection system would be suppressed effectively.