周界入侵检测系统宽带滤波器的设计及优化

Broadband Filter Design and Optimization for Perimeter Intrusion Detection Systems

针对传统m推演型滤波器插入损耗大、带内平坦度不理想等问题,提出了一种改进型带通滤波器设计优化方法。本文首先介绍了滤波器各子级的设计方法,利用ADS对滤波器参数进行迭代优化设计,并采用PCB工艺制备了带通滤波器样品同时进行了传输特性的测量,最后将其实际应用于泄漏电缆周界入侵检测系统中提高了硬件前端的信噪比。测量结果表明,在25.75~36.25 MHz的通带范围内,插入损耗小于1.5 d B,带内平坦度优于0.5d B,反射系数小于-15 d B,过渡带性能理想;在陷波点20 MHz、45 MHz处衰减大于-50 d B。在本文的最后,对周界入侵检测系统漏报率、误报率、正确率进行了初步测试,结果表明虚警率从每小时1次减少至2天内未发生报警,该滤波器结构有效地解决了系统虚警率高的问题,提高了系统的稳定性。

Aiming at the problem of large insertion loss and bad in-band flatness of traditional m-derived filter,an improved design method of band-pass filter is proposed. In this paper,the design method of the filter is introduced first,and the parameters of the filter are optimized by ADS and the band-pass filter samples were prepared by PCB process for the measurement of transmission characteristics. Finally,the filter is applied to the perimeter detection systems of the leakage cable to improve the signal to noise ratio of hardware front-end. The measurement results show that in the pass-band range of25. 75 ～ 36. 25 MHz,the insertion loss is less than 1. 5 d B,the flatness is better than 0. 5d B,the reflection coefficient is less than-15 d B,and the transitional band is ideal. At the notch points of 20 MHz and 45 MHz,attenuation is greater than-50 d B. At the end of this paper,it provides the preliminary measurement of missing report rate,false detection rate and correct rate for perimeter intrusion detection system,the results show that the false alarm rate reduces from 1 per hour to no alarm within 2 days. The structure of this filter effectively reduces false alarm rate and improves system stability.