Typical technical solutions for leaky cable perimeter intrusion prevention system

Single cable solution

The earliest technical solution for applying leakage cables to perimeter intrusion prevention systems only used a single leakage cable. The simplest system is formed by connecting a radio transmitter at the beginning of the cable and a receiver at the other end. The leakage field formed by the transmitter around the leakage cable first couples with the intruder body, then couples back to the leakage cable and transmits to the receiver. The intrusion signal in this solution needs to be coupled twice and then transmitted to the detection end. Its detection sensitivity is extremely low and its practical value is not high. Initial experiments can only capture huge intrusion targets that are only about 10 centimeters away from the leakage cable.

Dual cable solution

Two leakage cables are laid in parallel, one end of the first cable is connected to the transmitter excitation feeder, and one end of the second cable is connected to the receiver to detect and process the intrusion information characteristics, thus forming a dual cable system. The two cables are one for transmission and one for reception, and there is only one coupling. The intrusion target can be captured by simply detecting and identifying the impact of the intruder body on the existing signal in the leakage field. Compared with the single cable solution, this solution has greatly improved detection sensitivity and can meet the needs of practical applications. Most leakage cable perimeter intrusion detection systems use dual cable solutions.

In some cases, in order to laterally widen the width of the intrusion detection area or identify the direction of the intrusion behavior, one or more leakage cables laid in parallel can be arranged on the basis of the dual-cable solution, which is derived into a multi-cable solution in disguise.

Pulse Wave Solution

Based on the single cable solution, the transmitter outputs a timing pulse wave, and the receiver completes the time delay identification and detection between the transmitted pulse and the reflected pulse with intrusion information characteristics, and determines the intrusion location based on this, which constitutes a pulse wave solution. The pulse wave solution has the following characteristics:

.The pulse wave scheme improves the practicality of the basic single-cable scheme;

. Requires high-speed transmission of RF broadband narrow pulses, and the instantaneous pulse power is large, which may interfere with adjacent radio systems;

.Higher performance requirements are placed on leakage cables, and there is a tendency to use large-diameter, low-loss leakage cables.

Continuous wave solution

Regardless of whether it is based on a single-cable or dual-cable solution, the transmitter outputs a continuous carrier wave, the receiver completes the detection of received information with intrusion information characteristics, and determines the intrusion location based on this, which constitutes a continuous wave solution. The continuous wave solution has the following characteristics:

.No strict requirements on RF bandwidth and power, simplifying the level of electronic components and devices;

.It cannot provide accurate positioning of the intrusion location and is only applicable to the determination of intrusion information in the complete paragraph area;

.For longer perimeters, it is advisable to divide them into sections and mark them with address codes.

Conclusion

At this time when the domestic security market is growing rapidly, the perimeter intrusion prevention system has undoubtedly occupied an important position. Combined with the market demands of my country's anti-terrorism, Olympic Games and Expo, urban greening, and building a harmonious society, the leakage cable perimeter intrusion prevention system has a good application.