Technical means for perimeter detection

Infrared detectors are linear - designed to protect the perimeter of straight sections consist of two emitter units (DIP), forming a directional infrared radiation flow, and a photodetector unit that receives this radiation.

The detection unit and the photodetector must be installed in the pyarmoy view of each other, since infrared rays (IR rays) as any beam of light can be directed only straight (i.e. straight, without bends, rises, falls). Application of pereotrazhateley significantly reduces the intensity of infrared radiation, the quality of work in bad weather conditions and, as a consequence, the accuracy of the system as a whole.

Detection Zone of active infrared beam detectors looks like a thin invisible infrared beam, expanding from the transmitter to the receiver, which depends on the diameter of the geometric dimensions of the "transmitter-receiver" optical system. This system does not require the exclusion zone, but is vulnerable in terms of violations perimeter "on the border from the top", so to create effective protection should be installed at a height of several single beam detectors. The length (length) of the detection zone of the system can be from 10 to 300 m.

Capacitive detection means of perimeter protection systems - extended sensor element (SE) or antenna (antenna system), consisting of two symmetrical halves that are connected to a common signal processing unit. Typically, one half of the length of 250 m., Therefore the length of the capacitive detection zone 250 * 2 = 500 m.

The sensor element located on the perimeter of the object (often in the form of a wire bell enclosure above) to a contact element for its capacitance varies, picks up the electronic unit, immediately the information obtained is processed and the nature of the subject changes and an alarm is generated. This system is characterized by high sensitivity and stability, the absence of "dead zones", the possibility of adjusting the detection zone. The disadvantage is the relatively high cost of the system due to complex installation structures and fencing equipment.

Capacitive detectors are effectively applied to objects:

with a complex configuration of fences and rescue operations;

mechanically robust protections (reinforced concrete, brick, metal, etc.), built-in fencing PPC and other buildings.;

with integrated swing or sliding gates, especially if they are above pipes, cladding and buildings, etc., where the use of other means of ineffective or impossible (e.g. ray sirens).;

CHE length of both halves to be identical, or differ by no more than one section (2.5-4 m.); When installing the perimeter protection system based on capacitive annunciators must strictly observe the following rules:

the number of insulators must not differ by more than 2;

SE sections must be welded together in one wing;

along the entire area equipped with grounding bus shall be laid, connected to an uneven ground with spreading resistance of less than 10 Ohms (at a distance of 100 to 300 mm from the bottom of the SE.);

the minimum air gap between the SE and the generator cable between it and the Earth is designed - not less than 20 mm, between the "ground" and SE - about 100 mm.:.

the distance between the SE trees - not less than 1.5 m.

Vibration detection tools - based on the principle of capturing vibrations sensitive enclosure element (SE) and transforming these vibrations into an electrical signal. JAE is a shielded cable, which has the properties to strengthen and stabilize triboeffekta (appearance of an electric charge when mechanical stress on the cable).

In the spectrum of the electrical signal transmitted by the SE, you can determine the type of mechanical impact (wind, the bird sat on the fence, or someone tries to climb or break the integrity of, etc.). This system is used to protect all types of fences and metal structures (gates, doors, lattices, etc.). Swing system is different narrow detection area, weather and industrial resistance (wind, rain, snow, vibration, transportation, etc.), which allows the use of these funds in an urban environment.

Wire detection tools - are a separate class with unique performance characteristics. It is a Russian design, which has no analogues in the world. The uniqueness lies in the ability to create a volumetric detection zone of "visor" or "ground" type through the antenna system, which consists of two parallel wires running parallel to each other at a distance of 40-50 cm. And they form the system, repeating the relief of a protective boundary. The wires form the "open antenna", to one end of which the transmitting unit (FM power generator) is connected to the other - a receiving unit. Since the sensor antenna is not wired, it does not emit or receive interference signals, which provides a very high noise immunity of the system with good coordination of its units. Interference caused by cable bends with sharp corners and irregularities landshfta constitutes an insignificant figure, and are within the natural electromagnetic background. The boundaries of sensitive zones are determined by the distance between the wires and the detection element from the conductive surfaces, as a result of which the detection zone is obtained uniformly around the entire perimeter of the site, regardless of the terrain (elevation) and perimeter shapes (turns, bends, gaps, etc.).

The detection area can be formed along the ground surface, internal obstructions (such as a canopy over and along the fence web), walls, ceilings and other structures. Fences can be of any type and made of any material (concrete, metal, wood, plastic, mesh netting, barbed wire, polycarbonate sheets, etc.). Transmitting and receiving detector units are mounted at opposite ends of the monitored area and connected to the element by two wires. The upper wire is fixed to the frame, and the lower frame on or in the ground. Detectors can be single- or double-flanked, have different lengths and geometric configuration of the material and level of tightness of the housing, adaptation to different climatic conditions and installation methods (in the fence, located on special sites, etc.), as well as the possibility of remote health monitoring.

It is also included in the strut insulation of supports and, unlike the capacitive detector system does not require special adapters and insulators, allowing a clearance.Detection area when the angle of inclination of the isolation struts can be horizontal, inclined or vertical. The detector system antenna tracks all steep topography and configuration (turns, descents, ascents, and others.) In the length of the perimeter, defending its upper fences and roofs of all the construction of the mortise (PPC, buildings, gates, canopies, etc.) form. . As the sensor is preferable to use non-insulated bimetallic wire is characterized by high resistance and low loss.

The following rules must be followed when installing the system:

The lower wire must be located closer to the top than other foreign objects or fence details, such as barbed wire, protruding reinforcement bars, decorative elements;

There must be electrically conductive objects between the wires;

The presence of swinging objects (branches, bushes, tall grass, boom, mast, hammocks, swings, etc.) is not allowed at a distance of 1 m from the top of the wire.;

The grounding must be placed under the blocks instead of the projection unit on the ground surface.

Methods for blocking the perimeter boundaries of wire detection means:

1. Blocking the upper part of the barrier - mounting components installed in the form of a spike, their angle can be changed when passing obstacles. The distance between the consoles is 3-4 m. The cables (upper and lower) are fixed on the frame (dielectric consoles), so there is no contact with the parts of the fence structure and other foreign objects, as well as the highly undesirable presence of shaking objects in the detection area (tree branches, poles, etc.). As a result, the upper part of the box around the cables forms the detection zone.

2. Blocking surface lines along walls, barrier paintings - the upper wire attached to the frame (dielectric consoles), and the lower one is placed in the ground at a depth of 5-10 cm. Between the upper wire, the ground surface and the fence forms a volumetric detection zone. The console for fixing the wires should be installed at a height of no more than the distance from the top of the fence wire, so as not to cause interference in adverse weather conditions (rain, wind, snow, etc.).

3. Blocking open surface borders - the upper wire is connected through fiberglass poles at a height of 1.5-1.8 m, and the lower one - 5-10 cm into the ground ... In the forest or a park area, instead of fiberglass poles you can use tree trunks. The volumetric detection zone is formed between the conductor and the top of the ground, and the snow cover does not affect the operation of the detectors, but they should be approached from a zone of branches and other noise same.

Radio wave detectors - there are two-position (consisting of two units - a transmitter and a receiver) and a single-station (designed to protect local areas of the controlled territory). Create volumetric detection zone between the transmitter and the receiver, located at a certain distance from each other. The shape of the detection zone looks like an elongated rotating ellipsoyd with a diameter of 70 to 600 cm. (depending on the antenna and the frequency of radiation).

For proper operation of the system requires line of sight between the transmitter and the receiver, the detection area should not be a relief irregularity (the permissible level depends on the characteristics of the equipment), foreign objects, bushes, trees, street lamps, etc., as well as permanent "irritating" transport, railway, navigable river, etc., as it will lead to false alarms and malfunction of the system.

Radio wave detectors are used to detect the offender, overcoming defense line in the long length or bends, so the perimeter of the equipment should be taken into account that the system will have a "dead zone" near the installation sites of the transmitter and receiver. The longer the length of the detection zone, the larger the size of the dead zone, for example, 10 m. Starting from the detectors with a detection area of ​​200 m. And 17 m. For the length of 300 m. Elimination of "dead zones" is made by overlapping detection zones of adjacent perimeter sectors.

Detectors are different in design, technical specifications, operating conditions (the size of the exclusion zone, the height of the snow and grass cover, climatic conditions of work, the degree of protection, for example Blastguard et al.), The structure of the materials and other common basic transmission principle - signal transmission is carried out by a radio channel from a transmitter unit to a receiver unit, thus creating a volumetric controlled area. A distinctive feature is the minimum exclusion zone, can be mounted on any type of fencing, use on uneven terrain and the presence of snow and mowing. Detectors are designed to monitor open straight sections, subject to the availability of the exclusion zone, although some modifications Sensors such a zone can virtually absent. They consist of two units - a transmitter and receiver, as well as blocks of fixing points. The system has a very high operational reliability and precision, identifying any attempt to cross abroad.

Here are some examples of modification detectors:

Prism 2 - designed for small width of exclusion zone, as there may be potoronnie objects and structures The operating frequency of 9.4 GHz devices with an output power of less than 3 mW (poles, bushes, trees, fences and other items.). The maximum width of a detection zone depends on the length of the site monitored by one sensor and is determined by the program. The detection area consists of the main and auxiliary, its width is changed by adjustment, the main area can be approximated almost to the fence and reflection subjects.

Prism 3 - is designed to monitor the perimeter of plots without exclusion zone, which is characterized by extremely narrow detection zone limited by lines joining the edges of the detector unit. The operating frequency of 24.55 GHz with an output power of less than 3 MW. The units can be installed along walls, ceilings, fences on top or above and in other places.

The design principle and operation of the detector "Prism 2" and "Prism 3" differs from "Prism 1". Polarization of the vector antenna is inclined at an angle of 45 degrees to flat surfaces (fences, ground, etc.). The polarization vector of the reflected signal reaches the receiving antenna at an angle of 90 degrees to the polarization vector itself. That is, the reflected signals are passed to the transformation and do not affect the signal. This allows the detector to protect the fence fabric and the detection zone is formed directly on its canvas.