Modern technologies in perimeter alarm systems.

Modern technologies in perimeter alarm systems.

Modern technologies in perimeter alarm systems

Security specialists, designers, and builders have recently been increasingly faced with the issue of perimeter protection. At first glance, the market today offers a wide range of perimeter alarm systems. However, an experienced designer knows how difficult it can be to select the necessary means to protect a specific perimeter with its less than ideal configuration and terrain, as well as taking into account Russian climatic conditions. In addition, the equipment must meet the requirements of high detection reliability and the absence of vulnerable spots. In addition, any complex perimeter requires detectors of several types of action, which must be purchased from different manufacturers and then assembled into a complex, since all manufacturers, with rare exceptions, are narrowly specialized in operating principles. Publications in the press, materials from international exhibitions, and offers on the Russian market show that this situation is typical for the entire world community. GPS Standard offers a way out of this situation.

The company has been narrowly specializing in perimeter alarm systems for over 20 years, also installing its products. Its assets include more than 5 thousand objects, such as nuclear power plants, airports, oil fields, almost all of the largest industrial enterprises in Europe and many others.

What is so special about GPS Standard equipment?

1. The company produces perimeter security detectors with 4 detection principles: manometric, responding to human weight and ground vibrations; photoelectric beam; triboelectric tension, responding to stretching of the sensitive cable, and triboelectric vibration, responding to vibration of the fence. The first three detectors have unified microprocessors that ensure uniformity of output signals, a single protocol for exchange with the analyzer unit, common software and the ability to work on a single 3-core multiplex cable. Therefore, they represent a complete perimeter complex.

2. Perimeter equipment is the main product for the company, so it works with all consumers regardless of the time of purchase of the equipment.

3. In the process of changing generations of detectors, the principle of continuity of equipment is observed, which allows consumers to upgrade previously installed equipment with minimal costs.

The basis of the complex is a manometric GPS detector, which is a system of 2 or 4 hoses laid shallowly in the ground (under asphalt or concrete), filled with antifreeze and connected to highly sensitive differential membrane sensors. Such a system allows you to create a continuous detection zone on the surface of the earth 3 or 7 m wide (depending on the version), which guarantees recording of human movement by walking, running, crawling, rolling, jumping, on a ramp or with a pole. Detection is not hindered by various external interference and climatic conditions (freezing of the soil, snow cover up to 1.5 m). With the help of the system, you can block the bed of a stream, the roof of a building, in a word, any surface.

One of the most important features of this detector is its complete invisibility and impossibility of detection by any search equipment. Thus, in the New Olympic Village (Moscow), built for the participants of the World Youth Games, the perimeter security alarm system based on the specified detectors never came to the surface of the alienation zone. Another type of perimeter alarm, which can be used both in addition to the manometric and independently, is the JPS photoelectric beam detector. It is characterized by columns up to 3.5 meters high with impact-resistant, tinted polycarbonate casings, inside which optical and electronic units are installed, as well as the use of dual infrared beams, ensuring the insensitivity of the detectors to external interference. It should be noted that there is a built-in wide range of adaptation functions, protection from interference, adjustment and diagnostics.

The WPS pull-action detector is used in the same way as the photoelectric beam detector. Using a special cable with a steel core allows you to create canopies and vertical fences that physically prevent intruders from entering, and with a slight stretch of the cable, give an alarm signal. At the same time, the detector is insensitive to cable vibration under the influence of wind, atmospheric phenomena, birds, and also has adaptation and diagnostic functions and works under snow.

The main feature of the specified devices is the ability to connect them via a common multiplex cable in any ratio with a total number of up to 16 pieces at a distance of up to 3.5 km to a single analyzer unit, that is, the ability to create a complete complex of technical security equipment. In addition, they have a special pre-alarm signal designed to increase the attention of security personnel and address activation of CCTV cameras. Practitioners can appreciate the full setup, real-time monitoring with recording of analog signals of any detector on the perimeter using a debug computer connected to the analyzer unit, usually installed in the security room. If necessary, this work can be done remotely by telephone using modems. The triboelectric microphone detector, which uses a latest-generation microprocessor with higher processing and data transfer rates, has not yet been integrated into the overall complex. The latter is planned to be the basis for the entire complex. The triboelectric microphone detector is installed on mesh fences of various types and is not fundamentally different from domestic and foreign analogues in terms of detection capabilities. It also has intelligent signal processing, computer configuration and monitoring. The presence of such a powerful, flexible complex allows you to reduce the time and costs of pre-project inspection of objects, design, installation and adjustment of equipment, promptly respond to changes in customer requirements or at the site itself. The rights to sell and install the specified perimeter security alarm system are held by OOO Spetsmontazh-Bespozhnost, whose specialists have undergone appropriate training at the manufacturer, translated all technical documentation into Russian, Russified the software and created the main software Perimeter. The equipment is sold at manufacturer's prices from a warehouse in Moscow. Thus, transportation, duties and VAT do not increase the manufacturer's price. OOO Spetsmontazh-Bespozhnost also cooperates with the well-known state enterprise NIKIRET (Penza) and, if necessary, can integrate all the best that is in domestic perimeter equipment into GPS systems.

In perimeter alarm systems, the most pressing issue is the deep processing of signals coming from sensitive elements. Temperature changes, atmospheric phenomena, vegetation, animals, birds, random passers-by — all this can be the cause of the alarms being triggered or, conversely, a decrease in sensitivity below the permissible level and even the appearance of insensitive zones.

As an example, let's consider the underground manometric perimeter alarm GPS.

For such pressure sensors, the following are critical: changes in atmospheric pressure, wind, rain, hail, thunderstorms, transport, aviation. To adapt the sensor to these factors, which are quite regular in nature, in addition to the purely instrumental method of differential processing of signals from two hoses from each zone and comparison of signals from two zones served by one sensor, the principle of dynamic change of the sensor response threshold is used. The following formula is entered into the sensor microprocessor:

S=K+MR+MF*Dmin,

where S is the response threshold; K is the coefficient taking into account the fixed change in the response threshold by the user using the toggle switch on the control panel: MR is the coefficient determining the setting of the response threshold when adjusting the sensor; MF is the coefficient determining the magnitude of the sensor's response to changes in external factors; Dmin is the difference between the instantaneous and average values ​​of the signal.

For output signals, the response threshold S is used with the coefficients: 1 is for the pre-alarm signal, usually used for security television, and 3 is for the alarm signal.

Let's assume that the weather and other factors are favorable. Then, with the factory settings of the sensor microprocessor RAM, the formula will look like this:

S = 0.125 + 0.312 + 3 x 0.031 = 0.53 (V).

Accordingly, the pre-alarm threshold is 0.53 V, and the alarm threshold is -1.59 V. The wind began and the output signal increased. Then the formula will look like

S = 0.125 + 0.312 + 3 x 0.09 = 0.707 (V).

In this case, the pre-alarm threshold will increase to 0.707 V, and the alarm threshold — to 2.121 V.

Thus, the microprocessor constantly adjusts the response thresholds without changing the sensitivity to one-time impacts of the intruder.

Now let us consider the methods of signal processing that allow us to separate the signal of the intruder's passage from other one-time triggerings of the detector. To do this, we need to imagine a model of the intruder: a person weighing more than 40 kg, who can cross the detection zone by walking, running, jumping, crawling, rolling, using a pole, board.

An examination of the intruder model shows that it is determined by a sharp or smooth, large or not so large, but periodic change in ground pressure. To identify this, the second derivative of the signal is used, showing the direction of each change in the complex resulting signal. Therefore, to separate the periodic change from the random one, the microprocessor counts the number of changes that have occurred within the time base specified by the program and, if a certain number is exceeded, it generates a pre-alarm or alarm signal. If one or more detected changes were random, then after a specified period of time, the corresponding counter is reset. Such a processing algorithm quite accurately identifies the intruder's slow passage of the detection zone, as well as rolling and crawling. It should be noted that in the version with 4 pipes, additional signal processing is added to this algorithm, allowing you to determine the direction of the intruder's movement, and at the same time increase the noise immunity of the system.