Rapidly deployable perimeter security systems.
Modern perimeter security systems are characterized by a wide variety of physical principles and design options. Technological advances enable developers to create compact security systems that can quickly organize signal lines even in unprepared areas. Such systems are usually distinguished by covert installation of sensors. They are often used to protect temporary facilities in the field and are attractive for military applications.
New technologies for recording and processing signals make it possible to create very compact and cost-effective security sensors. The use of miniature radio transmitters of alarm signals built into sensors allows one to avoid laying connecting cables and build wireless security systems with autonomous power supply.
Passive infrared, radio beam or radio wave sensors are most often used in rapidly deployable security systems. This review briefly describes some modern foreign rapidly deployable systems designed to protect the external perimeters of objects.
Systems with passive infrared sensors
Such sensors are often made in the form of racks containing one or two sensors, a battery and a wireless alarm signal transmission system.
At the IFSEC’2007 exhibition in Birmingham (United Kingdom), the English company Zareba demonstrated two systems for perimeter protection with autonomous power supply. The Sentry Guard device body (Fig. 1), made of fiberglass, contains two passive IR sensors with a range of 50 m each, so one stand covers a perimeter of up to 100 m. The lower part of the sensor stand contains batteries and an alarm transmitter; the stand weighs 18 kg. According to the manufacturer, the “curtain” sensitivity zone allows the sensor to detect crawling, walking and running intruders.
The military version of the autonomous IR sensor from Zareba, released under the name Sentry Scout (Fig. 2), is made in a durable metal case and equipped with an integral three-support folding tripod. The stand has one built-in IR sensor with a sensitive zone of up to 50 meters. The built-in lithium battery with a capacity of 10 Ah is enough for 3 months of operation. The dimensions of the stand when folded are 77 x 12 x 12 cm; when unfolded, the height of the sensor is 114 cm. The antenna of the radio transmitter of alarm signals is located at the bottom of the stand. The design of the stand is such that when the supports are folded, the lens of the IR sensor is automatically closed with a metal cover, protecting it from damage during transportation. The sensor meets the requirements of the UK Ministry of Defense and can be used in any climatic zones at temperatures from -400 to +500C.The stand of the Sentor IR security sensor from Sensor Security (UK) has the shape of a tumbler doll: the battery and alarm transmitter are installed in the lower part of the sensor (Fig. 3). This configuration of the housing ensures the stability of the sensor in strong gusts of wind. The plastic stand, 127 cm high, contains 2 passive IR sensors with a range of up to 40 m each. A GSM network or radio channel is used as a communication line, which also transmits voice messages that help identify the zone in which the intrusion occurred.
Modern passive IR sensors can be very economical, consuming no more than a few microamps of current in standby mode. This allows for the creation of miniature sensors with built-in batteries that provide a service life of up to several years. Such sensors are used in security systems by Sensor Security. One of the most well-known systems is called AutoGuard. The sensor of such a system (Fig. 4) is made in a shockproof polystyrene case, sealed according to IP66 standards. The sensor operates in the temperature range of -400 to +700C. A miniature radio transmitter (frequency 174 or 433 MHz, power — up to 10 mW) is built into the sensor case, which turns on for 1-2 seconds when an alarm signal appears. The IR sensor consumes about 5 μA of current in standby mode, which, when using two built-in lithium batteries, ensures the sensor's operation for several years. The sensor's sensitivity zone is up to 30 m long; the width of the zone at the maximum distance from the sensor is about 2 m. The sensors can be mounted on screw brackets, on fence elements, trees, etc.
Alarm signals from AutoGuard sensors are sent to an 8-zone control panel (Fig. 4). The alarm receiver built into the panel, when working with a pin antenna, provides a radio channel length of up to 1.5 km in open space and up to 300 m in built-up areas. The panel with a universal power supply is equipped with a built-in battery, providing 36 hours of autonomous operation. Alarm output relays are used to control external equipment. In the basic version, the AutoGuard system consists of a control panel and 8 sensors; this set fits in a special transport case. The basic set can protect a perimeter with a total length of up to 240 m. Up to 10 sensors can be connected to each zone of the control panel, providing a total length of the protected perimeter of more than 2 km.
A modification of this system, released under the name Stealthguard, differs only in the design of the control panel. The 8-zone Stealthguard system panel is designed as a portable battery-powered unit (Fig. 5) and is used by the security guard as a wearable device for monitoring alarm signals.
Arkonia (UK) produces cost-effective passive IR sensors for perimeter protection. The ARK9130 series sensors are made in rigid metal housings, sealed to IP67 standards, and are designed for use in difficult atmospheric conditions. The sensor pyroelectric receivers are made of lithium tantalate. The precision lenses are made not of polymer, which is typical for most passive IR sensors, but of germanium. The ARK9133 sensor can detect a person at a distance of at least 100 m. The length of the sensor is 173 mm, the maximum diameter is 49 mm. The angular width of the sensor's sensitive zone is 4 degrees. The ARK9130 series devices are designed in accordance with the requirements of the UK Ministry of Defence and are used, in particular, to protect aircraft parking lots. The ARK9130 series sensors are distinguished by very low power consumption (140 μA at a voltage of 5–16 V). This allows the sensor to be combined with a portable radio transmitter of alarm signals and used as a wireless masked device. A specific feature of the sensor is the ability to determine the direction of movement of an intruder using a differential circuit of the pyroelectric receiver.
The sensor uses a circuit for automatic adjustment of the response threshold, as well as a circuit for compensating for interference from rain, hail, fog, etc. The sensors are immune to radio frequency radiation with a strength of up to 50 V/m in the frequency range from 10 kHz to 18 GHz and remain operational when exposed to sunlight.
The ARK9133 sensor is used as part of the Hornet kit, which consists of a passive IR sensor and a portable radar sensor (Fig. 6). The sensor is mounted on the radar body and is used to turn on the radar if a moving object enters the field of view of the thermal sensor. The radar signal is analyzed by a built-in microprocessor, which allows recognizing typical images of an intruder. After the radar information is processed, alarm signals are transmitted to the control post using a built-in radio transmitter. The alarm signal also contains the results of processing the sensor signals («person», «car», «movement from right to left», etc.). The Hornet kit is powered by built-in lithium-ion batteries or external accumulators. The radars operate in the J-band, the radar output power is 8 mW. The power of the alarm signal transmitter is 1-3 W. The voltage of the built-in batteries is 12 V; supply currents in standby mode — 0.7 mA, in active mode — 500 mA. The range of operating temperatures of the system is from -400 to +580C.
Combining the ARK9130 series of passive IR sensors with video cameras equipped with an autonomous power supply and a radio channel for transmitting video signals can effectively solve perimeter security problems. Such a quickly deployable system, called Cygnus, is shown in Fig. 7. The IR sensor with a range of 40 m is mounted on the body of the video camera.
When the IR sensor is triggered, the video camera is activated, and the still images in the form of JPEG files along with identification tags are transmitted via GSM or GPRS to the desired email address. The color video camera and IR sensor are powered by a built-in lithium-ion battery, which is enough to transmit 1000 still images without recharging.
Radio Beam Systems
One of the well-known manufacturers of rapidly deployable radio beam security systems is the American company Southwest Microwave. In 2007, the company demonstrated the upgraded M.I.L. PAC 316 system, which is a development of the well-known M.I.L. PAC 310B system. The two-position microwave sensor M.I.L. PAC 316 consists of a transmitter and receiver on three-support stands, two autonomous battery power supplies, a radio transmitter of alarm signals and a set of cables. The length of the sensor's sensitive zone is up to 244 m, the angle of radiation divergence is 3.5O horizontally and vertically, which ensures a zone width of no more than 7 m at maximum range. 6-channel radiation modulation prevents crosstalk in multi-zone security systems.
The transmitter of the M.I.L. PAC 316 system operates at a frequency of 24.162 GHz (K-band). The current consumption of the receiver and transmitter is 58 mA and 130 mA respectively (at a voltage of 12 V) and ensures continuous operation of the kit for 135 hours from four 5 A/h batteries. The radio transmitter of alarm signals is located next to the microwave receiver unit. The total weight of the kit is 119 kg; the operating temperature range is from -400 to +660 C.
The M.I.L. PAC 385 Rapid Deployment System from Southwest Microwave is a single-position microwave sensor that combines a transmitter and receiver in a single housing. The transceiver is similar in design to the M.I.L. PAC 316 system. The length of the sensor's sensitive zone is up to 122 m; the system has a function for limiting the zone length (from 30 to 122 m) and a function for suppressing interference from nearby objects. The system operates in the K-band with a peak radiation power of 32 mW. The sensor weighs 21 kg and is powered by a 12 V battery, consuming a current of no more than 220 mA. The system is equipped with a 16-channel modulation system. The system, upgraded in 2007, differs in its design in that the adjustment controls are not located under the protective cap of the module, but are located on the rear panel (Fig. 8).
The mobile, quickly deployable microwave barrier from the Italian company CIAS is based on the well-known two-position sensors of the ERMO 482x PRO series, which use a pattern recognition system based on the principles of «fuzzy logic». The MMD System (Fig. 9) includes a microwave transmitter and receiver on three-support stands, batteries, an alarm transmitter and a multi-channel radio receiver. The length of the sensitive zone of the system is up to 200 m. Autonomous power supply is enough for 20 days of continuous operation of the equipment. Rigid transport boxes are used to transport the system modules.
The American company Perimeter Products, Inc. produces microwave sensors used for quickly deployable field security systems. Various modifications of the TMPS-21000 series devices are used here as single-position or dual-position sensors. All sensors are made in standardized housings (Fig. 10) and are powered by built-in batteries that operate without recharging for about 30 hours. Alarm signals are transmitted to the guard post via cable or radio line.
Two-position sensors of the TMPS-21100 type are used to organize linear boundaries around temporary vehicle parking. The length of one security zone of such a sensor is up to 150 m; the sensors have an adjustable width of the detection zone and a range limitation mode (Range-Cut-Off) to eliminate the influence of objects located outside the security zone.
A single-position sensor of the TMPS-21200 type, which is a radar sensor, is placed in the center of the protected zone, for example, on the upper plane of the protected aircraft or car. The sensor antenna forms a sensitive zone in the form of a cylinder with a radius of up to 48 m. The operating frequency of the sensor is from 5.725 to 5.850 GHz; the range of detected object speeds is from 0.025 to 31 m/sec.
In the TMPS-21300 version, the single-position sensor has a hemispherical sensitivity diagram and is designed to protect the territory of objects from air intrusions. The radius of the sensitive hemisphere is adjustable from 22 to 78 m. The sensor generates an alarm signal according to a specified algorithm, responding only to entry into the protected area, only to exit from it, or to both actions of the intruder. The range of recorded object speeds is from 0.44 to 26.7 m/sec (from 1.6 to 96 km/h).
Radio wave systems
The American company DeTekion produces portable radio wave systems of the Wave-Guard series with sensitive elements in the form of two «radiating» coaxial cables that are laid on the ground along the boundaries of the protected object. The system operates at 16 discrete frequencies in the range of 66-88 MHz. The PSP-100-V complex provides protection for two zones 50 meters long, the four-zone PSP-200-V complex is designed for perimeters 200 m long.
The two-zone or four-zone processor and power supplies are placed in a special case equipped with connectors for quick connection of sensitive cables. A radio transmitter of alarm signals with a telescopic antenna is also mounted in this case. Batteries ensure the operability of the kit for 48 hours; a separately supplied solar battery can be used to recharge the batteries.
Geoquip (UK) is releasing a rapidly deployable version of its RAFID radio wave system. The new RAFID-RDS system is designed to protect temporary facilities and is used primarily for military purposes. Sensor cables, which act as transmitting and receiving antennas, are laid directly on the ground. The electronic units of the system are equipped with special connectors and can be supplemented with radio channel equipment for transmitting alarm signals.
The Canadian company Senstar-Stellar, traditionally specializing in «stationary» perimeter security systems, developed a radio wave quickly deployable system Repels several years ago (Fig. 11). The system's sensor is a pair of parallel conductors mounted on plastic posts at a height of 10 cm and 150 cm, respectively. The cross-section of the sensitive zone is a circle with a diameter of 2 m, the length of an individual zone is 100 m. The installation time for one zone on soft ground does not exceed 30 minutes. The system is supplied in two versions — Repels ST and Repels SP. The first version is intended for short-term use, when the main requirement is the speed of equipment deployment. In this version, batteries are used to power the transmitter and receiver, the resource of which is enough for one month of system operation. In the second version, stationary sources are used for power supply, and a specialized StarNet 1000 network is used for centralized control of the system.Systems with vibration-sensitive cables
The Italian company GPS Standard announced some time ago the creation of a quickly deployable perimeter security system with sensor cables, called Mobile WPS. The system is based on the principles previously used in the development of the «stationary» WPS system, and is designed to protect small areas of territory. The sensitive element here is a sensor cable with a central core made of stainless steel, generating an electric signal when stretched or deformed. The quickly deployable signal barrier is formed from fencing modules 2 m long, from which barriers of the required length can be assembled (usually no more than several tens of meters). Signals from the sensor cables are fed to a concentrator, which evaluates the signals received and transmits them further to the analyzer. The analyzer is configured using a computer connected via the RS-232 interface; it is made in a portable version and is located in a transport case.
The field version of the combined Sensor Coil 600 complex by DeTekion (USA) also belongs to the quickly deployable perimeter systems. It structurally combines a physical barrier made of a cutting spiral and a vibration penetration sensor in the form of a microphone sensor cable of the Defensor series by the English company Geoquip. The spiral with an external diameter of 0.76 or 1.00 m is supplied in separate coils deployed on the ground surface, on a wall or on the roof of a building into a barrier approximately 15 m long. Sensor cables of adjacent sections are quickly connected using connectors, forming a security zone up to 150 m long. Signal processing is performed by analyzers of the Defensor series. The analyzer uses a two-channel signal processing method, allowing to register both long-term impacts (climbing over the barrier) and short impact impacts (barrier destruction). The system is powered by a 10–24 V source, the consumed current is 60 mA. The operating temperature range of the system is from -400 to +660C.
It is obvious that all portable and quickly deployable perimeter security systems have common specific features that distinguish them from stationary security systems. Apparently, it is impossible to single out any one system that could be considered the best and most universal.
Most of the described systems are characterized by low power consumption, allowing the use of autonomous power sources.
A characteristic feature of many rapidly deployable systems is the use of radio frequency channels to transmit alarm signals to the guard post. Rapidly deployable perimeter security systems often have requirements for the concealment of the installation of sensors and other components. At the same time, it is very important that the rapidly deployable autonomous system is easy to install and configure in the field and does not require highly qualified personnel for maintenance.
The systems described above meet the listed requirements to a greater or lesser extent. It is obvious that when choosing a rapidly deployable security system, it is necessary to take into account many factors — terrain, facility configuration, surrounding natural conditions, industrial interference, etc. This requires serious training of designers and system integrators, who must be well versed in the variety of modern perimeter security systems.