Perimeter intrusion detection system reaches maturity

May 2003 Perimeter Security, Alarms & Intruder Detection

The ACL 20 intelligent optical perimeter intrusion detection system is in the news again with the company Perimeter Intrusion Detection Systems International. (PIDS). A massive high-value ACL 20 installation has just been commissioned in a Middle East country. The perimeter secured covers 15 km of harsh desert terrain and some 160 poles or sensor units (SUs) were deployed. In order to meet the demands of the customer and the environment a complete redesign of the system was undertaken by the CSIR who originally developed this key site protection system. The design engineer Neels Engelbrecht now believes that the hardware design is optimal and further improvements and tailoring to the needs of specific sites or customers will be through software and firmware enhancements.

In terms of the hardware used, the proven transmitter and receiver modules have been retained but in order to eliminate problems caused by lightning, communication is now over fibre-optic cable. The special cable that incorporates both the optical fibre and the three-phase power cable was manufactured by a local company and its outside protective sheath allows the cable to be reliably trenched. To ease installation the cable is looped in and out of each SU using screwless clip-in connectors for the power cables and normal splicing techniques for the fibre.

The surveillance units themselves have been completely redesigned and each 3 m pole has two 1,5 m high 180° access panels (previously the entire tube had to be lifted vertically off the sensor platform) the lower panel providing access to the on-board electronics. The new-engineered structure is such that it flexes in the case of very high wind conditions (typical of this part of the Middle East) without affecting performance and the access panels seal on closure to protect both the modules and electronics from the environment.

A major change to the surveillance units is that each one is now 'intelligent' with on-board flash memory and processor. This has expanded the capability of the system significantly in that each SU can be programmed individually. This is important for example where the specific zone crosses a gate where different access rules may apply (such as vehicles only or personnel only) or where there is large crossing by animals where the alarms caused by these can be suppressed (after positive identification). The on-board memory also means that new software can be downloaded in seconds from the control room. Each and every module in the entire network (there are 7 two-way beams per pole) can be checked and switched on and off remotely while BITE informs the control room of any potential module failure.

While the nominal distance between the surveillance units is 100 m the separation depends on the site and the terrain with minimum separations in hilly terrain dropping to 20 m and exceeding 200 m in clear line of sight situations. Even larger transmission distances have been achieved in test set-ups.

Another significant benefit of the new ACL design is the ease of installation. While it took many months to qualify the individual modules of this system for this particularly quality-conscious customer (even the concrete used for the pole bases was laboratory tested), the actual installation and commissioning took less than a month using a team of four South Africans.

The key to the success of the ACL 20 remains its unique neural network operation. The advantage of using a neural network is that it can be trained over time and to operate under new conditions. The ACL system has been honed over the years to the point where it can now carry out actual identification of vehicles, distinguishing between cars, trucks and armoured vehicles for example. While the system of sensors is extremely sensitive and with 150 plus zones can detect up to 10 000 events over an hour, the neural system with its object classification reduces this to virtually zero. Suspicious events are transmitted to the control room operator with a percentage confidence factor and he is trained to respond accordingly. For example, a confidence factor of 50% between a crawling man and a small animal would be cause for investigation. Another innovation introduced in the Middle East site is that each PC in the control room is equipped with a strobe light and audible alarm. There is no need for the operator to tediously watch the screen, as a positive event will trigger these alarms. The alarm itself identifies the zone in which the intrusion has been detected (the operator can display a mimic of the entire perimeter protection system together with numbered SUs) and icons are used to identify the identified object (people walking or crawling, vehicles, etc) so that even totally unskilled operators can tell mobile security units what they need to look for.

The latest version of the software is programmed so that alphanumeric data can be displayed in either English or Arabic, but any world language can be catered for. Another benefit for inexperienced operators is a newly added 'cause and action' panel. Following an alarm and its automatic classification the operator needs to make only one click on the mouse to reach a display that tells him what action to take. The operator or the software supervisor can add new causes and actions, which may be specific to a particular site (eg, the times of changing of shifts of security personnel that could generate false alarms in specific zones).

The reliability of the system is renowned and the major installation put into Turkey some years ago is operating with minimal support in terms of replacement module electronic boards. The Middle East site has now been operating for just on a year without a single hardware failure after installation.

The ACL 20 system should not be confused with any of the other home protection systems developed in the past by CSIR and marketed by other companies. The ACL 20 is specifically designed to address the requirements of key-point security and it is manufactured to full MIL standards. Typical applications include perimeter security of airports, military sites, borders and nuclear and other energy sites. It can also be used to protect high value assets such as museums and art galleries where theft of items with incredibly high value which are usually irreplaceable. PIDS has an exclusive agreement with the CSIR (signed in 1999) for the manufacture, marketing and technology associated with the ACL 20 and artificial neural network methodology. CSIR's Defencetek remains the technology partner and design authority for PIDS in the further development of the ACL 20, now specifically software and firmware directed.

While there are many ACL installations in South Africa the really major installations have been in foreign countries. The new system actually allows the local company to upgrade software over the Internet and customer problems with the system can also be resolved in this way as local experts can interrogate every SU and module. This is a major benefit for both PIDS and the customer as potential problems can be solved in realtime without the expense and time taken to travel to the overseas site.

For more information contact PIDS International 012 460 5578.

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