Perimeter Protection

The Lee Security Underground Perimeter Protection System

The Under Ground Perimeter System (UPS) is an invisible, buried perimeter detection system , which is an evolution of the traditional UPS system, designed using DSP (Digital Signal Processing) technology.

This type of system digitises the signals provided by the sensor, analyses them in both time and frequency domains, guaranteeing extremely accurate evaluation.

As well as high immunity to atmospheric interference, normal for buried tube systems, this sensor is able to process the signals to discriminate particular frequencies (railways, roads with high traffic density, irrigation systems) from those generated by attempts to cross the sensitive area during an actual intrusion.

This represents an ideal solution for high-risk sites, subject to high levels of environmental interference.

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The UPS Plus is based on the detection of differential pressure.

The tubes, buried along the perimeter, are filled with a liquid that allows the system to operate even at very low temperatures (anti-freeze), and then pressurised.

A crossing of the sensitive area creates a difference in pressure between the tubes that is detected and processed by an appropriate transducer. These signals are sent to the signal processor, which analyses them and signals any alarms or pre-alarms. The ability to adjust the sensitivity of each single zone allows the system to adapt to the characteristics of each individual application.

All of the system components are protected by a system called a "watch dog", which, in the event of a software interruption, restores the normal system operation automatically.

The system can be integrated with other protection systems (perimeter, internal sensors, CCTV) and central control systems creating flexible security solutions for any application.


The system is subdivided into two principal parts: the field equipment and the central control. The field is the "sensor" part of the system, with the capability to detect the events generated by an attempt to violate the protected perimeter. The different parts of this are: the concentrator, the UPS sensors, the UPS tube and valves, creating a sensitive area about 3m wide and up to 200m long (100m per zone). The Universal Communications Processor (UCP) comprises a power supply, a communications interface/analyser and the output relay cards. The system can manage up to 64 peripherals (concentrators) all connected to a single cable.

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