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What to Consider when Designing a Security System with Radars

Detection, delay and response are all required functions of an effective physical security system. These functions must be preformed in order and within a length of time that is less than the time required for the adversary to complete his task. A well designed system provides protection in depth minimizes the consequence of component failure and exhibits balanced protection. (Sandia National Labs- Design and Evaluation of Physical protection systems)

Physical Security Sensors

Time. Time is the enemy of any physical protection system. Most physical security sensors provide information about a point in space at a specific time. More specifically, most systems tell you where an adversary was, giving you the challenge of finding an adversary’s current location before they are able to carry out their objective. Having enough time to complete yourtask before the intruder is able to complete their’s is the challenge. If properly considered, positioned and integrated, ground surveillance radar can provide the responder critical time to interdict and respond to a threat.

The proper implementation of any security system, including radar, requires understanding of the threat, possible avenues of approach, sensor system performance and environmental conditions. Understanding the threat(s) to your facility can have a large impact on the selection, placement and operation of your system. For example if you are protecting a perimeter are the threats vehicle-borne, foot-borne or both?

In the case of radar, a vehicle-borne threat is easier to detect than a foot-borne infiltration. To detect vehicles radar must be carefully placed with direct line of sight to any vehicle capable avenues of approach. If the threat is foot-borne, then the line of sight issues become more complex. Blind spots must be filled and the probability of detection must be well understood. Response forces must also have a good working knowledge of the specific battle space the system is defending.

Sensor Performance

In describing sensor performance we use three terms: Probability of Detection (Pd), Nuisance alarm rate and vulnerability to defeat. Perfect probability of detection is measured as 1.0 for the ideal sensor. This means that a sensor will detect an intruder 100% of the time in all conditions. While no sensor is perfect, the closer the sensor performs to ideal the better overall system performance. Depending on the criticality of the asset being protected multiple sensors can be layered to provide the level of detection desired.

Nuisance alarms are alarms that are not caused by an intrusion. The ideal nuisance alarm rate would be zero. The most likely cause of nuisance alarms are environmental factors such as wildlife, vegetation and weather conditions, Selection of sensor systems and radars should take these factors into account. For example, some radar systems are easily fooled by moving vegetation while others are not. A cluttered background of shrubs and trees can cause challenges for any radar being able to “see” intruders. Careful consideration of the space the radar will survey will improve the overall security system performance.

Vulnerability of Defeat

The next factor for consideration is an understanding of the sensor system’s vulnerability of defeat. Most physical security sensors can be defeated depending on the skill of and time available to the adversary. Radar systems are particularly difficult to defeat given the proximity of the sensor to the edge of the detection zone. For example a single fence sensor can be defeated any number of ways most of which involve fairly simple techniques. A radar system may be defeated but only through complex technical means unavailable to most adversaries.

Summary

Radars operate at their best with long line of sight and clear environmental conditions. Superior security radars excel when the environmental conditions are less than perfect and the terrain is challenging. If careful consideration is given to the design of a physical security system; taking into account the threat, environment, and overall system performance requirement, it is evident that ground surveillance radars provide superior performance and value over other perimeter sensors.

• What to Consider