to cover the above mentioned dead zones. Compact surveillance radar Compact surveillance radar emits microwaves from a transmitter and detects any reflected microwaves. They are similar to microwave detectors but can detect the precise location of intruders in areas extending over hundreds of acres. With the capability of measuring the range, angle, velocity, direction, and size of the target, a CSR can pinpoint a precise GPS coordinate of an intruder. This target information is typically displayed on a map, user interface or situational awareness software that defines geographical alert zones or geofences with different types of actions initiated depending on time of day and other factors. CSR is commonly used to protect outside the fence line of critical facilities such as electrical substations, power plants, dams, and bridges. Photoelectric beams Photoelectric beam systems detect the presence of an intruder by transmitting invisible infrared light beams across an area, where these beams may be obstructed. To improve the detection surface area, the beams are often employed in stacks of two or more. However, if an intruder is aware of the technology's presence, it can be avoided. The technology can be an effective long-range detection system, if installed in stacks of three or more where the transmitters and receivers are staggered to create a fence-like barrier. Systems are available for both internal and external applications. To prevent a clandestine attack using a secondary light source being used to hold the detector in a sealed condition whilst an intruder passes through, most systems use and detect a modulated light source. - Advantages: low cost, easy to install. Require very little sterile clearance area to operate - Disadvantages: Affected by fog or very high luminosity. Position of the transmitter can be located with some cameras. Glass-break detection A glass-break detector may be used for internal perimeter building protection. Glass-break acoustic detectors are mounted in close proximity to the glass panes and listen for sound frequencies associated with glass breaking. Seismic glass-break detectors, generally referred to as shock sensors, are different in that they are installed on the glass pane. When glass breaks it produces specific shock frequencies which travel through the glass and often through the window frame and the surrounding walls and ceiling. Typically, the most intense frequencies generated are between 3 and 5 kHz, depending on the type of glass and the presence of a plastic interlayer. Seismic glass-break detectors feel these