Which perimeter intrusion detection category uses ground-based energy to determine range, speed, altitude, and direction of travel?

• A. Microwave sensors
• B. Photo-Electric transceivers
• C. Ground based radar
• D. Buried and seismic sensors

Answer: (C)

Perimeter detection relies on how energy is used to measure motion and position. Ground-based radar fits this best because it actively emits radio energy from a fixed ground location and analyzes the echoes to determine where something is and how it’s moving. By measuring how long it takes for the signal to return, the system calculates range (distance). The Doppler shift and successive range observations reveal speed. Using the antenna’s scanning pattern and elevation information, it can infer direction of travel and altitude above the ground. This combination of range, speed, altitude, and travel direction comes from actively emitting and processing radar signals, making it the category that does all of that well.

Microwave sensors mainly provide presence or motion detection and are not typically used to extract full range, altitude, and trajectory over a wide area. Photo-electric transceivers rely on optical beam interruption and give line-based presence without robust range or motion tracking. Buried and seismic sensors detect vibrations to indicate intrusion but do not furnish range, speed, altitude, and direction of travel through emitted energy.