In an electronic security system, magnetic contacts are the most widely used alarm sensor device for protecting a door. A magnet is attached to the door, and a contact (electrical switch) is attached to the door frame. When the door is opened, the magnet moves away from the contact such that the control panel sees a break. Other perimeter alarm sensors include a 'window bug,' which reacts to the sound of breaking glass; a shock sensor, which reports high-frequency shock waves associated with the violation of doors or windows; window foil, which reacts to the glass being broken; and security screens, which electronically report any violation. Alarm sensors for space protection include switch mats, which report being stepped on, a photoelectric beam, and an ultrasonic device that records motion. The control panel turns alarms on and off through its circuitry and determines if and when to actuate the reporting devices. Every home security system should have at least one audible reporting device located inside the house, with more audible devices used for outside the house to alert neighbors and the police. A central station is a control center located at an alarm company's facility where alarm systems are monitored. If an alarm is violated, the central station receives a signal and notifies the local police. Appended are specifications for a fully-zoned ultrasonic intrusion alarm system, application guidelines for exterior and interior intrusion detectors, and terms and definitions for intrusion alarm systems.