Basic Features of Security Alarm Systems Flashcards
What are five purposes of total security systems?
- Deterrence
- Prevention
- Detection
- Response
- Apprehension
What is the “onion-skin” principle?
A concept in security planning that employs successive layers of protection
What are the three layers of protection of an alarm system?
- Perimeter protection
- Space protection
- Spot protection
What are the three main circuits in a basic alarm system?
- The detection circuit
- The control circuit
- The output circuit
When a closed-loop detection circuit has current flowing through it, is it in the “alarm” or the “secure” condition?
Secure condition
What is circuit supervision?
The ability of the control panel to monitor if a loop is intact or not
What are the four loop types?
- Two-wire
- Two-wire ELR
- Four-wire
- Four-wire ULC
Why is it important to avoid even minor damage to magnetic reed switches?
To prevent the introduction of oxygen and water vapour inside the glass tube
What does a PIR detector detect?
Changes in the levels of infrared energy within the protected area
What are the advantages of PIR detectors?
- Self adjusting
- Relatively foolproof to install
- Passive detectors and do not emit radiation
- Detection pattern may be changed by replacing the lens
- Detection fingers may be easily masked to avoid problems
How do ultrasonic and microwave detectors detect movement?
They emit radiation, which is reflected off objects within the protected area. If an object is moving, it will cause a doppler shift in the reflected signal, and the detector will notice a change in frequency
What are three sources of false alarms for ultrasonic detectors?
- High-pitched noises
- Moving or rotating objects
- Changes in air humidity
What advantages do dual-technology detectors have over single-technology detectors?
Dual-technology detectors are more resistant to false alarms, since they are more stable in areas with harsh ambient conditions
Under what conditions would a photoelectric beam detector be suitable?
Photoelectric beam detectors are useful in areas where ambient conditions (such as temperature fluctuations, humidity, radio interference, sunlight or direct light sources, etc.) render other detectors unsuitable
What indication LEDs are commonly found on alarm keypads?
loop status, ready status and armed status
