Alarm System

The following alarms are all part of the variety of alarms within the Home Alarm System. Each has advantages and disadvantages. Read through and choose the alarms more suited to your needs (depended on the size of your house, how sophisticated you want the system and what your budget is).

 The following alarms are for indoor use only.

Passive Infrared Detectors – This is one of the most common, reliable and affordable alarm system detectors found in the home or small business environments. It is “passive” because it can function without the need to generate its own energy.

It uses the temperature of the monitored space to determine whether an intruder is there or not. A change in temperature caused by the presence of someone or something can verify whether it is an intruder or not.

Microwave Detectors- This device releases microwaves from a transmitter and detects microwaves at a receiver. The detector responds to motion causing reduction in energy received, a frequency phase shift and a change in Doppler shift frequency change. 

Photo-Electric Beams- These security alarm systems detect the presence of an intruder by visible or infra red light beam being transmitted across an area. The beams are often employed in stacks of two or more to increase the surface area that needs detection.  Photo-electric beams are an effective long range detection alarm system if the beams are stacked in threes or more. It creates a fence like barrier. There are downsides, however. If the intruder is aware of them, he/she can avoid them.

Ultrasonic Detectors - Using certain frequencies, these “active” detectors transmit ultrasonic sound waves that cannot be heard by humans. If a change of frequency is detected due to an object in motion (ie: the frequency of sound waves around it changes), then an alarm is activated. The Doppler shift principle technology is considered obsolete by many professionals who specialize in the installation of security alarms, and this type is not actively installed.

Glass Break Detectors - When glass breaks, sound in a wide band of frequencies is generated. Glass break acoustic detectors are set up close to windows and listen for frequencies associated with glass breaking. On the other hand, Seismic glass break detectors Installed in the glass pane)“feel” the shock frequencies of broken glass and in turn generate or set off an alarm.
Smoke, Heat, and Carbon Monoxide Detectors

These systems are as their name suggests, equipped to detect smoke, heat and carbon monoxide.

The following alarms are for outdoor use only.

Passive Magnetic Field Detection – As the name suggests, this Home Alarm System is only triggered when there is a change in the magnetic field above where the system’s cable wire is buried. It can be buried on top of fences, but cannot be installed near high voltage line or radars.

Vibration (Shaker) or Inertia Sensors- These simple devices are mounted on barriers such as fences and detect an attack on the actual structure itself (such as someone scaling the fence). The alarm system is triggered when the circuit moves and breaks the current flow. There are a range of sensors and more expensive and sophisticated uses piezo-electric components rather than mechanical circuits. These are extremely sensitive to vibrations and are very reliable.

E-Field - This alarm system is usually installed on fences, walls and building perimeters. It also has the ability to be free standing on dedicated poles. An electromagnetic field generator powering one wire, with another sensing wire running parallel to it, is how the alarm system is set up. The sensing wire that is connected to a signal processor, can detect and analyse the mass, movement of the intruder and the time the intruder is there. When all three characteristics are detected simultaneously, an alarm signal is created. 

Microphonic Security Systems – The Microphonic Security System is cheap and easy to install. Sensor cables are installed either underground or attached to rigid chain wire fences. Different systems are sensitive to different levels of vibration. The system can differentiate between whether an intruder is cutting the chain wire or cable or climbing over the fence, or if there are bad weather conditions. The sensors are certainly very sensitive and a lot more reliable now that DSP (Digital Signal Processing) are used.

Taut Wire Fence Systems – A taut wire fence system is often referred to as a perimeter security system. Tensioned tripwires are usually mounted on a wall or a fence. These wires sense or detect movement, but can be programmed to ignore objects only exerting a small amount of pressure (such as birds and small animals). These are very reliable home alarm systems, however are very expensive and use old technology.

Fibre Optic Cable - Fibre-optic cables are very similar to the Microphonic security system and easy to install. The difference is that intruders are detected by measuring the amount of light sent through the fibre core. The receiver unit detects the difference in the amount of light received as an intruder disturbs the cable. Buyers choose this system because of cost and easy installation, however, there is a high rate of false alarms.

Microwave Barriers- A Microwave barrier device passes an electromagnetic beam from a transmitter to a receiver by using high frequency waves. This creates an invisible, yet very sensitive wall which protects the home from intruders. When an intruder enters the home, a difference in condition is detected in the receiver. Once a detailed analysis of the situation is completed, an alarm signal is activated (in analogue or digital form.)

H-Field - This type of alarm system is based on an electro-magnetic field disturbance principle where two coaxial cables are buried about 10-15cm deep and approximately 2.1 m apart. Radio Frequency energy is emitted continuously from a transmitter along one cable and received by another cable. Basically, an alarm is triggered when there is a “weakened” field strength due to the presence of an intruder or object.