What is an alarm with early detection and how does it work?
PERIMETER SECURITY
Perimeter detection is always desirable, since it gives us an early warning, with the intruder at the very limit of the property. There are multiple methods of detection in the perimeters of a property, we will expose several detection mechanisms, its operating principle, its pros and cons.
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INFRARED BARRIERS
Principle of operation: It consists of 2 parts, a transmitter and another receiver, both parties must receive power, in general 12vdc from an alarm panel, the receiving part has the alarm contact connection that will also be connected to the alarm panel . The Transmitter emits infrared light beams until the receiver, in those of 2 beams, the 2 beams must be cut to generate the alarm, in those of 4 or more beams, 2 successive beams must be cut to generate the alarm signal. Because of the distance between transmitter and receiver, there are from 5m to 300m. Another classification is the number of beams, the standard ones up to 20m, 40m, 60m, 80m and 100m have 2 beams, after 200m they are 4 beams and those of 300m are 6 beams, then there are models called curtain that can be 8 at 10 beams, they are 70cm barral up to 1.5m.These beams are not laser type, concentrated, they are diffuse.
There are wired and wireless. You can put 2 more in series, one on top of the other, putting for example one at 50cm from the floor and another one at 1.50m from the floor, so as to form a wall. Sometimes they are camouflaged inside tubes of 2m high, With an open strap, covered with a glass or smoked acrylic, in this way an intruder knowledgeable of these systems, will not know the height at which the beam is and not even suspect the presence of a security system.
They allow a really early detection since they are usually installed in the same perimeter of the property. They can be used to protect windows, medians, wide perimeters in gardens, etc.
Detection by outdoor motion sensors
Working principle: Those by detection of the infrared energy emitted by the bodies (PIR) and by the movement of the bodies (Microwave). In general, there are one or two PIR sensors inside or PIR Microwave. The latter are called double technology. As for the transmission of the signal, there are wired and wireless. The wireless, to really do without wiring, work on battery. There are them of different scopes, with detection of pets, with immunity to cover, etc. They are usually installed from the property outward, so installation is easier, with less wiring. Advanced models can discriminate between an intruder and a pet, either because of its weight or height. If costs, installation times and products are added, they tend to end up being cheaper than a project with infrared barriers. Wireless models are considerably cheaper than wireless barriers.
VIBRATION MICROPHONE CABLE
Working principle: It is a cable, similar to the coaxial cable, but with different capacitive properties, before cuts, blows or vibrations, acts as a microphone, that sound or vibration captured, is transmitted to a central in the form of an electrical impulse. An Olympic wiring is covered with 2 cable passes, as shown in the figure above. It is advisable to divide the perimeter into zones, the control units can be one or two zones. As an advisory accessory to the control unit, an anemometer is associated, which lowers the sensitivity of the system as the wind speed increases. The control unit (s) can then be connected to a monitoring software that shows the perimeter on a screen or it can be connected to a simple alarm panel that shows the alarm condition on the display of a keyboard. It is advisable to zoning as much as possible, areas of no more than 150m, since in case of alarm, you should go to that area and travel it completely, in search of the intruder, short or anomalous situation. The wiring must be in good condition, in the total of each zone, the wiring tension must be homogeneous, there should be no vegetation that can hit the wiring in case of gusts of wind.
BY VIDEO ANALYSIS
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Working principle: It is based on a video system with IP cameras, IP management software licenses and Analytical licenses. Usually, video analysis licenses are purchased, including perimeters, abandoned objects, missing objects, loitering, etc. The IP cameras are installed in the perimeter, analysis tools are configured that allow to determine if a person crossed a set of lines, which determine the intrusion of the perimeter, even, the direction can be determined, so that someone leaving the perimeter does not generate alarm. All these analyzes are determined by changes in the pixelation of successive video frames. The system can be complemented with IP domes, in order to make an immediate video verification with approaches and monitoring of the possible intruder.
They allow immediate video verification, all the evidence is stored, the operator does not need to leave his post for verification, the sensitivity of the system can be adjusted continuously, everything is by software, does not require intervention on hardware such as systems Infrared or microphone. In the event that the event could not be seen live, you can go back to analyze the nature of the event. With the current systems of several megapixels, a lot of accuracy can be achieved in the verification, complementing with domes, the intruder can be monitored live, gathering more evidence.
INFRARED BARRIERS
What infrared barriers do is generate infrared beams (as the name implies) in such a way that they create an alarm when the continuity of said beams is interrupted. The existing models are lamppost columns or on supports at the top of the wall surrounding its plot.
MICROWAVE BARRIERS
A special antenna is installed on its perimeter that emits a microwave beam on its vertical axis to create an “invisible wall”. This creates a volumetric protection field with varying degrees of sensitivity that, if interfered with, activates the alarm in your home.
This perimeter alarm system is often used a lot in garden gardens, to maintain the aesthetics of the place and protect it at the same time.
FLUSH DETECTION
The fence detection perimeter alarm system aims to detect an early intrusion. The theory is that an immediate detection of the intruder induces the abandonment of the intrusion attempt. There are several models, but all try to detect if someone is climbing or cutting their fence to enter.
Thus, this safety system consists of vibration sensors placed on the metal fence, as well as torsion sensors for rigid metal fences. Both, as I say, designed to detect climbing or breaking your fence.
OUTDOOR VOLUMETRIC DETECTORS
These detectors cover the average existing plot between the perimeter and the limit of the house, so that if an intruder approaches your home, you will know it. It is designed for adverse weather conditions and the covered area, the detection pattern and its sensitivity can be adapted.