Urmet 1068 Série Mode D'emploi page 8

1.3.2.3 Cable contacts for rollers
The detector is installed inside the roller box. The sensor is an impulse counter that is paired with an automatic cable
winder. By connecting the end of the cable to the lower part of the roller, each time the blind is raised or lowered, the
cable winder turns and generates the impulses detected to the counter. Depending on the number of impulses generated
during a specific interval, the detector can signal an attempted intrusion. This type of detector makes it possible to keep
the windows open and the rollers closed to help air to circulate, thereby guaranteeing perimeter protection.
1.3.2.4 Broken glass detector
This detector can be created using various technologies and exploiting different principles of physics.
It can detect the oscillations caused by the breaking or cutting of glass when it is glued to the glass or crystal to be
protected, or detect the characteristic sound waves generated by glass breaking, when it is positioned in the immediate
vicinity.
It is used to signal the breaking of shop or showcase windows, large plate glass windows and skylights for perimeter
protection, but also for breaking of bulletin boards and display cases inside buildings.
1.3.2.5 Vibration detector
Also known as a seismic detector, this device picks up vibrations from the surfaces it is glued or screwed to and filters
them to prevent false alarms. When applied to a door or window, unlike the magnetic contact, it can signal an attempted
break-in before the door or window is actually opened. By seeking to force the opening, vibrations are produced that
generate a signal of attempted intrusion.
1.3.2.6 Passive infra-red detector (IR)
This detector is equipped with one or more IR sensors that measure the rapid variations of infra-red traces of the
environment being controlled, indicating the presence of human beings, animals, or other "warm" objects that move.
A variation of this type generates a signalling by the detector. The effectiveness of the detector and the area covered are
changed by adjusting its sensitivity, changing the Fresnel lenses that focus on the sensor the controlled area or by
suitably masking the sensor itself.
Some detectors make it possible to create a curtain covering, or to monitor a very long and narrow vertical area, typically
positioned parallel and not far from a group or windows or doors (hence its name).
In the intrusion alarm system, these detectors are used to control extensive spaces and obligatory passages, also being
identified as volumetric sensors.
1.3.2.7 Active infra-red detectors
This IR detector consists of two elements that face each other and are aligned to create an infra-red ray barrier.
When an object passes through the passage controlled by the detector, the rays are interrupted and the IR sensor
generates a signal. The detector can be realized through two different technical solutions.
It can be realized through two elements, one that contains the sensors and the other the light sources, which emit an
infrared light beam.
Alternatively it can be realized by means of a single element which contains both the sensor and the infrared light source
and a mirror that reflects the IR light towards the sensor.
1.3.2.8 Microwave detector (MW)
This detector acts like a radar: it emits a radio signal and then detects and analyses the return signal (reflected waves).
When the return signal varies, due to something that has moved in the area covered by the detector, a signal is
generated by the detector.
Unlike the passive IR detector, the movement are detected even if the person moving emits or blocks heat. In the
intrusion alarm system, these detector are used to control extensive spaces and obligatory passages, also being
identified as volumetric sensors.
1.3.2.9 Combined passive IR and microwave detector
This type of detector combines both technologies. The signals generated by the sensors can be compared to OR or AND
logic.
In the first case it is sufficient for just one sensor to detect an anomaly for the detector to send a signal; in the second
case, both sensors must detect an anomaly for a signal to be sent. The two settings have a mirror effect. The OR logic
the possibility of identifying attempts to intrude increase (what one sensor detects, the other sensor might not), together
with and increase in the generation of false alarms.
The AND logic the possibility of generating false alarms decreases (the sensors must essentially confirm each other), but
the sensitivity in detecting attempted intrusions also decreases.
DS1068-017 8 LBT20717