A sensitive motion sensor for signaling is an indispensable element of security systems that protect territories from intruders. To understand the features of his work, it is important to familiarize yourself with the existing varieties of these devices. You will also need to understand the features of the selection, installation and configuration of sensitive elements.
Varieties of devices their characteristics
Depending on the principle of detecting a moving object, known models of motion sensors are divided into the following classes:
- infrared;
- ultrasound
- microwave;
- combined.
The simplest and most affordable option for most is the use of infrared (IR) devices capable of sensing changes in the thermal background in the controlled area. Ultrasonic sensors (US) emitting waves in the corresponding part of the spectrum occupy the second most popular place. They include an emitter with a frequency generator and a receiver. The first radiates waves inaccessible to human hearing, and the second receives a signal reflected from a moving object.
Microwave sensors are also widely used in security systems. The basis of their action is the Doppler effect (the displacement of the wave frequency upon reflection from a moving object). They contain a separate microwave generator and its receiver. Advanced models of such sensors for security systems are delivered with a GSM module, which allows to inform the user about the operation via the air channel.
Combined devices combine the capabilities of various products, leveling the disadvantages of some types of sensors due to the advantages of others. Most of the considered varieties by the method of communication with the control module can be wireless or wired.
Principle of operation
Modern motion sensors for the protection of premises and surrounding territories, regardless of their type, work on the principle of detecting moving objects along the propagation path of an emitted beam. If available, the sensing element responds to movement and generates a signal, which is then supplied to the actuator. The latter forms an impulse of violation or triggers a mechanism that blocks the movement of an extraneous object.
Motion sensors are divided into passive and active radiation detectors. The former respond to any movements in the controlled sector due to the optical system built into them. Active sensors consist of two complementary devices, one of which generates and emits radiation, and the other - receives it. An object located in the coverage area changes the characteristics of the reflected beam, after which an alarm is generated in the receiver.
Features of choice
For the motion sensor to fully fulfill its protective functions, a competent approach to choosing the right model will be required. In this case, they are guided by the following technical characteristics and criteria:
- effective angle of capture of the controlled area;
- supply voltage and sensor sensitivity;
- minimum response time;
- for what purposes is it supposed to use the device;
- features of the installation site and climatic conditions;
- degree of protection against moisture and dust.
Do not forget about the configuration of the system and the particular settings of a particular model.The specificity of most of them is the ability to register movements only in the direct viewing area.
Installation and Connection Rules
The motion sensors are installed and connected according to the manufacturer's recommendations.
Installation Order:
- A switching scheme is selected that takes into account operating conditions and characteristics of the room or protected area.
- They are determined with the location of the sensor, optimal in terms of its location and functionality.
- The machine on the switchboard, responsible for the line with the burglar alarm, is turned off.
- Instrument wires are connected to power and signal terminals.
- Power is supplied to the line and the system is checked for operability.
In some models, it is possible to adjust the sensitivity of the built-in sensor, which is transferred to at the final stage of work. It is set in such a way that the sensor works only when a person appears and does not respond to flying birds and small animals.
Application area
Motion sensors for security systems are used wherever it is necessary to control and restrict the movement of unauthorized persons. The need for this arises at the following facilities:
- in the entrances of residential buildings and offices of organizations;
- at secure sites and storage facilities;
- in apartments and separate rooms;
- in the entrance areas of country houses and garages.
The scope of a particular model depends on the category to which it belongs. Passive IR devices, for example, are in demand in limited spaces inside enclosed spaces. Active street IR sensors are mainly used to protect significant open areas (restricted areas).
A distinctive feature of ultrasonic devices is that they are preferable to use in rooms with heating, since some models do not withstand significant temperature changes. When choosing the installation location of such devices, the presence of glasses and other fragile materials that can be destroyed by resonance phenomena is taken into account.
Popular models
In the domestic market there are many different models that differ in their design and functionality. Significant demand products under the brand name "Sentinel", characterized by increased sensitivity and high accuracy of positioning of the object within the viewing sector. Thanks to the ability to fine-tune the IR sensor, it is possible to achieve triggering only when large objects (weighing more than 25 kg) are detected.
Among the operational characteristics of the Sentinel, the following indicators stand out:
- range of up to 12 meters;
- horizontal viewing angle - not less than 110 degrees;
- vertical viewing angle - 80 degrees.
The power supply voltage of the device is 12 volts (stand-alone mode from the battery).
Another popular model is the Shtor wireless and wired infrared sensors, which are highly reliable and able to operate at distances of up to 50 meters in any weather conditions. In addition, the device in question has a wide range of settings, allowing you to select the appropriate operating mode for the serviced room or territory.
