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Motion sensors for alarms

Motion sensors for alarms

Security alarm motion detectors are advanced devices in the security system, they can be both outdoor and indoor, with their help the owner quickly learn about the movement in a given area. Motion detector for a modern security alarm system is a very necessary and effective element. It allows you to detect a moving object and eliminate false alarms as much as possible, such as:

  • Lighting of the artificial type;
  • Various systems that generate heat;
  • Small animals;
  • Electrical and radio interference from operating equipment;
  • Concussion, vibration.

In order to correctly select and buy a motion sensor for the alarm system, we need to understand - which device will be most effective for the planned surveillance area, whether it is an apartment, warehouse or outdoor area. And to do this, it is worth considering the principle or type of operation of these security devices.

Motion sensors by type of operation are divided into:

  • Ultrasonic;
  • Radiowave;
  • Infrared;
  • Combination (e.g. Ajax CombiProtect) .


In the ultrasonic sensor, the principle of operation is based on the reflection of sound from an external obstacle. If the sensor detects changes in the wave, it triggers.


The radio wave sensor works on the principle of the ultrasonic sensor, only instead of an ultrasonic wave, it measures microwave radiation, which is scattered by the built-in microchip. 


The infrared sensor is currently the most common and operates on the type of temperature change in the street, outdoor or indoor area entrusted to him. That is, the motion detector analyzes the temperature of the environment, comparing it with the temperature of the body that appeared in the monitored area and as a result it triggers. The device scatters several beams and if a person gradually crosses them, the sensor detects the change and sends a signal to the main unit.


Combined motion detector has both PIR sensor and microwave microchip, which also analyze the movement in a given square. First the motion is analyzed by the thermal spectrum and then by the microwave signal. If there is a signal in one or the other range the combined sensor will be triggered. This is done to increase the reliability of the system and to prevent a person wearing a fire suit, for example, which prevents the heat from escaping, from entering the area undetected.

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Wired or wireless?

Another important criterion when choosing a motion sensor by the type of installation and signal transmission, is - what will be the device - wired or wireless. And if not so long ago, many experts have made significant arguments about the significant imperfection and expensive cost of wireless alarm systems, then at the moment to buy a reliable alarm system without wires, and in particular motion detectors for apartments or offices has become commonplace.

The increasing demand for wireless sensors, whether for indoor or outdoor type of detection, has allowed a large number of manufacturing companies to successfully compete and participate in the development and sale of this product, which has had a tangible and inevitable effect on reducing its price. One such giant manufacturer, both domestically and equally in the international market of wireless alarms and security systems in general is the sales leader - the domestic company Ajax.

So, let's look at what motivates a buyer to choose and buy wireless devices:

  • No wires - stop drilling through the walls of apartments and houses;
  • Easy to install and connect outdoor or indoor sensors - why break your head, the developers have taken care that the sensors and the system as a whole can be installed as easy as possible without involving professionals;
  • Self-powered - battery with an average charge of up to 6 months (Ajax sensors - 5 years) and notification of when to replace - very convenient if you need an outdoor detector;
  • Radio transmission channels of different ranges - now it is possible to choose which one suits you best, or maybe you want several at once - no problem;
  • Mobility - if necessary, wireless devices can be easily moved to another place of observation;
  • Adding connections to the system - no problem adding sensors and not only motion;
  • Ability to receive notification of the alarm on any mobile device: smartphone, tablet, etc.

The disadvantages are the susceptibility to radio interference (can be solved by buying a repeater) and the higher price of the wireless system. But you do not damage the walls in the apartment, do not involve installers and do not pay for the connection, which is necessary when installing a wired system, which makes up for this seemingly high price.

Let's look at the advantages of wired motion detection devices. They can be outdoor and indoor, and are also widely used in modern security systems:

  • Low price - but do not forget that you need to buy additional fasteners and if the object is complex pay for the connection installers;
  • The distance from the detection device to the center is 400 meters - which is not unimportant for installation on large sites and tall buildings;
  • A reliable signal is the main advantage of a wired system over a wireless system;
  • Power supply on a permanent basis, and in case of main power outage there is an opportunity to connect an autonomous for a long period - up to six months.

Disadvantages of the wired security system - it is susceptible to cable damage due to its visibility, especially from the outside of the building - it is easy to remain without a signal; long recovery after damage, due to the fact that the damaged area to be found, say, 200 meters, may take several days; connected wired power supply - possible interruptions and breaks.  

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More security alarm motion detection devices are characterized by a variety of orientation to perform a particular task. Thus, as an example of motion sensors from the company Ajax, they can be divided into outdoor or outdoor Ajax MotionProtect Outdoor and for indoor detection Ajax MotionProtect, Ajax MotionProtect Plus, motion detector with a camera to confirm alarms Ajax MotionCam and combined motion sensor Ajax CombiProtect, which can capture both the movement in the range of 12 meters and glass breaking, while being at a distance of 9 meters from it.

Buy indoor and outdoor motion detectors Ajax and other manufacturers for apartments, houses or offices you can in our store And if you have any questions about the selection or connection of the necessary equipment, our specialists will gladly help you.

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