These days, the security and surveillance concerns have risen and so have the tools to deal with such menaces. Motion sensors are used primarily in the home and business security systems, but they can also be found in phones, paper towel dispensers, game consoles, and virtual reality systems. Microwave motion sensor / Doppler Radar is the best motion detector, results are better than PIR motion sensor.
What is a Microwave Motion Sensor?
A microwave motion sensor uses electromagnetic radiation (Microwave). Microwaves are electromagnetic radiations whose frequency ranges from 0.3 GHz to 300 GHz. It emits microwaves which are then reflected back to the receiver. The receiver analyzes the waves that are bounced back. If there is an object moving in the room, these waves are going to be altered. The microwave detector is able to identify changes from moment to moment. Ideally, the receiver should be receiving the same waves back again and again.
Microwave Motion Sensor
One of the unique use of these waves is in the operation of various security devices. The main guiding principle for almost all of these sensors has been the Doppler’s Effect.
Core compenents of Microwave Sensor
A microwave motion detector circuit mainly comprises components- the transmitter, receiver, and the alarm/related circuit.
How dose a Microwave sensor works?
The transmitter sends off microwaves into the area. These waves have a specific frequency. However, as they strike with an intruder moving with a velocity, the frequency and consequently, the phase of the wave signal gets altered. Once these reflected waves are received by the receiver, its phase analysis is done and consequently, an alarm is triggered if the analysis depicts some change in the phase of the wave signals. It is worth mentioning here that the change in phase of the signal wave is directly proportional to the velocity of the intruder.
Today, with advancements in technology, we are endowed with a variety of microwave motion detectors.
Detector combating false alarms: Most of the microwave motion detectors work upon the principle discussed in the previous section. However, there is a kind of disadvantages that these kinds of sensors suffer from.
The problem is related to the cases of false alarms which occur even due to slight vibrations of objects like curtains and swinging signs. To combat this problem, an improved detector has been designed which contains all the components of a normal sensor along with two receiver/mixer diodes. These diodes emit surveying signals which mix up with the transmitted microwave signal. These altered phase signals when received by the receiver, trigger the alarm only when the shift in phase has been up to the threshold frequency change pre-fed into the sensor.
Once, this pre-fed threshold frequency is over-crossed, the alarm is triggered. In another kind of detector, the sensor device consists of field transceivers that have microwave oscillators and antennae so that continuous-wave energy is transmitted into the specified area. These antennae contain certain devices which can easily recognize the human intrusion by analyzing the phase shift that occurred in the received wave. Thus, in this way, it is ensured that the cases of false alarms do not arise easily.
A detector based upon random motion: Some of the detectors contain diodes that enable the detector to sense whether the intruder is moving towards or away from the detector. These detectors are helpful in sensing and differentiating between ordinary movement and intruder movement. This feature of such sensors makes them highly reliable.
Uses of Microwave Motion Sensor
The microwave motion detectors have a wide array of applications.
These detectors, apart from addressing security problems, are also used in door openings.
These detectors are used to detect the heartbeat and breathing rate of a human.
These detectors are used in the elevator shaftway where they are used to display the information regarding the parking of a car in an elevated parking system.
These sensors are used in security issues and traffic law enforcement.
They are used in monitoring the light system of a house or a building.
Benefits of Microwave Motion Sensor
Some key benefits are:
Unlike other detectors, microwave motion detectors can be used in a harsh environment where the heat cycles are not regular.
Since microwave radiations can easily penetrate through the walls and holes, so, they can be used to impart security across the boundary/closings.
These detectors when combined with passive infrared detectors can become much reluctant to false alarms.
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