DUAL TECHNOLOGY DETECTORS
Technologies deployed in motion detection use optical, acoustic, microwave and transmitter for illumination purposes. Motion detectors have found wide use in the activation of automatic door openers and the operation of the street and indoor lights through the use of occupancy sensors. Technologies such as Passive Infrared (PIR), microwave, and ultrasound have been used to detect motion. However, with the weakness observed in using them for detecting motion independently dual technology have gain use. Dual technology which utilizes combinations of two or more of these technologies have been invented to help in reducing false triggering which arises from using a single motion detectors. A lot of efficacies have been achieved through the use of dual detection technology (Behnke, 2013).
Dual technology detectors combine multiple sensing technologies into one single detector with the aim of reducing false alarm. The process of combining multiple sensing technologies into one single entity require the use of AND logic gate. It does reduce chances of a false alarm occurring at the expense of increased vulnerability and reduced detection probability. The most commonly used dual technology detector integrates PIR and microwave together. As have been observed, PIR sensing technology is paired with other sensors to help in reducing usage of energy and in enhancing accuracy. PIR technology utilizes less energy in its operation compared to other detectors and its combination with microwave technology allows for activation of the sensor if both the PIR and the microwave are activated simultaneously. One of these dual technology detectors which utilize the use of PIR and microwave sensors is the PIRAMID indoor motion sensor (Hall & Greeno, 2007).
PIRAMID Indoor Motion Sensor
The PIRAMID (Passive InfraRed and Microwave Intruder Detector) utilizes a combination of passive infrared technology and Doppler microwave technology to form a single intrusion sensor. In this intrusion sensor, the two integrated technologies activate simultaneously to cause alarm when an intruder is detected. Stereo Doppler Microwave sensor get activated on detecting the movement of an intruder while passive infrared portion of intrusion sensor get activated on the change in the infrared radiation due to the intruder. The combination of these two sensing technologies with different capability help detector in eliminating false triggering which may arise from the movement of objects such as trees due to infrared radiation variation. Any different infrared radiation detected other than the expected one does not cause activation of the PIR sensor, and no alarm is caused in such event (Grupen et al., 2006).
Principle of Operation
The operation of dual technology detector which utilizes the combination of PIR and microwave and works on the principle of AND logic gate. A failure in either operation of PIR or microwave sensor as depicted in AND gate disables the sensor, and no alarm is triggered. The alarm is only triggered in the event that both the microwave and PIR detectors are activated simultaneously leading to an enabled state of the AND gate in the intrusion sensor. A sensor with combined PIR and microwave sensing technologies have the ability to lowers the probability of false alarm which might arise from tripping of PIR by heat and light changes through the use of microwave. Microwave, on the other hand, can easily be triggered by the movement of objects such as trees chances which is highly reduced by the use of PIR. As such, while it very possible for an intruder to fool either PIR or microwave, a combination of the two eliminate such occurrence (Fehlman & Hinders, 2009).
Strength of PIRAMID Indoor Motion Sensor
The combination of PIR and microwave technologies in the intrusion sensor takes advantages of the two technologies in its operation. A failure in one technology is substituted by another in dual detector technology and such help in strengthening the operation of the sensor. Some of the strengths of dual pyramid motion sensor include its high sensitivity, high security, durability and stability (Dereniak et al., 2002).
One of the key strengths of PIRAMID sensor is provided by its internal circuit inclusion of Microprocessor Controlled Unit (MCU). The integrated circuit design enhances the digital processing signal both in the PIR technology and the microwave in a way that help in achieving the desired output signal. This help a lot in giving correct alarm other than false alarm witnessed before the use of dual detection technology. In fact, due to high security witnessed through the use of dual detection technology, most of the securities urgencies today deploy the use of PIRAMID in their operation. The alarm given is very accurate and only happens in the event that a moving person approaches the door (Del, 2004).
The ability provided by the internal circuit design in the PIR technology has seen the dual detection technology having high security compared to single sensor. The Ten-position digital switch provided by the digital range control helps in maximizing the range over which motion of objects can be detected. Through the use of Ten-position digital switch, dual detection technology can detect moving object over the great range, and this enhances the security level of the device (Alabaster, 2012).
Greater Detection Sensitivity
The combination of PIR and microwave sensing technologies to form one single intrusion sensor has increased sensitivity of detector. PIRAMID indoor motion sensor has greater detection sensitivity due to the way it is able to differentiate the heat emitted by moving people and the background heat (Bertolini & Coche, 2008). Furthermore, the device has balanced temperature compensation circuit which is able to compensate for elevated temperature. This helps a lot in enhancing sensitivity of the dual detection technology. Before the incorporation of passive infrared radiation, false triggering of alarm could be witnessed through background heat generated. PIR technology has greatly eliminated the possibility of detecting movement of objects other than human beings.
Greater Stability and Energy Saving
A combination of PIR technology with any other sensor helps in saving a lot of energy in the operation of the sensor. As have been observed, PIR sensors switch to default manual-ON operation when there is not human motion detected. This help a lot in ensuring that energy is only consumed when it is necessary and in cases where there is motion of human being within the line of sight of the device the overall system is kept off (Ciccimaro et al., 2009).
The durability of PIRAMID motion sensor is enhanced through the use of metal casing. As have been observed, most of the sensors are very vulnerable to radio frequency interference and electromagnetic interference. Through the use of metal casing, the device is highly protected from RFI and EMI which greatly enhance its durability. The interference from the electromagnetic waves and radio waves was observed to lead to default in the operation of the device as they could result to false alarming. Much effect is observed in the inductor component of the sensor when it is exposing to the RFI and EMI (Carey, 2001).
Vulnerabilities of PIRAMID Indoor Motion Sensor
PIRAMID indoor motion sensor uses PIR and microwave technologies in its operation of detecting intruders. However, PIR as a sensing technology only detects objects in line of sight. Object out of sight can, therefore, move around undetected by the sensor. This makes it unreliable for the operation in places other than for indoor detection (Holst & Society of Photo-optical Instrumentation Engineers, 2007).
PIRAMID motion sensor is very vulnerable to slow motion of the object. The microwave portion of the device can only detect objects moving at a certain speed. There is, therefore, a threshold speed upon which a moving human being goes undetected by the sensor. This cause a lot of insecurity issues in using the device in areas where security is a major point of concern (Joines et al., 2012).
On the line of sight operation, the PIRAMID has a weakness of detecting moving persons due to blockage. Passive infrared radiation operates in a way that any object in the line of sight prevents activation of the PIR sensor. Some of the moving person when unauthorized has a tendency of blocking themselves from detection by the dual detection technology. This greatly reduces the efficacy of the PIRAMID motion sensor (Kingston, 2005).
Area of Operation
PIR technology as a portion of the PIRAMID motion sensor has a lot of weakness in the operation of the device. The efficacy of the sensor is greatly due to the weakness presented by the use of PIR technology. One of these is the inability of the PIR to detect motion of human being in places where there is no plenty flow of air. As have been witnessed, PIR works well in enclosed places and cannot be used in rooms which are highly ventilated such as computer rooms (Klein, 2004).
PIRAMID motion sensor uses infrared in its operation and detection of the moving objects. The infrared radiation emitted by PIR allows the dual detection technology to be activated. However, fluorescent lighting system also emits infrared radiation. This makes this lighting device to have the ability of activating the sensor leading to false triggering of the alarm. As such, in most areas of operation of PIRAMID sensor, fluorescent tubes are not allowed to avoid cases of false alarming (Bolozdynya, 2010).
Recommendation for Efficacy
The major aim of coming up with dual detection technology is to eliminate the possibility of a false alarm occurring. Efficacy of the system has been observed to increase through a combination of two or more sensing technology. However, in the case of the operation of the PIRAMID motion sensors, a lot of the observed vulnerability can be eliminated in order to increase the possibility of achieving the desired result (Los Alamos National Laboratory, United States, & United States, 2016).
As observed in the discussion on the vulnerabilities of the PIRAMID motion sensor, one of the greatest weaknesses of this dual sensing technology is its detection in the line of sight. The area coverage of the sensor is much limited by the line of sight operation. As such, in most cases, it is used in indoor motion detection to allow sensing of any moving in. However, this vulnerability can be eliminated through the use swivel mounting. Swivel mounting is a multi-directional switch which allows the sensor to rotate in all the direction at a defined speed. This if deployed in the operation the PIRAMID sensor can greatly eliminate the line of area coverage weakness (Mukhopadhyay, Lay-Ekuakille, & Fuchs, 2011).
Fluorescent lighting affects the operation of PIRAMID motion sensor to much greater extent. As mention in the vulnerability of this dual detection sensor, the efficacy of the PIRAMID motion sensor is reduced in cases where fluorescent lighting is used. However, it is recommended to use fluorescent filter module to prevent the infrared radiation being emitted by the tube from interfering with the sensor. While in some of the instances individuals do not use the sensor in a room with fluorescent lighting, the use of fluorescent filter module increases the efficacy of the sensor to a great extent (SPACE AND NAVAL WARFARE SYSTEMS CENTER SAN DIEGO CA, Ciccimaro, Everett, Bruch, & Phillips, 2009).
The efficacy of the sensor has been observed to decrease when there is an object blocking the moving human being from the line of sight. This reduces the sensitivity of the sensor to a great extent. However, integrating ultrasound together with microwave helps in enhancing the sensitivity of the sensor. As have been observed, ultrasound technology is very sensitivity to even a moving hand of a person (Saari, 2007).
While in some instances false alarm has been observed due a component failure in the PIRAMID operation, a lot has been done to reduce such occurrence. The use of stereo Doppler supervision helps in blocking the alarm in case there is any component within the PIRAMID operation. This has been observed to help in increasing the efficacy of the sensor and in enhancing the security of the system (Mullard Limited, 2001).
Detection technology is gaining a lot of use in security areas and in the field of science. A major concern of individuals has been ways of enhancing the efficacy of their operation in detecting the object. Dual detection technology is a modern technology which seems to enhance the efficacy of these devices through combining two or more sensing technology together. However, as observed in the discussion, there is still a lot which needs to be done in order to achieve optimum operation of these technologies. For the case of PIRAMID motion sensor, the major weakness observed arise as a result of its line of sight operation. However, this can be eliminated through the use of swivel mounting.
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