Home security and motion decorators go hand in hand when it comes to security. To enhances the protection inside and outside the house, motion detectors with PIR sensor in security cameras are essential now.
Motion sensor, defined!
As the name specifies, motion detectors are used to detect moving objects inside or outside of the home. If anything comes in the range of a motion detector, they give an alarm or a notification.
These sensors are integrated into security cameras, doorbells, and other objects that are used for the purpose of security.
Why not just a motion sensor, you may ask?
Whereas motion sensors are a good first step towards security, but solely relying upon motion detectors is not the ultimate solution to home security as they are prone to false alarms.
PIR Motion Detection
PIR, Passive Infrared Motion Sensors, are designed particularly for larger and smaller objects, based not just on the motion but also the heat. They are more accurate when it comes to detecting things that are actually questionable, such as people and cars instead of a tree branch blowing in the wind.
PIR operation principles
All the existing objects have some kind of heat that is emitted in the form of radiation. These radiations are not visible to the human eye because of their infrared nature but can be detected by electronic devices designed particularly for this very purpose.
The term “passive” in infrared refers to the fact that passive infrared devices are not designed to generate or radiate energy for detection purpose, but instead, they are constructed to detect infrared radiations reflected or emitted from other objects. They are not in any way are designed to measure heat.
How does the PIR sensor work?
Using a pair of pyroelectric sensors, PIR sensors detect thermal radiations emitted from the source, humans or animals, in the surrounding environment. These sensors are integrated side by side. When the signal differential between these two sensors is changed or interrupted, the sensor engages, which means that the sensor triggers an alarm, light or notification.
The infrared sensor itself is housed in a sealed metal that improves protection against temperature or humidity. However, there is a window made up of IR-transmissive material that is typically coated with silicone as it is very easy to come by. Silicone offers the best protection to the sensing elements behind the window.
PIR sensor is more of the lenses
PIR is mostly about the lenses than sensors that are generic and more or less are of the same price. The real magic happens behind the lens or optics. PIR motion sensors come in dollars, whereas, lens cost only a few cents. Not to underestimate the price lens come in, they play an important role in enhancing the breadth, depth, range, sensitivity patterns and focus.
Lenses are all about range and angle
The radiations that are detected by an infrared device are converted into electrical signals as they are visible to the human eye. These electrical signals are proportional to heat radiations detected. To make these signals stronger and measurable, a built-in FET is used that further feed signals to an output pin of the device. The detected radiations are passed through this process in order to trigger an alarm or amplify alarming.
The range and the angle to which these devices are capable of detecting the radiations is determined by the lenses that are used along with an IR sensor. So, alone an IR sensor, without a good lens, compromises performance.
There are Fresnel lenses or mirror segments that offer an effective range of 10 meters that is up to 30 feet. The field of view such a lens offers is around 180.
The models with a wider field of view, such as 360 degrees, are capable of offering infrared detection over 30 meters that comes around 100 feet from the PIR.
Applications; PIR motion sensors!
The lens and infrared sensor technology is a sophisticated one when it comes to practical use. PIR motion sensor detection is widely used in various fields, almost everyone. They have perfectly replaced other motion detection systems.
The only thing you need to do is to give power to your motion activated video cameras along with the ground to produce discrete output. Here are some of the most common applications of PIR motion detection.
- Outdoor lights
- Multi apartment complexes
- Common staircases
- Shopping malls
- Outdoor spaces in houses
- Garden lights
- Parking areas
- Light fixture hidden camera
- Outdoor floodlight hidden camera
How to connect a PIR motion sensor?
Depending on manufacturing, every product is different from the other. Hence, the connectivity may vary as per the model. Generically speaking of a standard PIR sensor.
Here are the simple steps that you can follow to understand the connectivity of a PIR sensor.
A passive infrared sensor consists of three pins. Let’s just say A, B, and C.
- Pin A goes to the drain terminal of the device you are going to connect it to. It is important to connect it to the positive supply of at least 5V.
- Pin B corresponds to the source terminal that must be connected to a ground terminal via a 100K, or 47K resistor. Pin B is the output pin of the sensor. All the detected signals are carried to an amplifier via this pin.
- Pin C is connected to the ground.
Buying the right PIR motion detector
Entering the market you will find a huge range of products that offer different performance depending on the specifications, price, and brand. To get the best performance out of any motion detector, make sure to look out for essential features and specifications, such as;
- Wide range input voltage
- Output voltage
- Object movement vs. human movement differentiation
- Operating modes; repeatable (H) and non-repeatable
- Range, or cover distance; minimum of 120 degrees and 7 meters
- Low power consumption; minimum of 65mA
- Standard TTL output
- Delay time adjustment
- Low noise and high sensitivity; dual-element sensor
Friendly tip on eliminating false PIR triggers
Differential amplification is the key!
Differential detection sensor element pairs wired opposite to input differential amplifier that cancels each other. The average temperature of the field of view is removed from the electrical so that sudden change in temperature due to any reason is not detected by the device. It helps in resisting false alarm because of sudden flashes of light or field-wide illumination.
This differential arrangement also minimizes the common-mode interference that helps in resisting trigger because of nearby electrical fields. Such a differential arrangement does not measure temperature, but only offer motion detection.
Owning a motion sensing spy camera for your personal use that offers ultimate security is not an issue with an understanding of what creates the whole difference between quality, performance, and durability when it comes to the right camera.