Posted 2 years 303 days ago ago by Jake Thomas
False alarms a problem? Radar detection is the solution.
The best security solutions are often a strategic combination of technologies with each playing a critical role. To achieve the best result, select the best tool for the job. For example, you wouldn’t want to use a visible light camera at night on its own, nor would you get the most out of using a PIR sensor in an area with lots of windows. Below are a series of some of the most widely used motion detection solutions with their strengths and weaknesses.
Passive infrared (PIR) sensors pick up heat signatures from objects within their field of view. The sensor detects changes in the amount of infrared radiation, and when a threshold is reached will trigger whatever it is connected to – a light, alarm or camera.
PIR sensors bring with them a few inherent challenges. First, the sensor is essentially a simple on/off switch that activates upon detection. Also, the way in which they operate means it doesn’t have the greatest range and can be triggered easily by objects like spider webs, leaves, small animals, etc. That can, at times, mean false alarms.
Negatives aside, PIR is effective provided one is aware of its limitations. They work best in smaller indoor areas, like an office, but don’t “see” through windows. However, given their longstanding use they are affordable and don’t require visible light to work.
Video Motion Detection (VMD)
This option combines images generated by a surveillance camera with software that can analyze images as they are captured. It works similarly to a camera operator sitting and watching a video feed but is automated.
One drawback is that it operates using visible light. Meaning, if there isn’t enough light or if there is too much light behind and objects, the camera is effectively blind. This method relies heavily on both the quality of the image and the quality of the software.
Surprise! Thermal cameras aren’t true cameras in the sense the don’t pick up visible light. At the risk of an oversimplification of how they work, they use sensors to create an image from differences in temperature between objects.
Pros include their excellent range and ability to see heat signatures through smoke and fog. They are also immune to many conditions problematic to visible light cameras – shadows, backlight, lack of light, etc.
The main con is the price tag, which puts the technology out of range in some cases. But, in the right situation a thermal camera can be just the right tool for the job.
Essentially, radar works by emitting radio waves and receiving them after they bounce off objects within its range. This technology calculates distance, velocity and size of objects in relation to the detector.
This approach holds great benefit over that use infrared or visible light, as there is comparatively less interference caused by day-to-day obstructions that can trigger false alarms. Radio waves simply pass through minor objects such as spider webs, leaves and smoke, enabling equipment to focus on objects of significance. They also work independent of the visible light spectrum, and thus unimpeded by light conditions and shadows.
Advantages include being able to work within specific ranges and the ability to detect across a much wider area than thermal cameras, even if it does so within a shorter range. Additionally, the price is well below that of thermal cameras and not far from PIR sensors.