How Do Motion Detection Security Cameras Work?

Installing motion detection security cameras at your home or business is a great way to up your security, and knowing a little bit about the technology behind them can help you make the best use out of them.

Here is a look at the mechanics behind motion detection security cameras.

CCD vs. CMOS

First, you should know that there are different types of motion detection cameras depending on the type of image sensor being used. The two major types are CCD (charge-coupled device) and CMOS (complementary metal-oxide semiconductor). Both types of cameras have image sensors that must convert light into electrons, but the technology behind them makes them different from one another. In CCD cameras, the charge is transported across the chip and read at one corner of the array. Then an analog-to-digital converter assigns a digital value to each pixel. CCD sensors are able to detect motion even in dimly lit rooms and can produce high quality, low-noise images. In CMOS cameras, there are several transistors at each pixel that amplify and move the charge using more traditional wires. This allows each pixel to be read individually. CMOS sensors generally do not produce as high-quality images as CCD sensors, but they are more affordable and consume much less power (which makes for a better battery life). CMOS technology is advancing, however, so many of today’s CMOS cameras rival CCD cameras in quality.

How they detect motion

In the simplest of terms, motion detection cameras work by comparing each image captured by the camera to the previous one and by detecting major changes between consecutive images. The camera will interpret significant changes between consecutive images as motion. Keep in mind here that there are two different types of changes that could occur between images. An overall change occurs when the image as a whole as changed—as can occur when a light is switched on or even when sunlight streams in through a window. Then, of course, there are those more focused changes that occur as a result of motion within the image. You can adjust a camera’s sensitivity and “percentage” so that it will only report certain types of change between images.

A camera installation specialist will have the expertise necessary to install your camera in a location and at an angle that would help reduce the likelihood of a false alarm (such as one caused by motion detected in a window reflection). Therefore, your best bet for installing motion detecting security cameras in your home is to hire a professional.