What Is a Motion Activated Security Camera?

Motion activated dome cameraMany of today’s security cameras have something called a motion detector installed. This is—as it sounds—a device that’s capable of detecting movement. What kind of motion it detects depends on the user’s custom settings. In the case of a home security camera, this will typically include any moving objects, and people in particular. The great feature of motion detection home security camera is its ability to send alerts the second it begins to record movement based on its settings. One of the great things about motion detection is that your camera still works for you in the background even when you’re away or logged out of the system.[1]

Motion detectors are a critical component in two areas of home security, which include:

  1. Cameras (indoor and outdoor)
  2. Automated security lighting

Some of the more sophisticated, next generation camera systems, even have unique object tracking using smart, complex algorithms. These are generally more useful for commercial premises though.

NOTE: You can jump to any part of this post by clicking the links in the table of contents

Table of Contents

  1. How Motion Detection Works
  2. Trouble Shoot Motion Detection
  3. How to Position Your Home Security Camera
  4. Rules, Modes and Schedules

How Motion Detection Works

The best way to understand how motion detection works is to first look at how a camera functions. Inside every camera is the image sensor which the lens of the camera directs light to. The moment light reaches the image sensor, pixels then record how much light they receive. These dark and light areas then form the video images that we see. Motion detection works by comparing successive video images. So if the pattern of light changes between frames (a change in pixels) the smart camera concludes that something has moved and starts to record. As it begins to record, it also sends you an alert. The camera determines when enough has changed based on the motion detection settings (see below). There are different methods of motion detection, i.e. infrared (heat vision) and microwave. We won’t get too much into the deeper technical aspects in this piece.[2]

Trouble Shoot Motion Detection

One of the early gripes with motion detection security cameras was that they picked up too much. In other words they were too sensitive and sent alerts out for things people didn’t need alerts for. They still can do, but you’re not stuck with it. Fortunately, this is a problem of the past as today’s cameras give you easy configuration options. They allow the end user to adjust the motion sensitivity in a few easy steps. What you have to do is go to the camera’s settings and find the motion detection test.

Setting Motion Sensitivity

The basic principle is the same for most cameras. The first thing you need to do is position the camera where you intend to keep it. It’s a good idea to start the motion detection at a low setting on your smart phone. All you have to do then is walk in front of the camera and check to see if the device’s LED comes on. If not, increase the motion detection setting and try again. Continue like this until the LED flashes. That’s it. The camera has detected your motion so you can set (save) the settings right there. You may have to play around with the motion sensitivity a bit until you find your optimal setting.

Not Receiving Alerts

Another problem people report is that they don’t receive email alert notifications even though their camera detects motion based on their settings. There are usually three reasons for this:

  1. Your email address is wrong (check again carefully)
  2. You have not confirmed your email address in the setup procedure
  3. The alert setting has been accidentally disabled

How to Position Your Home Security Camera

For indoors, there are a few basic rules for positioning your home security cameras. Once you know where you want the camera to monitor, you then have to think “height.’ Although different systems can have varying fields of view (FOV), ideally you want to mount the camera at least 7ft above the ground. Once in position, make sure it points down slightly.

Security cameras detect motion best with side to side movements across the lens’ FOV. This is important to know because it helps you to position the camera for the best effect. Let’s say you want to detect motion at your front door. In this case you want to place the camera to one side so that it senses movement as the intruder walks by the lens rather than toward it. Remember to also give your camera space to focus and keep the units out of reach.[3]

Point to a Solid Background

It’s better to have your camera point toward a solid background, away from windows. The problem with cameras that can see through glass is that they might pick up plants moving around on a blustery day, or passing vehicles even. Again, if you want to detect motion at a first floor window, then place the camera to one side, not opposite it. This will eliminate two problems at once. The first is that it avoids detecting irrelevant motion. The second is that it catches the intruder as they walk “across” the camera’s field of view rather than into it. Be careful when positioning outdoor cameras too, as you don’t want trees and shrubs sending you false alerts all day long.

Recap: If the camera isn’t picking up motion, increase the motion sensitivity. If it picks up too much motion (overly sensitive), then decrease the sensitivity settings, reposition the camera, or both.

Rules, Modes and Schedules

Finally we have rules, modes and schedules. The majority of home security cameras—outdoor or indoor—will have some options for rules, modes and schedules. However, some may use different wording that means the same thing. Use rules to determine what action(s) you want the camera to take once it detects motion. For example, if your camera detects motion at the front door, you might want to set up a rule for the living room camera to start recording and set the duration of that recording. Note that you can group any rules you create into modes.

Default modes for security cameras are usually armed and unarmed. You should be able to edit modes freely. You can also schedule your modes by start date, end date, and times of day in a given week that you want the mode to apply. For example, if there’s always someone home on the weekend, you will more than likely want your camera mode set to unarmed. If you’re familiar with using a smartphone, configuring your security camera’s motion detection setting, rules, modes and schedules will be a walk in the park.


  1. https://en.wikipedia.org/wiki/Motion_detector
  2. http://www.ehow.com/how-does_5557581_motion-detection-cameras-work.html
  3. https://www.cnet.com/how-to/where-to-place-home-security-cameras/

About Mark Bickmore

Hi, my name is Mark Bickmore. I'm an Engineer, who has a keen interest in home security and keeping my family, property and valuables safe from burglars. This website was set up to help me explore the research, facts and myths about burglars and burglary. Please feel free to contact me should you have any questions, comments or suggestions.

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