Introduction To Security Camera Systems

A security camera system basically consists of a number of security cameras, a digital video recorder to record the cameras, and the wiring and connectors to connect it all together.

Security cameras come in a variety of styles:

  • Bullet cameras, with a cylinder shape and a built-in lens, are weatherproof and are great for outdoor applications
  • Dome cameras, with a dome shape and a built-in lens, are typically used indoors although some come with an ‘armor housing’ which allows them to be used outdoors
  • C-Mount or ‘box’ cameras, with a rectangular shape and a lens that is selected and attached separately, is used indoors only unless it’s enclosed in a separate housing for outdoor use. These cameras are typically used in commercial settings
  • Hidden cameras can come in a variety of shapes including super-small ‘eye’ type cameras that can easily be hidden, or hidden cameras that are designed to look like something else, such as a teddy bear, a smoke detector, or a sprinkler head. These cameras are usually designed for indoor use only and have a built-in lens.
  • Pan – Tilt – Zoom (PTZ) cameras allow a remote operator to pan (back and forth), tilt (up and down) and zoom the lens out and in. They are usually large and can be used inside or out.

Your choice for each camera in your system will depend on whether you want to install it inside or outside, what size lens you need, the resolution (the higher the resolution the clearer the image), whether you need infrared for nighttime viewing, and the mount type (do you need to mount it on a wall, ceiling, pole, etc.) and of course, your budget.

A 3.6mm lens will provide the widest angle of view you can get on a camera without distorting the image. This will provide facial detail to about 30 feet. If you need facial detail farther than 30 feet from the camera, then you will need a higher millimeter lens. A higher millimeter lens gives you further focal distance but reduces the angle of view. Varifocal lenses (for example, 5 to 100mm) are available which allow variation of the focal distance of the camera. That is handy when you don’t know exactly what size lens you are going to need up front.

You also want to choose what type of digital video recorder (DVR) you need to record the cameras. Most DVRs come in 4, 8, or 16 camera input (aka ‘channels’) versions, although there are DVR models that can record as many as 64 cameras. Keep in mind that adding camera inputs later to an existing DVR is not usually feasible so you’ll want to provide for future growth. Look for a DVR with a ‘real-time’ recording rate of 30 frames per second (fps) per camera. DVRs also differ in the compression technology they use. The best compression technology compresses the video data so it can be stored in least amount of space on the hard drive, and loses the least amount of information (picture quality) in the process. The compression technologies from oldest (worst) to newest (best) are: J-PEG, M-JPEG (aka MPEG), MPEG4, and H.264. Next, determine how much hard drive space you will need. When the hard drive space is all used up, the DVR will start recording over the oldest video on the system. Many people choose to keep 2 to 4 weeks of recorded video on the hard drive. Other features to look for in a DVR are remote viewing and operation, audio support, and ease of operation and event backup.

Finally, you will need all of the cabling and connectors to power the cameras and the DVR, and to connect the video signal from the cameras to the DVR. There are two basic approaches to wiring your system: using plug-and-play cables which have the connectors pre-attached vs. using RG59 cable which is shielded more heavily (so less problems with interference) but requires that you apply the connectors yourself. Using plug and play cable is easier but will only be dependable if the cable runs are less than 100 feet, and no florescent lighting is used in the building it’s in, and no high powered infrared cameras are being used. Your security dealer will be able to help you determine if you have all of the connectors and parts you need.
Other items to consider when designing your camera system are power and surge protection, a lockbox for securing the DVR, and a monitor for viewing the cameras directly from the DVR (vs. over the network).

Once you have all the components powered, the cameras connected to the DVR, and a monitor plugged in, you should be able to view your cameras right away. The software on the DVR will allow you to customize your application for features like viewing over the network and motion detection.

For more on Security Camera Systems view our Introduction To Security Systems video series.

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