The technology used in home security surveillance systems has changed dramatically over the years. Video cameras used in surveillance systems today are smaller, better and cheaper. Up until a few years ago video footage was recorded onto VHS tape, but today DVR (digital video recorder) systems record video footage onto a hard drive. The price of home security surveillance system has come down dramatically over the last few years. A home security surveillance system consists of two main parts: the video recording device, and the surveillance cameras.
1. Surveillance Camera Technology
Surveillance cameras either use CMOS or CCD (charge couple device) chips to record video images. CMOS is used in cheaper cameras, and the video quality is not as good as CCD cameras. CCD camera formats are measured in inches, and the larger the format the brighter the images produced. A CCD format of 1/4″ or 1/3″ is good enough for most situations.
The number of TV Lines (TVL) is how the resolution of a surveillance camera is normally specified. This determines how detailed the video picture quality is. A resolution between 350-400TVL is normally produced by surveillance cameras. The frame rate of a surveillance camera is the number of separate images that the camera can record per second. Most camera’s can record at 30fps (frames per second), and video below 30fps is not smooth and begins to look jerky.
A color surveillance camera is not as good as a black and white camera in poor lighting conditions. The unit of measurement for a camera’s light sensitivity is the lux. The light sensitivity of a camera must be 0.5 lux or less to be able to see anything under nighttime conditions.
2. Surveillance Camera Lenses
The lens of a surveillance camera should match the CCD format of the camera – 1/3″ lenses should be used with cameras with a 1/3″ CCD format. Most home security surveillance systems have cameras with fixed focal length lenses, which means that the cameras do not have a zoom in/out facility. Cameras with a motorized zoom are quite expensive, and allow you to remotely change the camera’s focal length.
3. Other Surveillance Camera Features
Some surveillance cameras include Infrared (IR) LEDs, which project an infrared light allowing you view video in complete darkness. In complete darkness, the range that these cameras can see varies, and is normally somewhere between 10 to 50 feet. Cameras with a pan, tilt and zoom (PTZ) facility are included with the more expensive home security surveillance systems. PTZ cameras allow you to remotely pan the camera’s view left and right, tilt the camera’s view up or down, or zoom in and out.
4. Surveillance Camera Housings
A home security surveillance system can have large, visible cameras, which are cheaper, have larger housings, and can deter criminals by being clearly visible. Covert (hidden) cameras are generally quite expensive, are very small, and are hidden in other objects, such as a light fixture. Cameras with dome housings are mounted on the underside of ceilings. Dome housings are normally used to house cameras with a PTZ (pan, tilt and zoom) facility. Protective weatherproof security camera housings are used by cameras that need to be protected from the elements. Outdoor surveillance cameras need to be waterproof and to be able to withstand extremes in temperature.
5. Video Surveillance Monitors
Using a standard TV as a video surveillance monitor does not produce the best picture quality. Computer monitors produce better picture quality, and also offer an extended lifespan. If you want to display video from multiple cameras onto a single monitor, then a 15″ monitor should be the minimum size you purchase.
6. Video Surveillance System Recorders
Most home security surveillance systems today record video onto a hard drive and not VHS tape. This has several advantages. Firstly, you do not need to fast-forward or rewind a tape to go to a specific point in a recording – you can immediately go to that specific point in the recoding. Secondly, you can playback an earlier part of any camera recording whilst that camera is still recording.
Some home security surveillance systems have cameras with built-in motion detection, which can be set to only record video when motion is detected in a room. This will reduce the hard drive storage space requirements. The only advantage of purchasing a VCR system today is its cheaper price.
7. PC Based DVR Versus Standalone DVR
There are two types of home security surveillance system, PC based DVR systems, and standalone DVR systems. A PC based DVR system is quite cheap, and is run off an existing PC. An expansion board must be installed into the PC case, and the required software must be installed onto the PC. The problem with PC based DVR systems are that these systems are unstable and slow when compared to standalone DVR systems.
The recording on a standard DVR security camera system is done using hardware, and this eliminates software crashes that you sometimes get with the PC based DVR systems. PC based systems generally do not perform as well, and are not as reliable as DVR systems.
8. Considerations when buying a Home Security Surveillance System
Your first consideration is the quality of the video you want to record. This is the resolution of video recordings in TV Lines, as well the video frame rate (smoothness) of the recordings. The second consideration is the number of cameras that you will need for your home security surveillance system. Entry-level systems come with 4 cameras. The third important consideration is the hard drive size that you will require for the DVR system. Low-end DVR systems come with 80 gigabyte (GB) hard drives, whilst top-end systems come with a 750GB hard drive.
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