CCTV (closed-circuit TV) security surveillance systems have been around for decades now, but the technology used in CCTV systems has changed quite a bit over the years. The video cameras used in surveillance systems today are smaller, better and cheaper. Up until a few years ago video footage was recorded from security cameras onto a VHS tape. Today DVR (digital video recorder) systems have just about replaced these VHS systems, and video footage is recorded onto a hard drive.
The cost of purchasing a DVR security camera system has come down dramatically over the last few years. This guide will give you an overview to DVR security systems, and tell you what to look out for when purchasing a DVR security camera system. The two main parts of any DVR security camera system are the cameras used by the system, and the DVR video recording device.
Surveillance cameras either use CMOS or CCD (charge couple device) chips to record video images. CMOS is used in cheaper surveillance cameras, and the video quality is not as good as the video produced by CCD cameras. CCD cameras also have better light sensitivity and record better video in poor lighting conditions. CCD camera formats are measured in inches, which is the size of the image recorded inside the camera unit. A DVR security camera system today normally uses a 1/4″ or 1/3″ CCD format, which is good enough for most situations, but cameras with a larger CCD format produce brighter images in poor lighting conditions.
Another factor to consider when buying surveillance cameras is the camera resolution. This is measured in the number of TV lines (TVL) produced by the camera, which determines how detailed the video picture quality is. A typical DVR security camera system today has cameras that produce a video resolution between 350-400 TVL, whereas the top-of-the-range cameras produce a video resolution of over 400 TVL.
The frame rate of a video surveillance camera is the number of separate images that the camera can record per second. Most surveillance camera’s today can record at 30fps (frames per second), which is the smooth “full motion” video that one normally sees on TV. Lower frame rates look jerky, but have the advantage that they require less storage space for recordings.
Black and white surveillance cameras are better in poor lighting conditions than color cameras, but today, most people buy color cameras, as the price of cameras have come down significantly in recent years. A surveillance camera’s sensitivity to light is measured in lux. A camera with a sensitivity of 2 lux produces bright enough video for rooms lit by 40W light bulbs. An outside camera must be rated at 0.5 lux to be able to view images at night.
The lens of a video surveillance camera should match the CCD format of the camera – 1/3″ lenses should be used with cameras with a 1/3″ CCD format. The type of lens a video surveillance camera has can also determine its cost. Today a typical DVR security camera system consists of cameras with fixed focal length lenses, which mean the cameras does not have a zoom in/out facility. A camera with manual zoom allows you to adjust the camera’s level of zoom on the camera itself. Motorized zoom cameras allow you to change the zoom focal length remotely – this is the most expensive camera option.
A lot of surveillance camera’s today also have Infrared (IR) LEDs built in, which project an infrared light, allowing you view video images in complete darkness. The range that these camera’s can see in the dark vary from camera to camera, and can be anywhere between 10 to 50 feet. Also , most surveillance cameras today come with a microphone, which is handy to record sound as well as video.
Typically, a DVR security camera system has cameras where you fix each camera’s view when installing each camera. Advanced DVR systems have a pan, tilt and zoom (PTZ) facility. PTZ cameras are quite expensive, and allow the user to remotely pan the camera’s view left and right, tilt the camera’s view up or down, or zoom in or out.
The type of housing of a security video camera is determined by what the camera is going to be used for. A DVR security camera system can have large, visible cameras, which are cheaper, have larger housings, and can deter potential criminals by being clearly visible. Covert surveillance, or hidden cameras are more expensive, generally smaller, and cannot be seen as they are hidden in other objects, such as a wall clock. Dome housings are mounted on ceilings, and are commonly used with cameras that have a pan, tilt, and zoom facility. Dome housings are also the most practical design, and blend well into most surroundings. Weatherproof housings are used with outdoor surveillance cameras that need to be protected from the elements.
A standard TV can be used as a video surveillance monitor, but the picture quality will not be great. Computer monitors are a better option, as they offer better picture quality, and offer an extended lifespan as they are designed to be on 24 hours a day. As flat-panel LCD screens have dropped dramatically in price, this is the route to go when purchasing a DVR security camera system. If you want to display video from multiple cameras on a single monitor, then a 15″ monitor should be the minimum size you purchase.
Up until a few years ago, most surveillance systems used VCR tape for recording video from the system’s security cameras. Today, the digital video recorder (DVR) is the more popular choice for security surveillance systems. With DVR recording, video is recorded and saved onto a hard drive.
DVR systems offer several advantages over VHS systems. DVR systems allow you to instantly go to any point in time within a recording without having to fast-forward a VHS tape. Also, with DVR systems, you can playback an earlier part of any camera recording whilst that camera is still recording.
It’s common today for a DVR security camera system to come with camera’s that have built-in motion detection. DVR systems often come with a feature whereby camera recording is only activated when motion is detected in a room. This is recommended to reduce the amount of hard drive storage space used for video recordings.
The only advantage of purchasing a VCR system today is the price – they are cheaper than DVR systems. But with VHS systems being phased out by many manufacturers, VCR systems are not a good long-time choice!
The are two main types of DVR security camera system are the PC based DVR system, and standalone DVR system. A PC based DVR system is run off an existing PC, and requires that a PC board (containing the camera input connections) be added inside the PC, and special software be installed on the PC. A PC based DVR system can be bought quite cheaply, and are considered the entry-level of DVR systems. The main problem with PC based DVR systems are that these systems are unstable when compared to standalone DVR systems, as PCs are vulnerable to software crashes and other system instabilities. Encoding and recording video to hard drive is quite a resource intensive task, and can cause software to hang, especially when running other software on the same PC.
A standalone DVR security camera system is the route to go if you want peace of mind that the system will continue to function 24/7 without any hang-ups. With these systems, most of the video recording is done by hardware, and this eliminates software crashes that you get with the PC based DVR systems. As standalone DVR systems are designed to perform only a single task, the performance and reliability of these systems exceed PC based systems.
Your first consideration when purchasing a DVR security camera system should be the quality of the video you want to record. This will be the resolution of video recordings in TV lines, and also the video frame rate (video smoothness) that can be recorded by the system. Obviously, better video quality costs more.
The second consideration should be the number of cameras that you will need for your DVR security camera system. Entry-level systems come with 4 cameras, whilst top-of-the-range systems come with 16 or more cameras.
Your third consideration should be the size of the hard drive of the DVR system. Low-end DVR systems come with 80 gigabyte (GB) hard drives, whilst top-end systems come with a 750GB hard drive. Some DVR systems allow you to have multiple hard drives, whilst others allow you to swap out replaceable hard drives, which allow you to store your video footage in a safe location.
Today a top-end DVR security camera system can include Internet remote viewing, which allows you to view video from your DVR security system from a remote location – the video is transmitted over broadband connections, and can be view on a remote PC or even a smartphone! At the end of the day you need to balance your essential security requirements against your available budget when selecting a DVR security camera system.
Tags: DVR security camera system, DVR security system, DVR system, home security camera
