How Does a Surveillance System DVR Work?
A DVR is a recording device for digital images that come from digital cameras. These images are stored on a hard drive in the DVR. This allows the user to playback what the camera recorded through a monitor, burn the images to a CD or connect the DVR to the Internet. You can review the DVR using your web browser from anywhere in the world.
The security DVR or network DVR must not be confused with a television DVR or TiVo. The security DVR is more sophisticated and reliable than those for your television. This DVR is also made so that they are compatible with security cameras and computers and able to record from 4 to 16 cameras at the same time in a CCTV DVR configuration. They will allow you to review from one to all 16 cameras in real time or play back a previous recording. The latest video surveillance DVR is a standalone unit, meaning that all the required software is already installed in the DVR. Also by utilizing a hard drive you can go back and review a recording without having to re-wind. These recorders will allow you to freeze a frame, fast forward or reverse without any loss of tracking or streaking.
Being able to remotely view your office or home over the internet is one of the biggest advantages of video surveillance. Use of a low quality DVR or using software on your computer to connect to your cameras can create problems. With the computer controlled software or a low quality DVR you are susceptible to hacking or viruses. When setting up your video security system, you should choose a high quality stand alone DVR.
There are many advantages of a DVR Security system. You are able to control cameras remotely and the DVR can detect motion to turn cameras on and off, thus saving disk space and power. The video information is “stamped” meaning that the recoding has the time and date of each frame. Finally the security DVR is just that, more secure because all the software is loaded in the DVR and doesn’t rely on the computers operating system.
Previous technology for a video security system used a time lapse VCR. The disadvantages were limited recording time (usually a maximum of 8 hours) and the hassle of rewinding tapes. Another factor was the vulnerability of the tape itself, either getting jammed or deteriorating. Information such as time stamping was usually not available, and the fidelity of the video was poor. For prosecution, there is no better evidence than a time stamped video to present in court. The high quality video from a stand-alone DVR will help the police know who to look for.
A DVR can detect motion by looking at the videos pixels. The change in the pixels tells the camera there is motion. Due to the way the DVR screen is broken up into cells, the camera will not see things that are normally in motion such as a fan because not only do the pixels have to change, but adjoining cells must also have a change in pixels. The camera has nothing to do with motion sensing as this is accomplished by the DVR.
The components of a DVR Security System are the camera or cameras, stand-alone digital video recorder and monitor or computer with network capability. Cameras are connected to the stand alone DVR with either cables or wirelessly using a transmitter at the camera and a receiver to feed the DVR. Most DVRs have a quad or screen splitter built into them. This allows you to use one monitor to see as many as four cameras at the same time. The security DVR can be bypassed by a device known as a USB DVR which is a very economical device that connects the camera to a network capable computer. The disadvantage is that the USB DVR does not store any video or time stamp the video frames. This is useful for monitoring a location for vandalism or damage with a low cost system. The USB DVR allows you to watch your property in real time over the Internet from anywhere in the world.
Modern technology has developed a small one-channel DVR capable of being placed inside of a hidden camera. This small DVR records video on a memory card. Memory cards today can hold 16 GBs or more of information which will cover 24 to 48 hours of recorded video. If this DVR is capable of motion sensing than it could cover a much longer time period. The user simply goes and takes the card out of the hidden camera and reads the video on their computer. This will allow a hidden camera and DVR to be placed in a common object such as a radio, clock or mirror. The hidden camera becomes a mobile device and can simply be placed in a room and plugged in. This is especially useful to catch internal theft in a small business or to use the hidden camera as a nanny cam.
To summarize, a stand-alone DVR is useful for controlling multiple cameras, obtaining high quality images with a time stamp, and storing this information for later use in recognition and prosecution. The DVR gives an extra layer of security by eliminating software based programs that are susceptible to being hacked or receiving a virus. A high quality DVR will allow motion sensing and remote controlling of a PTZ camera.
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ABOUT THE AUTHOR
Doug Harper is a former Marine, Drug and Transport Officer and Airline Pilot. Doug retired from the airlines in 2011 and opened SharperSafety.com to sell video surveillance equipment and accessories. http://www.sharpersafety.com