What Is a DVR Anyway?

The term "DVR" stands for Digital Video Recorder. Strictly speaking, it is a digital version of a VCR whereby video is stored and played back from a computer hard disk instead of video tape. When used in the context of a CCTV system, it means a dedicated computer with many more functions than just recording and playing back video from a single source. The modern surveillance DVR is the heart and control center of the CCTV system. Please check out the How It Works section to see a visual diagram showing how basic components are connected. The term "DVR" generally means a dedicated, closed system that runs the Linux operating system, and is said to be "standalone". There is also another flavor which is a Windows based, custom-built PC which has specialized hardware installed to capture video and perform all the functions of a standalone DVR. WattWire installs both types of these "DVRs". Selecting which type depends on the needs of the client as each has its advantages and disadvantages. For clarity when explaining concepts, the term DVR may be of either type (PC or Standalone). Here are some of the main characteristics and functions of a typical surveillance DVR:

	Displays output to either a computer or TV monitor, showing live or record video in one or more windows (ie, split screen).
	The primary mode of operating the DVR locally is by using a hand held remote control. However, knobs and buttons on the unit itself can also be used. Some models provide for the use of a mouse to navigate through the user interface.
	Can record multiple sources (cameras) of video simultaneously. Most DVRs have sophisticated methods of controlling how recording is activated or scheduled. Automatic recording can be triggered through the detection of activity in the video scene, alarm sensors, or scheduled intervals.
	Connects to a local area network which in turn may allow access to other computers. Optionally, remote computers can access the DVR over the internet. While connected to the DVR, the computer can display and control video as though one were at the unit, watching its monitor and accessing its features.
	Stores and associates information with recorded video clips. Aside from camera ID, time and date, the type of action that caused the recording is also saved. This makes searching and retrieving recorded video a lot easier. For instance, one could make a request to see all the video sequences that were recorded because of motion detection over a certain four hour period on a given date, by a given camera. Also, one can just search the recording logs and then playback clips from suspicious looking log entries
	Recording capacity can be customized by size and number of hard disks installed. The minimum sized hard disk that we install is 250GB.  While this suits the needs of many, it is possible to install a larger drive or in some cases, multiple drives. See Hard Drive Options.
	Has audio recording capabilities. Entry level systems generally can record 1 channel of audio; 4 channels for mid-level systems; 16 channels (all video channels get sound) for high-end systems. Caution has to be exercised when recording audio as it is illegal in many instances. For more information on using audio, see the Options section.
	Most DVRs can control Pan-Tilt-Zoom (PTZ) cameras. Control wires are connected between the DVR and PTZ camera. These conductors are often included within the same cable that also carries the power and video signals. This allows the DVR to control the PTZ using the DVR’s hand held remote or through another computer communicating with the DVR over the network. For more information, see the Options section.
	Can also function as an alarm annunciator. Most DVRs have alarm inputs and outputs. When an alarm sensor (input) is triggered, it can activate video recording from a designated camera and/or send power to external devices such as a siren, strobe lights, or anything else you might want to activate. Electrical current can also be sent through the alarm outputs when the DVR detects motion within a camera’s scene, thus activating an alarm sounder, etc.
	Can send email alerts if motion is detected or an alarm sensor is triggered. These are called events. System events can also cause one or a series of snapshot images to be sent to a holding spot somewhere on the internet. This is a good way to retrieve visual scene information in the event the DVR is stolen, destroyed, or for whatever reason cannot be accessed directed over the internet.
	Perform scene analysis and other advanced functions. For example, some systems can count cars or people as they enter and leave designated regions or keep track on an object in a scene and sound an alarm if it moves.

Can three families live inside a DVR?

You may have heard the terms "simplex","duplex", "triplex" and "pentaplex" used to describe a DVR.  These words do not refer to different types of housing but attempt to indicate the number of major functions that the DVR can perform simultaneously.  For example, because a simplex DVR can only perform one function at a time, it would be necessary to stop recording before initiating play back.  All the DVRs that WattWire installs are of the pentaplex variety.  Typically, the five (pentaplex) functions that DVR manufacturers cite for simultaneous operation are: recording, live view, play back, network viewing, and network recording.  Because there's no real standard on what functions are used (especially pentaplex) it's much better to just study a DVR's spec sheet or better yet, the user manual to see exactly what it can do.  Unfortunately, even reading the user's manual can leave one confused about how and if the DVR can meet your needs.  That's where WattWire provides enormous value.  We are DVR experts and know the products we sell inside and out.  We'll make sure you get equipment that is easy to use and meets all the surveillance needs of your home or business.

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