What is a DVR / NVR?
Story by: admin
29 September 2021
At the heart of your CCTV system is a DVR (or NVR depending on the type of system supplied). Often this is referred to as a ‘recorder box’.
This box is essentially a computer, dedicated to processing the video your cameras capture, recording the video data to hard disk drive storage, and outputting video for streaming to your devices, as well as many other functions like scheduling and smart features.
DVRs support analogue cameras, whereby an analogue signal is fed to the DVR and converted to digital data when recorded to the hard disk.
The power supply to the DVR and analogue cameras are usually separate parts, (although sometimes Power over Coax (PoC) is used).
NVRs support digital cameras which send a digital data stream to the NVR. Power is supplied to the cameras from the NVR over the (CAT5e) ethernet cable. This is known as PoE (Power over Ethernet).
The number of channels your recorder box has, determines the number of cameras you can connect to it. Please refer to your invoice for the number of channels your recorder has (it will be marked as 4CH for a four channel, 8CH for an eight channel etc).
Video data is recorded to a hard disk drive within the DVR / NVR unit. Sometimes there may be more than one hard disk installed. Once the hard disk is full, the oldest recordings are overwritten first.
You may have specified a certain number of days or weeks recording time, and the amount of recording time is dependent upon a few factors:
- The total storage space
- The number of cameras
- The resolution of the cameras
- The frame rate
- Scene complexity on each camera
- The encoding method being used
Please check your invoice for details of any agreed recording time at the point of sale.