A Basic Guide to CCTV – Frequently Asked Questions

There is a lot of mystique about security and security systems which is unhelpful if you are in the business of either buying or managing one. This guide will hopefully explode some of the myths that abound, delivering some clarity.

What is the difference between a Video Server, an NVR and a DVR?

A network video server is a computer that runs special Video Management Software known as VMS and is used to record video from IP cameras. A windows computer is usually the platform for the VMS, and video is recorded onto the computer’s hard drives in a special video format.

Sometimes people are confused by this term because a number of years back a device that attached an analogue camera to the networks was also called a video or camera server.  This is now known as a Video Encoder.

A Network Video Recorder, or NVR, is a complete IP camera recording device. It includes a computer and special Video Management Software.  VMS is required for recording video, but it also allows multiple viewers to monitor real time and recorded video.


The DVR or Digital Video Recorder is a device that records video from analogue cameras to one or more hard drives. The term DVR is also used by the consumer TV market.

The DVR used in the security market has a fixed number of BNC connections to attach cameras. DVRs are available with 4, 8, 16, 32, and 64 channels, or connections. This means that you have a maximum number of cameras that can be supported by one unit. Once you exceed the number of connections available on that particular DVR, you will need to add another DVR to your system.

There are some DVRs that can connect to the network and be viewed using a Windows computer.


What is the difference between a DVR and NVR?

There are several differences, some of the major ones being:

  • The NVR connects to the computer network along with the IP cameras.  The main advantage of this is that you can use the existing network infrastructure, meaning you don’t have to run wire from a home base location.
  • The DVR uses coaxial connections to each of the analogue cameras.
  • The NVR supports high resolution megapixel cameras
  • The DVR supports only cameras with VGA resolution


What are the differences between a Network Video Service and a Digital Video Recorder?

The Video Server and Network Video Recorder are similar in that they both record video. The Network Video Recorder comes with the Video Management Software already installed.

The Video Server does not include VMS. You select the software you like and load it.

The Video Server usually runs on a Windows operating system and it’s more flexible than the NVR because it is easier to expand and add cameras. The NVR, on the other hand usually has a fixed limit as to the number of cameras it can support.


Which VMS product fits my requirements?

This is where the skill, knowledge and experience of a Doyle Security expert come into play.

There are a number of VMS products out there each with different features and methods of use.  The main job of any Video Management Software is to record the video from many IP cameras on the network.  It is very important to select software that’s reliable and doesn’t crash; the loss of important images can be more than just embarrassing.

It’s important to use a dedicated computer system to run the software, ideally a ‘server’ which has a higher capacity and faster hard drives, processors, more RAM and better networking capabilities.

The various VMS products available have many additional functions, including motion detection, sending special alerts to tell you if something important has happened, flexible displays of real time and recorded video, easy location and display of multiple recorded video channels.  Which features you choose depends on your particular needs and objectives.


Do I need a Network Switch?

You may well have to add a network switch if you don’t have any empty ports on your current switch, or if you don’t have a network switch installed.  One port is required for each camera, ideally one that includes PoE on all ports.


What is PoE?

The latest IP cameras get power over the network. This is known as Power over Ethernet or PoE. You can also add a PoE midspan, or a power injector between the switch and the camera.

Using PoE means you only need to run one network cable to each camera making installation easier and reducing costs.


Do I need a Video Switch?

No, the LAN network switch operates as the switch allowing hundreds of cameras to be viewed on a network.