Surveillance Solutions

What is CCTV? How do they work?

Cctv Camera

CCTV stands for closed-circuit television, it is a video surveillance system. CCTVs have a wide range of application areas, from Airports, Schools, Homes, Hospitals, Police stations, Public spaces, Business Premises etc. Depending on the area of application, CCTV can be used for different reasons. For example, CCTV can be used in a public space to provide evidence to relevant enforcement agencies, traffic and accident control, maintain public order, prevent antisocial behavior and nuisance, provide reassurance, and promote economic well-being and be used in a business to monitor employee behavior, recording daily activities and for security purposes.

How CCTV Systems Work

A CCTV System works by the camera(s) taking a constant sequence of images, this images are then transmitted by cable or wirelessly to the recording device and then on to the display monitor, which enables an individual to see the sequence of images as video footage.

To transmit images to a recording device via cable or wirelessly depends on choice of system. There are two main types of systems namely Digital Video Recorder (DVR) and Network Video Recorder (NVR). Although these two system serve the same purpose, there is a huge difference on how they work with each having its pros and cons.


Type of cameras used

DVR work with analog cameras that generate raw analog data and then the recorder converts to digital. NVR work with IP Cameras, both WIFI and PoE, the camera converts the raw video to a digital format before reaching the recorder.

DVRs have coaxial ports that connect to analog cameras and are totally dependent on coaxial cables to transmit their signals. NVRs have RJ45 ports to connect to IP cameras, they do not entirely depend on cables since NVRs can be connected wirelessly.


DVRs are tied down by distance, the use of coaxial cables limits connection and transmission to 300ft. NVRs are not limited by distance for connection and transmission as long as the network is available.

Image resolution

NVRs make use of IP cameras which have an image resolution ranging from 2MP to 12 MP and higher. DVRs have use analog or HD cameras which have an image resolution of about 720p or 1080p max.


Analog video signals do not support voice transmission to and from camera. To incorporate sound transmission, one has to add an individual RCA connector to the DVR. NVRs are equipped to record video footage with sound. With IP cameras you can integrate voice on the footage. In live video mode you can use the speaker of the camera to talk to someone on the other side.


DVR systems allow for in premise storage using hard drives. Hard drives can be damaged, stolen or corrupted. NVR with its ability to connect to the internet allows for incorporation of cloud based storage which is not easily accessible to thieves and also offers large storage capacity as one can upgrade based on their storage need.

Advantages and disadvantages of DVR


Lower upfront cost

Majority of analog CCTV cameras are more affordable than IP cameras, this is because of their limited capabilities. Therefore, the upfront costs of setting up a DVR are much lower.

Camera interoperability

DVR systems allow you to have different types of analog security cameras, which can save you money if you need to replace a camera, unlike NVR systems which often require you to have cameras made from the same brand.


Running cables

DVR system are entirely dependent on coaxial cables for transmission, running the coaxial and power cables can be more challenging because those cables are more rigid and thicker compared to Ethernet cables.

Lower-quality video

DVR systems mostly provide 4CIF resolution (704×480) at a frame rate of 7 to 15 fps at best, this is because of the limited bandwidth of coaxial cables. Newer analog HD are providing up to 720p or 1080p video resolution, however, they are less common. This low resolution quality may make you to lose out on some analytic applications e.g. tracking faces or license plates.

Limited audio capabilities

DVR do not support audio transmission and therefore need to add RCA connector to incorporate sound transmissions on DVR systems.

Lower coverage area

Because cameras must be placed within 300 feet of the DVR box, you are limited in the total coverage area of a single system.

No network connectivity

DVR systems aren’t connected to a network, which means you can’t remotely access or manage your security footage.

Higher maintenance cost

Ultimately, this largely outdated technology has a limited supply as many vendors have stopped manufacturing them. Therefore you have higher maintenance cost


Advantages and Disadvantages of NVR


Video quality

IP cameras offer higher-quality video, typically between 2MP (1080p) to 12MP (4K) with a frame rate of 30 fps (real-time video) which is much better compared to DVR systems.

Wiring installation

The single Ethernet cable per camera is much easier to set up than the coaxial cables required by DVR systems.

Camera placement flexibility

The option to have wireless cameras or PoE extenders means that it’s easier to place cameras where you want.

Audio included

Because Ethernet transmits audio, each camera can deliver an audio stream to the NVR system with the video footage.

Network connected

NVR systems can be connected to a network therefore, footage can be accessible remotely.


Low security

With NVR capabilities to be connected to the network arises a security threat, it is possible to hack the system and access the security footages.

Camera compatibility

NVR system require use of cameras from the same brand, this makes it costly and harder to change the cameras when required.

Greater upfront cost

NVR systems are more expensive to set up compared to the DVR system.

Low life cycle

Most NVR system components have a short life cycle of between 3- 8 years. Some components like hard drives have an even shorter lifespan.

It is clear from the wide range of advantages offered by the NVR system and even the change in the market, manufacturers reducing production of DVR that the NVR system is best for your security surveillance. However, in some cases the DVR system may make more sense over the NVR system.

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