What is CCTV?
CCTV stands for Closed Circuit Television and refers to one or more cameras linked to a monitoring point and/or recording device.
What is CCTV used for?
CCTV is used for cameras to view an area for the use of Security, Safety or Monitoring.
How many types there are in CCTV Cameras?
There are two types of CCTV Cameras:
- Analogue HD CCTV Camera
- Network IP CCTV Camera
What is an Analogue HD CCTV camera?
An analogue HD (AHD) camera is a specific kind of analogue camera that records in high definition (HD), 720p, 1080p and beyond. Previously, this feature was only available on IP cameras. It’s suitable for situations where HD footage is needed for evidence, but not all the features of an IP camera are required.
In an analogue HD CCTV system, the camera captures an analogue signal and this is transferred via a coaxial cable to the DVR (Digital Video Recorder) where the signal is converted to digital, compressed and stored on a hard drive within the DVR. The footage can be viewed on monitors attached to the DVR or the signal can be sent across a network to be viewed on a computer screen.
What is a Network IP camera?
With digital IP (Internet Protocol) cameras, each camera captures an analogue signal, but the important difference is that this is converted to a digital signal within the camera itself. Digital processing may also be completed within the camera. The digital signal is then sent via a LAN (Local Area Network).
Instead of the analogue system’s DVR, for IP cameras, the video from each camera is compressed and recorded onto an NVR (Network Video Recorder). The key difference is that the signal is sent digitally and an at a much higher resolution than analogue. The NVR streams the video from all cameras and broadcasts over LAN and over the internet for remote viewing.
What are the advantages and disadvantages of Analogue HD Camera?
|Low price||Lower quality than IP|
|When replacing old analogue cameras can use existing infrastructure/cable||Records onto DVR locally not in the cloud|
|Easily available online and in shops||Does not have built-in UPS (uninterruptible power supply)|
|Less technical and easier to install, less troubleshooting required||Does not have built-in camera memory card functionality|
|Not smart like IP, more of a ‘dumb’ camera|
|Requires 2 cables for power and video|
What are the advantages and disadvantages of Network IP Camera?
|Better quality picture than analogue HD||Expensive compared to analogue.|
|Firmware upgrade allows improvements to cameras, e.g. better compression||Slight latency (delay)|
|Uses one Ethernet cable for power and video||Need Gigabit network switch and NVR to handle network bandwidth|
|Cloud recording, camera direct to cloud||Need network infrastructure|
|Max 100 metres ethernet cable length but extendable|
|Can utilise UPS (Uninterruptable Power Supply)|
|If camera and NVR are the same brands then usually installation is plug and play, for immediate us…||…But if camera and NVR are different brands, then you need a technical background to configure it. An IT engineer or experienced CCTV installer required and often need manufacturer technical support.|
Do the cameras light up at night?
If your camera has infrared, Starlight or White Light, then yes. There will be a small row of infrared or White lights that cast light that’s invisible to the human eye. Without this, your camera wouldn’t be able to see in the dark.
What is Wide Dynamic Range?
There are situations when there is too much difference between dark and light frame areas of the IP camera frame. Areas of the frame with more intense light stream at recording will look too light, while areas of the frame with poor illumination, on the contrary, may look dark. The reason is that the camera must record both light and dark areas at one exposure.
The WDR function provides a special recording mode when the camera records two frames with different exposures at the same time.
How does Wide Dynamic Range work?
The IP camera records the first frame at a minimum exposure time, as a result, a too bright light stream does not have enough time to light areas of the image. The second frame is recorded by the IP camera with maximum exposure and during this time the matrix manages to capture the image of the most shaded areas. Thus, there are two frames: one is adapted best for viewing lit objects, the second allows viewing too dark objects in detail. Then, these two frames are combined into one. The resulting frame has advantages of each of the two originals and does not have their drawbacks at the same time.