CCTV Camera Monitor Type

B/W Monitor and Color Monitor

  In the past, 9 to 12 inch (diagonal) B/W CCTV cameras monitors were very popular in the field. Nowadays, more and more people are looking for high inches and color monitors. As it known to us, 3 different color dots can produce one pixel of information, so, color monitor  usually has lower resolution than B/W monitor.

Single Monitor, Quad Monitor and 4-Channel Monitor

  Single Monitor is usually professional monitor with one video input of BNC jack.In order to combine multiple cameras, we should use Quad splitter, video switcher or multiplexer. Quad monitor has built-in quad splitter and usually has 4 DIN jacks for video inputs. 4-Channel Monitor contains 4 channel video switcher inside and usually has 4 DIN jacks for video inputs. Quad Monitor or 4-Channel Monitor is usually a part of packaged observation system and does not match other manufacturer's camera or cable.

Video Switcher Introduction

Video Switcher is a device which can show multiple CCTV cameras on one monitor screen, manually or automatically. When it runs on automatic sequential mode, the dwelling time on each camera can be changed from 1 second to 30 or 60 seconds. When video switchers have BNC jacks and your cameras have RCA connections, you will need BNC/RCA adapters. you can buy it at any electronic shop like Radio Shack or Best Buy, etc. The equipment supplier should provide adapter or you can buy it at any electronic shop like Radio Shack or Best Buy, etc. Most commercialized video switchers have 4 channels or 8 channels, that is, we can connect 4 or 8 cameras. Video Switcher works for both B/W and color cameras. A Video Switcher can be connected to a CCTV monitor, TV or VCR.

Quad Splitter

  Quad Splitter is device which can combine 4 cameras and show them on one monitor screen at the same time. A built-in switcher can display the pictures one by one. There are two types for video inputs to choose, BNC jacks or RCA jacks. You can select one based on camera's video connection type. But, if the video input jack does not match your camera's type, a BNC/RCA converter is needed, you can buy it at any electronic shop like Radio Shack or Best Buy, etc. B/W splitter works with B/W cameras and color splitter with color cameras. A quad splitter can be connected to a CCTV monitor, TV or VCR.

Network Lines for CCTV Transmission

Nowadays, we use the Internet or intranet line as a video transmission method. DSL and T-1 are used for the Internet and LAN (or WAN) is for intranet. 

DSL
  DSL (Digital Subscriber Line) speed is from 144 Kbps to 1.1 Mbps. (More than 1.5 Mbps speed is called T-1), you need use a router with RJ45 jack to connect a web camera to a DSL, DSL supplier provides the router. If you need to connect several web cameras, you need a hub with multiple RJ45 jacks. You will have static and public IP address(es) (provided by the DSL supplier) assigned to the web camera(s). This IP address will act as a web site address on the Internet. 

  SDSL(Symmetric DSL) is strongly recommended. SDSL has same upstream and downstream bandwidth, while downstream bandwidth of other DSL (IDSL or ADSL) is larger than upstream bandwidth. We should upload web camera's video data to the Internet, so a SDSL is more suitable for the web camera. To see the pictures from the camera, a residential DSL or even Cable TV line will be fine. (Refer to the bandwidth and the speed of a web camera for detail) 

LAN
  LAN (Local Area Network) or WAN (Wide Area Network) has intranet network in a limited area or organization and has several computers connected to the network. Web camera servers acting as computers can be connected to LAN or WAN so that each computer can share the video data. The jacks between Web camera servers and LAN or WAN is RJ45.

What is Web Camera

Web Camera

  Web Camera (Network Camera) consists of a CCTV Camera and built-in network video server so that it can be connected to a network line such as DSL or T-1 for the Internet or LAN. When the camera is assigned an IP address, you can view the camera's video no matter where the network line is available.

  One of the important features of web camera is the speed. The image compression technology for Web camera is very pivotal. For now, the Wavelet is the most competitive compression algorithm with compression rate 30% to 300% higher than other technology such as JPEG or MPEG.

  Another excellent ability of web camera is programmable, when detecting movement by web camera, the maximum 5 pictures can be send to your email 

Coax Cables for CCTV Camera

  RG means military specs Radio Guide and the numbers of RG are kind of arbitrary. Nowadays, the most popular RG designations are RG-6, RG-8, RG-11, RG-58 and RG-59. RG-58 and RG-8 are 50 ohm coaxes which is unsuited for video work. RG-6, RG-59 and RG-11 are 75 ohm cable types, RG-59 is the smallest (20 AWG centre conductor), RG-11 is the largest (14 AWG), between RG-59 and RG-11 is RG-6 which is 18 AWG.

About Wireless Transmitter and Receive

Wireless transmission is considered When it is difficult for camera to use a cable to transmit video signals to the monitor. But, heavy metal walls, high voltage power lines, microwave equipment can attenuate or block the wireless signals.

FCC strictly controls the wireless transceiver system. Manufacturers initialize the commercialized models and you don't need to get a separate FCC approval. When you want to change or modify the model specification, you need to get prior approval from the FCC. Each manufacturer has unique bandwidths of frequency derived from the FCC and cannot be compatible with other manufacturer's models. 

  Most commercialized wireless systems have 4 or 10 channels, given conflicts of the overlapped channel(s), it is impossible to use more than 4 or 10 transmitters in one area. But you can increase wireless receivers as far as they are within the range.

About Power Source for Cameras

<12VDC>

Most mini cameras and board cameras, as well as 1/3” professional CCTV cameras use 12VDC, 100mA to 200mA for B/W cameras and 150mA to 300mA for color cameras. In order to accept DC power plugs, these cameras are designed to have DC jacks. You should pay attention to the polarity (negative and positive) for power source. 12VDC power could be provided by AC Adapter or battery pack. A "power cord" plugged to the cigarette lighter in the vehicle should be used.

<24VAC>

About 2/3 of the professional cameras use 24VAC, 20VA to 40VA. Normally, the cameras have screw type connections, so you don't be concerned with the polarity. Given the power provided by AC Adapter, you need separate power cable for connection. For 24VAC power, the max transmission range is up to 450ft, meanwhile, it is very suitable for cameras which only can be installed outdoor and no outlet nearby.

< DIN Cable>

When using DIN cable to connect a camera and a monitor like in most "observation system*", the power(usually 12VDC) comes from the monitor so you can don't need to worry about the power for the camera

Connectors for CCTV Systems

Followings are some type of cables for CCTV cameras, you can clearly understand.

Cables for CCTV Systems

<Coaxial Cable>

  Coaxial CCTV cable is used to transmit signals from the surveillance camera to monitor. Among various coaxial cables, RG59/U with a 75-ohm impedance is most popular and can be installed up to 450ft distance without any quality lose. BNC connectors are used to connect both ends of this cable

<Fiber-Optic Cable>

 Fiber-Optic Cable has good electrical features, it is not affected by electrical interference and has good performance even under high-voltage power. It transmits video signals with extremely high efficiency and can run up to miles. It is a pity that Fiber-Optic Cable is expensive and hard to control

<RCA Cable>

  RCA cable is not standard but it is widely used in the market, specially for short distances up to 250ft. Although its transmission quality is worse than Coaxial Cable or Fiber-Optic, RCA cable is still widely used because of its easy use and no video signal lose up to 250ft distance.

<DIN Cable>

  Most observation systems pre-assembled at the factory have DIN cables with DIN connectors at both ends. DIN cables have 5 or 6 wires inside, for example, wire 1 is for video, wire 2 is for audio, wire 3 is for power(12VDC, positive), wire 4 and 5 are for speaker(positive and negative), wire 6 is for ground. Mini DIN cable, which is used for mini camera package, has 4 wires inside. DIN cable, large or mini, can run up to 250ft distance without any video quality loses.

<Cable Tie>

  Because the transmission of video signals has tight relationship with the spacing between the inner wires or conductor and shield, any changes in the distance between the wires or conductor and shield can result in decreasing picture quality. This is the reason why you need to use suitable cable tie which are sold at any hardware or electrical parts shops when working with Coaxial Cable or DIN cable.

CCTV Camera Illumination

  A video surveillance camera needs some lights generated by natural or artificial illumination. B/W cameras can work regardless of any type of light sources, but color cameras work with lights which include all the colors in the visible spectrum.

  We usually use LUX(Lumens per Square Meter) to define the amount of lights. a candle light volume per meter distance is One LUX. some examples of natural lights in LUX as follows:

Full daylight: 10,000 LUX
Very dark day: 100 LUX
Twilight: 10 LUX
Deep twilight: 1 LUX
Full moon: .1 LUX
Quarter moon:0.01LUX   

  A good B/W camera is able to see in full moon, however, a color camera require an extra artificial light 

Focal Speed Introduction

  Optical Speed means how fast a CCTV cameras lens collects lights and is usually described by the f-number such as f/1.2, f/2, etc. This speed can be calculated by the Focal Length and the Diameter(D) of a lens as follows：

f-number = FL/D

  Under the same diameter, Larger FL, higher f-number lens which means lens need less lights to the camera sensor and results a slower lens, Lower f-number lenses need more lights. Larger Diameter, if focal length is fixed, will make f-number lens.

  In summary, the lower f-number, the more lights, the better video picture. The f-numbers are often marked at the iris rings of lenses.

Focal Length and Angle of View

  For a thin double convex lens, all parallel rays will be focused to a point referred to as the principal focal point. The distance from the lens to that point is the principal focal length of the lens. focal length play a role part to ascertain the angle of view of a lens. For instance, 1/3" sensor format with a 6.0mm focal length lens has 56.8 degree of diagonal angle of view, however, the same 6.0mm focal length lens on 1/2" sensor format is 75.5 degree. Each manufacturer has different angle of view of the lens.

  Take 1/3" CCD chip camera for example, the formula below is a simple way calculate focal length of a lens we need

(Distance to subject / Width of subject) x 4.5mm = Focal Length.

  For example, if you use 1/3" CCD CCTV cameras to watch a item with 5.5ft width at 10ft distance, you will use a 8.0mm focal length lens. That is to say, 10ft / 5.5ft x 4.5mm = 8.18mm. A 8.0mm FL lens can meet your requirement

The Difference between C Mount and CS Mount Lens

  The flange back is the distance from the surface to the focal point. The flange back of CS-Mount lens is 12.5mm which is 5mm shorter compared to C-Mount lens. This is the only difference between the C-Mount lens and CS-Mount len. You’ll need a 5mm spacer ring when you mount a C-Mount lens to some CS-Mount camera. CS-Mount camera is always suitable for C- or CS-Mount lens. But, C-Mount camera isn't suitable for CS-Mount lens. Most professional cameras are CS-Mount cameras including a C-ring. A 5mm spacer ring is necessary when a C-Mount lens is mounted to a CS-Mount camera unless the camera has built-in Flange-back Adjusting Ring.

Electronic Shutter Introduction

  Electronic Shutter, one of the main features of CCD CCTV cameras is an signal processing. At low light conditions, the CCD is able to gather signal at the electronic shutter speed of full 1/60th per second. Under bright lighting conditions, the video processing chip automatically responds by reading the CCD and immediately “early purging” it in order to precisely control the video level. Even at a shutter speed of 1/100,000th per second, the CCD camera can deliver 60 images per second, but each image is gathered at a much shorter period of time. The image is continually monitored and optimized by signal processing circuit. At last, we an get an excellent picture, without any fiddling, no adjustments, what’s more, unbelievable reliability.