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CCTV SYSTEMS. CCTV MONITORS. CCTV SYSTEMS. A monitor simply allows remote viewing of cameras in a CCTV system from a control room or other location. A video monitor should have a resolution that is at least as good as the camera’s resolution if not better. CCTV SYSTEMS.

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CCTV SYSTEMS

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CCTV SYSTEMS

CCTV MONITORS


CCTV SYSTEMS

  • A monitor simply allows remote viewing of cameras in a CCTV system from a control room or other location.

  • A video monitor should have a resolution that is at least as good as the camera’s resolution if not better.


CCTV SYSTEMS

  • There is a saying that a surveillance system is only as good as its monitor.

  • There is another saying that a surveillance system is only as good as it’s cameras.

  • There is yet another saying that a surveillance system is only as good as the installer…


CCTV SYSTEMS

  • Recent advances in technology ensure that a customer can purchase a high quality system.

  • There are two types of security monitors: the older, bulky CRT monitor and the newer, sleeker LCD monitor.

  • The CRT monitor can be B/W or color, LCDs are color only.


CCTV SYSTEMS

  • CRT stands for Cathode Ray Tube.

  • It is the traditional box type of monitor or television.

  • The inside of a CRT monitor consists of three phosphor layers, one each for red, green, and blue colors.


CCTV SYSTEMS

  • When these layers are hit with electron beams, energy from the electrons is converted into light radiation, different compositions of the phosphor create different colors.


CCTV SYSTEMS

  • LCD stands for Liquid Crystal Display and it is actually not new.

  • It was first introduced in 1970 but for a long time it was inferior in image quality.

  • The inside of an LCD monitor consists of a liquid suspended between two glass or plastic panels.


CCTV SYSTEMS

  • The liquid crystals are naturally aligned to let light pass through except for when a current is applied, In this case, it blocks light, turning the affected area dark.

  • Different amounts of light are made to pass through the crystals by altering the amount of current used.

  • Red, green, and blue chambers inside the monitor produce color when varying amounts of current is passed through these chambers.


CCTV SYSTEMS

  • LCDs provide better image quality than CRTsthey produce a sharper, brighter picture because they can process CCTV signals at a higher resolution.

  • These monitors are also more responsive than CRTs, making them ideal for live video monitoring.

  • They are much lighter and less bulky than CRT monitors so they take up much less room.


CCTV SYSTEMS

  • LCDs also come in large sizes for multiple camera viewing situations.

  • A big advantage of CCTV LCDs over CRTs is that LCDs do not suffer from magnetic interference.


CCTV SYSTEMS

  • Speakers, for example, do not need to be shielded to be used in conjunction with the monitor.

  • Another advantage of a CCTV LCD is screen flicker is not an issue.

  • With CRT monitors, low refresh rates leads to screen flicker, an annoying occurrence.


CCTV SYSTEMS

  • Despite all these advantages, there are some disadvantages to a CCTV LCD, One is the contrast ratio.

  • It is easier to produce higher contrast in CRT monitors because the electron gun can be turned off for true blacks.

  • In an LCD the backlight is always on so a certain amount of light will always show through, Because of this, buyers should be aware of an LCD monitor’s contrast ratio,an effective ratio is 400:1.


CCTV SYSTEMS

  • Another drawback is LCD monitors sometimes generate dead pixels, or areas of the screen that remain black because they no longer function.

  • If the monitor is under warranty, most manufacturers will repair dead pixels, but this leads to system downtime.


CCTV SYSTEMS

  • An important distinction should be made between CCTV LCD monitors and regular LCD monitors.

  • CCTV LCD monitors have a processing scaler, which is a device designed to display the best possible picture from a security camera by up converting the signal.

  • CCTV LCD monitors can cost as much as two to three times more than a regular LCD monitor.


CCTV SYSTEMS

  • The viewing angle is a limiting factor of LCD monitors.

  • LCDs typically come with VGA, HDMI, composite and BNC connections as well as audio connections.


CCTV SYSTEMS

  • It should be noted that any time we use the word monitor it means there is no TV tuner in it.

  • Monitors, both CRT and LCDs have controls for contrast, brightness etc., on CRTs the adjustment knobs are on the monitor, for LCDs it is an on screen menu.


CCTV SYSTEMS

  • Monochrome CRT monitors are typically deployed in CCTV systems over color CRTs.

  • Monochrome is considered a better choice because of it’s clarity and resolution, monochrome is not the same as black and white.

  • Monochrome is one color and the absence of that color.


CCTV SYSTEMS

  • Monitor sizes are measured diagonally, CRT monitors have an aspect ratio of 4:3and LCDs monitors are typically 16:9 which is the widescreen standard.


CCTV SYSTEMS

  • All CRT’s use the NTSC (National TV standards committee) standard which is the analog standard.

  • LCDs use the ATSC (Advanced TV systems committee) which is the digital standard, most LCDs also support the NTSC standard.

  • Most CRT monitors will also support the PAL (Phase Alternating Line) European standard.


CCTV SYSTEMS

  • Another thing to consider is the TVL (television lines) of the CRT monitors.

  • TVL is a standard used by cameras as well.

  • 450 TVL and below is considered a standard resolution where approximately 500 TVL is closer to be a HD (high definition) standard.


CCTV SYSTEMS

  • LCD monitors will support all TVL standards however resolution for flat screens are 720P, 1080i and 1080P.

CAN YOU TELL THE DIFFERENCE?

1080i1080P


CCTV SYSTEMS

  • What does the “I” and the “P” in 1080i and 1080P stand for?

THE “i” STANDS FOR INTERLACED AND THE “P” STANDS FOR PROGRESSIVE SCANNING, INTERLACED SCANNING HAS A TENDENCY TO BLUR DURING ACTION SEQUENCES, THIS DOESN’T HAPPEN IN PROGRESSIVE SCANNING.


CCTV SYSTEMS

  • Cameras use impedance to synchronize signaling when connecting monitors and other inline equipment to the output of the camera.

  • Connecting two monitors to a single camera using a T-connector will not work properly.


CCTV SYSTEMS

  • Assume that both monitors are terminating monitors, they both only have 75 ohm input jacks.

  • If you simply connect them both to the same camera you will experience negative effects, such as signal fading, alternating contrast and even lost video framing.


CCTV SYSTEMS

  • Both present 75 ohms of impedance and thus signaling is affected, the correct way to connect two monitors to the same video source is to use a video loop through.

  • Most terminating monitors have a switch that toggles between 75 ohms and zero ohms.

  • This switch must be turned to the off position (zero ohms) at the first monitor and 75 ohms at the second.


CCTV SYSTEMS

  • The output of the camera is connected to the first monitor and then looped through to the second monitor.

  • The second monitor provides the proper 75 ohm termination.

  • Some monitors are auto-terminating, they sense whether a signal is being looped or not.


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