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CCTV Video Surveillance Chennai India. About CCTV Video Surveillance Chennai India. CCTV Video Surveillance Products Chennai India. CCTV Related Terms - Glossary Chennai India. CCTV Video Surveilance Sitemap, Chennai India. CCTV Video Surveillance Contact Us, Chennai India.  
 
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GLOSSARY OF COMMON CCTV TERMS

AC refers to alternating current electricity. 110 volts AC is the type of electricity most often found in home and office electrical outlets in the United States. Outside the U.S. many countries have standard outlet voltage of 220 ~ 240 volts AC. In addition, many CCTV products use 24 volts AC, for which a separate power transformer is required.

AC/DC refers to changing between alternating current (AC) and direct current (DC). Switching from AC power from your home or office outlet to DC current is required for most of our products. A transformer can easily be used to regulate the current; for this reason, we include AC/DC power supplies with almost all of our products. There are also power inverters which convert DC current to AC current. Such power inverters are commonly used to power 110 volt AC devices (such as a VCR video recorder) from a DC automotive or marine battery.

Alarm/Event Operation is a feature found in many CCTV video recording devices like VCRs and DVRs. This allows the user to interface alarm sensors (like a PIR motion detector) with the recording device through an alarm in/out port (this port has a physical electrical contact). An alarm/event capable recorder can then be set to automatically start and stop recording when the alarm is triggered (such as by motion). However, the digital revolution is replacing the need for bulky and expensive alarm sensors. Many newer digital DVR recorders feature advanced video motion detection, which can provide dynamic motion detection recording with built-in software alone.

Alarm Input Some cameras and video servers have the ability to accept alarm inputs. These are inputs from standard sensor devices such as, Passive Infra-red (PIR) detectors, door contacts, active beams etc. or relay outputs from intruder alarm panels, or access control panels. Alarm input circuits can come in a number of forms. Most commonly they are self powered, so will operate with a passive switch style circuit. However, in some cases, they expect to be provided with power (normally 12V) as the signal of open or closed. In a few cases manufactures only supply TTL (very low voltage) level inputs. In that case, they can only be safely used with normal alarm sensors in conjunction with some additional isolation circuitry. In this case, it is best to contact the manufacturer for advice.

Alkaline Battery - This is a type of battery most commonly found at retailers around the world. Alkaline batteries are suggested to power all video equipment using the mobile BAT-1, BAT-3, or BAT-AAA battery packs. For some products (those with input voltage as low as 9.6 volts DC), however, rechargeable Nickel-Metal-Hydride batteries may also be used. In addition, using lead acid, lithium-ion, or lithium polymer batteries may also provide adequate power for video cameras and other devices so long as the +/- polarity is correct and the battery's output voltage falls within the device's safe operating range.

Amps (A) are used to measure electrical current consumption. 1 amp (A) = 1000 milliamps (mA).

Amplifier typically refers to a device which adds strength to a signal for a 'better' and / or longer performance ability. Amplifiers can be found for both wired and wireless equipment. A VDA (video distribution amplifier) is designed to extend a video signal through wires by boosting the power of the video signal. Transmitter-end and receiver-end amplifiers can be found for wireless equipment to help increase broadcast range potential.

Analogue Continuously variable numerical values such as voltage, current, etc. (The CCD camera produces analogue video signals.)

Angle of View the scene angle that a video camera lens can show on the monitor, like Diagonal Angle, Horizontal Angle and Vertical Angle, usually described in degree.

Antenna Element - Antennas for wireless equipment are constructed of elements which are specifically tuned to a given frequency or range of frequency to improve gain.

Antenna Gain refers to any increase or decrease in the strength of a wireless RF radio frequency signal when considering external antenna equipment. Gain is typically measured in terms of decibels (dB) or a number of times of magnification.

Antenna Type refers to the design of a particular antenna. Common antenna types for wireless CCTV are dipole whip antenna (the most common), yagi, flat panel, omni-directional, parabolic dish, and heliophase.

Aperture The light gathering area of a lens, controlled by the iris.

ARP Address Resolution Protocol; for mapping an IP address to a physical machine address.

Aspherical Lens A lens designed with a non spherical shape so that it passes more lights or decreases barrel distortion on wide angle lenses.

Aspect Ratio is a specification for monitors. This term refers to the ratio between the width and height of a video image. Typically, CCTV cameras produce an aspect ratio of 4:3 (the vertical size of the picture is 75% of the horizontal width). This is the same ratio for compatibility with standard consumer televisions and video equipment as well as security-industry monitors and video recorders. Widescreen televisions, on the other hand, have a 16:9 aspect ratio. Attenuation A decrease or loss in a signal, usually measured in decibels.

Audio indicates sound. When audio is listed as a feature of some video product, this usually means one of a few things: a device for monitoring sound (microphone), a wireless transmitter's ability to broadcast sound, or a video recorder's ability to record audio.

Audio Input Plug refers to the type of connector plug for a device's audio input jack. In most cases, this is a standard RCA connector or 1/8" (3.5mm) mini plug.

Audio Input Type - There are two basic kinds of audio found for video equipment connections: line-level and mic-level. Line-level indicates that the audio input device (like a microphone) must be preamplified in order to record or broadcast the audio signal. All wireless products, recorders, and monitors require line-level microphone connections. For compatibility's sake, all microphones found on this site are line-level and contain preamplifiers.

Auto electronic shutter (AES) Feature of a camera to adjust for light changes without the use of an auto-iris lens.

Audio Output Plug refers to the type of connector plug for a device's audio output. In most cases, this is a standard RCA connector or 1/8" (3.5mm) mini plug.

Audio Output Type - Audio output for a device can be either line-level or mic-level (see note above in audio input type). So long as the audio output is line-level, there is no need for mic-level connections. Video recorders and monitors typically have line-level inputs, making connections simple.

Auto Iris (AI) Cameras with an Auto Iris feature, have the ability to compensate for large variations in light levels. Particularly useful for cameras that need to compensate for changes from bright sunlight to dark shadows. The auto iris circuitry is normally linked to a motorised iris drive that physically opens and shuts the iris on the lens. Closing a physical iris is a much better way to protect a camera from being damaged by bright sunlight then simply using electronics to reduce the signal strength. A diaphragm device in the lens that adjusts to light level changes. The iris diaphragm opens or closes the aperture to control the amount of lights coming through the lens.

Auto-focus Lens automatically adjusts the lens focus from surrounding scene and keeps a moving object in focus.

Automatic Gain Control (AGC)  refers to a circuit within the camera which regulates image brightness levels for optimum performance and highest video quality. This is a feature of many CCTV cameras that helps keep the strength of the output signal constant, even when the light level changes. In other words, it boosts the signal strength at low light levels, and caps it at higher levels.

Auto Homing An automatic sequential video switcher which has manual switches or buttons, which allow a single CCTV camera to be displayed on screen without sequential switching.

Automatic Level Control (ALC) Allows the auto-iris circuitry to either take bright spots more into consideration (peak), bringing out detail in bright areas, or less into consideration (average) bringing out detail in shadows.

Automatic Light Control (ALC) is a built-in feature of every camera found on Eyespyvideo.com. ALC indicates the image sensor's ability to automatically adjust in diverse lighting conditions to yield the most vivid video image possible.

Auto-Iris Lens is a lens with a built-in method of automatically controlling the lens aperture for the best video quality under diverse and changing lighting conditions. Auto-iris lenses can be especially helpful under very low light and bright direct forward light. In order to use an auto-iris lens, however, the video camera you are using must have a built-in auto-iris port to supply the lens with a small amount of DC electrical voltage. Manual iris lenses are also available and do not require any special ports or cable connections.

Auto Terminating Automatically select the correct termination depending on whether the video output is connected.

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