Glossary #2

Terms used by: Security professionals

A
Active Video Lines - All video lines not occurring in the horizontal and vertical blacking intervals.
AF - Abbreviation for automatic frequency control, a circuit built into some VCR's and TVs to automatically lock onto an incoming channel.
AFM - Audio frequency modulation is the type of audio recording used on Beta HiFi and VHS HiFi VCR's. The audio is laid on the tape by audio heads located on the video head assembly.
AGC - Abbreviation for automatic gain control. On a TV or VCR, AGC is a circuit that automatically adjusts the incoming signal to the proper levels for display or recording. On a video camera, AGC is a circuit that automatically adjusts the sensitivity of the pickup tube to render the most pleasing image.
Alarm Activated VCR - After pressing 'record'', a normal VCR takes about 20 seconds before it starts recording usable pictures. With and alarm activated recorder it can be set so that the tape is ready to start recording in about one second. The signal to begin recording can be from an alarm or any other input. Aperture - The light gathering area of a lens, controlled by the iris.
Aspect Ratio - The ratio of the vertical to the horizontal image size. This is usually 3:4.
Attenuation - This refers to signal loss in a transmission system.
Audio S/N Ratio - Signal-To-Noise Ratio is the ratio of pure audio signal versus noise.
Automatic Iris - A lens that adjusts automatically to allow the right amount of light to fall on the imaging device. There is a tiny motor and amplifier built in which receives a control signal from the camera to maintain a constant one volt peak to peak (1.0 Vp-p) video level.

B
Back Focus - A mechanical adjustment in a camera that moves the imaging device relative to the lens to compensate for different focal lengths of lenses. This is important when a zoom lens is fitted.
Balanced Signal - A video signal is converted to a balanced signal to enable it to be transmitted along a 'twisted pair' cable. Used in situations where the cabling distance is too great.
Bandwidth - The range of signal frequencies that a piece of audio or video equipment can encode or decode; the difference between the limiting frequencies of a continuous frequency band. Video uses higher frequency that audio, thus requires a wider bandwidth.
BetaCam & BetaCam SP - BetaCam was first introduced in 1982. It is currently geared for broadcast use, although there have been some less expensive models destined more for industrial use. Pictures you will get using a BetaCam system (or other component format) will generally be markedly superior to those you would get using any of the preceding formats. Colors in particular come out looking much more vibrant and objects appear three-dimensional. The superiority of BetaCam shots comes partly from the technical aspects of the tape format but also in large part because of the use of superior optics and other camcorder and VTR components (and generally better operators!). The difference between BetaCam and BetaCam SP, introduced in 1986, is in the tape. Betacam SP uses a metal tape and is an improvement over BetaCam. BetaCam cassettes are large. Ninety minute cassettes measures 5.5 by 10 inches (14 by 25 cm). Typically BetaCam field units (camcorders or dockable decks) handle only smaller cassettes with shorter lengths of tape (30 minutes and less). These smaller cassettes are 4 by 6 inches (10 by 16 cm) in size.
Betamax - Betamax tapes were a format originally introduced by Sony in the 80's. It was thought to be a better format at the time. However, the Beta vs VHS wars took place and VHS was the victor. There are still a few Beta fans out there though and you can still get a Betamax machine if you look around.
Blooming - Picture distortion caused by a high video level. Blooming results when the image sensor of the video camera picks up a very bright subject or an area with high illumination.
Burst - A component of a television signal that carries color information.
Brightness - In color video, the characteristics that makes pictures appear to be most intense, created by luminosity; also the quality of being filled with light.

E
EIA - Electronic Industry Association. An industry lobbying group; it collects statistics and establishes testing standards for many types of home electronics.
EIAJ - Electronics Industry Association of Japan. The Japanese equivalent of the EIA.

F
F-Connector - The standard connector used with coaxial cable and the RF inputs/outputs of most video equipment.
Field - One-half of a video field, comprising the odd or even scan lines. There are 60 fields in one second of video.
Flagging - Bending at the top of a picture played back by a VCR.
Focal Length - The distance between the secondary principal point in the lens and the plane of the imaging device. The longer the focal length, the narrower is the angle of view.
Footcandles - (Ft-c) Lumens per square foot; the measurement of the intensity of light on a camera.
Frame - One complete video picture, comprising both odd and even fields. There are 30 video frames per second.
Frame Store - An electronic method of capturing and storing a single frame of video. All slow scan transmitters include a frame store that holds the picture at the moment of alarm, while the control is being dialed up. When the link is confirmed, the picture is transmitted

G
Gain - The level of amplification of a signal.
Gen-Lock - Alignment of the sync generators of one or several sources to main sync source. Used in multi source camera shoots or editing.

H
Helical Scan - The technical name for the way the video heads in a VCR record and play back picture information. Also used to record and play back stereo HiFi audio.
HI-8 - HI-8 camcorders record their signal at about 400 lines of resolution, slightly less than Mini DV, but substantially higher than 8mm or regular VHS formats. Most often, HI-8 camcorders record sound in hi-fi stereo. Slight quality loss is suffered when copying or editing from HI-8, but a better than average image is maintained. Tapes from HI-8 camcorders generally must be played using the camera as the source, which means the user often must connect cables to their television or VCR.   HI-8 tapes can be bought in 30, 60, and 120-minute lengths.
Horizontal Resolution - The number of vertical black and white lines that can be defined, as measured along a horizontal line.

J

K

L
Line Locked - The sync pulses of cameras are locked to the AC mains frequency.
Line Powered - A camera in which the power is supplied along the same coaxial cable that carries the video signal.
Loop Frame Store - The principal is that a series of video frames is compressed and stored in a continuous loop. This records a certain number of frames and then records over them again until an alarm signal is received. When this happens it carries on recording for a dozen frames or so and then stops. This means that frames before and after the incident are recorded. This eliminates the boring searching through hours of video tape and concentrates on the period of activity.
Luminance - The term used to denote the brightness or black-and-white picture of a video image.
Lux - A measurement of illumination. The metric equivalent of footcandle.

M
Macro-Focus - Some zoom lenses include this feature, which allows you to get as close as one or two inches to your subject. This is a great feature for video taping small objects such as coins, stamps, or insects.
Macro-Lens - Lens capable of close-up focusing.
MII - Introduced in 1986, MII is Panasonic's answer to Betacam SP. All MII tape is metal. The 90 minute cassette at 4 by 8 inches (11 by 19 cm) is considerably smaller than the 90 minute Betacam SP cassette. However the dockable decks take only a small 20 minute cassette (3.6 by 5 inches - 9 by 13 cm). Technically, MII is equal to or superior to Betacam SP. Panasonic MII field equipment includes several small dockable decks usable with a variety of camera heads and some excellent portable decks.
Be aware if you get into MII that at some point repairs may become an issue and that few duplicating facilities or clients are likely to have MII. Therefore you will probably have to copy your MII programs to another format at some stage.
Mini DV - Mini DV tapes are the smallest of the video formats. They take and maintain crystal clear images because of the nature of a digital format. Editing enthusiasts benefit from Mini DV as well, since copying between two units is done with no quality loss. That means edited or copied video looks and sounds every bit as good as the original footage. Mini DV tapes are available in 30, 60 and 63 minute lengths.  You can also have Mini DV tapes transferred to VHS.
Modulation - A way in which one signal modifies or controls another signal for such purposes as enabling it to carry information. Often used to describe radio frequency (RF) transmission. FM is a frequency modulation; AM isamplitude modulation.
Monitor - A video display. A monitor is like a TV except it lacks the ability to tune in channels. A monitor may or may not have a sound amplifier and speaker.
Monochrome - Black and White.
MPEG4 - Moving Picture Experts Group. A standard for digital video & audio compression.
Multiplexer - An electronic system that can accept a number of camera inputs and record them virtually simultaneously. They can also provide multi screen displays with four, nine, sixteen etc. cameras on the screen at once. Mulitplexors can be used to transmit multiple pictures down a single video line whether it is a coaxial cable, microwave, infrared link etc. This requires a multiplexor at each end of the line.

Q
Quad Screen - Display where 4 cameras are viewed on the same screen, each camera image occupying a quarter of the display area. Other 'multi-screen' modes are possible such as 9, 16 and 25 way. The splits do not always have to be equal and other configurations can be possible.

R
Real Time Recording - Refers to the top speed of a video recorder; governed by the monitor - pictures are available as fast as the video can accept them.
Remote Switcher - A video switcher which is connected to the camera cables and which contains the switching electronics. This unit may be remotely located and connected to a desk top controller by a single cable for each monitor.
Residual Color - This is the amount of color in the image of a white target after a color camera has been white balanced. The less color, the better the camera.
Resolution - The clarity or sharpness of the picture. Resolution is most often stated in the number of total lines that make up an image or in MHz.

S
Saturation - The strength or amount of a certain color present in a television picture; saturation is expressed as the purity of the color.
Scene Illumination - The density of light falling on the area to be viewed. For best results the ratio of the lightest to the darkest areas should not be more that a factor of two.
Screen Splitter - A term usually used for a device that can combine the views from two cameras on a single screen. Normally the camera syncs need to be locked together.
S/N Ratio - Signal-to-Noise ratio is the amount of desired signal as compared to undesired signal. In video Tape, noise appears as "snow," audio noise is the tape hiss heard upon playback. A way of measuring how good a picture or a sound will be.e The higher the ratio between the desired type of signal and the unwanted noise, the better the results.
S-VHS or Super VHS - A VHS format that enables recording and playback of very high resolution video. The format uses a 4 pin din cable to carry the separated signals, chrominance and luminance, versus the composite type that combines the signal over one wire.
S-Video - Type of video signal used in the Hi8 and SVHS videotape formats. S-Video transmits luminance and colour portions separately, using multiple wires, thus avoiding the colour encoding process and its inevitable loss of picture quality.
Switcher - A simplified SEG that selects and mixes video signals from two or more sources.
Sync - Short for synchronization, a broad term to indicate the proper order of electrical signals to generate and display sound and picture from a videotape.

T
Telemetry - The system by which a signal is transmitted to a remote location in order to control CCTV equipment e.g. to control pan and tilt and zoom functions, switch on lights, move to preset positions etc. The controller at the operating position is the transmitter and there is a receiver at the remote location. The signal can be transmitted along a simple 'twisted pair' cable or along the same coaxial cable that carries the video signal.
Terminating Resistor - A resistor (usually 75 ohms) attached to the end of a cable or to an input or output on a piece of video equipment. The resistor restores proper system impedance.
Test Patterns - A test pattern is used to check out video systems, cameras and control equipment.
Time Lapse VCR - A type of video recorder that can be set to record continuously over long periods. This can be anything from three hours to 480 hours, achieved by the tape moving in steps and recording one frame at a time. This means that if set to record over long periods much information can be lost. On receipt of an alarm signal these machines can be automatically switched to real time mode.

U
U-Matic - U-Matic also known as 3/4" video tape. The format was introduced in 1971 but it is still used by some videographers who have been using the format for a long time. It can produce good quality video and 3/4" decks are still commonly available in duplicating houses. However, there is little reason for somebody to persue this format given the technical advantages of some of the other more recent formats. UMatic has been used by professionals the world round and found mostly in studios. The format is slowly being replaced with digital equipment such as DV and Mini DV.
Underscanning - A technique generally used by some TV and video systems as a way of ensuring that the complete image is always visible within a display area; the opposite of overscanning.

V
VHS & VHS/C - Abbreviation for video home system, a VCR format pioneered by JVC. VHS/C and full size VHS record at a slightly lower resolution than 8MM. Their appeal, or course, is the convenience of easy playback. The large VHS camcorders are almost a thing of the past at this point. There are still a few models available, but their substantial size and weight make them a difficult sell against smaller camcorders. VHS/C compact models, on the other hand, remain a popular choice, offering many of the same key features as 8MM camcorders, at an equally affordable price.
Video Motion Detector - A method of detecting movement in the view of the camera by the electronic analysis of the change in picture contrast.
VU - Volume Unit is measured by sound-level meter. VU meters are usually marked from -20 to +5 Vus.
O Represents the loudest level before distortion occurs.

W
White Balance - Assures the correct balance of red, green, and blue. Because these colors are used to create all other colors in television, white balancing a camera enables you to bring the colors in line for the existing lighting conditions. Also refers to a camera control that accurately sets light levels on a white surface.
Wide Angle - The wide-angle position of a lens enables the lens to capture a wider area of view. Be careful when video taping people with a wide-angle lens at close range.

X

Y
Y/C Video - See S-Video

Z