Abbreviations used in security systems documentation

AC. Alternating current. Alternating current.

AC/DC. Alternating current/direct current.

A/D, AD.A/D. Usually refers to analog-to-digital conversion.

ADC. Analog-to-digital conversion. Usually refers to the first stage of an electronic device that converts an analog signal (video, audio, control, etc.) into a digital format.

AGC.Automatic gain control. AGC. Automatic gain control. Part of the electronic circuit with feedback, maintaining the voltage at a certain level.

ALC. Automatic light control. APO. Automatic illumination control. Part of the automatic aperture control circuit, functionally similar to backlight compensation in photography.

Alphanumeric video generator (text inserter).Video character generator (text generator). A device for inputting additional information, usually superimposed on the reproduced image; the amount of information can vary from one or two characters to text occupying the entire screen. Such generators use video signal sync pulses as a reference signal for inserting text; this means that if the video signal is of low quality, the stability of the text will also be low.

Amplitude. Amplitude. The maximum value of the signal.

Analog signal.Analog signal. Representation of data in the form of continuously changing values. An analog electrical signal is characterized by different values ​​of voltage or current (volts or amperes) and is an electrical representation of the original excitation (sound, light) within the dynamic range of the system.

ANSI. American National Standards Institute. National Standards Institute of the United States.

Aperture. Aperture. The opening in a lens that controls the amount of light reaching the surface of a photodetector. The size of the aperture is controlled by the diaphragm setting. The larger the F-number (F/1.4, F/1.8, F/2.8, etc.), the less light reaches the photodetector.

Archive.Archive. Long-term, offline storage of data. In digital video systems, images are typically stored on devices such as hard drives, magnetic tapes, floppy disks, or DAT cartridges (digital audio cassettes).

Artifacts. Artifacts. Unwanted elements or defects in a video image. They may occur naturally during the video process and must be eliminated to obtain a high-quality image. The most common artifacts are luminance and chroma crosstalk.

ASCII.American Standard Code for Information Interchange. A 128-character set that includes uppercase and lowercase letters of the English alphabet, digits, special symbols, and 32 control codes. Each character is represented by a 7-bit binary number. One character in the ASCII code can be stored in one byte of computer memory.

Aspect ratio.Aspect ratio. The ratio of the width of a television or film image to its height. Currently, the aspect ratio of a television screen is 4:3, i.e. 4 units wide and 3 units high. This aspect ratio was chosen in the early days of television, when most films had this format. The new HDTV (high definition television) format has an aspect ratio of 16:9.

Aspherical lens.Aspherical lens. A lens with an aspherical surface. The cost and labor intensity of producing such lenses is much higher, but they have certain advantages over a conventional spherical lens.

Astigmatism. Astigmatism. Blurred images in the foreground and background.

Asynchronous.Asynchrony. Lack of synchronization. A video signal is unsynchronized if its duration differs from the duration of the system reference signal. An external video signal is unsynchronized until it is processed by the frame synchronizer of the video system.

ATM. Asynchronous transfer mode. A method of transmitting and switching a signal in which the information is non-periodic with respect to some reference signal.

ATSC.Advanced Television System Committee. (Modern NTSC). The Advanced Television Standards Committee. The American committee that sets standards for the transmission and format of high-definition television (HDTV) signals.

Attenuation. Attenuation. The decrease in amplitude of a signal as it passes through a medium or electrical system. Measured in decibels (dB).

Auto iris (AI). Auto iris. An automatic method of changing the aperture of the iris in response to changes in scene illumination.

AWG.American wire gauge. Specifications for wire diameters according to American standards. The smaller the AWG number, the larger the wire diameter (see reference table 5.3 in the Video Camera Power Supplies section).

Back-focus. Back focus. The procedure for setting the CCD/lens position to obtain correct focus for all focal length settings (especially critical for zoom lenses).

Back porch. 1. The part of the video signal corresponding to the blanking period, from the end of the horizontal sync pulse to the beginning of the active part of the video signal. 2. The part of the blanking signal lying between the trailing edge of the horizontal sync pulse and the trailing edge of the corresponding blanking pulse. The color synchronization pulse is located in this area.

Balanced signal.Balanced signal. In CCTV systems, this refers to the transmission of a video signal over a twisted pair cable. The signal is called balanced because it passes through both wires, so it is equally susceptible to external interference, so that before the signal reaches the receiving end, the interference will be mutually compensated at the input of the differential buffer amplifier stage.

Balun.Balancing transformer. This device is used to match or convert an unbalanced coaxial cable to a balanced twisted pair cable.

Bandwidth.Bandwidth. The full range of frequencies that a circuit or electronic system can operate with minimal signal loss, typically measured at a level of 3 dB. In PAL systems, the maximum bandwidth is 5.5 MHz; in NTSC, it is 4.2 MHz. In both PAL and NTSC systems, to ensure accurate digital representation of the video signal without aliasing within the luminance signal bandwidth, the luminance signal sampling frequency was chosen to be 13.5 MHz (1 Ti601).

Baseband. Baseband. The frequency band occupied by a group of signals used to modulate a carrier before they are combined with the carrier during modulation. In CCTV systems, the majority of the signals are baseband signals.

Baud.Baud. A unit of data transfer rate named after Maurice Emile Baude, equal to 1 bit/s. Baud is equivalent to bits per second when each signal element corresponds to exactly 1 bit. If devices exchange data, the baud rate settings of the two devices must be consistent.

BER.Bit error rate. The ratio of erroneously received bits to the total number of received bits, used as a measure of distortion caused by noise in a digital data stream. BER is expressed in powers of 10. For example, with 1 erroneous bit per 1 million bits, BER = 106.

Betamax. Betamax format. A video recording format developed and used by Sony, a competitor to VHS.

Bias.Bias, Feed. Current or voltage applied to a circuit to set a particular operating condition in order to improve the circuit's performance; for example, high-frequency bias current applied to an audio recording head to improve linearity and reduce distortion.

Binary.Binary. A base-2 numbering system that uses two digits, 0 and 1 (as opposed to the ten digits [0-9] of the decimal system). In computer systems, binary digits represent two different values ​​of voltage or current, one representing zero and one representing one. All computer programs are executed in binary form.

Bipolar. Bipolar. A signal that contains both positive and negative amplitude. It may also include a zero amplitude value.

B-ISDN.Broadband Integrated Services Digital Network. ISDN, broadband digital network with integrated services. An advanced ISDN network consisting of an intelligent combination of a large number of channels, which allows for higher data transfer rates.

Bit. Bit (short for binary digit). Elementary digital information, can take the value 0 or 1. The smallest unit of information in the binary system. A group of bits, for example, 8 or 16, make up a byte. The number of bits in a byte depends on the processing system used. Standard byte sizes are 8-bit, 16-bit, or 32-bit.

Bitmap (BMP). Bitmap. Pixel-by-pixel description of an image. Each pixel is considered a separate element. Also a standard computer graphic file format.

Bit rate.Bit Rate. Bytes per second (Bps) = Bytes per second, Bits per second (bps) = Bits per second. The digital equivalent of bandwidth, bit rate is measured in bits per second. It is commonly used to express the speed at which a compressed bit stream can be transmitted. The higher the bit rate, the more information can be transmitted.

Blackburst (color-black). Black Burst. A composite color video signal that contains sync pulses, a color reference signal (bursts), and a black signal, typically 7.5 (50 mV) above blanking level.

Black level.Black level. The portion of the video signal that is close to the sync level but slightly above it (usually 20-50 mV) to distinguish it from blanking. Corresponds to the black area of ​​the image, with the white portion being equivalent to 0.7 V above the sync level.

Blanking level.Blanking level. The beginning of the video information in the video signal. The reference point is taken as 0 V, which is 300 mV higher than the bottom of the sync pulses. Sometimes called the «pedestal» — a level in the video signal that separates the area containing image information from the sync area.

Blooming. Image blurring. Defocusing of parts of the image that have excess brightness.

BNC (Bayonet-Neil-Concelman connector).Bayonet connector. The most common connector in closed-circuit television and broadcasting systems for transmitting baseband video signals over coaxial cable.

B-picture. Bidirectional predictive picture; an MPEG term for pictures encoded using a motion-compensated prediction method based on the previous and/or next reference picture.

Braid. A set of interwoven textile or metal threads braided around one or more wires, having a round or flat shape.

Brightness. Brightness. For NTSC and PAL video signals, information about the image brightness at any given moment is transmitted by the corresponding instantaneous level of constant voltage in the area of ​​the active video signal. Brightness is adjusted by adjusting the settings (black level, reference black level).

Burst (color burst).Color burst signal. Seven to nine (NTSC) or ten (PAL) subcarrier periods are placed at the end of the horizontal blanking pulse as a phase (color) reference signal for the modulated color subcarrier. The color burst signal serves as a standard for the color image.

Bus. Bus. In computer architecture, it is used for internal transmission of information between various system components and is available to each of the components.

Byte. Byte. A digital word consisting of 8 bits (zeros and ones).

Cable equalization. Cable correction, compensation. The process of changing the frequency response of a video amplifier in order to compensate for high-frequency losses in a coaxial cable.

Candela [cd].Candela [cd]. A unit of luminous intensity. One candela is approximately equal to the amount of light energy emitted by a standard candle. In 1948, a more precise definition of the candela appeared: «the candela is the luminous intensity emitted by a black body heated to the temperature at which platinum changes from a liquid to a solid state.»

CATV. Community antenna television. Subscription television.

C-band. C-band. A range of microwave frequencies from 3.7 to 4.2 GHz, commonly used in satellite communications,

CCD. Charge-coupled device. PZD. Charge-coupled device. A modern photodetector that has replaced the old transmitting tubes. It first appeared in the 1970s and was initially used as a storage device. It is most often used in video cameras, but is also used in telecine sensors, fax machines, scanners, etc.

CCD aperture.CCD aperture. The photosensitive area of ​​a CCD matrix.

CCIR. Committee Consultatif International des Radiocommunique or Consultative Committee for International Radio. The European committee that sets standards for television in Europe. Initially for black and white, today the term CCIR is usually used for black and white video cameras used in countries that have adopted the PAL standard.

CCIR 601.An international standard (renamed ITU 601) for digital television components derived from SMPTE RP1 25 and EBU 3246E. ITU 601 specifies sampling systems, matrix values, and filter characteristics for the X Cr, Cb, and RGB components of digital television. It specifies a 4:2:2 sampling scheme at 13.5 MHz for the luminance channel and 6.75 MHz for the chrominance channels, with 8-bit sampling for each channel. These sampling frequencies were chosen because they work for both 525-line, 60 Hz and 625-line, 50 Hz video system components. The 4:2:2 designation denotes the ratio of the number of luminance channel components to the number of chrominance channel components; each four luminance components correspond to two color channel components. The digital video recording format DI complies with ITU 601.

CCIR 656.An international standard (renamed ITU 601) that specifies the electrical and mechanical interfaces for digital television equipment operating under the ITU 601 standard. ITU 601 specifies the pinout of parallel and serial ports, as well as the blanking, synchronization, and multiplexing schemes used in both parallel and serial interfaces.

CCTV.Closed circuit television. Closed circuit television, security television. A television system intended for a limited number of viewers, as opposed to a mass television broadcasting system.

CCTV camera. A video camera that is part of a closed circuit television system. The device includes a photoreceiver that provides a video signal in the main frequency band.

CCTV installation.Installation of closed-circuit television systems. A closed-circuit television system or a connected group of systems, together with all necessary technical support, auxiliary lighting devices, etc., located in a protected area.

CCTV system. Closed-circuit television system. Security television system. A video camera and lens, plus additional equipment necessary for monitoring a specific protected area.

CCVE.Closed circuit video equipment. An alternative acronym for CCTV.

CDS. Correlated double sampling. A technique used in the design of some CCD video cameras that reduces the noise in the video signal generated by the chip.

CFA (Color filter array). A set of optical filters used in single-chip color CCD cameras to shape the color components of the video signal.

Chip. Chip, IC, microcircuit. An integrated circuit in which all components are located on a small plate made of silicon or similar material.

Chroma crawl.Chroma creep. An artifact of video encoding, also known as dot crawl or luminance crosstalk. In a video image, it appears at the edges of highly saturated colors as a continuous sequence of crawling dots due to the mixing of color and luminance information in the decoder circuitry.

Chroma gain (chroma, color, saturation). Color gain, color saturation. In video, the gain of an amplifier that affects the intensity of color in an image.

Chroma key (color key).Chroma key (color key). A video effect in which one video signal is substituted into the area of ​​another video signal that has a specific color.

Chrominance. Color, color signal. Color information of a color video signal.

Chrominance-to-luminance intermodulatlon (crosstalk, cross-modulation).Chroma-luminance intermodulation (crosstalk, cross-modulation). Undesirable change in the amplitude of the luminance signal caused by the superposition of color information on the luminance signal. Manifested in the TV image as unjustified variations in luminance associated with changes in color saturation levels.

CIE. Commission Internationale de I’Eclairage. International Commission on Illumination (CIE). The International Committee on Light, organized in 1985. Formulates definitions and recommendations for the use of luminous units.

Clamping (DC).DC Restoration. A circuit or process that restores the DC component of a video signal. The DC restoration circuit, usually gated by horizontal sync pulses, restores the DC component of a video signal to a fixed reference level. The primary benefit of level restoration is the elimination of low-frequency interference and especially power line noise.

Cladding.The sheath of the light-conducting core. The outer part of the fiber-optic cable, also fiber, but with a lower material density than the core part. Makes possible the effect of total reflection — the light transmitted along the inner core remains inside.

Clipping Level. Limiting level. Electronic limiting that allows to avoid overloading the video component of the television signal.

C-mount.C-mount. The first standard for threaded lens mounting for closed-circuit television systems. It is defined by a thread of 1″ (2.54 mm) in diameter, a pitch of 32 threads per inch, and a distance from the rear flange to the CCD matrix equal to 17.526 mm (0.69″). The C-mount standard is applicable to both lenses and video cameras. C-lenses are compatible with both C- and CS-video cameras, only the latter requires an adapter ring.

CMYK.Cyan-Magenta-Yellow-Black (CMYK). A color coding system used by printers in which colors are expressed by the «subtractive primaries» (Cyan-Magenta-Yellow) plus black (K). A layer of black is added to enhance contrast and increase the dynamic range of printing devices.

Coaxial cable.Coaxial cable. The most common type of cable used to transmit video signals. In cross-section, it has a coaxially located central core, which is the signal conductor, and an outer braid that protects against external electromagnetic interference.

CODEC. Code/Decode. Codec. A codec-decoder is an electronic device that performs compression and decompression of digital signals. Usually performs A/D and D/A conversion.

Color bars.Color bar scale. A pattern formed by a TV test signal generator, consisting of eight color bars of equal width. Colors: white (75%), black (7.5% setting level), with 75% saturation of the primary colors — red, green and blue — and with 75% saturation of the additional colors — yellow, cyan, purple (a mixture of two primary colors in a 1:1 ratio, without adding a third color).

Color carrier.Color carrier. The carrier frequency of a color video signal (4.43 MHz for PAL), modulated with color information. The frequency of the color carrier is chosen so that its spectrum alternates with the luminance spectrum with minimal overlap.

Color difference signal. Color difference signal. A color video signal created by subtracting the luminance and/or color component from one of the primary color signals (red, green, blue — RGB). In the Betacam color difference format, for example, the luminance (Y) and color difference components (R-Yn B-Y) are related as follows:

Y = 0.3 Red + 0.59 Green + 0.11 Blue

R-Y= 0.7 Red — 0.59 Green — 0.11 Blue

B-Y = 0.89 Blue — 0.59 Green — 0.3 Red

The color difference signal G-V is not created, since it can be reconstructed from the other three signals.There are other color subtraction conventions: SMPTE, EBU-N1 0 and MP. Color difference signals should not be called video signal components. This term is reserved for RGB components. Loosely, the term «video signal component» is often used in the sense of color difference signals.

Color field.Color frame. In NTSC, the color subcarrier is phase-locked to the horizontal sync pulses, so that the phase of the subcarrier changes by 180° with each line. In PAL, the phase of the color subcarrier changes by 90° with each frame. In NTSC, this creates four different field types, and in PAL, there are eight. To obtain clean images, it is important to align the sequence of color fields from different sources.

Color frame. Color frame. In color television, four (NTSC) or eight (PAL) strictly consecutive color fields make up one color frame.

Color phase.Color phase. The time relationship in a video signal, measured in degrees, responsible for the correctness of the color signal tones.

Color subcarrier. Color subcarrier. A signal with a frequency of 3.58 MHz that transmits color information. This signal is superimposed on the luminance signal. The amplitude of the color subcarrier represents the saturation, and the phase angle represents the color tone.

Color temperature.Color temperature. Determines the color tone. Derived from photography, where the color spectrum is based on comparing tones as the color changes when a black body is heated (as in physics) from red to yellow and then to blue, the hottest. Color temperature is measured in degrees Kelvin.

Comb filter.Comb filter. An electronic circuit that passes a range of frequencies and blocks frequencies in between, producing a serrated frequency response. Uses a composite video signal to separate the chrominance signal from the luminance signal, reducing chrominance crosstalk, or vice versa, to separate the luminance signal from the chrominance signal, reducing luminance crosstalk. Used in S-VHS systems to improve the resolution of the luminance signal.

Composite sync. Sync mixture. A signal consisting of horizontal sync pulses, vertical sync pulses, and equalization pulses (without video signal).

Composite video signal. Composite video signal. A signal in which brightness and color information are combined according to one of the coding standards: NTSC, PAL, SECAM, etc.

Concave lens. Concave lens. A lens with a negative focal length, has an imaginary focus and reduces the image of objects.

Contrast.Contrast. A general term used to describe the dynamic range of a video image, i.e. the difference between the darkest and lightest parts of the image.

Convex lens. A convex lens. A lens with a positive focal length, has a true focus and magnifies the image of objects, so is commonly called a magnifying glass.

CPU.Central processing unit. A common computer term. CRO. Cathode ray oscilloscope. (See Oscilloscope.)

Crosstalk. Crosstalk. A type of interference, unwanted transmission of a signal from one circuit to another circuit within the same system. Usually caused by capacitive coupling (AC coupling).

CS-Mount.CS Mount. A new standard for lens mounting. Same thread as the C-mount, but the distance from the rear flange to the CCD is reduced to 12.5 mm, making the lens smaller, more compact, and less expensive. CS-mount lenses can only be used on CS-mount video cameras.

CS-to-C-mount adaptor.C/CS adapter, transition ring. The adapter is used to convert a CS camcorder to a C camcorder, that is, to work with a C lens. This is a 5 mm thick ring with an external thread on one side and an internal thread on the other, has a thread diameter of 1″ and a thread pitch of 32 threads per inch. Usually included with the new type of camcorders (CS).

CVBS. Composite video bar signal. In television broadcasting, this is a video signal that includes color information and sync pulses.
D/A (DA). DAC, digital-to-analog conversion (the opposite of ADC).

Dark current.Dark current. The signal that appears at the output of a CCD matrix in the absence of incident light.

Dark noise. Dark noise. Noise associated with the quantum nature of dark current.

DAT (digital audio tape).Digital audio cassette. A CD-quality system originally designed for recording and reproducing digitized audio signals. Recent hardware and software developments may lead to similar low-cost systems for archiving, recording, and reproducing video signals.

dB. Decibel. The common logarithm of the ratio of two signals or two values, usually related to power, but may also relate to voltage or current. If power is being considered, the logarithm is multiplied by 10, and for voltage or current, by 20.

DC.Direct current. Current that flows in one direction (as opposed to alternating current).

DCT.Discrete cosine transform. A mathematical algorithm used to generate a frequency representation of a block of video pixels. The DCT is an invertible discrete orthogonal transform between the spatial and temporal domains. There is a forward discrete cosine transform (FDCT) and an inverse discrete cosine transform (IDCT).

Decoder. A device for restoring the component signals coming from a coded signal source.

Degauss. Demagnetization.

Delay line.Delay line. An artificial or real transmission line or equivalent device designed to delay a signal for a specified time interval.

Demodulator. Demodulator. A device that separates video and audio signals from the carrier frequency.

Depth of field.Depth of field. The area in front of and behind an object in focus that appears sharp on the screen. Depth of field increases as focal length decreases, i.e. the shorter the focal length, the greater the depth of field. Depth of field is always greater behind an object in focus.

Dielectric. Dielectric. Insulating (non-conducting) material.

Differential phase. Differential phase. The change in phase of the video signal subcarrier caused by a change in the signal brightness level. The color tones of a scene change along with the change in scene brightness.

Digital disc recorder. Hard disk recording device.

Digital signal. Digital signal. Electronic signal in which each value of real excitation (sound, light) is represented by a combination of binary signals corresponding to an analog signal.

DIN. Deutsche Industrie-Normen. German standard.

Distortion.Distortion. A disproportionate representation of the original.

DMD. Digital micro-mirror device. A new video projection technology that uses matrices with a large number of miniature mirrors whose projection angle can be controlled with digital precision.

DOS.Disk operating system. A software package that enables a computer to operate with such technical devices as a hard disk drive, floppy disk, monitor, keyboard, etc.

Dot pitch.Dot pitch. The distance in millimetres between individual dots on a video monitor screen. The smaller the pitch, the better, as more dots will be displayed and the resolution will be higher. The dot pitch determines the resolution of the video monitor. A computer monitor or a high-resolution CCTV monitor has a dot pitch of less than 0.3 mm.

Drop-frame time code.Drop Frame Time Code. An SMPTE time code format that continuously counts at 30 frames per second, but drops two frames every minute except every tenth of a minute (dropping 108 frames every hour) to synchronize the time code with the clock. This is necessary because the actual frame rate of an NTSC video signal is 29.94 frames per second, not 30.

DSP. Digital signal processing. Usually refers to the portion of a device's electronic circuitry that performs digital signal processing.

Dubbing. Dubbing from one medium to another.

Duplex.Duplex, two-way. A communication system that carries information in both directions. In CCTV, the term «duplex» is often used to describe a type of video multiplexer that can perform two functions simultaneously — recording in multiplex mode and playing back in multiplex mode. It can also refer, for example, to duplex communication between a matrix video switcher and a receiver for remote control signals of a pan-tilt device.

DV-Mini.Mini digital video. Mini digital video. A new audio and video recording format for small camcorders, adopted by most camcorder manufacturers. Video and sound are recorded in digital format on a small cassette (66x48x12 mm), surpassing S-VHS and Hi 8 in quality.

D-VHS. A new standard proposed by JVC for recording digital signals on a VHS video recorder.

Dynamic range.Dynamic range. The difference between the smallest and largest values ​​that a system can represent.

EBU. European Broadcasting Union.

EIA. Electronic Industries Association. Develops television standards used in the United States, Canada, and Japan, based on 525-line interlaced scanning. Formerly known as RMA or RETMA.

Encoder.Encoder. A device that superimposes information from one electronic signal onto other electronic signals.

Encryption.Encoding. The systematic rearrangement of the bit stream of a previously digitized signal, making the information unrecognizable until reconstructed with an authorized access key. This technique is used to protect information transmitted over communications channels to prevent anyone but authorized users from interpreting the message. It can be used for voice, video, and other communications signals.

EPROM. Erasable and programmable read only memory. An electronic chip used in many security systems that stores program instructions for performing various operations.

Equalizer.Equalizer, frequency corrector. A device designed to compensate for frequency losses or delays in a system. A part of a system or circuit that allows you to adjust a signal within a given frequency band.

Ethernet. A local area network that connects computers, printers, workstations, terminals, etc., located in the same building. An Ethernet network uses twisted pair cables and coaxial cables at speeds up to 10 Mbps.

Ethernet uses the CSMA/CD (collision-detection multiple access) method. CSMA/CD is a method of sharing a common medium (wires, coaxial cables) between different devices.

External synchronization. External synchronization. A means of synchronizing equipment from a single source. FCC. Federal Communications Commission (US). FFT. Fast Fourier Transformation.

Fiber optics. Fiber optics. Technology for transmitting signals in the form of light pulses. Fiber optic cable is known for such properties as electrical insulation and resistance to electrostatic and electromagnetic interference.

Field.Frame field. Half of a TV frame, consisting of even or odd lines. In CCIR systems, each field consists of 625/2 = 312.5 lines, and in EIA systems — 525/2 = 262.5 lines. In the CCIR/PAL TV system, 50 fields/second are transmitted, and in EIA/NTSC — 60 fields/second.

Film recorder. A device for recording on photographic film. A device that converts digital data into data recorded on film. Continuous tone recorders allow you to get color photographs in the form of slides, prints or negatives.

Fixed focal length lens. A lens with a fixed focal length, focus and aperture control.

Flash memory. Flash memory. Non-volatile digital memory. Flash memory access time is lower than SRAM or DRAM access time.

Flicker.Flicker, flicker noise. An annoying artifact primarily related to frame synchronization and field mapping. Some flicker is natural, caused by interlaced scanning, and is more noticeable in 50 Hz systems (PAL). Flicker also occurs when static objects are displayed on the screen, such as computer-generated text converted to video. Insufficient digital image processing, common in low-quality converters (when converting from PAL to NTSC and back), creates an annoying flicker on the screen. Several electronic methods exist to minimize flicker.

F-number. F-number. In lenses with adjustable iris, the maximum aperture opening is expressed as the ratio (focal length of the lens)/(maximum aperture diameter). The value corresponding to the maximum aperture is applied to the front ring of the lens.

Focal length.Focal length. The distance between the optical center of the lens and the main focal point.

Focusing control. Focusing. The means of adjusting the lens to obtain a sharp image of objects located at different distances from the video camera.

Foot-candle.Foot-candle. A unit of illuminance used primarily in American terminology. A foot-candle is ten times (or more precisely, 10.764 times) larger than one lux.

Fourier Transformation. Fourier Transform. A mathematical transformation of functions from the time domain to the frequency domain.

Frame.Frame. (See also TV field). Refers to the set of lines that make up one TV frame. In the CCIR/PAL TV system, one frame consists of 625 lines, and in the EIA/NTSC system, it consists of 525 lines. The CCIR/PAL system transmits 25 frames per second, and the EIA/NTSC system transmits 30 frames per second.

Frame store. Video memory (frame memory). An electronic device that digitizes a frame (or TV field) of a video signal and places it in memory. Video multiplexers, video quadrators (screen splitters), and some of the latest color video cameras have built-in frame memory.

Frame switcher.Frame video switcher. Another name for a simplex video multiplexer, which can record video signals from several video cameras to a single VCR (and play back the image from any of the video cameras in full-screen format), but does not have a multi-screen playback function.

Frame synchronizer.Frame synchronizer. A digital buffer that stores and compares synchronization information with the video signal's sync pulses, thereby continuously adjusting the signal to avoid synchronization errors.

Frame transfer (FT). Frame transfer. One of three charge transfer principles in CCD matrices. The other two are interline transfer and frame-interline transfer.

Frame-interline transfer (FIT). Frame-interline transfer. Refers to one of the charge transfer principles in CCD matrices. The other two are interline transfer and frame transfer.

Frequency. Frequency. The number of complete cycles of a periodic signal in a given period of time. Usually measured in hertz.

Frequency modulation (FM). Frequency modulation (FM). Modulation of a sinusoidal oscillation by changing the frequency in accordance with the amplitude variations of the modulating signal.

Front porch.The leading edge of the horizontal blanking pulse (between the end of the active line signal and the beginning of the horizontal sync pulse).

Gain. Gain, amplification factor. Any increase or decrease in an electrical signal. Measured in decibels or times.

Gamma.Gamma Correction. Correction of the linear characteristic of a video camera to compensate for the nonlinear characteristic of the phosphor screen of a video monitor. It is measured by the exponential value of the curve describing the nonlinearity. A typical gamma value of a black-and-white video monitor is 2.2; in order for the overall system characteristic to be linear, the video camera should be set to the reciprocal of 2.2 (i.e. 0.45).

Gamut. Range. The range of permissible voltages of a video signal or video signal components. Exceeding this range may result in clipping, crosstalk, and other distortions.

Gen-lock. A method of synchronizing camera video signals from an external sync generator.

GHz. GigaHertz. GHz. Gigahertz. One billion periods per second.

GB. Gigabyte. Gigabyte. A unit of computer memory, equal to about one thousand million bytes (about one thousand megabytes). The actual value is 1,073,741,824 bytes.

GND. Ground (electrical).

Gray scale. Gray scale, brightness scale. A series of shades (usually 10) from true black to true white.

Ground loop.«Ground loop», parasitic circuit with a short circuit through the ground (ground loop). Unwanted interference in the lines of transmission of an electrical signal with a shielded cable, arising as a result of the appearance of parasitic currents in the case when the system has more than one point of «ground». In security television, for example, it occurs if the video camera and the switch or video monitor have different ground resistances. The interference induced by the surrounding electrical equipment (including the power supply network) is unevenly discharged through the two grounds (since they are different) and appears on the video monitors as interference.

GUI. Graphical user interface.

HAD. Hole accumulated diode. A type of CCD sensor with a layer designed to accumulate electron holes in order to reduce noise.

HDD.Hard disk drive. A magnetic medium designed to store digital information in most computers and electronic equipment that processes digital data.

HDDTV.High definition digital television. High definition digital television. HDTV. An emerging television broadcasting standard with extremely high resolution and an aspect ratio of 16:9. It is a further development of analog high definition TV, already used experimentally in Japan and Europe. The image resolution is approximately 2000×1000 pixels, and the MPEG-2 standard is used.

HDTV. High definition television. High definition television. HDTV. Usually used in reference to the analog version of HDTV. SMPTE in the US and ETA in Japan proposed the HDTV standard: 1125 lines at 60 Hz with 2:1 interlaced scanning, 16:9 aspect ratio, 30 MHz bandwidth for RGB and luminance signal.

Headend.Headend (station). Electronic equipment at the transmitting end of a television system: antennas, ground stations, preamplifiers, frequency converters, demodulators, modulators, and similar equipment.

Helical scan. Helical scan. A method of recording video information on magnetic tape, commonly used in consumer and professional video recorders.

Horizontal Drive (also Horizontal sync).Horizontal control pulse (also horizontal sync pulse). This signal is obtained by dividing the subcarrier by 227.5 and then shaping the pulses. The signal is used by video monitors and video cameras to determine the beginning of each line.

Horizontal resolution.Horizontal resolution. Chromatic and luminance resolution (detail) assessed horizontally across the image on a CRT screen. Usually expressed as the number of transitions from black to white or the number of distinguishable lines. Limited by the video signal bandwidth or the equipment bandwidth.

Herringbone. Jaggedness. The formation of a special pattern on an image when displaying a color-modulated composite video signal (PAL or NTSC) on a black-and-white video monitor.

Horizontal retrace.Horizontal sync pulse. The short period at the end of each line of a video signal when the scanning beam returns to the other side of the screen to begin a new line.

Horizontal sync pulse. Horizontal sync pulse. The synchronization pulse at the end of each scan line that determines the beginning of the horizontal retrace.

Hertz. Hertz. A unit of measurement equal to the number of oscillations per second.

Housings, environmental.Camcorder housing. Usually refers to a housing for a camcorder with a lens; may have accessories — heating, glass washers, wipers, designed for specific environmental conditions.

HS. Horizontal sync.

Hue (tint, phase, chroma phase).Hue (shade, phase, color signal phase). One of the characteristics of color discrimination. Hue defines a color based on its position in the spectrum, i.e. red, blue, green, or yellow, etc. Hue is one of three characteristics of color in television: see also «saturation» and «brightness». In NTSC and PAL video signals, information about the hue of each image point is transmitted by the corresponding instantaneous phase of the active video signal subcarrier.

Hum.Hum, mains interference. A term used to describe unwanted interference caused by the power grid.

Hum bug. A synonym for ground loop protection device.

Hyper-HAD. An advanced version of HAD technology that uses microlens technology to increase sensitivity without increasing the pixel size of the CCD.

IDE.Interface device electronics. A standard for communications software and hardware when connecting peripheral devices to a computer.

I/O. Input/Output.

1/P. Input. A signal applied to an element of electrical equipment or to the connectors of equipment to which a signal or voltage is supplied.

IEC.International Electrotechnical Commission (also CEI). International Electrotechnical Commission. IEC.

Imaging device. Photodetector (video signal former). A vacuum tube or solid-state device in which the light-sensitive plate of the tube or the light-sensitive CCD matrix forms an electronic signal with which an image is created.

Impedance.Total resistance, impedance. A characteristic that describes the overall resistance of an electrical circuit. Resistance, inductance, capacitance, and conductance affect total resistance differently, depending on frequency, insulators surrounding the conductor, physical interactions between conductors, and external factors. Impedance is usually denoted by the letter Z, and is measured in ohms.

Input. Same as 1/P.

Inserter (alphanumeric video generator). Text generator, generator for inserting alphanumeric characters into a video signal. A device for inputting additional information, usually superimposed on the reproduced image; the amount of information can vary from one or two characters to text occupying the entire screen. Such generators use video signal sync pulses as a reference level for inserting text; this means that if the video signal is of low quality, then the stability of the text will also be low.

Interference. Interference, pickup. Disturbances of an electrical or electromagnetic nature that cause undesirable consequences in the operation of electronic equipment.

Interlaced scanning.Interlaced scanning. A technique for combining two television fields (half-frames) to produce a full frame. Each field consists of only even or only odd lines, the fields are output one after the other, but the physical position of the lines is interleaved, which is why the scanning is called interlaced. This type of television image formation was proposed at the dawn of television in order to obtain a smoothly moving image with a minimum amount of information.

Interline transfer. Interline transfer. One of three principles of charge transfer in CCD matrices. The other two are frame and frame-interline transfer.
IP.Index of protection. A numerical system that describes the protection of devices from external influences such as moisture, dust, and impact.

IRE. Institute of Radio Engineers. Institute of Radio Engineers. IRE. A unit of measurement that divides the area from the sync signal pulses to the peak white level into 140 equal parts. 140 IRE corresponds to a full-scale video signal of 1 V. The range of the active video signal is 100 IRE.

IR light. Infrared radiation. Infrared light, invisible to the human eye. Usually refers to wavelengths longer than 700 nm. Black and white video cameras have high sensitivity in the infrared range of the light spectrum.

Iris. Aperture (iris). A means of adjusting the size of the lens aperture and, therefore, the amount of light passing through the lens.

ISDN.Integrated Services Digital Network. The latest generation of telephone networks, using a transmission rate of 64 kbps (since the network is digital, it is characterized not by the signal bandwidth in kHz, but by the transmission rate). This is much faster than a regular PSTN (public switched telephone network) telephone line. To use the ISDN network, you need to contact a communications service provider, and a special set of interface elements (such as modems) is required.