Abbreviations used in security systems documentation

sokrasheniya

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.

ISO. International Standardization Organization. International Organization for Standardization. ITU. International Telecommunications Union (UIT). International Telecommunication Union.

JPEG.Joint Photographic Experts Group. The group that proposed a digital image compression algorithm with a compression ratio greater than 10:1. Also the name of this format.

kb/s. Kilobits per second (kbps). 1024 bits per second.

Kelvin.One of the main physical units of temperature measurement. The Kelvin scale has the same divisions as the Celsius scale, only the reference point of 0 ° K is equivalent to -273 ° C. Color temperature is also measured in Kelvin and is denoted by K. In color photography, the temperature of the illuminators affects the colors of the illuminated scene.

K factor. K-factor. An assessment method according to which video interference that causes the most noticeable deterioration in image quality is designated by a higher K-factor value.

kHz. Kilohertz. kHz. Kilohertz. One thousand hertz.

Kilobaud.Kilobod. A unit of data transfer rate equal to 1000 baud.

Kilobyte. Kilobyte. 1024 bytes.

Lambertian source or surface. Lambertian source or surface. A surface is called a Lambertian radiator or reflector (depending on whether the surface is a primary or secondary light source) if it is a uniformly diffusing surface.

LAN.Local Area Network. A communications network for transmitting data over short distances (usually within a single building), used to link computers and peripheral devices (such as printers, CD-ROM drives, modems) into a single system with common control.

Laser (Light amplification by stimulated emission of radiation). Laser, quantum generator. A laser produces very strong and coherent radiation of a single frequency.

LED. Light Emitting Diode. A semiconductor that emits light when a low voltage of a certain polarity is applied to it.

Lens. An optical system that focuses the desired objects onto a video camera's photoreceiver.

Level.Level. In relation to a video signal, refers to its level in volts. In CCTV lenses, refers to the level of the electronics settings that process the video signal and control the iris.

Line-locked. Line Sync. In CCTV, usually refers to multiple video cameras powered from a common AC source (24V or 110V or 240V) and, as a result, synchronizing their field frequencies to the frequency of the AC source (50Hz in CCIR systems and 60Hz in EIA systems).

Liquid crystal display (LCD)Liquid Crystal Display (LCD). A text/graphics display screen using liquid crystal technology where ultra-low currents change the reflectivity or transparency of the screen. Advantages of LCDs include very low power consumption (batteries can be used) and low cost for mass production. Disadvantages include a narrow viewing angle, slow response time (too slow to be used for video), poor visibility in the dark (unless the display is backlit), and difficulty achieving true color reproduction on color LCDs.

Lumen [Im]. Lumen [lm]. The luminous flux emitted by a light source with a luminous intensity of 1 candela within a unit solid angle.

Luminance.Brightness. Refers to the information contained in a video signal about the illumination of an object. A measure of brightness in a video signal. Differs from «lightness» — the latter is not measured, but is a sensory sensation. Color information about a video image consists of two components: brightness (brightness and contrast) and chroma (color tones and saturation). A photometric unit of measurement of light emission.

LUT.Look-up table. A cross-reference table in computer memory that converts input data from a scanner or computer and adjusts values ​​to compensate for equipment deficiencies or differences in photo emulsions.

Lux [Ix]. Lux [lx]. A unit of illumination. Defined as the illumination of a 1 m2 surface exposed to a luminous flux of 1 lumen. Sometimes referred to as «lumen per square meter» or «meter-candle.»

MAC.Multiplexed analog components. A system in which components are time-multiplexed onto a single channel using time-division techniques, i.e.the components are separated as they are transmitted at different times over a single channel. There are many different MAC formats and standards.

Manual iris. A method of manually changing the size of the lens aperture.

Matrix.Matrix. A logical network configured as a rectangular array of input/output channel intersections.

Matrix switcher. Matrix video switcher. A device for connecting multiple video cameras, a VCR, a video printer, etc. to multiple

video monitors, a VCR, a video printer, etc. A much more complex and efficient device than a regular video switcher.

MATV.Master antenna television. Television reception on a collective antenna.

MB. Megabyte. Megabyte. A unit of computer memory, approximately one million bytes. The actual value is 1,048,576 bytes. Kilobyte x kilobyte = megabyte.

MB/s.Megabytes per second. Mbyte/s. Megabyte per second. A million bytes per second, or 8 million bits per second. Mb/s. Megabits per second. Mbit/s. Megabits per second. A million bits per second.

MHz. Megahertz. MHz. Megahertz. One million hertz.

Microwave. Microwave. One definition refers to the range of the electromagnetic spectrum from 300 MHz to 3000 GHz. Another definition refers to microwave transmission media. Microwave transmissions typically use frequencies from 1 GHz to 12 GHz.

MOD. Minimum object distance. A characteristic of a lens with a fixed or variable focal length indicating the minimum distance from the object to the image plane of the lens, expressed in meters. The minimum object distance for zoom lenses is approximately 1 m; for prime lenses it is usually much less and depends on the focal length.

Modem.Modem. This popular term is formed from two words: modulate — demodulate. The function of a modem is to connect one device (usually a computer) via a telephone line to another device.

Modulation. Modulation. The process during which some characteristic (amplitude, phase) of one radio signal changes in accordance with another signal (message signal).

Moir pattern.Moire effect. An undesirable effect that appears in an image when a CCD video camera has a pixel count close to (but smaller than) the pixel count of the object in the image.

Monochrome. Monochrome. Black and white video signal. A video signal that contains information about the brightness of the image, but does not contain information about the color.

MPEG.Motion Picture Experts Group. An ISO-initiated group of experts that develops standards for the recording of moving pictures. There are currently several standards, the best known being MPEG-1 and MPEG-2. The latter is widely adopted in high-definition digital television and multimedia presentations.

MPEG-1.A standard for compression of progressive scan images and audio. Provides transmission rates from 1.5 Mbit/s to 3.5 Mbit/s.

MPEG-2. A standard for compression of video signals with progressive interlaced scanning and high-quality audio in a wide range of compression ratios with transmission rates from 1.5 to 100 Mbit/s. Adopted as the HDTV and DVD standard for video/audio coding.

Noise.Noise. An unwanted signal produced by electrical circuits operating at temperatures above absolute zero. Noise cannot be eliminated, but it can be minimized.

Non-drop frame time code.Continuous Frame Time Code. SMPTE time code continuously counts 30 frames per second. Because NTSC video does not operate at exactly 30 frames per second, continuous frame time code counts 108 extra frames per hour; this is more than the NTSC video signal actually contains. The result is that the time code is not correctly synchronized with the clock. Continuous frame time code solves this problem by skipping 2 frames every minute, except every tenth of a minute.

Noninterlaced. Non-interlaced. A scanning process in which each line of the image is displayed during the vertical scan.

NTSC.National Television System Committee. An American committee that sets the color television standards currently used in the United States, Canada, Japan, and some South American countries. NTSC uses a subcarrier at 3.57945 MHz whose phase changes with the instantaneous value of the transmitted color tones, and whose amplitude corresponds to the instantaneous value of the color saturation. In NTSC, there are 525 lines in a frame and 59.94 fields per second are transmitted.

Numerical aperture.Numerical aperture. The number that determines the light-collecting ability of an optical fiber. The numerical aperture is equal to the sine of the maximum acceptable angle.

О/Р, Output. Output.

Objective. Optics. The front element of the objective optical system.

Ocular. Eyepiece. The last element of the objective optical system, located closest to the CCD matrix.

Ohm. Ohm. Unit of resistance. Electrical resistance between two points of a conductor with a potential difference of 1 V, creating a current of 1 A in the conductor, while the conductor is not a source of electromotive force.

Oscilloscope (CRO, cathode ray oscilloscope).Oscilloscope (or ELO — cathode-ray oscilloscope). An electronic device that allows you to measure changes in a signal over time. A must-have device for any security television specialist.

Overscan. Unscanned area. A condition for displaying on a video monitor in which the raster slightly exceeds the physical boundaries of the kinescope screen, cutting off the edges of the image.

Output impedance.Output resistance. The resistance of the device relative to the load. The output resistance is measured at the output terminal of the device with the load disconnected and no externally supplied voltage.

PAL.Phase alternating line. Describes the change in color phase in the PAL color signal. PAL is a European color television system with the following characteristics: 625 lines per frame, 50 fields per second, and a 4.43361875 MHz subcarrier. It is used mainly in Europe, China, Malaysia, Australia, New Zealand, the Middle East, and some African countries. PAL-M is a Brazilian color television system with progressive phase alternation, but this system uses 525 lines per frame, 60 fields per second, and a 3.57561149 MHz subcarrier.

Pan and tilt head (P/T head).Pan/Tilt Unit. An electromechanical device that allows vertical and horizontal positioning of a video camera. Typically 24 VAC motors are used, but 110 VAC or 240 VAC motors may also be used.

Pan unit. Pan unit. An electromechanical device that only allows horizontal positioning of a video camera.

Peak-to-peak (pp). Signal peak-to-peak. The difference in amplitude (voltage) between the largest positive and smallest negative peak of an electrical signal.
Pedestal.The level of the video signal that corresponds to black.

Phot. Phot. A photometric unit of light for very high illumination levels. One phot is equal to 10,000 lux.

Photodiode. A type of semiconductor in which the p-n junction of the diode acts as a photosensor.

Photo-effect.Photoelectric effect. The phenomenon of electrons being knocked out of a metal surface by light.

Photon. Photon. Represents the quantum nature of light. The minimum part of light radiation.

Photopic vision. Photopic vision. The range of light intensities discernible by the human eye; lies within the limits from 105 lux to approximately 10’2 lux.

Pinhole lens.Eye of the Needle lens. A lens with a fixed focal length and a very small aperture, used in situations where covert surveillance is necessary. Such lenses usually do not have focus adjustment, but may have different relative apertures.

Pixel. Pixel. From «picture element» — the smallest element of an image. Usually used in relation to the elementary cell of a CCD matrix.

Phase locked loop (PLL).Phase-locked circuit. A circuit containing an oscillator whose output phase or frequency is synchronized with the phase or frequency of an input reference signal. To ensure synchronization conditions, the circuit detects any phase shifts between the two signals and generates a correction voltage that is applied to the oscillator to adjust its phase or frequency.

Photo multiplier.Photomultiplier tube, photoelectron multiplier tube, PMT. A highly light-sensitive device. Its advantages include fast response, good signal-to-noise ratio, and wide dynamic range. Its disadvantages include its fragility (it is an electron-vacuum device), high voltage, and sensitivity to interference.

Pixel or picture element. Pixel, picture element. The smallest visible element transmitted in a raster file, usually one element in a matrix of numbers describing an image.

Plumbicon. Plumbicon. A thermionic vacuum tube developed by Philips, using a photoconductive layer of red lead. This device was the only photodetector until the advent of CCD matrices.

Polarizing filter.Polarizing filter. An optical filter that transmits light in only one direction out of a possible 360° (perpendicular to the light path). Using a filter helps eliminate some unwanted effects, such as bright spots or reflections, such as those that appear when you look through a glass window. In photography, polarizing filters are often used to darken blue skies.

POTS. Plain old telephone service, (or PSTN). A telephone network widely used throughout the world today.

P-picture. Prediction-coded picture. Predictive-coded picture (coding with motion compensation). MPEG term for describing a picture coded using motion compensation based on a previous reference picture.

Preset positioning.Preset position. A PTZ function, including zoom lens settings. A number of specific positions can be stored in the system memory (usually in the PTZ receiver) and recalled as needed by an alarm, programmatically, or by a command from the remote control.

Primary colors. Primary colors. A small group of colors that, when mixed, form the rest of the color spectrum. In television, the primary colors are red, green, and blue, and all other colors in the image are formed from them.

Principal point. Principal point. One of two points lying on the optical axis of the lens. The principal point closest to the photodetector (in our case, the CCD matrix) is the reference point when measuring the focal length of the lens.

PROM.Programmable read-only memory. Read-only memory that can be programmed by the equipment manufacturer (rather than the PROM manufacturer).

Protocol. Protocol. A specific set of rules, procedures, or conventions concerning the format and timing of data transfers between two devices. A standard procedure by which two devices can «understand» each other. A data transfer protocol covers such aspects as encoding, error handling, user-invisibility, and control.

PSTN.Public switched telephone network. This is the common name for the regular telephone network (or POTS).

PTZ camera. Pan, tilt and zoom camera. PTZ camera, a video camera on a rotating device, with a servo-controlled zoom lens.

PTZ site driver (or receiver or decoder).PTZ unit, pan/tilt/zoom control unit (or receiver, or decoder) — a receiver of telecontrol signals.

An electronic device, usually part of a matrix video switcher, that receives digitally encoded control signals and controls pan, tilt, zoom, and focus.

Pulse.Pulse. Current or voltage that changes abruptly (in a jump) from one value to another and returns back to the initial value over a finite period of time. Used to describe one specific oscillation in a series of wave oscillations.

QAM. Quadrature amplitude modulation. A method of modulating two carriers. The carriers can be analog or digital.

Quad compressor (split screen unit).Video quad (screen splitter). A device that displays parts of an image, or more than one image, simultaneously on a single video monitor. Usually refers to a four-quadrant display.

Radio frequency (RF). Radio frequency. A term used to describe radio signals coming into a receiver or coming out of a radio transmitter above 150 kHz. TV signals, although not strictly radio signals, also fall into this category.

RAM.Random access memory — A storage device with random access. An electronic circuit, commonly called «memory», that stores digital information for as long as voltage is applied to it. Memory capacity is measured in kilobytes. Memory represents the working space of a computer.

RAID.Redundant arrays of independent disks. A technology for combining multiple hard disk drives into a single high-capacity storage device that can be used, among other things, for digital video recording.

Random interlace. Autonomous scanning. In a video camera that has autonomous line synchronization, different from interlaced synchronization, due to which both fields in the frame are very accurately aligned.

Registration.Alignment of the electron beam with the phosphor dots. Adjustment for color and projection televisions: the electron beams of the three primary colors must hit the corresponding color dots/bars.

Resolution. Resolution. A measure of the ability of a video camera or television system to reproduce detail. The number of picture elements that can be reproduced with good clarity.

Retrace.Flyback. The return of the electron beam in a CRT after scanning to the starting point. During flyback, the beam is usually off. All synchronization information is placed in this invisible part of the video signal. Can mean flyback after each line or after each field.

Remote control.Remote control. Transmitting and receiving signals for remotely controlled devices such as pan/tilt units, lenses, washers/wipers, etc.

RETMA. Old name for EIA (Electronic Industries Association). Some older television test charts are called the «RETMA Chart».
RF signal. Radio frequency signal in the range up to 300 GHz.

RG-11.A coaxial video cable with an impedance of 75 ohms. It has a much larger diameter than the popular RG-59 (approximately 12 mm). RG-11 cable can be used for longer systems (the distance can be almost twice as long as with RG-59), but it is more expensive and more difficult to work with.

RG-58. A coaxial cable with an impedance of 50 ohms; therefore, it is not suitable for CCTV. Very similar to RG-59, only slightly thinner.

RG-59.The type of coaxial cable most commonly used in small/medium CCTV systems. It has a characteristic impedance of 75 ohms. The outer diameter is about 6 mm, which is a compromise between the maximum allowable distance (up to 300 m for a black and white signal and 250 m for a color signal) and good transmission.

Rise time.Rise Time, Settling Time. The time it takes for a signal to transition from one state to another; typically measured between the 10% and 90% points of completion of the transition. A short or fast rise time requires more bandwidth for the transmission channel.

RMS. Root Mean Square. A measure of the effective (as opposed to peak) voltage of an AC signal. For a sine wave, this value is 0.707 times the peak voltage. For any periodic oscillation, the RMS value is equal to the square root of the average sum of the squares of the values ​​of one cycle.

ROM. Read only memory — Read-only memory. An integrated circuit containing digital information that is not erased when the power is turned off.
Routing Switcher. Routing switcher. An electronic device that routes a signal (audio, video, etc.) from any input to any output selected by the user. This is the name for matrix switches in television broadcasting.

RS-125.SMPTE Parallel Component Digital Video Standard.

RS-170. A document developed by the EIA that provides guidelines for NTSC color television signals in the United States.

RS-485. An improved digital data transmission format compared to RS-422. The main improvement concerns the number of devices controlled by this format — up to 32.

RS-232.A digital data transmission format that requires only two wires. Also known as «serial data transmission». RS-232 defines an asynchronous data transmission scheme, but not a bit representation of the data, so it does not define a common message format or protocol. In CCTV systems, it is often used to transmit data between a keyboard and matrix video switches, or between matrix switches and PTZ units. The advantages of RS-232 over other standards are its simplicity and the use of only two wires.

RS-422.An improved digital data transmission format compared to RS-232. The main differences are the use of four wires instead of two, since the connection is not asymmetrical, as in the case of RS-232, but differential. Simply put, the transmitted signal is read at the receiving end as the difference between two wires without a common ground. So, if there was noise on the line, it will be eliminated. RS-422 can be used on lines longer than a kilometer and distribute data between several receiving devices, the system can have up to 10 receiving devices.

Saturation (in color).Saturation (of color). The intensity of color in the active part of an image. The degree to which a color perceived by the eye differs from the gray or white scale of the same brightness. A 100% saturated color contains no white; adding white reduces saturation. In the NTSC and PAL systems, the color saturation of an image at any given moment is conveyed by the corresponding instantaneous value of the amplitude of the active video signal subcarrier.

Scanning. The rapid movement of an electron beam in a kinescope of a video monitor or television. The beam runs line by line on the photosensitive surface, providing video reproduction. In relation to a PTZ camera, this is panning or horizontal movement of the camera.

Scanner. Scanner. 1. In relation to security television systems, this is a rotating device with movement only in the horizontal plane. 2. In relation to imaging devices, this is a device with a CCD matrix that scans documents and images.

Scene illumination.Illumination of an object. The average level of light falling into the observation area. Usually measured within the visible spectrum using an exposure meter (photometer) with a spectral characteristic close to the sensitivity of the human eye, given in lux.

Scotopic vision. Scotopic vision. Illumination levels below 10~2 lux, invisible to the human eye.

SCSI.Small computer systems interface. A computer standard that defines the software and hardware for connecting peripheral devices to a computer bus.

SEC AM. Sequential Couleur Avec Memoire, sequential color with memory. A joint color television system of the former USSR and France, using 625 lines per frame (previously 819) and 50 fields per second. The color difference signal information is transmitted sequentially on alternating lines as an FM signal.

Serial data. Serially transmitted data. Sequential time data transmission over a single wire. In CCTV systems, the most common method of data exchange between the control panel and the matrix video switcher and a method of controlling a PTZ camera.

Serial interface.Serial interface. A digital communications interface, data is transmitted and received sequentially over one or two wires. Common serial interface standards are RS-232 and RS-422.

Serial port. Serial port. A computer input/output port through which the computer «communicates» with the outside world. A standard serial port is based on the RS-232 interface and allows for bidirectional data transfer over a fairly simple wired connection, since the data is transmitted sequentially.

Sidebands. Sidebands. The frequency band on either side of the carrier in which the energy of the modulation process is transmitted.

Signal-to-Noise ratio (S/N).Signal-to-noise ratio (S/N). S/N can be specified for the luminance signal, color signal, and audio signal. S/N is the ratio of noise to the actual full signal, it shows how much higher the signal level is than the noise level. It is expressed in decibels (dB), and the higher the S/N, the sharper and clearer the image and sound during playback. S/N is equal to the logarithm of the ratio of the normal signal to the root-mean-square value of noise.

Silicon. Silicon. The material from which modern semiconductor devices are made.

Simplex.Simplex. Generally used to describe a communication system that transmits information in only one direction. In closed-circuit television systems, the term simplex is used to describe a method of multiplexed operation in which only one function, such as recording or playback, is performed at a time.

Single-mode fiber.Single-mode fiber optic light guide (single-mode fiber). Optical glass fiber consisting of fibers of very small diameter. A typical single-mode fiber used in CCTV has a core diameter of 9 µm and a cladding diameter of 125 µm. Single-mode fiber attenuates the signal less and can transmit signals over longer distances (up to 70 km). Typically, such fiber, due to the very small input angular aperture, is used only with laser sources.

Skin effect. Skin effect. The tendency of alternating current to spread along the surface of a conductor as the frequency increases.

Slow scan. Slow scan. Transmission of a sequence of «frozen» images via analog or digital signals using transmission media with a very limited bandwidth, usually a telephone.

Smear.Vertical fringing. An unwanted side effect of charge transfer on a CCD. Bright vertical stripes appear where bright areas of an image should be. In improved video cameras, the effect has been minimized to almost imperceptible levels.

SMPTE. Society of Motion Picture and Television Engineers.

SMPTE time code.SMPTE time code. In video editing, a time code that complies with SMPTE standards. It contains 8-bit numbers representing hours:minutes:seconds:frames. Each number identifies one frame of video. SMPTE time code may or may not be drop-frame.

Snow. Random noise on the screen, often caused by dirty video heads or poor video reception conditions.

S/N ratio. See signal-to-noise ratio.

Spectrum.Spectrum. In electromagnetism, spectrum refers to the description of the amplitude-frequency components of a signal. In optics, spectrum refers to the frequencies of light that make up white light, which can be seen as the colors of the rainbow.

Spectrum analyzer. Spectrum analyzer. An electronic device that displays the spectrum of an electrical signal. SPG. Sync pulse generator. A source of synchronization signals.

Split-screen unit (quad compressor).Screen splitter (video quadrator, quad compressor). A device that simultaneously displays parts of an image or more than one image on a single video monitor. Usually refers to a four-quadrant display.

Staircase (in television).Steps (in television). Same as color bars. A pattern generated by a TV test generator consisting of equal-brightness bars with steps of 0, +20, +40, +60, +80, and +100 IRE and a constant-amplitude color signal in phase with the color burst signal. The color signal amplitude is selected to be 20 IRE (low steps) or 40 IRE (high steps). This test signal is used to check the linearity of the luminance and chrominance channels, differential gain, and differential phase.

Start bit.Start bit. The bit preceding the group of bits representing a character. Used to signal the appearance of a character during asynchronous transmission.

Sub-carrier (SC).Subcarrier. 3.58 MHz for NTSC, 4.43 MHz for PAL. The main signals among all sync signals of the NTSC and PAL systems. This is a continuous sinusoidal oscillation with an amplitude of 2 V and a frequency of 3.579545 MHz (NTSC) and 4.43361875 MHz (PAL). In NTSC, for example, the subcarrier is usually obtained by dividing the primary quartz frequency of 14.318180 MHz by four, which is equal to 3.579545. The same is true for the PAL system. All other sync signals are extracted from the subcarrier by direct division.

S-VHS. Super VHS video recording format. The new standard proposed by JVC retains backward compatibility with the VHS format. Provides better horizontal resolution — up to 400 TVL. All this is achieved mainly due to separate color signals, high-quality video heads and better tapes. S-VHS is usually associated with separate Y/C signals.

Sync. Synchronization pulse. Sync pulse. Synchronization pulse.

Sync generator (sync pulse generator, SPG).Synchronization pulse generator, sync generator. A device that generates synchronization pulses required for normal synchronization of video signal sources. A sync generator can form a subcarrier signal, a «flash» pulse (color synchronization signal), a sync mixture, blanking signals, horizontal sync pulses, frame sync pulses, and a color black field signal. In security television, horizontal and frame sync pulses are most often used.

T1. T1 line. A digital data transmission channel with a transmission rate of 1.544 Mbit/s. The line uses two twisted pairs. T1 lines are used to connect networks over long distances. Bridges and routers are used to connect local networks to T1.

T1 channels. T1 channels. In North America, a digital data transmission channel with a transmission rate of 1.544 million bits per second. In Europe, a digital transmission channel with a transmission rate of 2.048 million bits per second. AT&T uses this term to refer to data transmission channels in the DS-1 digital signal format at 1.544 Mbps.

T3 channels.T3 Channels. In North America, the 45.304 Mbps digital channel is commonly referred to as DS-3.

TVS. Time base correction. Correction of time differences. Synchronization of various signals within devices such as a video multiplexer or time distortion corrector.

TDG. Time and date generator.

TDM.Time division multiplex. Multiplex transmission with time division of channels. Each user is assigned a special segment in each transmission cycle, thus achieving time division of the transmission channel.

Tearing. Tearing (line shift). Shifting of video image lines due to synchronization instability. It seems as if the image is torn.

Teleconferencing.Teleconferencing. A «conference» of participants located in different geographic areas, supported by electronic means of communication.

Telemetry — In CCTV, telecontrol. A remote control system based on digital data, used to control pan, tilt, zoom, focus, presets, washer/wiper unit, etc. Since the system is digital, the signal is usually transmitted over twisted pair or coaxial cable along with the video signal.

Termination. Termination, connectors at the ends of a cable. Usually refers to the physical method of termination of the cable: for coaxial cable, this is usually a BNC, for fiber optic cable, an ST connector. In the case of transmitting electrical signals, it can also refer to the matching of the characteristic impedance. This is especially important for high-frequency signals (including video signals), where the characteristic impedance is taken to be 75 ohms.

TFT. Thin-film-transistor. This technology is used mainly in the production of flat computer and video screens (panels), which are superior in quality to classic LCD monitors. The quality of color rendering, fast response time and high resolution are perfect for video.

Time lapse VCR (TL VCR).TL-video recorder. A video recorder, usually in VHS format, which can provide up to 960 hours of video recording on one tape (for a 180-minute cassette). This type of video recorder is often used in CCTV systems. The operating principle is very simple — the tape does not move at a constant speed of 2.275 cm/s (as in the case of household VHS-recorders), but moves with a discrete step that can be controlled. Such video recorders also have a number of other functions useful for CCTV, such as an external alarm input, superimposing time and date on the video signal, searching for a video recording with an alarm, etc.

Time lapse video recording. TL-video recording. Intermittent recording of video signals, allowing to increase the recording time on the storage medium. Usually judged by comparison to a 3-hour film (180 min.).

Time multiplexing.Time multiplexing. A technique for recording from several video cameras to one TL-video recorder: images from the video cameras are transmitted sequentially with a delay interval corresponding to the mode selected on the recorder.

T-pulse to bar.T-pulse and square pulse. The term refers to the analysis of the frequency response of video equipment. A video signal containing T-pulses (sine-square) and square pulses of the same amplitude is passed through a channel of video equipment, and then the amplitudes of the T-pulses and square pulses are measured at the output. The nature of the amplitude-frequency response is indicated by the fact that one part of the signal is smaller in amplitude than the other.

Tracking. Tracking. The angle and speed at which the tape passes the video head.

Transcoder. Transcoder. A device that converts one type of coded video signal to another, for example, NTSC video signals to PAL. Sometimes mistakenly used to mean translator.

Transducer. Converter (primary). A device that converts one form of energy into another. For example, in fiber optics, it is a device that converts light signals into electrical signals.

Translator. Translator, converter. A device that converts one set of components into another, such as X R-Y B-Yb RGB signals.

Transponder.Transponder (repeater). Electronic equipment installed on a satellite; the device receives a signal from Earth, amplifies it, converts it to other frequencies, and transmits it back to Earth.

TTL.1. Transistor-transistor logic. TTL. A term from digital electronics that refers to the ability to directly connect a device or circuit to the input or output of digital equipment. This compatibility eliminates the need for interface circuitry. TTL signals can only have two states, low and high, and are thus much more limited than analog signals. 2. Through-the-lens. Viewing through a lens or measuring color after a lens.

Twisted-pair. A cable made of two insulated, twisted conductors. Since both wires are nearly equally susceptible to interference, the differential noise is negligible.

UHF signal. Ultra high frequency signal. UHF signal (UHF range). In television: radio frequency range from 470 MHz to 850 MHz.

Unbalanced signal.Unbalanced signal. In security television, this is a type of video signal transmission over a coaxial cable. The signal is called unbalanced because it passes only through the central conductor, while the cable braid is used to equalize the potential difference between the ends of the coaxial cable.

Underscan. Raster reduction. Reducing the size of the raster horizontally and vertically so that all four edges of the image are visible on the video monitor.

UPS.Uninterruptible power supply. Power supplies used in almost all high-security systems; their purpose is to support the system for at least 10 minutes after the utility power is disconnected. The length of this period depends on the UPS rating (usually expressed in volt-amperes) and the current draw of the system itself.

UTP.Unshielded twisted pair. A cable carrier consisting of one or more pairs of twisted insulated copper conductors in a single sheath. Currently the most common method of connecting a telephone line and transmitting data to a workplace.

Variable bit rate. Variable bit rate. A type of operation in which the bit rate during decoding of a compressed bit stream varies over time.

VDA. See (video distribution amplifier) ​​video distribution amplifier.

Vectorscope.Vectorscope. An instrument similar to an oscilloscope used to check and/or align the amplitude and phase of a three-color (RGB) signal.

Velocity of propagation. Velocity of propagation. The speed at which a signal is transmitted. In empty space, electromagnetic waves propagate at the speed of light. In a coaxial cable, this speed is reduced by dielectric materials. Usually expressed as a percentage of the speed of propagation in a vacuum.

Vertical interval. Vertical (field) interval. The portion of the video signal between the end of one field and the beginning of the next. During this time, the video monitor's electron beam is off (invisible) and returns from the bottom to the top of the screen to begin a new scan cycle.

Vertical interval switcher.Synchronized video switcher. A sequential or matrix video switcher that switches from one video camera to another precisely at the field interval, thus ensuring switching without disrupting frame synchronization. This is only possible if the video cameras are synchronized.

Vertical resolution. Vertical resolution. Color and brightness resolution (detail) expressed along the vertical of the CRT screen. Limited by the number of scan lines.

Vertical retrace.Frame scan reverse. The return of the electron beam to the top of the CRT or CCD screen after the end of the field scan.

Vertical shift register. Vertical shift register. A CCD mechanism in which the charge is read from the photosensors in a line-by-line or frame-by-line transfer process.

Vertical sync pulse.Frame sync pulse. Contains part of the frame blanking interval, is at the level of the frame blanking pulse. Synchronizes the frame scan of the TV with the composite video signal. Each frame starts from the same vertical position.

Vestigial sideband transmission. Transmission with partially suppressed sideband. A transmission system in which the sideband on one side of the carrier is transmitted only partially.

VGA.Video graphics array. Video graphics logical matrix, VGA adapter.

Video bandwidth.Video bandwidth. The highest frequency in the video signal spectrum that a device can pass. The higher the video bandwidth, the higher the image quality. A VCR with a wide video bandwidth produces a well-detailed, high-quality image on the screen. Video bandwidths in studio work range from 3 to 12 MHz.

Video distribution amplifier (VDA). Video distribution amplifier, video distributor. A specialized amplifier for amplifying a video signal transmitted to several video monitors simultaneously.

Video gain.Video signal swing. The range of values ​​from light to dark in an image that is proportional to the difference in voltages corresponding to the black and white levels in the video signal. Displayed on a control oscilloscope as the «whiter than white» voltage level in the active signal. Video signal swing is related to the contrast of the video image.

Video equalization corrector (video equalizer).Video equalizer (video corrector). A device that corrects frequency response unevenness and/or phase shifts during video signal transmission.

Video framestore. Video frame memory. A device for storing one or more digital images and subsequent stable playback on a video monitor.

Video in-line amplifier. Video amplifier (trunk). A device that provides video signal amplification.

Video matrix switcher (VMS).Matrix video switch. A device for connecting several video cameras, a video recorder, a video printer, etc. to more than one video monitor, video recorder, video printer, etc. A much more complex and effective device than a video switch.

Video monitor. Video monitor. A device that converts a video signal into an image.

Video printer.Video printer. A device that converts a video signal to print a hard copy. The printout may be black and white or color.

Can have various formats. Requires special paper.

Video signal. Video signal. An electrical signal containing all the elements of an image transmitted by a video camera or other source of video information.

Video switcher.Video switch. A device for connecting several video cameras to several monitors manually, automatically or by alarm signal.

VITS. Video insertion test signals. Test line signal. A specially shaped electrical signal inserted into invisible lines (in the case of PAL, lines 17, 18, 330 and 331) that determine the reception quality.

Video wall.Video wall. A video wall is a large screen formed by several monitors placed close together; when viewed from a distance, they form a large video screen or wall.

VOD. Video on Demand. A service that allows users to watch their chosen programs at their chosen time, with VCR-like controls such as pause, fast-forward, and rewind.

VHF.Very high frequency. Very high frequency (MW range). Signal with frequencies from 30 to 300 MHz. In television, the IVHF frequency band is in the range of 45-67 MHz, band III — 180-215 MHz. Band II is reserved for FM radio 88-108 MHz.

VHS.Video home system. VHS format. Video recording format proposed by JVC, usually used in home systems, but also in CCTV. Limitations are recording speed, magnetic tapes used and separation of color signals. Modern CCTV equipment exceeds the VHS format in resolution.

VLF. Very low frequency. Refers to frequencies in the range of 10-30 kHz.

VMD.Video motion detector. A detector that generates an alarm in response to changes in the video signal, usually movement, but it can also be a change in illumination. It is very important in security television, since a video motion detector accurately controls what the video camera “sees”, i.e. without losses.

VR. Virtual Reality. Computer-generated audio and visual images perceived by the viewer through high-tech displays and sensor systems under his control.

VS.Vertical sync. Frame synchronization. WAN. Wide area network. Global network.

Waveform monitor. Waveform indicator, control oscilloscope. Oscilloscope for displaying the shape of video signals.

Wavelet. Wavelet. A special type of video signal compression, especially suitable for CCTV. Provides a higher compression ratio with quality equal to or better than JPEG.

White balance. White balance. An electronic process used in video cameras to restore true colors. It is performed electronically, using the white part of the image object as a basis.

White level. White level. The portion of the video signal that electronically represents the white part of the image. It is 0.7 V below the blanking level, while the black part is taken to be equal to 0 V.

Wow and flutter. Frequency drift, low-frequency (wow) and high-frequency (flutter) sound wow. Frequency drift refers to low-frequency variations, and flutter to high-frequency variations caused by changes in the speed of the tape relative to the tape head.

W-VHS. A new advanced standard proposed by JVC, characterized by high resolution and an aspect ratio of 16:9.

Y/C. Video format of Super-VHS video recorders. Brightness is designated Y and is transmitted separately from color C. Thus, two coaxial cables are required for the Y/C output of S-VHS.

Y, R-Y, B-Y.A set of component video signals used in the PAL system, and in some cases when encoding and in most cases when decoding in NTSC; Y denotes the luminance signal, R-Y— the first color difference signal, B-Y— the second color difference signal.

Y, U, V. The luminance and color difference components of the PAL system; New designations for X B-Y, R-Y, the relationship with RGB is identical.

Z. In electronics and television, this is usually used to denote impedance (full resistance).

Zoom lens. A zoom lens is a lens with a variable focal length. A video camera lens that can change its focal length, keeping the subject in focus and giving the impression that you are moving closer or further away from the subject. Usually controlled from a keyboard with buttons labeled «zoom-in» and «zoom-out».

Zoom ratio. The number of times the focal length changes. A mathematical expression for the two extreme focal lengths of a particular zoom lens.

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