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FCC. Federal Communications Commission. FFT. Fast Fourier Transformation. Fiber optics. A technology designed to transmit signals in the form of pulses of light. Fiber optic cable is noted for its properties of electrical isolation and resistance to electrostatic and electromagnetic interference. Field. Refers to one-half of the TV frame that is composed of either all odd or even lines. In CCIR systems each field is composed of 625/2 = 312.5 lines, in EIA systems 525/2 = 262.5 lines. There are 50 fields/second in CCIR/PAL, and 60 in the EIA/NTSC TV system. Film recorder. A device for converting digital data into film output. Continuous tone recorders produce color photographs as transparencies, prints or negatives. Fixed focal length lens. A lens with a predetermined fixed focal length, a focusing control and a choice of iris functions. Flash memory. Nonvolatile, digital storage. Flash memory has slower access than SRAM or DRAM. Flicker. An annoying picture distortion, mainly related to vertical syncs and video fields display. Some flicker normally exists due to interlacing; more apparent in 50 Hz systems (PAL). Flicker shows also when static images are displayed on the screen such as computer generated text transferred to video. Poor digital image treatment, found in low-quality system converters (going from PAL to NTSC and vice versa), creates an annoying flicker on the screen. There are several electronic methods to minimize flicker. F-number. In lenses with adjustable irises, the maximum iris opening is expressed as a ratio (focal length of the lens)/(maximum diameter of aperture). This maximum iris will be engraved on the front ring of the lens. Focal length. The distance between the optical center of a lens and the principal convergent focus point. Focusing control. A means of adjusting the lens to allow objects at various distances from the camera to be sharply defined. Foot-candela. An illumination light unit used mostly in American CCTV terminology. It equals ten times (more precisely, 9.29) of the illumination value in luxes. Fourier Transformation. Mathematical transformation of time domain functions into frequency domain. Frame. (See also Field). Refers to a composition of lines that make one TV frame. In CCIR/PAL TV system one frame is composed of 625 lines, while in EIA/NTSC TV system of 525 lines. There are 25 frames/second in the CCIR/PAL and 30 in the EIA/NTSC TV system. Frame store. An electronic device that digitizes a TV frame (or TV field) of a video signal and stores it in memory. Multiplexers, fast scan transmitters, Quad compressors and even some of the latest color cameras have built-in frame stores. Frame switcher. Another name for a simple multiplexer, which can record multiple cameras on a single VCR (and play back any camera in full screen) but does not have a mosaic image display. Frame synchronizer. A digital buffer that, by storage and comparison of sync information to a reference and timed release of video signals, can continuously adjust the signal for any timing errors. Frame transfer (FT). Refers to one of the three principles of charge transfer in CCD chips. The other two are interline and frame-interline transfer. Frame-interline transfer (FIT). Refers to one of the few principles of charge transfer in CCD chips. The other two are interline and frame transfer. Frequency. The number of complete cycles of a periodic waveform that occur in a given length of time. Usually specified in cycles per second (Hertz). Frequency modulation (FM). Modulation of a sine wave or carrier by varying its frequency in accordance with amplitude variations of the modulating signal. Front porch. The blanking signal portion that lies between the end of the active picture information and the leading edge of horizontal sync. Gain. Any increase or decrease in strength of an electrical signal. Gain is measured in terms of decibels or number of times of magnification. Gamma. A correction of the linear response of a camera in order to compensate for the monitor phosphor screen nonlinear response. It is measured with the exponential value of the curve describing the non-linearity. A typical monochrome monitor’s gamma is 2.2, and a camera needs to be set to the inverse value of 2.2 (which is 0.45) for the overall system to respond linearly (i.e., unity). Gamut. The range of voltages allowed for a video signal, or a component of a video signal. Signal voltages outside of the range (i.e., exceeding the gamut) may lead to clipping, crosstalk or other distortions. Gen-lock. A way of locking the video signal of a camera to an external generator of synchronization pulses. GHz. GigaHertz. One billion cycles per second. GB. Gigabyte. Unit of computer memory consisting of about one thousand million bytes (a thousand megabytes). Actual value is 1,073,741,824 bytes. GND. Ground (electrical). Gray scale. A series of tones that range from true black to true white, usually expressed in 10 steps. Ground loop. An unwanted interference in the copper electrical signal transmissions with shielded cable, which is a result of ground currents when the system has more than one ground. For example, in CCTV, when we have a different earthing resistance at the camera, and the switcher or monitor end. The induced electrical noise generated by the surrounding electrical equipment (including mains) does not discharge equally through the two earthings (since they are different) and the induced noise shows up on the monitors as interference. GUI. Graphical user interface. HAD. Hole accumulated diode. A type of CCD sensor with a layer designed to accumulate holes (in the electronic sense), thus reducing noise level. HDD. Hard disk drive. A magnetic medium for storing digital information on most computers and electronic equipment that process digital data. HDDTV. High definition digital television. The upcoming standard of broadcast television with extremely high resolution and aspect ratio of 16:9. It is an advancement from the analog high definition, already used experimentally in Japan and Europe. The picture resolution is nearly 2000×1000 pixels, and uses the MPEG-2 standard. HDTV. High definition television. It usually refers to the analog version of the HDDTV. The SMPTE in the US and ETA in Japan have proposed a HDTV product standard: 1125 lines at 60 Hz field rate 2:1 interlace; 16:9 aspect ratio; 30 MHz RGB and luminance bandwidth. Headend. The electronic equipment located at the start of a cable television system, usually including antennas, earth stations, preamplifiers, frequency converters, demodulators, modulators and related equipment. Helical scan. A method of recording video information on a tape, most commonly used in home and professional VCRs. Horizontal Drive (also Horizontal sync). This signal is derived by dividing sub-carrier by 227.5 and then doing some pulse shaping. The signal is used by monitors and cameras to determine the start of each horizontal line. Horizontal resolution. Chrominance and luminance resolution (detail) expressed horizontally across a picture tube. This is usually expressed as a number of black to white transitions or lines that can be differentiated. Limited by the bandwidth of the video signal or equipment. Herringbone. Patterning caused by driving a color-modulated composite video signal (PAL or NTSC) into a monochrome monitor. Horizontal retrace. At the end of each horizontal line of video, a brief period when the scanning beam returns to the other side of the screen to start a new line. Horizontal sync pulse. The synchronizing pulse at the end of each video line that determines the start of horizontal retrace. Hertz. An unit that measures the number of certain oscillations per second. Housings, environmental. Usually refers to cameras’ and lenses containers and associated accessories, such as heaters, washers and wipers, to meet specific environmental conditions. HS. Horizontal sync. Hue (tint, phase, chroma phase). One of the characteristics that distinguishes one color from another. Hue defines color on the basis of its position in the spectrum, i.e., whether red, blue, green or yellow, etc. Hue is one of the three characteristics of television color: see also Saturation and Luminance. In NTSC and PAL video signals, the hue information at any particular point in the picture is conveyed by the corresponding instantaneous phase of the active video subcarrier. Hum. A term used to describe an unwanted induction of mains frequency. Hum bug. Another name for a ground loop corrector. Hyper-HAD. An improved version of the CCD HAD technology, utilizing on-chip micro-lens technology to provide increased sensitivity without increasing the pixel size. |