- Industry: Telecommunications
- Number of terms: 29235
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ATIS is the leading technical planning and standards development organization committed to the rapid development of global, market-driven standards for the information, entertainment and communications industry.
In electrical circuits, for a four-terminal network, the impedance that, if connected across one pair of terminals, will match the impedance across the other pair of terminals. Note: The iterative impedance of a uniform line is the same as its characteristic impedance.
Industry:Telecommunications
In electrical circuits and networks, to adjust the impedance to achieve specific objectives, such as to reach specified return loss objectives at a hybrid junction of two-wire and four-wire circuits.
Industry:Telecommunications
In display systems, the relation between the intensity of color or brightness of an area occupied by an element or an image and the intensity of the area not occupied by that element or image. Deprecated synonym brightness ratio. 2. In optical character recognition, the difference between color or shading of the printed material on a document and the background on which it is printed. 3. In display systems, the extent to which the various luminance values in a picture are mapped to very dark and very light values. Note: A high-contrast picture is dominated by black and white and few values between. A low-contrast picture has many middle tones without many very dark or very light areas.
Industry:Telecommunications
In display systems, the number of scanning lines per unit distance perpendicular to the scanning direction.
Industry:Telecommunications
In digital video, a sampling where the luminance and the color-difference samples are generated from pixels arranged in common, continuous vertical and horizontal lines on a rectilinear grid that remains constant field/frame to field/frame.
Industry:Telecommunications
In digital transmission, the number of discrete signal levels transmitted as the result of signal digitization.
Industry:Telecommunications
In digital transmission, the loss of a bit or bits, caused by variations in the respective clock rates of the transmitting and receiving devices. Note: One cause of bit slippage is overflow of a receive buffer that occurs when the transmitter's clock rate exceeds that of the receiver. This causes one or more bits to be dropped for lack of storage capacity.
Industry:Telecommunications
In digital transmission, angle modulation in which the phase of the carrier is discretely varied in relation either to a reference phase or to the phase of the immediately preceding signal element, in accordance with data being transmitted. 2. In a communications system, the representing of characters, such as bits or quaternary digits, by a shift in the phase of an electromagnetic carrier wave with respect to a reference, by an amount corresponding to the symbol being encoded. Note 1: For example, when encoding bits, the phase shift could be 0° for encoding a "0," and 180° for encoding a "1," or the phase shift could be -90 for "0" and +90° for a "1," thus making the representations for "0" and "1" a total of 180° apart. Note 2: In PSK systems designed so that the carrier can assume only two different phase angles, each change of phase carries one bit of information, i.e., the bit rate equals the modulation rate. If the number of recognizable phase angles is increased to 4, then 2 bits of information can be encoded into each signal element; likewise, 8 phase angles can encode 3 bits in each signal element. Synonyms biphase modulation, phase-shift signaling.
Industry:Telecommunications
In digital television technology, a video frame created from the preceding key frame by modifying only those pixels that have changed. Note: The use of delta frames reduces (a) the data rate required to transmit a given number of video frames per second (frame rate,) or (b) the storage capacity required to store multiple video frames. Synonym difference frame.
Industry:Telecommunications
In digital telephony, a test signal consisting of eight 8-bit words corresponding to one cycle of a sinusoidal signal approximately 1 kHz in frequency and one milliwatt, rms, in power. Note 1: The digital milliwatt is stored in ROM. A continuous signal of arbitrary length, i.e., an indefinite number of cycles, may be realized by continually reading out and concatenating the stored information into a data stream to be converted into analog form. Note 2: The digital milliwatt is used in lieu of separate test equipment. It has the advantage of being tied in frequency and amplitude to the relatively stable digital clock signal and power (voltage) supply, respectively, that are used by the digital channel bank. 2. A digital signal that is the coded representation of a 0-dBm, 1000-Hertz sine wave.
Industry:Telecommunications
