- 업종: Telecommunications
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In audio and video teleconferences, the user in charge of the conference when the service is invoked and the conference reaches the active state. Note: The conference controller may perform any or all of the following actions: drop, floating, isolate, reattach, and split. Synonym moderator.
Industry:Telecommunications
In audio and video analog recording, pertaining to the number of duplication steps between an original recording and a given copy. Note 1: A second generation duplicate is a copy of the original master and a third generation duplicate is a copy of a copy of the original master, etc. Note 2: Relative to digital duplication, the copy is almost always identical to the original, so the term generation is irrelevant.
Industry:Telecommunications
In asynchronous transmission, the time interval between the end of the stop signal of one character and the beginning of the start signal of the next character. Note: The intercharacter interval may be of any duration. The signal sense of the intercharacter interval is always the same as the sense of the stop element, i.e., "1" or "mark. "
Industry:Telecommunications
In asynchronous data transmission, the ratio of (a) the absolute value of the maximum measured difference between the actual and theoretical intervals separating any significant instant of modulation (or demodulation) from the significant instant of the start element immediately preceding it to (b) the unit interval. 2. The highest absolute value of individual distortion affecting the significant instants of a start-stop modulation. Note: The degree of distortion of a start-stop modulation (or demodulation) is usually expressed as a percentage. Distinction can be made between the degree of late (positive) distortion and the degree of early (negative) distortion.
Industry:Telecommunications
In any technology or process involving (a) sampling a signal, e.g., an electrical signal or (a series of images of) a moving subject; (b) processing, storing, or transmitting representations of the samples; and (c) replicating the original signal from the representations: the production of artifacts as a result of sampling at intervals too great to permit faithful replication of the original signal. Note 1: A common example of aliasing in video or motion picture technology is the apparent slowing, freezing, or even reversing of direction of, the motion of spokes in the wheels on a moving vehicle. Note 2: In the sampling and replication of electrical signals, if the sampling interval is too great, high-frequency components may, for example, be replicated as low-frequency components, distorting the replicated signal. Note 3: Faithful reproduction of a sampled electrical signal requires a theoretical sampling interval not greater than one-half the inverse of the highest Fourier frequency component in the sampled signal (Nyquist interval. ) In practice, to achieve a given level of fidelity in the replicated signal, the sampling interval must usually be somewhat shorter than the theoretical (Nyquist) interval, because the samples are usually processed, stored, or transmitted in digital form, and quantization errors in the digitizing process will also result in distortion of the (waveform of the) replicated signal. Note 4: The effects of aliasing in the replicated signal may be avoided by filtering the original signal to remove frequency components that are higher than those desired in the replicated signal. Note 5 (from SMPTE) : Video images are sampled in two or three dimensions, and computer graphics are sampled in three. In a composite (complex) spectral channel, any crosstalk of the information cannot be eliminated by filtering, and will produce aliasing, for example as cross-color and/or cross-luminance. In a rectilinearly sampled system, lines not parallel to a sampling axis will appear stepped unless anti-aliasing processing algorithms have been applied.
Industry:Telecommunications
In angle modulation, the ratio of the frequency deviation of the modulated signal to the frequency of a sinusoidal modulating signal. Note: The modulation index is numerically equal to the phase deviation in radians.
Industry:Telecommunications
In angle modulation, the fraction of a specified reference modulation, expressed in percent. 2. In amplitude modulation, the modulation factor expressed in percent. Note: Percentage modulation may also be expressed in dB below 100% modulation.
Industry:Telecommunications
In analog recording, cumulative deterioration of signal quality introduced as a consequence of limitations of the recording electronics and storage medium, when successive copies of an original recording are made, each from the preceding copy. Note 1: Examples of signal deterioration attributable to generation loss are increased distortion, increased noise, change in frequency response, and change in the relative phase of one frequency component with respect to another. Note 2: As a specific example, in the recording of television baseband signals, generation loss may manifest itself in the loss of fine detail, color distortion, erratic synchronization, etc. In audio recording, generation loss may manifest itself as audible distortion or loss of frequency response. Note 3: Generation loss is limited to analog recording because digital recording and reproduction may be performed in a manner that is essentially free from generation loss. Digital signals may be reshaped before being rerecorded, so successive generations are extremely faithful to one another, with possible exceptions attributable primarily to occasional uncompensated flaws that may be present in the recording medium. The degree to which this affects the outcome (signal quality) depends on the specific recording technique involved, but it is usually negligible. In digital recording, essentially all of the distortion introduced in the recording and playback process takes place in (a) the analog-to-digital conversion that occurs during the initial recording, and (b) the digital-to-analog process that occurs during playback. Note 4: Generation loss in digital recordings can quickly become non-negligible unless all transfers of the recording take place solely in the digital domain and lossless compression/decompression is used.
Industry:Telecommunications
In analog facsimile systems, a baseband frequency generated by scanning an object. Note: Picture frequencies do not include frequencies that are present in a modulated carrier.
Industry:Telecommunications
In analog computing, a functional unit that compares two analog variables and indicates the result of that comparison. 2. A device that compares two items of data and indicates the result of that comparison. 3. A device for determining the dissimilarity of two items such as two pulse patterns or words.
Industry:Telecommunications
