- 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 voice, video, or data communications, a circuit between two points that is ready for service, but is in the idle state. 2. In facsimile transmission, the portion of the scanning line that can be specifically used for image signals. Synonym useful line.
Industry:Telecommunications
The lowest modulation frequency at which the RMS peak-to-valley amplitude (optical power) difference of an intensity-modulated monochromatic signal decreases, at the output of the fiber, to a specified fraction (usually one-half) of the RMS peak-to-valley amplitude (optical power) difference of a nearly-zero (arbitrarily low) modulation frequency, both modulation frequencies having the same RMS peak-to-valley amplitude (optical power) difference at the fiber input. Note 1: In multimode fibers, multimode distortion is usually the most significant parameter limiting fiber bandwidth, although material dispersion may also play a significant role, especially in the first (850-nm) window. Note 2: In multimode fibers, the bandwidth•distance product (loosely, "fiber bandwidth") is customarily specified by vendors for the bandwidth as limited by multimode distortion only. The spectral width of the optical source is assumed to be extremely narrow. In practice, the effective fiber bandwidth will also be limited by dispersion, especially in the first (850-nm) window, where material dispersion is relatively high, because optical sources have a finite spectral width. Laser diodes typically have a spectral width of several nanometers, FWHM. LEDs typically have a spectral width of 35 to 100 nm, FWHM. Note 3: The effective risetime of multimode fibers may be estimated fairly accurately as the square root of the sum of the squares of the material-dispersion-limited risetime and the multimode-distortion-limited risetime. Note 4: In single-mode fibers, the most important parameters affecting fiber bandwidth are material dispersion and waveguide dispersion. Practical fibers are designed so that material dispersion and waveguide dispersion cancel one another at the wavelength of interest. Note 5: Regarding effective fiber bandwidth as it affects overall system performance, it should be recognized that optical detectors such as PIN diodes are square-law devices. Their photocurrent is proportional to the optical power of the detected signal. Because electrical power is a function of the square of the current, when the optical power decreases by one-half (a 3-dB decrease,) the electrical power decreases by three-fourths (a 6-dB decrease. ) 2. Loosely, synonym bandwidth•distance product.
Industry:Telecommunications
The original band of frequencies produced by a transducer, such as a microphone, telegraph key, or other signal-initiating device, prior to initial modulation. Note 1: In transmission systems, the baseband signal is usually used to modulate a carrier. Note 2: Demodulation re-creates the baseband signal. Note 3: Baseband describes the signal state prior to modulation, prior to multiplexing, following demultiplexing, and following demodulation. Note 4: Baseband frequencies are usually characterized by being much lower in frequency than the frequencies that result when the baseband signal is used to modulate a carrier or subcarrier. 2. In facsimile, the frequency of a signal equal in bandwidth to that between zero frequency and maximum keying frequency.
Industry:Telecommunications
See binary-coded decimal notation.
Industry:Telecommunications
