- Industry: Telecommunications
- Number of terms: 29235
- Number of blossaries: 0
- Company Profile:
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.
Of a set of redundant clocks, the clock that is selected for normal use. Note 1: The principal clock may be selected because of a property, e.g., superior accuracy, that makes it a unique member of the set. Note 2: The term "principal clock" should not be confused with, or used as a synonym for, the term "primary frequency standard. "
Industry:Telecommunications
Of a signal, the ratio of (a) the sum of the powers of all harmonic frequencies above the fundamental frequency to (b) the power of the fundamental frequency. Note 1: The THD is usually expressed in dB. Note 2: Measurements for calculating the THD are made at the output of a device under specified conditions.
Industry:Telecommunications
Of a sinusoidal wave, an integral multiple of the frequency of the wave. Note: The frequency of the sine wave is called the fundamental frequency or the first harmonic, the second harmonic is twice the fundamental frequency, the third harmonic is thrice the fundamental frequency, etc. 2. Of a periodic signal or other periodic phenomenon, such as an electromagnetic wave or a sound wave, a component frequency of the signal that is an integral multiple of the fundamental frequency. Note: The fundamental frequency is the reciprocal of the period of the periodic phenomenon.
Industry:Telecommunications
Of a sinusoidal wave, an integral multiple of the frequency, i.e., the fundamental, of the wave, other than the fundamental itself. Note 1: The first overtone is twice the frequency of the fundamental, and thus corresponds to the second harmonic; the second overtone is three times the frequency of the fundamental, and thus corresponds to the third harmonic, etc. Note 2: Use of the term overtone is generally confined to acoustic waves, especially in applications related to music.
Industry:Telecommunications
Of a system or device, a plot of the amplitude as a function of frequency. Note: The insertion-loss-vs. -frequency characteristic may be expressed as absolute gain or loss, or it may be normalized with respect to gain or loss at a specified reference frequency.
Industry:Telecommunications
Of a television baseband signal (e.g., NTSC composite video,) the voltage level corresponding to black or to the maximum limit of black peaks.
Industry:Telecommunications
Of a transmission medium, its length expressed as a multiple or submultiple of the wavelength of a periodic electromagnetic or electrical signal propagating within the medium. Note 1: The wavelength may be expressed in radians or in artificial units of angular measure, such as degrees. Note 2: In both coaxial cables and optical fibers, the velocity of propagation is approximately two-thirds that of free space. Consequently, the wavelength will be approximately two-thirds that in free space, and the electrical length, approximately 1. 5 times the physical length. 2. Of a transmission medium, its physical length multiplied by the ratio of (a) the propagation time of an electrical or electromagnetic signal through the medium to (b) the propagation time of an electromagnetic wave in free space over a distance equal to the physical length of the medium in question. Note: The electrical length of a physical medium will always be greater than its physical length. For example, in coaxial cables, distributed resistances, capacitances and inductances impede the propagation of the signal. In an optical fiber, interaction of the lightwave with the materials of which the fiber is made, and fiber geometry, affect the velocity of propagation of the signal. 3. Of an antenna, the effective length of an element, usually expressed in wavelengths. Note 1: The electrical length is in general different from the physical length. Note 2: By the addition of an appropriate reactive element (capacitive or inductive,) the electrical length may be made significantly shorter or longer than the physical length.
Industry:Telecommunications
Of a UPT call, any network function associated with the termination of the call to the destination terminal.
Industry:Telecommunications
Of a virtual connection section, the long-term percentage of scheduled service time during which that section is available.
Industry:Telecommunications
Of a wave propagating in a material medium, a phenomenon in which the direction, frequency, or polarization of the wave is changed when the wave encounters discontinuities in the medium, or interacts with the material at the atomic or molecular level. Note: Scattering results in a disordered or random change in the incident energy distribution.
Industry:Telecommunications
