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For telecommunications, a frequency grid is a table of all the central frequencies (and corresponding wavelengths) of channels allowed in a communications system.. The most common frequency grid used for fiber-optic communication is that used for channel spacing in Dense Wavelength Division Multiplexing (DWDM) at wavelengths around 1550 nm and defined by ITU-T G.694.1. [1]
In 2002, the ITU standardized a channel spacing grid for CWDM (ITU-T G.694.2) using the wavelengths from 1270 nm through 1610 nm with a channel spacing of 20 nm. ITU G.694.2 was revised in 2003 to shift the channel centers by 1 nm so, strictly speaking, the center wavelengths are 1271 to 1611 nm. [ 5 ]
Fax standards T.2 – T.4, T.30, T.37, T.38 F.780.2 G.114 is an ITU Recommendation that addresses acceptable delays for voice applications, is oriented to national telecommunications, and is more stringent than what is normally applied in private voice networks.
The range of mode field diameter permitted in G.655 is 8 to 11 μm in non-zero dispersion-shifted fibre. G.655.C fibre has a maximum PMD link design value of 0.20 ps/sqrtkm, which is the lowest value recommended by ITU-T. G.655 has the cable cut-off wavelength and cable attenuation coefficients in the C and L bands. [2]
G.652 is an international standard that describes the geometrical, mechanical, and transmission attributes of a single-mode optical fibre and cable, developed by the Standardization Sector of the International Telecommunication Union that specifies the most popular type of single-mode optical fiber (SMF) cable.
The ITU-T V-Series Recommendations on Data communication over the telephone network specify the protocols that govern approved modem communication standards and interfaces. [ 1 ] Note: the bis and ter suffixes are ITU-T standard designators of successive iterations of a standard ( bis and ter are the Latin words for "twice" and "thrice").
As a matter of convention, the ITU divides the radio spectrum into 12 bands, each beginning at a wavelength which is a power of ten (10 n) metres, with corresponding frequency of 3×10 8−n hertz, and each covering a decade of frequency or wavelength. Each of these bands has a traditional name.
Going beyond 200 Gbit/s per WDM channel requires the use of multiple carriers to make up a single WDM interface. The resulting multiplex, called a super-channel (or superchannel), creates a multi-wavelength signal in which each wavelength will operate at the maximum data rate permitted by commercially available ADC components.