For
telecommunications
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...
, a frequency grid is a table of all the central
frequencies (and corresponding
wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, t ...
s) of channels allowed in a
communications system
A communications system or communication system is a collection of individual telecommunications networks, transmission systems, relay stations, tributary stations, and terminal equipment usually capable of interconnection and interoperat ...
.
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
The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Comm ...
G.694.1.
[ITU-T G.694.1, "Spectral grids for WDM applications: DWDM frequency grid]
ITU-T website
/ref> The grid is defined relative to 193.1 THz and extends from 191.7 THz to 196.1 THz with 100 GHz spacing. While defined in frequency, the grid is often expressed in terms of wavelength, in which case it covers the wavelength range of 1528.77 nm to 1563.86 nm with approximately a 0.8 nm channel spacing.
For practical purposes, the grid has been extended to cover 186 THz to 201 THz and subdivided to provide 50 GHz and 25 GHz spaced grids.
References
External links
Complete ITU grid table for 100 Ghz spacingInternational Standardization Activities on Optical Interfaces
Multiplexing
ITU-T recommendations
ITU-T G Series Recommendations