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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.
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]
It equals the spatial frequency. For example, a wavenumber in inverse centimeters can be converted to a frequency expressed in the unit gigahertz by multiplying by 29.979 2458 cm/ns (the speed of light, in centimeters per nanosecond); [5] conversely, an electromagnetic wave at 29.9792458 GHz has a wavelength of 1 cm in free space.
The ITU arbitrarily 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 times a power of ten, and each covering a decade of frequency or wavelength. [3] [41] Each of these bands has a traditional name: [42]
FM channel 200, 87.9 MHz, overlaps TV 6. This is used only by K200AA.; TV 6 analog audio can be heard on FM 87.75 on most broadcast radio receivers as well as on a European TV tuned to channel E4A or channel IC, but at lower volume than wideband FM broadcast stations, because of the lower deviation.
Very low frequency or VLF is the ITU designation [1] for radio frequencies (RF) in the range of 3–30 kHz, corresponding to wavelengths from 100 to 10 km, respectively. The band is also known as the myriameter band or myriameter wave as the wavelengths range from one to ten myriameters (an obsolete metric unit equal to 10 kilometers).
Frequency range Wavelength range ITU designation IEEE bands [5] Full name Abbreviation [6] Below 3 Hz >10 5 km — 3–30 Hz 10 5 –10 4 km: Extremely low frequency: ELF — 30–300 Hz 10 4 –10 3 km: Super low frequency: SLF — 300–3000 Hz 10 3 –100 km: Ultra low frequency: ULF — 3–30 kHz 100–10 km: Very low frequency: VLF — 30 ...
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. [1]: 26‑1 As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. [2]