Файл:Damped Waves.svgA series of damped waves, such as would be radiated by a spark-gap transmitter. In this graph, the vertical axis is the amplitude of the wave, in units such as voltage or electric field strength; the horizontal axis is time.
Such transmissions have a wide bandwidth and generate electrical "noise" (electromagnetic interference) which interferes with other radio transmissions. Because of their potential to cause interference and their resulting wasteful use of radio spectrum resources, there is an international prohibition against the use of class B damped wave radio emissions (except in the USA under Part 15: "§15.521 Technical requirements applicable to all UWB devices. (i) The prohibition in §2.201(f) and 15.5(d) of this chapter against Class B (damped wave) emissions does not apply to UWB devices operating under this subpart."), established by the International Telecommunication Union in 1938.[1][2]
However the definition of "damped waves" in these regulations is unclear when applied to modern technology, and recently there have been moves to amend this prohibition to exempt emerging radio technologies such as ultra-wideband transmission systems.[3]
↑individual nations enforce this prohibition in their communication laws. In the United States this is implemented in regulations of the Federal Communications Commission: Шаблон:Cite web