Damped wave - Citizendia

A damped wave is an electromagnetic wave whose amplitude of oscillation decreases with time, eventually going to zero. Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. Amplitude is the magnitude of change in the oscillating variable with each Oscillation, within an oscillating system Oscillation is the repetitive variation typically in Time, of some measure about a central value (often a point of Equilibrium) or between two or more different states This term also refers to an early method of radio transmission from spark gap transmitters, or other types of transmitters having characteristic decrement similar to spark transmitters, in which a carrier wave is switched on and off. In Telecommunications transmission is the process of sending propagating and receiving an analogue or digital information signal over a physical point-to-point or A spark-gap transmitter is a device for generating Radio frequency electromagnetic waves. In Telecommunications, a carrier wave, or carrier is a Waveform (usually Sinusoidal) that is modulated (modified with an input signal This is generally referred to as "Class B" emission. Information is carried in the rhythm and spacing with which the signal is sent. Damped waves were used for a form of on-off keying (OOK). On-off keying ( OOK) is a type of Modulation that represents Digital Data as the presence or absence of a Carrier wave. However, such transmitters were noisy and generated a wide emission bandwidth. Bandwidth is the difference between the upper and lower Cutoff frequencies of for example a filter, a Communication channel, or a Signal spectrum

There is a currently an international prohibition against the use of Class B, damped wave emission. This prohibition forms part of the International Telecommunication Union regulations and is a throwback to the days when spark gap transmitters were employed. The prohibition against Class B emissions was intended to prevent the generation of wasteful radio frequency energy and the use of inefficient transmission techniques. However, ironically there is no longer a clear definition of a Class B, damped wave emission.

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