continuous wave

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Related to Continous wave: Continuous wave radar, continuous wave laser, continuous wave Doppler

continuous wave

[kən¦tin·yə·wəs ′wāv]
(electromagnetism)
A radio or radar wave whose successive sinusoidal oscillations are identical under steady-state conditions. Abbreviated CW. Also known as type A wave.

continuous wave

(communications)
(CW) A term from early radio history, when the spark gap method of transmission was replaced by vacuum-tube oscillators. A spark gap initiates a ringing, damped sinusoidal wave in a tuned circuit consisting of an inductor and capacitor. The energy in this circuit is constantly changing between the capacitor's electrostatic field and the inductor's magnetic field. The energy is then coupled, loosely (so as not to dampen the wave too quickly), to the radiating antenna.

In contrast, a vacuum-tube oscillator constantly adds energy to the tuned circuit, compensating for the amount coupled to the antenna, and the transmitted energy or "wave," is therefore "continuous".

Many (especially radio amateurs) continue to understand "CW" to mean transmission by means a signal of a single frequency which is either on or off (e.g. Morse code), as opposed to a carrier which varies continuously in amplitude, frequency or phase. Some would even call the former "unmodulated" even though turning on and off is actually an extreme form of amplitude modulation.
References in periodicals archive ?
The increasing demand for Head Up Display equipments, pico projectors and video survellinacce systems is pushing the sales for continous wave laser diodes globally.
For the achievement of the welding tests, a 3,3 kW Nd:Yag continous wave laser was used as a thermal source together with an ABB 6-axes robot and a coaxial cladding unit made by Rofin.