Editing Continuous wave (section)

== Radar == 
Morse code is all but extinct outside the amateur service, so in non-amateur contexts the term CW usually refers to a [[continuous-wave radar]] system, as opposed to one transmitting short pulses. Some [[Monostatic radar|monostatic (single antenna) CW radars]] transmit and receive a single (non-swept) frequency, often using the transmitted signal as the [[local oscillator]] for the return; examples include police speed radars and microwave-type motion detectors and automatic door openers. This type of radar is effectively "blinded" by its own transmitted signal to stationary targets; they must move toward or away from the radar quickly enough to create a Doppler shift sufficient to allow the radar to isolate the outbound and return signal frequencies. This kind of CW radar can measure [[range rate]] but not [[Slant range|range]] (distance).

Other CW radars linearly or pseudo-randomly "chirp" ([[frequency modulation|frequency modulate]]) their transmitters rapidly enough to avoid self-interference with returns from objects beyond some minimum distance; this kind of radar can detect and range static targets. This approach is commonly used in [[radar altimeter]]s, in [[meteorology]] and in oceanic and atmospheric research. The [[landing radar]] on the [[Apollo Lunar Module]] combined both CW radar types.

CW [[bistatic radar]]s use physically separate transmit and receive antennas to lessen the self-interference problems inherent in monostatic CW radars.