Compared to the emitted frequency, the received frequency is higher during the approach, identical at the instant of passing by, and lower during the recession. It is named after the Austrian physicist Christian Doppler, who described the phenomenon in 1842.Ī common example of Doppler shift is the change of pitch heard when a vehicle sounding a horn approaches and recedes from an observer.
The Doppler effect or Doppler shift (or simply Doppler, when in context) is the apparent change in frequency of a wave in relation to an observer moving relative to the wave source.
