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  2. Relativistic Doppler effect - Wikipedia

    en.wikipedia.org/wiki/Relativistic_Doppler_effect

    The relativistic Doppler effect is the change in frequency, wavelength and amplitude [1] of light, caused by the relative motion of the source and the observer (as in the classical Doppler effect, first proposed by Christian Doppler in 1842 [2]), when taking into account effects described by the special theory of relativity.

  3. Doppler effect - Wikipedia

    en.wikipedia.org/wiki/Doppler_effect

    The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. [ 1 ] [ 2 ] [ 3 ] The Doppler effect is named after the physicist Christian Doppler , who described the phenomenon in 1842.

  4. Relativistic beaming - Wikipedia

    en.wikipedia.org/wiki/Relativistic_beaming

    Only a single jet is visible in M87. Two jets are visible in 3C 31.. In physics, relativistic beaming (also known as Doppler beaming, Doppler boosting, or the headlight effect) is the process by which relativistic effects modify the apparent luminosity of emitting matter that is moving at speeds close to the speed of light.

  5. Doppler cooling - Wikipedia

    en.wikipedia.org/wiki/Doppler_cooling

    Doppler cooling involves light with frequency tuned slightly below an electronic transition in an atom. Because the light is detuned to the "red" (i.e. at lower frequency) of the transition, the atoms will absorb more photons if they move towards the light source, due to the Doppler effect. Consider the simplest case of 1D motion on the x axis.

  6. Pulse compression - Wikipedia

    en.wikipedia.org/wiki/Pulse_compression

    The advantages [4] of the Barker codes are their simplicity (as indicated above, a de-phasing is a simple sign change), but the pulse compression ratio is lower than in the chirp case and the compression is very sensitive to frequency changes due to the Doppler effect if that change is larger than .

  7. Doppler radar - Wikipedia

    en.wikipedia.org/wiki/Doppler_radar

    The Doppler effect (or Doppler shift), named after Austrian physicist Christian Doppler who proposed it in 1842, is the difference between the observed frequency and the emitted frequency of a wave for an observer moving relative to the source of the waves. It is commonly heard when a vehicle sounding a siren approaches, passes and recedes from ...

  8. Fluctuation loss - Wikipedia

    en.wikipedia.org/wiki/Fluctuation_loss

    Fluctuation loss is an effect seen in radar systems as the target object moves or changes its orientation relative to the radar system. It was extensively studied during the 1950s by Peter Swerling, who introduced the Swerling models to allow the effect to be simulated.

  9. Doppler radio direction finding - Wikipedia

    en.wikipedia.org/wiki/Doppler_radio_direction...

    Doppler DF is one of the most widely used direction-finding techniques. Other direction-finding techniques are generally used only for fleeting signals or for longer or shorter wavelengths. The Doppler DF system uses the Doppler effect to determine whether a moving receiver antenna is approaching or receding from the source. Early systems used ...