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  2. Doppler effect - Wikipedia

    en.wikipedia.org/wiki/Doppler_effect

    [1] [2] [3] The Doppler effect is named after the physicist Christian Doppler, who described the phenomenon in 1842. A common example of Doppler shift is the change of pitch heard when a vehicle sounding a horn approaches and recedes from an observer. Compared to the emitted frequency, the received frequency is higher during the approach ...

  3. 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.

  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 broadening - Wikipedia

    en.wikipedia.org/wiki/Doppler_broadening

    A particular case is the thermal Doppler broadening due to the thermal motion of the particles. Then, the broadening depends only on the frequency of the spectral line, the mass of the emitting particles, and their temperature , and therefore can be used for inferring the temperature of an emitting (or absorbing) body being spectroscopically ...

  6. Radar signal characteristics - Wikipedia

    en.wikipedia.org/wiki/Radar_signal_characteristics

    Doppler spectrum. Deliberately no units given (but could be dBu and MHz for example). This is an issue only with a particular type of system; the pulse-Doppler radar, which uses the Doppler effect to resolve velocity from the apparent change in frequency caused by targets that have net radial velocities compared to the radar device. Examination ...

  7. Frequency modulation - Wikipedia

    en.wikipedia.org/wiki/Frequency_modulation

    FM also keeps the tape at saturation level, acting as a form of noise reduction; a limiter can mask variations in playback output, and the FM capture effect removes print-through and pre-echo. A continuous pilot-tone, if added to the signal – as was done on V2000 and many Hi-band formats – can keep mechanical jitter under control and assist ...

  8. Doppler radar - Wikipedia

    en.wikipedia.org/wiki/Doppler_radar

    Doppler Effect: Change of wavelength and frequency caused by motion of the source. The formula for radar Doppler shift is the same as that for reflection of light by a moving mirror. [ 3 ] There is no need to invoke Albert Einstein 's theory of special relativity , because all observations are made in the same frame of reference. [ 4 ]

  9. Doppler radio direction finding - Wikipedia

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

    Where S is the Doppler shift in frequency (Hz), r is the radius of the circle, W is the angular velocity in radians per second, λ is the target wavelength and c is the speed of light in meters per second. [13] Converting to more common units: To convert Hz to radians per second, multiply by 6.28 (2π) To convert MHz to Hz, multiply by one million