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  2. Coherence time (communications systems) - Wikipedia

    en.wikipedia.org/wiki/Coherence_time...

    That is, where () is the maximum Doppler spread or, maximum Doppler frequency or, maximum Doppler shift given by = with being the center frequency of the emitter. Coherence time is actually a statistical measure of the time duration over which the channel impulse response is essentially invariant, and quantifies the similarity of the channel ...

  3. Doppler radio direction finding - Wikipedia

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

    Doppler radio direction finding, also known as Doppler DF, is a radio direction-finding method that generates accurate bearing information with minimal electronics. It is best suited to applications in VHF and UHF frequencies and takes only a short time to indicate a direction. This makes it suitable for measuring the location of the vast ...

  4. Continuous-wave radar - Wikipedia

    en.wikipedia.org/wiki/Continuous-wave_radar

    Continuous-wave radar without frequency modulation (FM) only detects moving targets, as stationary targets (along the line of sight) will not cause a Doppler shift. Reflected signals from stationary and slow-moving objects are masked by the transmit signal, which overwhelms reflections from slow-moving objects during normal operation.

  5. 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.

  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. Ambiguity function - Wikipedia

    en.wikipedia.org/wiki/Ambiguity_function

    In pulsed radar and sonar signal processing, an ambiguity function is a two-dimensional function of propagation delay and Doppler frequency, (,).It represents the distortion of a returned pulse due to the receiver matched filter [1] (commonly, but not exclusively, used in pulse compression radar) of the return from a moving target.

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  9. Frequency modulation - Wikipedia

    en.wikipedia.org/wiki/Frequency_modulation

    This dynamic frequency modulation is called the Doppler Shift Compensation (DSC), and was discovered by Hans Schnitzler in 1968. Magnetic tape storage.