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Examples of pulse shapes: (a) rectangular pulse, (b) cosine squared (raised cosine) pulse, (c) Dirac pulse, (d) sinc pulse, (e) Gaussian pulse. A pulse in signal processing is a rapid, transient change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value. [1]
Radial velocity aliasing occurs when reflections arrive from reflectors moving fast enough for the Doppler frequency to exceed the pulse repetition frequency (PRF). Frequency ambiguity resolution is required to obtain the true radial velocity when the measurements is made using a system where the following inequality is true.
The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity onto the relative direction or line-of-sight (LOS) connecting the two points.
In this example there are 1000 pulses per second (one kilohertz pulse rate) with a gated pulse width of 42 μs. The pulse packet frequency in this example is 27.125 MHz of RF energy. The duty cycle for a pulsed radio frequency is the percent time the RF packet is on, 4.2% for this example ([0.042 ms × 1000 pulses divided by 1000 ms/s] × 100).
Radar Pulse Train. The carrier is an RF signal, typically of microwave frequencies, which is usually (but not always) modulated to allow the system to capture the required data. In simple ranging radars, the carrier will be pulse modulated and in continuous wave systems, such as Doppler radar, modulation may not be required
Radial velocity is essential for pulse-Doppler radar operation. As the reflector moves between each transmit pulse, the returned signal has a phase difference, or phase shift, from pulse to pulse. This causes the reflector to produce Doppler modulation on the reflected signal. Pulse-Doppler radars exploit this phenomenon to improve performance.
Pulse duration using 50% peak amplitude. DECT phone pulduration measurement (100 Hz / 10 mS) on channel 8. In signal processing and telecommunications, pulse duration is the interval between the time, during the first transition, that the amplitude of the pulse reaches a specified fraction (level) of its final amplitude, and the time the pulse amplitude drops, on the last transition, to the ...
The radial component of the source's motion along the line of sight is equal to . The equation below can be interpreted as the classical Doppler shift for a stationary and moving source modified by the Lorentz factor γ : {\\displaystyle \\gamma :}