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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.
Aliasing in spatially sampled signals (e.g., moiré patterns in digital images) is referred to as spatial aliasing. Aliasing is generally avoided by applying low-pass filters or anti-aliasing filters (AAF) to the input signal before sampling and when converting a signal from a higher to a lower sampling rate.
Range aliasing occurs when reflections arrive from distances that exceed the distance between transmit pulses at a specific pulse repetition frequency (PRF). Range ambiguity resolution is required to obtain the true range when the measurements are made using a system where the following inequality is true.
Pulse-Doppler ambiguity zones. Each blue zone with no label represents a velocity/range combination that will be folded into the unambiguous zone. Areas outside the blue zones are blind ranges and blind velocities, which are filled in using multiple PRF and frequency agility. The unambiguous zone is in the lower left corner.
Ringing artifacts pose a problem with search, detection, and ambiguity resolution in pulse-Doppler radar. Ringing is reduced in two ways. First, the shape of the transmit pulse is adjusted to smooth the leading edge and trailing edge so that RF power is increased and decreased without an abrupt change.
The disadvantage of pulsed Doppler is that the measurements can suffer from aliasing. The terms Doppler ultrasound and Doppler sonography have been accepted to apply to both pulsed and continuous Doppler systems, despite the different mechanisms by which the velocity is measured. [citation needed] There are no standards for displaying color ...
This image was scaled up using nearest-neighbor interpolation.Thus, the "jaggies" on the edges of the symbols became more prominent. Jaggies are artifacts in raster images, most frequently from aliasing, [1] which in turn is often caused by non-linear mixing effects producing high-frequency components, or missing or poor anti-aliasing filtering prior to sampling.
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.