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A form of spatial aliasing can also occur in antenna arrays or microphone arrays used to estimate the direction of arrival of a wave signal, as in geophysical exploration by seismic waves. Waves must be sampled more densely than two points per wavelength , or the wave arrival direction becomes ambiguous.
Spatial aliasing is also an issue with 2D data due to the lack of resolution between the lines. Beginning with initial experiments in the 1960s, the seismic technique explored the possibility of full three-dimensional acquisition and processing.
Seismic arrays can be classified by size, which is defined by the array's aperture given by the largest distance between the single seismometers. The sensors in a seismic array are arranged in different geometric patterns horizontally. The arrays built in the early 1960s were either cross (orthogonal linear) or L-shaped.
Multidimensional seismic data processing forms a major component of seismic profiling, a technique used in geophysical exploration. The technique itself has various applications, including mapping ocean floors, determining the structure of sediments, mapping subsurface currents and hydrocarbon exploration .
Spatial sampling in the other direction is determined by the spacing of scan lines in the raster. The sampling rates and resolutions in both spatial directions can be measured in units of lines per picture height. Spatial aliasing of high-frequency luma or chroma video components shows up as a moiré pattern.
For discrete aperture antennas (such as phased arrays) in which the element spacing is greater than a half wavelength, the spatial aliasing effect causes some sidelobes to become substantially larger in amplitude, and approaching the level of the main lobe; these are called grating lobes, and they are either identical, or nearly identical as shown in the figure, copies of the main beams.
A typical radiation pattern of phased arrays whose inter-element spacing is greater than half a wavelength, hence the radiation pattern has grating lobes.. For discrete aperture antennas (such as phased arrays) in which the element spacing is greater than a half wavelength, a spatial aliasing effect allows plane waves incident to the array from visible angles other than the desired direction ...
For land acquisition, different types of sources may be used depending on the acquisition settings. Explosive sources such as dynamite are the preferred seismic sources in rough terrains, in areas with high topographic variability or in environmentally sensitive areas e.g. marshes, farming fields, mountainous regions etc. [4] Such type of sources needs to be buried (coupled) into the ground in ...