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coherent sources

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coherent sources 

If light beams from two independent sources reach the same point in space, there is no fixed relationship between the phases of the two light beams and they will not combine to form interference effects. Such light waves are called incoherent. If, on the other hand, the two light beams are superimposed after reaching the same point by different paths but are both radiated from one point of a source, interference effects will be seen because the phase difference in the two beams is constant. The two virtual sources from which these two beams are apparently coming are called coherent sources and any rays in which there is a constant phase difference are called coherent rays. Prior to the advent of the laser, the only way in which one could obtain coherent rays was by dividing the light coming from a point source into two parts. See Young's experiment; holography; clinical maxwellian view system; optical coherence tomography.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
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Assume that two uncorrelated sources from {-32.2[degrees], -11.5[degrees]} and two coherent sources from {6.7[degrees], 23.4[degrees]} with fading coefficients [1,0.2891 - 0.7567j] impinge on this ULA.
Consider two coherent sources from 10.1[degrees] and 10.1[degrees] + [DELTA][theta] with the angular separation [DELTA][theta] ranging from 3[degrees] to 10[degrees].
In this paper, we develop a DOA estimation algorithm for a mixture of uncorrelated and coherent sources using SBI.
Wang, "Real-valued DOA estimation for a mixture of uncorrelated and coherent sources via unitary transformation," Digital Signal Processing, vol.
Caption: Figure 9: RMSE versus angular separation with the fixed SNR 10 dB and number of snapshots 500 for coherent sources.
DOA Estimation for a Mixture of Uncorrelated and Coherent Sources Based on Hierarchical Sparse Bayesian Inference with a Gauss-Exp-[Chi.sup.2] Prior
The performance of the proposed method is also evaluated by considering noncoherent and/or coherent sources. Furthermore, the improvement in performance is also investigated by using more than one snapshot of the received signals.
The same effect is also investigated by considering two coherent sources. The sources are located at ([[theta].sub.1] = 70[degrees], [[phi].sub.1] = 50[degrees]) and ([[theta].sub.2] = 80[degrees], [[phi].sub.2] = 60[degrees]).
Effect on Standard Deviation (STD) in the Presence of Noncoherent and Coherent Sources Together.
The scatter plot is also obtained for the proposed method in the presence of noncoherent and coherent sources separately.
Two coherent sources are located at ([[theta].sub.1] = 40[degrees], [[phi].sub.1] = 50[degrees]) and ([[theta].sub.2] = 60[degrees], [[phi].sub.2] = 70[degrees]), and SNR = 0 dB.
Parallel Factor-Based Model for Two-Dimensional Direction Estimation
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