Here, we only read FAQ consider the reciprocal case, i.e., sHV = sVH.Similar to [J], the 6��6 coherency matrix [T[ is defined as [6][7][T]?[k1k2][k1Hk2H]?=[[T11][��12][��21][T22]](5)where H denotes PR-171 the complex Inhibitors,Modulators,Libraries conjugation and transpose.To extend the scalar formulation into a vector expression, two normalized complex vectors w1 and w2 are introduced. Then two scattering coefficients ��1 and ��2 are defined as the projections of the scattering vectors k1 and k2 onto the Inhibitors,Modulators,Libraries vectors w1 and w2, respectively,��1=w1Hk1,��2=w2Hk2(6)Then the interferometric phase is derived as?s=arg(��1��2*)=arg(w1Hk1k2Hw2)(7)for the single-look (SL) case, and?m=arg(?��1��2*?)=arg(w1H[��12]w2)(8)for the multi-look (ML) case.
The generalized vector expression for the coherence �� is then given by��=|?w1H[��12]w2?|?w1H[T11]w1??w2H[T22]w2?(9)To maximize the coherence ��, the Lagrange multiplier method is used to transform the problem into two eigendecompositions Inhibitors,Modulators,Libraries [6][7][T11]?1[��12][T22]?1[��12]Hw1=vw1[T22]?1[��12]H[T11]?1[��12]w2=vw2(10)The Inhibitors,Modulators,Libraries maximum coherence value is then given by the square Inhibitors,Modulators,Libraries root of the maximum eigenvalue [6]��max=vmax(11)and the corresponding optimum eigenvectors of (10) are w1opt and w2opt.Finally, a sensible constraint is to requirearg(w1optHw2pot)=0(12)In Inhibitors,Modulators,Libraries this method, the interferometric coherence �� is optimized directly and the maximal coherence value can be obtained by w1opt and w2opt. The corresponding interferometric phase ? defined in (8) is much better than the original phase in each polarimetric channel.
The authors derived a decomposition of target scattering characteristics.
It is one of the most important methods Inhibitors,Modulators,Libraries to explore the scattering structure and behavior of the vegetation-covered area.Though Inhibitors,Modulators,Libraries the coherence might indicate the phase noise, however, it is usually estimated by using neighborhood information and not accurate. So for phase improvement, coherence optimization is not the best approach. Especially in weak signal area, the improved phase by coherence optimization is still noisy. Fortunately, the proposed method can be used to obtain a nearly noise-free phase result in the moderate noise case.3.?Relationship between the amplitude and the phase of a complex signalIn SAR interferometry, only one polarimetric channel signal can be received, e.
g., HH. For each scattering element, the amplitudes of the complex signals s1 and s2 vary with the terrain Dacomitinib fluctuation and the scattering characteristic of the ground targets.
In some areas, the amplitude of the received signals may be very low. Carfilzomib When a complex www.selleckchem.com/products/Lenalidomide.html noise is added to a weak signal, a considerable change in the signal phase may occur. In this case, the interferometric phase between two weak signals will be severely affected by blog of sinaling pathways noises and will be of low quality and unreliable. Therefore, a lot of residue points may exist to deteriorate the performance of phase unwrapping. In addition, weak signals usually imply a low signal-to-noise ratio (SNR).