  The cosmological power spectrum of the coherent matter flow is measured
exploiting an improved prescription for the apparent anisotropic clustering
pattern in redshift space. New statistical analysis is presented to provide an
optimal observational platform to link the improved redshift distortion
theoretical model to future real datasets. The statistical power as well as
robustness of our method are tested against 60 realizations of 8 Gpc/h^3 dark
matter simulation maps mocking the precision level of upcoming wide--deep
surveys. We showed that we can accurately extract the velocity power spectrum
up to quasi linear scales of k~0.1 h/Mpc at z = 0.35 and up to k~0.15 h/Mpc at
higher redshifts within a couple of percentage precision level. Our
understanding of redshift space distortion is proved to be appropriate for
precision cosmology, and our statistical method will guide us to righteous path
to meet the real world.
