  Accurate measurements of angular power spectrum of Cosmic Microwave
Background (CMB) radiation has lead to marked improvement in the estimates of
different cosmological parameters. This has required removal of foreground
contamination as well as detector noise bias with reliability and precision. We
present the estimation of CMB angular power spectrum from the multi-frequency
observations of WMAP using a novel {\em model-independent} method. The primary
product of WMAP are the observations of CMB in 10 independent difference
assemblies (DA) that have uncorrelated noise. Our method utilizes maximum
information available within WMAP data by linearly combining all the DA maps to
remove foregrounds and estimating the power spectrum from cross power spectra
of clean maps with independent noise. We compute 24 cross power spectra which
are the basis of the final power spectrum. The binned average power matches
with WMAP team's published power spectrum closely. A small systematic
difference at large multipoles is accounted for by the correction for the
expected residual power from unresolved point sources. The correction is small
and significantly tempered. Previous estimates have depended on foreground
templates built using extraneous observational input. This is the first
demonstration that the CMB angular spectrum can be reliably estimated with
precision from a *self contained analysis* of the WMAP data.

Astrophysics