  We discuss the problem of CMB spectrum corruption during Galactic emission
removing. A new technique of spatial--frequency data reduction is proposed. The
technique gives us a possibility to avoid a spatial harmonics nonorthogonality.
The proposed technique is applied to the two-year COBE DMR sky maps. We exclude
the harmonics with l=7, 9,13, 23 and 25 as having anomalous statistics noise
behavior. One shows that procedure do not give systematic errors, if the data
are statistically regular. The spectral parameter of the power spectrum of
primordial perturbation $n=1.84 \pm 0.29$ and quadrupole moment $Q_2=15.22 \pm
3.0$ are estimated. The power spectrum estimation results are inconsistent with
the Harrison-Zel`dovich $n=1$ model with the confidence 99%. It is shown a
necessity of an increasing a survey sensitivity to reach a more reliable
estimation of the cosmological signal.
