  We present a power spectrum analysis of interferometric 21 cm observations of
the Ursa Major high-latitude cirrus, obtained with the Dominion Radio
Astrophysical Observatory (DRAO) of Penticton (Canada). These high-resolution
data reveal the intricate structure of the diffuse Galactic HI, at angular
scales from 1 arcminute to 3 degrees. A filtering method based on a wavelet
decomposition was used to enhance the signal-to-noise ratio of the data. The
power spectra of the integrated emission and of the centroid velocity fields
were used to deduce the three-dimensional (3D) spectral index of the density
and velocity fields of the HI cirrus. The spectral index is similar for the 3D
density and velocity fields with a value of -3.6\pm0.2. Using the
Leiden/Dwingeloo observations, this analysis was extended to the whole North
Celestial Loop (which includes the Ursa Major cirrus), showing that the scaling
laws prevail from 0.1 to 25 pc. The centroid velocity and integrated emission
fields show moderate correlation, with a maximum cross-correlation value of
0.44.
