  The power spectrum of HI intensity fluctuation of the interstellar medium
carries information of the turbulence dynamics therein. We present a method to
estimate the power spectrum of HI intensity fluctuation using radio
interferometric observations. The method involves correlating the visibilities
in the u-v plane at different baselines. This method is particularly use full
for evaluating the power spectrum for the faint dwarf galaxies. We apply this
method to 3 spiral galaxies and 5 dwarf galaxies. The measured power spectrum
seem to follow a power law P_HI(U) = A U^\alpha, suggesting turbulence to be
operational. Further, depending on the slope of the power spectrum, we expect
the presence of 2D and 3D turbulence in those galaxies.
