  We simulate the distribution of neutral hydrogen (HI) at the redshifts z=1.3
and 3.4 using a cosmological N-body simulation along with a prescription for
assigning HI masses to the particles. The HI is distributed in clouds whose
properties are consistent with those of the damped Lyman-\alpha absorption
systems (DLAs) seen in quasar spectra. The clustering properties of these
clouds are identical to those of the dark matter. We use this to simulate the
redshifted HI emission expected at 610 MHz and 325 MHz, two of the observing
bands a the GMRT. These are used to predict the correlations expected between
the complex visibilities measured at different baselines and frequencies in
radio-interferometric observations with the GMRT. The visibility correlations
directly probe the power spectrum of HI fluctuations at the epoch when the HI
emission originated, and this holds the possibility of using HI observations to
study large-scale structures at high z.
