  The first scientific runs of kilometer scale laser interferometric detectors
like LIGO are underway. Data from these detectors will be used to look for
signatures of gravitational waves (GW) from astrophysical objects like
inspiraling neutron star/blackhole binaries using matched filtering. The
computational resources required for online flat-search implementation of the
matched filtering are large if searches are carried out for small total mass.
In this paper we report an improved implementation of the hierarchical search,
wherein we extend the domain of hierarchy to an extra dimension - namely the
time of arrival of the signal in the bandwidth of the interferometer. This is
accomplished by lowering the Nyquist sampling rate of the signal in the trigger
stage. We show that this leads to further improvement in the efficiency of data
analysis and speeds up the online computation by a factor of $\sim 65 - 70$
over the flat search. We also take into account and discuss issues related to
template placement, trigger thresholds and other peculiar problems that do not
arise in earlier implementation schemes of the hierarchical search. We present
simulation results for 2PN waveforms embedded in the noise expected for initial
LIGO detectors.
