A bulk delay estimating circuit matches time intervals representing a signal
with
time intervals representing an echo of the signal to identify the echo and estimate
bulk delay. Bulk delay is estimated by computing (1, 2, . . . n) intervals representing
the signal, computing (1, 2, . . . n) intervals representing an echo of the signal,
computing absolute differences between corresponding intervals to produce n absolute
differences, summing the n absolute differences, and providing an output indicating
whether or not the sum is less than a predetermined amount. The intervals are determined
by defining a plurality of numbered frames, comparing the energy of a signal during
each frame with at least one threshold, storing the numbers of the frames in which
the threshold is exceeded, and defining an interval as the period from one frame
in which the threshold is exceeded to the next frame in which the threshold is
exceeded. Bulk delay is estimated from the frame numbers of the signal, its echo,
and the duration of a frame.
