Title:
ESTIMATING BULK DELAY IN A TELEPHONE SYSTEM
Document Type and Number:
WIPO Patent Application WO2004015961
Kind Code:
A3
Abstract:
A bulk delay (tbd) estimating circuit correlates time intervals representing a signal (11) with time intervals representing an echo (12) of the signal to identify the echo and estimate bulk delay. Bulk delay is estimated by computing (1, 2, ... n) intervals (e.g. 14, 17) representing the signal, computing (1, 2, ... n) intervals (e.g. 15, 18) 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.
Inventors:
EBENEZER SAMUEL PONVARMA
STORY FRANKLYN H
STORY FRANKLYN H
Application Number:
PCT/US2003/025140
Publication Date:
July 15, 2004
Filing Date:
August 11, 2003
Export Citation:
Assignee:
ACOUSTIC TECH INC (US)
International Classes:
H04M9/08; (IPC1-7): H04B3/23
Foreign References:
| US4764955A | 1988-08-16 |
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