Pulse or digital communications – Spread spectrum – Direct sequence
Patent
1992-09-01
1994-05-03
Chin, Stephen
Pulse or digital communications
Spread spectrum
Direct sequence
328 63, 328 72, H04L 704
Patent
active
053094840
ABSTRACT:
In an asynchronous communication system such as a V.32 modern (80), an input signal is sampled at a near-end clock rate. Each sample is then interpolated in an interpolation filter (92) to provide corresponding interpolated values. The interpolation filter (92) uses a selected one of a predetermined number of sets of windowed sinc function coefficients, each set having a successively greater phase offset. A time drift between near-end and far-end clocks is measured by tracking the coefficient shift in a passband phase-splitting, fractionally-spaced equalizer (95). When the time drift exceeds a threshold, a subsequent set of windowed sinc function coefficients is selected. When the time drift exceeds the threshold after the last set of coefficients is used, the first set is again selected and an interpolated value is either dropped or repeated in forming the far-end data samples.
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Park, S. et al., "Analysis and Digital Implementation of Jointly Adapting Echo Canceller, Transversal Equalizer and Decision Feedback Equalizer for the V.32 Modem," Proc. of Int. Conf. on Acoustics, Speech and Signal Processing, Toronto, Ontario, Canada, May 14-17, 1991.
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Funderburk Dion M.
McLane Peter J.
Park Sang-il
Chin Stephen
Clingan Jr. James L.
Motorola Inc.
Polansky Paul J.
Webster Bryan
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