A far-end echo canceller with a digital filter for simulating a far end echo containing a frequency offset

Year	Description
1991	Invention patented by Chin-Pyng J. Tzeng on August 26th, 1991. Abstract: A far-end echo path may be simulated at a terminal which utilizes QAM by processing the in-phase and quadrature data symbols by a pulse shaping filter whose transfer function may be a raised cosine function. The in-phase and quadrature data symbols are then multiplied by cos (.omega..sub.c +.omega..sub.o)t and sin (.omega..sub.c +.omega..sub.o)t, respectively, where .omega..sub.c is the carrier frequency and .omega..sub.o is the adaptively determined offset frequency of the far-end echo signal. The output signals of the multipliers are then summed and the result is processed by a single transversal filter whose transfer function is determined adaptively. The output of this filter is a simulated far-end echo signal.
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Invention: A far-end echo canceller with a digital filter for simulating a far end echo containing a frequency offset