Multiplex communications – Duplex – Transmit/receive interaction control
Patent
1995-05-22
1997-02-25
Olms, Douglas W.
Multiplex communications
Duplex
Transmit/receive interaction control
379411, 370290, 370278, H04B 323
Patent
active
056065507
ABSTRACT:
An echo canceller for use in fixed-wireless telephony networks using low-rate packetized speech coding and DSI is disclosed. An adaptive filter is used to cancel an echo signal of a far-end signal introduced at the near-end by operating to provide a replica signal to cancel the echo signal. The replica signal is updated in the absence of a near-end talker signal presence of near talker signal is detected using an estimated echo-residual loss. The echo replica signal updating process is frozen upon the detection of double-talk. Residual echoes are suppressed without the use of non-linear processing. A residual suppression flag detection and a voice activated switching device are used to detect the absence of near-end signals. The switching device is opened if the signal to be transmitted is not a near-end signal or is noise.
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Denson-Low Wanda K.
Hughes Electronics
Lindeen III Gordon R.
Nguyen Chau T.
Olms Douglas W.
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