Telephonic communications – Echo cancellation or suppression
Patent
1995-07-19
1997-07-15
Zele, Krista M.
Telephonic communications
Echo cancellation or suppression
379407, 379410, 379411, H04M 900
Patent
active
056490100
ABSTRACT:
Send filter for an echo canceler. A circuit includes a send path carrying a send signal, a receiver path carrying a received signal, an adaptive filter, a compensator contained in the received path, a digital/analog converter, a transmission unit, and a transmission line attached to the transmission unit, wherein over the transmission line, at least the send signal, the received signal, the echo signal portions are transmitted, and the send and received path are additionally connected with the transmission unit and the send signal is transmitted to the adaptive filter for the estimation of the echo signal which is processed in the compensator for the production of the receiving signal, with the send signal being conveyed, on the send path, to digital/analog converter, which, with the symbol rate of the send signal, produces square pulses, which in turn are transformed, in the send filter, connected with the digital/analog converter, into pulse forms useable for transmission via the transmission line, with the send filter being so conceived that the digital/analog converter merely has a resolution of two bits, whereby non-identities, particularly non-linearities, are compensated with the aid of the adaptive filter, the latter including at least one FIR filter portion of the storage compensation type.
REFERENCES:
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Gysel Peter
Kaelin August
Mueller Daniel
Wenger Bruno
Saint-Surin Jacques M.
Siemens Schweiz AG
Zele Krista M.
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