| 摘要 |
PROBLEM TO BE SOLVED: To secure excellent call quality by reducing nonlinear distortion generated when expanding a voice signal subjected to irreversible compression such asμ-LawPCM, and to simplify a circuit configuration. SOLUTION: When a digital voice compression signal which is the call voice of an entrance slave unit 1a and generated by subjecting the call voice to the irreversible compression such asμ-LawPCM by a slave unit voice compression circuit 105 is expanded by a master unit extending circuit 207 of a room master unit 2a, the nonlinear distortion generated in th expansion is reduced by the action of a weighted average filter 208 and the expanded digital voice signal is made smooth. The call voice inputted to the master unit microphone 202 of the room master unit is expanded by a slave unit extending circuit 106 by the same route. The nonlinear distortion generated in the expansion is reduced by the action of a weighted average filter 107 and the expanded digital voice signal is made smooth. The weighted average filter of the entrance slave unit and the weighted average filter of the room master unit each perform weighted average calculation by the power multiplication of the two filters. COPYRIGHT: (C)2008,JPO&INPIT
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