| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for judging message transmission state not relying upon the signal level or the level difference between signals. SOLUTION: An operating section 44 clips an analysis frame consisting of a predetermined number of signal samples in the past from a frame time of a fixed interval every frame time from a reception signal time series r(n) and a transmission signal time series s(n) supplied from the operating section 44, and determines LSP coefficients by performing linear prediction analysis and LSP (Line Spectrum Pair) conversion on each analysis frame. Furthermore, the operating section 44 calculates an error power from these LSP coefficients and compares it with a predetermined threshold. The message reception state judging section 48 judges whether the near end is in message transmission state or not at current frame time and if the near end is not in message transmission state, an echo cancel section 50 performs echo cancellation. COPYRIGHT: (C)2007,JPO&INPIT
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