| 摘要 |
PURPOSE: A circuit for preventing an echo phenomenon of a subscriber terminal in an exchange is provided to compare sizes of voice signals received from two subscribers, and to transmit a larger voice signal to a far-end user, or to mute a smaller voice signal. CONSTITUTION: A power calculator(331) calculates powers of voice signals transmitted from two subscribers, and outputs calculated values. A comparator(340) receives each power calculated value of the voice signals from the two subscribers, and compares the power calculated values, then outputs signals corresponding to a compared result. Selectors(361,362) select voice signals transmitted to the two subscribers, and outputs the selected voice signals. A controller(350) receives the signals outputted from the comparator(340), and controls the selectors(361,362).
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