| 摘要 |
<p>A voice band signal is compression-encoded at a voice compression-encoding portion (12) and is assembled into a cell at a cell assembling portion (13). Conversely, the voice band signal is disassembled at a cell disassembling portion (15) and is decoded at a voice compression-decoding portion (16). When, from both of up and down data judging portions (11, 17), receiving a judgement of coincidence of the voice band signal with a signal at the time when the line is unused, a timer (18) counts a continuation time. When the continuation time exceeds a protection time, a protection time judging portion (19) causes the cell assembling portion (13) to stop the cell transmission. When, from either of the up and down data judging portions (11, 17), receiving a judgement of no coincidence with the signal at the time when the line is unused, or when the continuation time does not exceed the protection time, the cell assembling portion (13) is directed to transmit the cell. <IMAGE></p> |
