| 摘要 |
<p>The unit includes a transmission channel (1) and a reception channel (2) which are connected to a telephone line (10) by a two-wire/four-wire hybrid circuit (20). In each channel, part of the output from a controlled attenuator (16,26) is fed to an echo suppression filter (24,14) in the other channel. These filters are interconnected via a central unit (30) comprising a signal energy measurement circuit (31) and a mismatch-measuring microprocessor (32) which controls the attenuators. An anti-Larsen filter (15) is positioned in the transmission channel only.</p> |
