| 摘要 |
An echo suppression arrangement for use in a digital portable telephone prevents sidetone echo appearing in the base unit of the telephone from being coupled to and emanating at the handset unit of the telephone. The echo suppression arrangement determines the direction of dominant speech signals appearing in the base unit while communicating with the handset unit. These dominant speech signals either originate at the handset unit or at a remote telephone station and are received by the base unit over a telephone line connected to the base unit. If the dominant signal in the base unit is from the handset unit, the echo suppressor arrangement inserts a predetermined amount of loss into a receive voice path which couples signals to the handset unit. This prevents the sidetone echo from being produced in the handset voice receiver when the user of the handset unit is speaking. If the dominant signal is from the remote telephone station, however, the echo suppression arrangement removes the predetermined amount of loss from the receive voice path. This allows for normal receiver voice response at the handset unit. Since users of the handset unit expect to receive some sidetone level, a desired level of normal sidetone is provided locally in this handset unit.
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