| 摘要 |
PURPOSE:To decrease the feeling of interruption due to voice switching at the use of an external microphone by making an insertion loss different to a transmission side voice signal when a built-in microphone or an external microphone is used. CONSTITUTION:When the built-in microphone 2 is used, an output of an NAND gate 16 turns to L level and a switch SW2 of a variable loss device 12 at the transmission side is turned off. Thus, the insertion loss at the transmission side is (R1+R2). When the external microphone 3 is connected to any microphone jack 4, an output 4, an output of the NAND gate 16 turns, to H level, and the switch SW2 of the variable loss device 12 at the transmission side is turned on. Then the insertion loss at the transmission side is R1. Since the insertion loss is large when the built-in microphone is used and small when the external microphone is used in this way, the feeling of interruption of the transmission/reception switching at the use of the external microphone is reduced. |
