| 摘要 |
A portable radio telephone-device has a main telephone unit (5) and a microphone-speaker/headphone set (3) connected to the main telephone unit by a curled cord cable (4). The microphone-speaker/headphone set (3) includes a transmitter amplifier (8) and a receiver amplifier (9) which function as differential amplifiers for amplifying the difference between an AC component on a voice signal ground line (21) connected to the main telephone unit (5) and the transmitted and received voice signals, respectively. Variations (AC component) in the ground level of the main telephone unit are added to the voice signals to cancel noise produced in the voice signals even when periodic level variations are developed between the ground levels of the microphone-speaker/headphone set (3) and the main telephone unit (5). <IMAGE> |
