| 摘要 |
PURPOSE:To prevent a user from getting confused even in a circuit cut-off (no sound) state by letting the user previously perceive the possibility of the circuit cut-off state in a busy mode of a portable telephone set. CONSTITUTION:This radio telephone set consists of a reception circuit 1 which receives a modulated signal and outputs an intermediate frequency signal, a reference signal oscillator 3, a circuit quality detecting circuit 2 which calculates the circuit quality based on the reference signal and the intermediate frequency signal, a demodulated signal receiving circuit 4 which outputs the deterioration of the quality of a radio circuit as a warning tone or superposes this tone based on the detecting result of the circuit 2, an SP CODEC (voice coder/ decoder) 5, and a receiver 6. Then a fact that the circuit may possibly be cut (no sound) in a busy mode due to the deterioration of the circuit quality is informed to a user by a warning tone. |
