| 摘要 |
PURPOSE:To improve the rise characteristics of a tone signal by injecting a trigger pulse to a status variable type BPF in a tone generator at the start of transmission. CONSTITUTION:An oscillation loop is constituted by inputting an output from a status variable type BPF 11 to an amplifier 12 through a switch SW1 at the time of transmission and feeding back the output of the amplifier 12 to the input of the BPF11 and a tone signal with prescribed frequency is continuously generated from the BPF11 during the transmission period. A single-oscillation pulse generator 13 is started by a switch SW2 interlocking with the SW1 at the start of the transmission and a trigger pulse generated by the generator 13 is impressed to the input stage of the BPF11. Consequently, a tone signal is generated almost simultaneously with the depression of the switches SW1, SW2, so that the head of a sound signal is prevented from being cut off by a squelch when no tone signal exists on the receiving side. |
