| 摘要 |
PURPOSE:To avoid the overmodulation or nonmodulation by making the output level of a synthesizing signal constant. CONSTITUTION:A spread signal generating circuit 2 generates a symmetrical triangle signal having a prescribed amplitude as a spread signal (a), which is outputted to a variable amplitude circuit 3. A level detection circuit 4 detects the level of an audible tone signal (b), a comparator 5 compares the relation of quantity between the signal level of the detected signal and a reference value and outputs required error signal to the variable amplitude circuit 3. The variable amplitude circuit 3 changes the signal level of the diffusion signal (a) and applies control that the amplification factor is smaller when the level of the audible tone signal (b) is larger and the factor is larger when the level of the signal (b) is smaller. Then the synthesizing circuit 1 synthesizes the spread signal (a) and the audible tone signal (b). |
