| 摘要 |
PURPOSE:To change a circuit to one chip, and also to make it unnecessary to adjust it, by passing a signal which has removed of an amplitude component of a receiving stereo signal through a PLL circuit and a triangular wave converting circuit, multiplying both these output signals, and constituting a distortion correcting circuit. CONSTITUTION:A Motorola system AM stereo signal to which a distortion correcting signal COSphi has been applied is inputted to an amplitude limiter 2, its amplitude component is removed, and the signal is inputted to a PLL circuit 3 and a triangular wave converting circuit 21. The circuit 21 converts an input square wave to a triangular wave signal, and also inputs an output of the circuit 21 to a waveform converting circuit 22 in order to reduce the higher harmonic and raise the accuracy. A signal generated by the circuit 3, and an output signal of the circuit 22 are multiplied by a multiplier 4, and when its output is passed through an LPF5, a distortion correcting signal is obtained. An input AM stereo signal is divided by the output signal of the LPF5, its output signal and signals having a phase difference of 90 deg. to each other from the circuit 3 are multiplied by multiplier 7, 8, respectively, and a sum signal L+R and a difference signal L-R are obtained by output terminals 9, 10, respectively. In this way, a distortionless stereo signal is obtained without adjusting it. |
