| 摘要 |
PURPOSE:To prevent the generation of burst tone, by supplying an intermediate frequency signal from a limiter to a PLL and applying the phase comparison output to a matrix circuit. CONSTITUTION:An intermediate frequency signal from a limiter 11 is applied to a phase comparison circuit 21, an oscillation output of a VCO22 is applied to the comparison circuit 21, and the comparison output Sc is applied to the VCO22 as a control signal through a low-pass filter 23 to constitute a PLL20. The cutoff frequency of the filter 23 is made sufficiently low, a damping factor of the PLL 20 is sufficiently increased to close the characteristic to the primary loop characteristic so that poles at high frequencies can be equal to the time constant tau of the preemphasis. The compared output Sc of the comparison circuit 21 is taken as a difference signal L-R and applied to a matrix circuit 8, and the sum signal L+R from a detection circuit 6 is applied to the matrix circuit 8 as it is. |
