Matsushita Electric Industrial Co., Ltd.

Shinichi Aki

Masaaki Kobayashi

Akihiro Takeuchi

Masahiro Honjo

Atsuo Ochi

Tsutomu Muraji

Yukio Nakagawa

A magnetic recording and reproducing apparatus which converts a video signal to an FM signal and records the FM signal on a magnetic recording medium has a filter which eliminates an upper sideband component of the FM signal before recording so as to thereby enhance an increase of the levels of the lower sideband components of the reproduced and thereby improve its S/N ratio FM signal.

Magnetic recording and reproducing apparatus for recording

A PLL circuit for a phase comparator, a low-pass filter (LPF), a voltage-controlled oscillator (VCO) and a frequency divider. A first control circuit is responsive to a discontinuous phase change of a reference signal of the PLL circuit for inhibiting the operation of the phase comparator or disconnecting the LPF from the phase comparator during a predetermined period so that the discontinuous phase change information is not transmitted through the LPF to the VCO. At the same time, a second control circuit resets the frequency divider by a pulse of the reference signal after the discontinuous phase change or applies a voltage corresponding to the discontinuous phase change to the VCO so that the output signal of the frequency divider is locked in phase to the reference signal after the discontinuous phase change. With the cooperation of the first and second control circuits, the PLL circuit quickly recovers its stable state after the discontinuous phase change of the reference signal.

Phase locked loop circuit with quickly recoverable stability

Growing community of inventors

Osaka, Japan

Shinichi Aki