| 摘要 |
PURPOSE:To attain demodulation with high speed and stable phase synchronization by transmitting a channel signal while a carrier is inserted to a head idle data part, and providing a phase demodulator having PLL structure capable of switching a loop constant at the reception side. CONSTITUTION:A start command STRTc is sent from a transmitter 1 via a return line (not shown) at the initial state of receiving a reception channel signal. A low pass loop filter 23b filters a demodulated I channel data signal I-CH by the start command and supplies the result to a VCO 25a. An identification circuit 22a confirms the phase synchronization to select a high loop filter 23c. A holding circuit 23d holds the output of the high loop filter 23c being stably synchronized in phase and the phase detection is applied based on the holding loop output. |
