| 摘要 |
PURPOSE:To reduce a waiting time of transient response, and to shorten a pull-in time by setting a tap coefficient of a roll-off filter operation based on a result of decision of an extracted timing component, varying a phase of an output of the roll-off filter operation, and bringing a timing signal and a baud rate clock to phase synchronization. CONSTITUTION:When a training signal is applied through a circuit from a transmitting side, it is brought to a band limit by a band pass filter 1, digitized by an A/D converter 2, demodulated and processed by a demodulating part 3, and its waveform is shaped by a roll-off filter part 5. By this output, a carrier is detected by a CD detecting part and a transmission start is detected. An output of the roll-off filter part 5 is brought to automatic gain control by an AGC part 8, and thereafter, a timing component is extracted by a timing extracting part 4, and a phase of the timing component is decided by a deciding part 6. As a result of this decision, a tap coefficient of the roll-off filter part 5 is given to the roll-off filter part, a phase of a receiving signal from the circuit is controlled, and a timing lead-in is ended. |
