| 摘要 |
PURPOSE:To improve the equalizing capability of a transversal equalizer by providing an algorithm control circuit, an asynchronous detecting circuit, first and second area discriminating means, and an automatic gain control, amplifier. CONSTITUTION:When an 8-phase phase modulated signal is deviated from a normal signal point, area discriminating means 104 and 105 discriminate whether its signal point is in an effective area, where an error signal and a data signal effective for the control of a transversal equalizer 101 can be generated, or not and generate an effective area discrimination signal and level signals YS and YL which discriminate the level position. Orthogonal demodulated signals are inputted to binary discriminators 17-20 by DC coupling after full-wave rectification and obtained error signals EPU, EPL, QPU, and QPL are subjected to logic operation, thereby obtaining said effective area discrimination signal and level signals. An AGC circuit 103 keeps the input level to the equalizer 101 constant in accordance with signals YS and YL. An algorithm control circuit 3 generates a tap control signal of the equalizer 101 by an output AS of an asynchronous detecting circuit 47 and the signal YM to control the equalizer 101 when the system is asynchronous. Thus, the leading-in limit of the equalizer for the asynchronous state is improved. |
