| 摘要 |
PURPOSE:To avoid an eye pattern used for identification from being a form such as an RZ code waveform and to eliminate the deterioration of an S/N by retarding one of branched intermediate frequency signals by one bit in delay detection and comparing the phase after the phase is inverted. CONSTITUTION:When an intermediate frequency signal from a detection circuit 9 is inputted to a delay detection circuit 10, the intermediate frequency signal is divided into two, one is inverted for the phase by a phase inversion circuit 103, the result is retarded by one bit at a delay circuit 101, inputted to a mixer 102, and the other is inputted directly to the mixer 102, the mixer 102 compares the phase of the intermediate frequency signal from the delay circuit 9 with the phase retarded by the delay circuit 101 and inverted by a phase inversion circuit 103 and a base band signal is outputted. In this case, the phase difference with a signal of one preceding bit does not reach an H level on the way of alternate transition from pi to -pi or -pi to pi and the eye pattern used for the identification is not formed to be an RZ code waveform. |
