| 摘要 |
PURPOSE:To surely and efficiently detect collision independently of the collision phase by sampling outputs of two comparing circuits different in threshold by clocks different in phase and providing a delay circuit in the succeeding stage of one code rule illegality detecting circuit. CONSTITUTION:The output of a partial response filter 11 is given to a comparator 12 having a threshold slightly higher than the zero level and a comparator 13 having a threshold slightly lower than the zero level. Outputs of comparators 12 and 13 are sampled in shift registers 15 and 19 by clocks whose phases are made different from each other by a phase shifting circuit 23. Outputs of registers 15 and 19 have code rule illegal patterns detected by code rule illegality detecting circuits 25 and 26. Outputs of circuits 25 and 26 are given to a collision deciding circuit 29 through an OR circuit 28, and the circuit 29 counts the number of pulse of circuits 25 and 26; and if the counted value exceeds a prescribed value, collision is decided to output the detection signal. A delay circuit 27 is provided following the circuit 25 to avoid overlap between outputs of circuit 27 and 28, and collision is efficiently detected. |
