| 摘要 |
PURPOSE:To detect a phase pulse signal early before the time corresponding to a prescribed number of cycles elapses by subtracting an average noise level from an average receiving level in every phase unit and detecting the phase pulse signal if their difference is larger than a prescribed value. CONSTITUTION:Each time a phase pulse signal carrying range 7 in one cycle is terminated, an operating circuit 15 averages the lavel during the preceding time from a prescribed number of cycles S to the current cycle in each phase unit to obtain this veraged level as an average receiving level. The level during the time from the two times preceding time of cycles S to the preceding time of cycles S is averaged in each phase unit, and this averaged level is used as an average noise level. An operating circuit 15 subtracts the average noise level from the average receiving level and outputs this difference as a phase pulse signal level. If the difference of the highest level in phase units U1-U10 exceeds a receiving threshold level 14 in every channel, an audit circuit 16 outputs an output pulse from an output terminal. Since the prescribed number cycle S is set on the supposition that a carrying line is at the badest state, a phase pulse signal 18 is deteced early in many cases. |
