| 摘要 |
<p>PURPOSE:To make it possible to perform accurate asynchronous alarm operation by taking a frame signal in a shift register as coincidence when output of desired step of the shift register is discordant while the alarm of asynchronism of the frame signal and a frame counter output signal. CONSTITUTION:A shift register clock signal 117 is generated by a frame signal 111 only when the first step output of a shift register 121 is in discordant state while an asynchronous alarm signal 135 is being generated, and the frame signal 111 is taken as concordant and taken in the shift register 121. In other cases, a clock signal 117 is generated by a frame count signal 115 coincidence with the frame signal 111 is detected. Thus, decrease of number of steps of posterior protection is eliminated and malfunction of asynchronous alarm is prevented being basing on the result of coincidence detection.</p> |
