INSTRUMENT FOR MEASURING TRANSMISSION DELAY TIME

摘要

PURPOSE:To highly accurately measure the transmission delay time of a digital transmission line by a simple circuit. CONSTITUTION:The time interval of a phase difference of a frame pulse signal 44 is counted by a 1st clock signal 46 inputted to a transmitting equipment 41 and a 2nd clock signal obtained by inverting the phase of the signal 46 by 180 deg.. A reference clock signal whose frequency is slightly different from that of the clock signal is generated and time when the phase of the reference clock signal coincides with the phase of the signal 47 and coincident time with the phase of a 3rd clock signal 47 outputted from a receiving equipment 42 are respectively detected. A time interval between two detected coincident time values is counted by the reference clock signal. Required transmission delay time is computed in accordance with the count values based upon the reference clock signal, the 1st clock signal and the 2nd clock signal. Consequently delay time can easily be managed and highly accurate clock distribution can be attained.