| 摘要 |
PURPOSE:To cause sampling periods of time to coincide accurately with each other by making the directions of transmission through two transmission routes opposite to each other and by performing a synchronous control through using a difference in the time of arrival of a transmitted signal. CONSTITUTION:When a signal is sent at the same time TS in opposite directions from a master station 2 to two loop transmission routes, said signal makes a round of all branch stations and returns to the master station 2. The master station 2 sends sampling synchronous flags, measures the time tLP required for each flag to go round said loop, and transmits said time to each branch station. The periods of time tR, tL required for each branch station to receive two clockwise and anticlockwise synchronous flags are equal to a transmission delay time. The total of said periods of time is equal to the time tLP required for each flag to go round said loop. The difference tR-tL in the flag-receiving time can be measured accurately by each branch station and the delay time tLP is transmitted from the master station, so that sampling periods of time can be caused to coincide accurately with each other when a synchronous control is performed by said branch station. |
