PURPOSE: To supply an accurate reference time to respectively general stations by measuring the delay time of the transmission line of each general station, and determining the transmission phase of the reference time signal in consideration of the delay quantity.

CONSTITUTION: A reference station 11 is connected to the general stations 31W3n through transmission lines 21W2n. The reference time signal is generated by the reference station 11 and received by the general stations 31W3n through the transmission lines 21W2n. Each of the general stations 31W3n knows the reference time from the received reference time signal and the reference time signal is branched and sent from the general stations 31W3n back to the reference station 11 through the same routes with onward paths through the transmission lines 21W2n. The reference station 11 measures the time delay quantity from the transmission to the reception of the reference time signal. Then, the transmission phase of the reference time signal is determined in consideration of the delay; quantity to send out the accurate reference time to the respective general stations 31W3n.