Patent ID: 8442175

Claim:
A method for time synchronization of a digital subscriber line (DSL), the method comprising: receiving, by a first apparatus, a second symbol transmitted by a second apparatus, and obtaining time Ts 1 indicating the moment that the second symbol is received; transmitting, by the first apparatus, a first symbol to the second apparatus, and obtaining time Ts 2 indicating the moment that the first symbol is transmitted; obtaining, by the first apparatus, time Tm 2 indicating the moment that the first symbol is received by the second apparatus and time Tm 1 indicating the moment that the second symbol is transmitted by the second apparatus; calculating, by the first apparatus, an offset between a clock of the first apparatus and a clock of the second apparatus according to the times Ts 1 , Ts 2 , Tm 1 , and Tm 2 ; adjusting, by the first apparatus, the clock of the first apparatus with the offset to synchronize with the clock of the second apparatus; and obtaining a phase difference between a receiving point phase and a check point phase, wherein the receiving point is a position where a signal of the second symbol is received by the first apparatus and the check point is a position where the same signal of the second symbol is transmitted by the second apparatus.