Patent ID: 8886986

Claim:
A clock synchronization method, comprising: reading, by a customer premises equipment, a first time stamp when receiving a first specific position of a first discrete multi-tone (DMT) signal sent by a central office equipment; and reading a second time stamp when sending a second specific position of a second DMT signal; correcting, by the customer premises equipment, the first time stamp by eliminating a first symbol synchronization offset, a first analog receiving circuit delay of the customer premises equipment and a first digital receiving circuit delay of the customer premises equipment from the first time stamp; correcting, by the customer premises equipment, the second time stamp by eliminating a second analog sending circuit delay and a second digital sending circuit delay of the customer premises equipment from the second time stamp; receiving, by the customer premises equipment, a corrected third time stamp and a corrected fourth time stamp that are sent by the central office equipment through a data information channel; wherein the corrected third time stamp is obtained after the central office equipment corrects a third time stamp by eliminating a first analog sending circuit delay and a first digital sending circuit delay of the central office equipment from the third time stamp; the corrected fourth time stamp is obtained after the central office equipment corrects a fourth time stamp by eliminating a second symbol synchronization offset, a second analog receiving circuit delay of the central office equipment and a second digital receiving circuit delay of the central office equipment; wherein the third time stamp is read when the central office equipment sends the first specific position of the first DMT signal, and the fourth time stamp is read when the central office equipment receives the second specific position of the second DMT signal; and determining, by the customer premises equipment, a clock offset between the customer premises equipment and the central office equipment according to the corrected first time stamp, the corrected second time stamp, the corrected third time stamp, and the corrected fourth time stamp, and adjusting a clock of the customer premises equipment according to the clock offset.