The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 07, 2021
Filed:
Feb. 15, 2019
Nippon Telegraph and Telephone Corporation, Tokyo, JP;
Hiroki Sakuma, Tokyo, JP;
Kaoru Arai, Tokyo, JP;
Ryuta Sugiyama, Tokyo, JP;
Takaaki Hisashima, Tokyo, JP;
Shunichi Tsuboi, Tokyo, JP;
Osamu Kurokawa, Tokyo, JP;
Kazuyuki Matsumura, Tokyo, JP;
Nippon Telegraph and Telephone Corporation, Tokyo, JP;
Abstract
[Problem] To synchronize timings of transmitting and receiving a pulse signal (1 PPS signal) at a constant interval between communication apparatuses even in a case where an optical fiber connecting the communication apparatuses fluctuates in an optical characteristic and an optical fiber length. [Solution] The time synchronization systemtransmits and receives a pulse signal at a constant interval between a local apparatus L (apparatus L) and a remote apparatus R (apparatus R) connected through the two-core bidirectional optical fibers Fand Fto synchronize time. A propagation delay amount τin the fiber Fis calculated, from a proportional relationship between Tand Tand a proportional relationship of τud and τ, where Trepresents a propagation delay time difference between a pulse signals Pand Pof an identical wavelength λreturned after transmitting a pulse signal Pof wavelength λand a pulse signal Pof wavelength λdifferent from λto the remote apparatus R, Trepresents a propagation delay time difference between the pulse signal Pof wavelength λand a pulse signal Pof wavelength λ, and τud represents the round-trip delay time between the apparatuses L and R. The pulse signals Pand Pare transmitted with a time difference td corresponding to a difference between the current and last calculated propagation delay amounts τbeing set so that the difference is zero.