Title:
METHOD FOR IMPROVING PRECISION IN CLOCK REPRODUCTION AND CLOCK REGENERATOR
Document Type and Number:
Japanese Patent JP3935893
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To obtain clock stability required for synchronous multiplexing transmission as a clock for a transmission device using an Ethernet interface for transmitting and receiving data to and from the Ethernet (R).
SOLUTION: An Ether frame including data having preset lengths from a transmission section 100 of the Ethernet (R) is transmitted at least at a preset time interval. Timelike variations in the clock extracted from reception data are detected at a clock speed adjustment section 13 based on an SFD (frame start section) detected by a speed conversion/frame conversion section 12 in the received Ether frames. A clock frequency generated at a clock generation section 14 is corrected based on the extracted clock. The corrected clock frequency is used for allowing a voltage-controlled crystal oscillator 17 to oscillate. The stability in the clock frequency at a network synchronization system level is obtained as the clock for transmitting devices at a desired frequency. When a fraction is generated while the clock for transmitting devices is divided, a division ratio is controlled by an automatic control division section 19.
Inventors:
Norio Sasaki
Takeshi Oda
Hanaumi
Takeshi Oda
Hanaumi
Application Number:
JP2004118733A
Publication Date:
June 27, 2007
Filing Date:
April 14, 2004
Export Citation:
Assignee:
Tohoku Electric Power Co., Inc.
Tsuken Electric Industry Co., Ltd.
Tsuken Electric Industry Co., Ltd.
International Classes:
H04L7/00; H04L7/02; H04L7/033; (IPC1-7): H04L7/00
Domestic Patent References:
| JP62271540A | ||||
| JP5225128A | ||||
| JP9505705A | ||||
| JP60152143A | ||||
| JP11313107A | ||||
| JP58116831A |
Attorney, Agent or Firm:
Akinaka Takano
Susumu Iwano
Susumu Iwano