Wave correction clock and method

• US 20050094496A1
• Filed: 09/10/2004
• Published: 05/05/2005
• Est. Priority Date: 09/10/2003
• Status: Active Grant

• Current Assignee: Seiko Solutions Inc. (Seiko Group)
• Original Assignee: Seiko Precision Incorporated (Seiko Group)
• Inventors: Ozawa, Kenji
• Granted Patent: US 7,288,974 B2
• Time in Patent Office: Days
• US Class Current: 368/184
• CPC Class Codes: G04R 20/08 the radio signal being broadcast from a long-wave call sign, e.g. DCF77, JJY40, JJY60, MSF60 or WWVB
• CPC Class Codes: G04R 40/06 by computing the time value implied by the radio signal

Abstract

A wave correction clock of the present invention receives a wave signal including time information based on information defined by a pulse width of a rectangular pulse output at a predetermined period, and a period measuring section measures a signal period TRn of the rectangular pulse. A time difference measuring section obtains a time difference between the signal period TRn and an internal reference period TB where the signal period TRn is within a predetermined range, and a time difference determining section corrects generation timing of a reference pulse at the internal reference period TB from an average value of time differences obtained when the rectangular pulse where the signal period TRn is within a predetermined range is detected multiple times.

Claims

1. A wave correction clock that counts time, receives a wave signal, having time information defined by a pulse width of a rectangular pulse having a predetermined basic period by a receiving section and detects time information from the pulse width of each rectangular pulse to correct the counted time thereof based on the detected time information, comprising:

an internal reference period generating section that generates a reference pulse at an internal reference period that is same as the basic period of the rectangular pulse;

a period measuring section that measures a signal period of the rectangular pulse received by said receiving section;

a time difference measuring section that obtains a phase difference of the reference pulse with respect to the rectangular pulse; and

a correcting section that corrects, when a rectangular pulse which satisfies a predetermined condition is detected, generation timing of the reference pulse such that the generation timing is synchronous with the rectangular pulse.

2. The wave correction clock according to claim 1, wherein the correcting section obtains, when a plurality of adjacent rectangular pulses whose measured signal period is within a predetermined range are detected, an average value of phase differences of the reference pulse with respect to the plurality of adjacent rectangular pulses which phase differences are obtained by the time difference measuring section, and corrects generation timing of the reference pulse by the average value.

3. The wave correction clock according to claim 2, wherein the internal reference period generating section starts generation of the reference pulse at the internal reference period using the rise of the rectangular pulse received and detected by the receiving section as generation timing, and corrects generation timing of the reference pulse by the average value of the phase differences obtained by the correcting section.

4. The wave correction clock according to claim 2, further comprising a pulse width detecting section that detects a pulse width of the rectangular pulse with reference to the reference pulse after generation timing is corrected by the correcting section.

5. A time correction method for a wave correction clock which measures time, receives a wave signal, having time information based on information defined by a pulse width of a rectangular pulse output at a predetermined basic period to detect time information from the pulse width of each rectangular pulse and to correct the measured time, said method comprising the steps of:

generating a reference pulse at an internal reference period that is the same as the basic period of the rectangular pulse;

measuring a signal period of the received rectangular pulse;

obtaining a phase difference of the reference pulse with respect to the rectangular pulse; and

obtaining, when a plurality of adjacent rectangular pulses whose measured signal period is within a predetermined range are detected, an average value of phase differences of the reference pulse with respect to the plurality of adjacent rectangular pulses, and correcting generation timing of the reference pulse based on the average value.

6. A program for controlling a computer to execute the steps according to claim 5, and for correcting time measured by a radio wave clock which receives a wave signal, having time information defined by a pulse width of a rectangular pulse having a predetermined basic period and detects time information from a pulse width of each rectangular pulse.