Casio 3145 Manual page 26

• The watch receives the calibration signal for two to seven minutes everyday
when the time in the Timekeeping Mode reaches a calibration time. Do not
perform any button operation within seven minutes before or after the
calibration times. Doing so can interfere with correct calibration.
• Remember that reception of the calibration signal depends on the current
time in the Timekeeping Mode. The receive operation will be performed
whenever the display shows any one of the calibration times, regardless of
whether or not the displayed time actually is the correct time.
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