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USER’S GUIDE 2581/2671
What is a radio-controlled watch?
Your radio-controlled watch is designed to receive a time
calibration signal that contains standard time data and adjust its
current time setting accordingly.
Signal data
Transmitter
Long-wave time
calibration signal
Inside the watch
Decoding
Watch
Time data
Signal received using
built-in antenna.
Watch decodes
received data
and converts it
to time data.
Time is
adjusted
according to
time data.
Cesium
atomic clock
After the watch receives the Standard Time signal, it
performs internal calculations to determine the current time.
Because of this, there may be an error of up to one second
in the displayed time.
Calibration Signal
The Japanese calibration signal (Call Sign: JJY) is maintained by
the independent Japan Ministry of Posts and Telecommunications
Communication Research Laboratory (CRL). It is a long wave
signal transmitted 24 hours a day from the Mt. Otakadoya
transmitter (40kHz) located in Tamura-gun, Fukushima Prefecture,
and from the Mt. Hagane transmitter (60kHz) located on the
border between Saga Prefecture and Fukuoka Prefecture.
The U.S. calibration signal (Call Sign: WWVB) is transmitted by
the National Institute of Standards and technology from Fort
Collins, Colorado.
Though the calibration signal is normally transmitted 24 hours
a day, transmission may be interrupted occasionally due to
maintenance, lightening, etc.
How a Radio-controlled Watch Works
Reception Range
This watch is designed to receive the standard time calibration signal of Japan (JJY) or of the United States (WWVB). The signa l that is
received depends on the current Home City setting.
When this Home City is selected: You can receive this signal
Either the Mt. Otakadoya signal (40kHz) or the Mt. Hagane signal (60kHz)
Fort Collins, Colorado signal
1000km
Mt. Hagane
(60kHz)
Mt. Otakadoya
(40kHz)
500km
1000km
500km
Transmitter Locations
Under optimum conditions, the calibration signal should be
receivable up to 1,000 kilometers from the transmitter. Note
that the wave is relatively weak at distances greater than
500km, so reception may be poor at long distances.
Location
Reception is difficult and may even be impossible in the locations
described below. A void such locations when performing signal
reception.
You should think of your watch operating like a radio or TV when it
is receiving the calibration signal.
If you are experiencing problems with reception, move away from
the types of locations described above to a location with better
reception, and try again.
Receiving the Calibration Signal
There are two methods you can use to receive the time calibration
signal.
Auto reception (Reception is performed automatically at 2:00,
4:00, and 6:00 each morning.)
Manual reception (You initiate reception using a button
operation.)
The watch is set up for auto reception at the factory, so all you
need to do is to place it in a location that allows good reception
each night.
Setting Up to Make Reception Easier
Remove the watch from your wrist and place it somewhere so its top
(12 o’clock side, where the antenna is located) is facing
approximately in the direction of the signal transmitter. Keep the
watch away from metal objects.
Resin band
Metal band
Orienting the watch so it is sideways to the transmitter makes it
more difficult to receive the signal.
Do not move the watch while it is receiving the calibration signal.
Time Required for Reception
Signal reception takes anywhere from about two to six minutes.
Note that when “A/T” (auto) is specified as the transmitter
selection mode, signal reception can take up to 12 minutes.
* See “Specifying the Transmitter Selection Mode in Japan” for
more information.
Triggering Reception Manually
In the Timekeeping Mode:
Hold down the
BB
BB
B button for
about two seconds.
The watch beeps and reception
starts. Ongoing reception is
indicated by the icon and the
receive indicator. See “Receive Icon
and Indicator” for more information.
To interrupt reception
Press the
BB
BB
B button.
All other buttons besides B are disabled during signal reception.
When reception is successful
The watch adjusts its current time setting, and then beeps and
displays the time and date of the adjustment.
The icon and the receive indicator remain on the display to
indicate that reception was successful.
When reception fails
The watch does not adjust its current time setting, and displays
“ERR” instead.
The display also return to the normal timekeeping screen
automatically if you do not perform any operation for about one
or two minutes.
Receive Icon and Indicator
While reception is in progress, the
icon and the receive indicator
cycle from “Unstable” through
“Stable” as shown below. How far
they cycle depends on the signal
strength. Keep the watch in a
location where reception is stable
while reception is in progress.
Unstable Stable
Even under optimum reception conditions, it takes at least
10 seconds before reception starts.
Use the receive icon and receive indicator to check
reception status and to determine the best location for
signal reception.
Note that weather, the time of day, surroundings, and other
factors can all affect reception.
Receive icon
Receive indicator
Near high-voltage linesAmong or near buildings
Next to a household
appliance or office equipment
(TV, speaker, fax, PC, etc.)
Inside a vehicle
(automobile, train, plane, etc.)
Near mountains
In a location where there is
radio interference
(construction site, airport, etc.)
Fort Collins
3000km
1000km
Transmitter Location
Under optimum conditions, the calibration signal should be
receivable up to 3,000 kilometers from the transmitter. Note
that the wave is relatively weak at distances greater than
1,000km, so reception may be poor at long distances.
Geographic contours, nearby buildings, the season, and the time of day can make reception impossible even when you are within range of
the transmitter.
Best reception is possible late at night.
MA0302-A
The following explanation covers the radio-controlled timekeeping function only.
For other functions, go to the download page for Module 2578,
which is the export model that has the same functions, except for radio-controlled timekeeping.