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Operation Guide 5012 (OC)
3
How a Radio-controlled Watch Works
What is a radio-controlled watch?
A radio-controlled watch is designed to receive a time calibration
signal that contains standard time data and adjust its current time
setting accordingly.
Cesium
atomic clock
Transmitter
Long-wave
time calibration signal
Watch
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 National Institute of Information and Communications
Technology (NICT). It is transmitted 24 hours a day from the Mt.
Otakadoya transmitter (40 kHz) located in Tamura-gun,
Fukushima Prefecture, and from the Mt. Hagane transmitter (60
kHz) 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.
• The U.K. calibration signal (Call Sign: MSF) is transmitted by the
National Physical Laboratory (NPL) from Anthorn, which is located
near Anthorn, Cumbria.
• The German calibration signal (Call Sign: DCF77) is transmitted
by Physikalisch - Technische Bundesanstalt (PTB) in Mainflingen,
which is located southeast of Frankfurt.
• Time calibration signal frequencies and transmitter locations are
subject to change.
The time data of the Japanese calibration signal (Call Sign:
JJY) is maintained by the Japan Standard Time Group of the
National Institute of Information and Communications
Technology (NICT).
Note that transmission of the calibration signal may be
interrupted occasionally due to maintenance, lightning, etc.
For more information, visit the website of the Japan Standard
Time Group of the National Institute of Information and
Communications Technology (NICT) at the following URL.
http://jjy.nict.go.jp
• Note that the above URL is subject to change.
Reception Ranges
The table below shows the time calibration signal that the watch
receives when a particular city code is selected as your Home City.
••
••
• For information about Home City settings, see “Configuring
Home City Settings”. See the “City Code List” for information
about city codes.
Home City
(Supports signal reception)
United States (WWVB)
Receivable Transmitter
Japan (JJY)
HNL, ANC, LAX,
DEN, CHI, NYC
U.K. (MSF) and
Germany (DCF77)
LON, PAR, ATH
TYO, HKG
• Signal reception is possible in the time zones represented by
HKG (Hong Kong), HNL (Honolulu), and ANC (Anchorage) when
reception conditions are good.
• Certain conditions can make reception impossible even when the
watch is within one of the reception ranges shown above. Signals
become weaker outside of the smaller circles indicated by dashed
lines in the nearby maps, so the reception environment has a
greater effect on signal reception.
• The following also can affect signal reception: geographic
contours, structures, weather, climate, time of day (afternoon,
evening), noise.
Reception Time
A receive operation can take anywhere from about two to seven
minutes.
• Under certain conditions, a receive operation can take as long as
13 minutes.
Positioning the Watch for Best
Reception
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 for the watch to receive the signal.
• Do not move the watch while it is receiving the calibration signal.
Important!
Reception is difficult and may even be impossible in the locations
described below. Avoid such locations when performing signal
reception.
• You should think of your watch as 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 a Calibration Signal
There are two methods you can use in order to receive the time
calibration signal.
• Auto Receive up to six times per day
• Manual Receive where you hold down the A button in the
Timekeeping Mode.
Among or near
buildings
Near high-voltage
lines
Inside an automobile,
train, plane, or other
vehicle
Next to a TV,
speaker, fax,
computer, cellphone,
or other household
appliances or office
equipment
At a construction
site, airport, or other
location where there
is radio interference
Near mountains
Auto Receive
Getting Ready for Auto Receive
You will need to perform the operations described below in order to
use Auto Receive.
• Configure the Home City setting of the Timekeeping Mode so it
matches your current location. The Home City must be in a time
zone where calibration signal reception is supported. See:
“Reception Ranges” and “Configuring Home City Settings”.
• Put the watch into the Timekeeping Mode or World Time Mode.
See: “Modes and Indicators”.
• During the Auto Receive times, position the watch correctly for
best reception. See: “Auto Receive Start Times” (below) and
“Positioning the Watch for Best Reception”.
How Auto Receive Works
Calibration signal reception will start automatically whenever the
current time in the Timekeeping Mode reaches one of the Auto
Receive Start Times listed below. Auto receive can be performed up
to six times a day, but any time a signal receive operation is
successful, no more auto receive operations are performed that day.
Note that the Auto Receive Start Times differ according to the
current Home City setting and the summer time setting.
• Summer time, or Daylight Saving Time (DST) as it is called in
some countries, calls for setting clocks ahead one hour from
standard time during the summer season.
• Note that the start and end of summer time, and whether summer
time is used at all depends on each country.
Auto Receive Start Times
3
2:00 a.m.
2:00 a.m.
3:00 a.m.
4:00 a.m.
4:00 a.m.
5:00 a.m.
5:00 a.m.
Midnight*
4
3:00 a.m.
3:00 a.m.
4:00 a.m.
5:00 a.m.
5:00 a.m.
Midnight*
Midnight*
1:00 a.m.*
5
4:00 a.m.
4:00 a.m.
5:00 a.m.
Midnight*
Midnight*
1:00 a.m.*
1:00 a.m.*
2:00 a.m.*
6
5:00 a.m.
5:00 a.m.
Midnight*
1:00 a.m.*
1:00 a.m.*
2:00 a.m.*
2:00 a.m.*
3:00 a.m.*
TYO, HKG
HNL, ANC, LAX,
DEN, CHI, NYC
LON
PA R
AT H
Standard Time
Standard Time
Summer Time
Standard Time
Summer Time
Standard Time
Summer Time
Standard Time
Summer Time
2
1:00 a.m.
1:00 a.m.
2:00 a.m.
3:00 a.m.
3:00 a.m.
4:00 a.m.
4:00 a.m.
5:00 a.m.
1
Midnight
Midnight
1:00 a.m.
2:00 a.m.
2:00 a.m.
3:00 a.m.
3:00 a.m.
4:00 a.m.
Auto Receive Start TimesAuto Receive Start Times
Home City
* Following day
1000km
Mt. Hagane
(60kHz)
Mt. Otakadoya
(40kHz)
500km
1000km
500km
Transmitter Locations
Japan (JJY)
3000km
1000km
Fort Collins
United States (WWVB)
U.K. (MSF), Germany (DCF77)
1500km
500km
Mainflingen
Anthorn
The signal transmitted
out of Anthorn may be
receivable within this
range.