How a Radio-controlled Watch Works. Casio (W3), MRG-8000B

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.

Transmitter

Cesium atomic clock

Long-wave time

Watch

Operation Guide 5011 (W3)

How a Radio-controlled Watch Works

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.

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)

TYO, HKG

HNL, ANC, LAX,

DEN, CHI, NYC

LON, PAR, ATH

Receivable Transmitter

Japan (JJY)

United States (WWVB)

U.K. (MSF) and

Germany (DCF77)

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.

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.

• 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.

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.

Among or near buildings

Near high-voltage lines

Inside an automobile, train, plane, or other vehicle

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”.

Transmitter Locations

Japan (JJY)

1000km

Mt. Hagane

(60kHz)

500km

500km

Mt. Otakadoya

(40kHz)

1000km

United States (WWVB)

Fort Collins

3000km

1000km

U.K. (MSF), Germany (DCF77)

Anthorn

500km

The signal transmitted out of Anthorn may be receivable within this range.

1500km

Mainflingen

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.

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.

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

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.

Auto Receive Start Times

TYO, HKG

LON

PAR

ATH

Home City

HNL, ANC, LAX,

DEN, CHI, NYC

Standard Time

Standard Time

Summer Time

Standard Time

Summer Time

Standard Time

Summer Time

Standard Time

Summer Time

Auto Receive Start Times

1

Midnight

2

1:00 a.m.

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.

1:00 a.m.

2:00 a.m.

2:00 a.m.

3:00 a.m.

4:00 a.m.

4:00 a.m.

5:00 a.m.

* Following day

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*

Auto Receive Start Times

4

3:00 a.m.

5

4:00 a.m.

3:00 a.m.

4:00 a.m.

4:00 a.m.

5:00 a.m.

5:00 a.m.

Midnight*

Midnight*

1:00 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.*

3

When reception is successful

After a receive operation is complete, the watch returns to the

Timekeeping Mode, which shows the newly adjusted time.

When reception fails

The watch will return to the Timekeeping Mode without adjusting the time setting.

Manual Receive

You will need to perform the operations described below in order to use Manual 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. See: “Modes and

Indicators”.

• Position the watch correctly (see “Positioning the Watch for Best

Reception”).

■ To start a Manual Receive operation

In the Timekeeping Mode, hold two seconds until the indicator hand moves to the last signal reception result

(“Y” or “N”), and then to

“READY” (“R” for some models).

• The hour hand, 24-hour hand, and minute hand continue to operate normally.

• The second hand will stop at “0”.

30

READY (or R)

Operation Guide 5011 (W3)

■ To cancel a manual receive operation

While reception is in progress...

• The indicator hand moves to

“WORK” (or “W” for some models).

• The hour hand, 24-hour hand, and minute hand will continue to operate normally.

• Do not perform any watch operations while signal reception is in progress (indicator hand at

“WORK” or “W”).

• Under some reception conditions, the indicator hand may cycle between “READY” (or “R”) and

“WORK” (or “W”) until reception stabilizes.

30

WORK (or W)

Press any button.

■ To check the result of the last receive operation

• The indicator hand will move to “Y” (or “YES”) if the last receive operation was successful or to “N” (or “NO”) if the last receive operation was unsuccessful.

• Press the A button once to return to normal timekeeping.

• If you do not perform any operation for about five seconds, the watch will revert automatically to normal timekeeping.

When reception is complete...

• If reception was successful, the hands will move to the correct time. After that, the indicator hand moves to “Y” (or “YES” for some models). Then after about five seconds the watch will resume regular timekeeping.

• If the receive operation fails, the indicator hand will move to “N” (or

“NO” for some models) and the hands will move to the unadjusted time. Then after about five seconds the watch will resume regular timekeeping.

Y (or YES)

N (or NO)

30

Y (or YES) when successful

30

N (or NO) when not successful

The last receive status changes each time a new time calibration signal reception operation is performed.

Calibration Signal Reception Precautions

• Auto Receive is not performed while the watch is in the Stopwatch

Mode or Alarm Mode.

• Operating any button while Auto Receive is in progress will cause the watch to beep and then exit the receive operation.

• Make sure you are within the range of a calibration signal transmitter before performing the receive operation. Remember that geographic contours, nearby buildings, the season, or the time of day can make reception impossible even when you are within range of the transmitter.

• Proper reception may be impossible if there is something blocking the signal. If reception is unsuccessful, try again.

• This watch is designed to adjust its current time setting in accordance with the calibration signals transmitted in Japan, the

United States, the U.K., and Germany. Note that you will need to make your own adjustments when using this watch outside of the range of the time calibration signal transmitters.

• When the watch is unable to adjust its time using the calibration signal for some reason, timekeeping accuracy is within ±15 seconds per month.

• Strong electrostatic charge can cause timekeeping error.

• Receive is cancelled if an alarm operation starts while it is being performed.

• The watch’s calendar shows dates up to the year 2099.

Attempting a receive operation after that causes an error.

Troubleshooting

1. The watch cannot receive the time calibration signal.

• Is there something in the immediate area that may be interfering with reception?

Even if you are within the reception range of a transmitter, electrical noise or objects between you and the transmitter can interfere with reception. Avoid such areas (see “Positioning the

Watch for Best Reception”) during signal reception.

• Are you within the reception range of a transmitter?

See “Reception Ranges” for information about areas where the watch can receive the signal.

• Are your Home Time settings configured correctly?

See “Configuring Home City Settings”.

• Is the signal being transmitted?

Transmission of time calibration signals may be interrupted occasionally due to maintenance, lightning, etc.

2. Time calibration signal reception is successful, but the hourly time signal and current time are slightly off.

• After the watch receives the time calibration signal, it performs an internal decoding process before updating its time setting.

Because of this, the time setting may be off slightly (within one second).

3. Time calibration signal reception is successful, but the current time setting is wrong.

• Are your Home Time settings configured correctly?

See “Configuring Home City Settings”.

• If you cannot receive the calibration signal or if the time setting is incorrect after signal reception, check the setup of the watch.

• The following are the watch’s factory default settings, which are configured automatically whenever you have the battery of the watch replaced.

Home City

Summer Time

TYO Tokyo

AT (AUTO)

Auto

(according to signal data)

4