Casio 3707 Operation Manual Download Page 2

Operation Guide 3707

2

How a Radio-controlled Watch Works

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

Internally

Decode

Watch

Time data

Long-wave 
time 
calibration 
signal

Cesium 

atomic clock

Signal is received 
using built-in antenna.

Watch decodes 
received data 
and converts it 
to time data.

Time is adjusted 
according to 
time data.

Calibration Signal

The Japanese calibration signal (Call Sign: JJY) is maintained by the National Institute of Information
and Communications Technology (NICT). 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.

Note that transmission of the time calibration signal may be interrupted occasionally due to
maintenance, lightning, etc.

Reception Range

This watch is designed to receive either the Mt. Otakadoya signal (40kHz) or the Mt. Hagane signal
(60kHz), whichever is strongest.

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.

Geographic contours, nearby buildings, seasonal conditions, the time of day, can even make reception
impossible even when you are within range of the transmitter.

Reception is best at night.

1000km

Mt. Hagane

(60kHz)

Mt. Otakadoya

(40kHz)

500km

1000km

500km

Transmitter Locations

Location

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 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 receive (Reception is performed automatically at midnight, 1:00, 2:00, 3:00 and 4:00 each

morning.)

Auto receive is terminated as soon a reception is successful.

If auto receive is not successful for any of the normal auto receive operations shown above, auto
receive is performed one more time at 5:00 a.m.

Successful auto receive keeps timekeeping accurate.

Manual receive (You initiate reception using a button operation.)

To position the watch for optimum reception

Remove the watch from your wrist and place
it somewhere so its right side (9 o’clock side,
where the antenna is located) is facing a
window.

Do not move the watch while it is receiving
the calibration signal.

Time Required for Reception

A calibration signal receive operation takes
anywhere from about two to seven minutes.

To perform manual receive

In any mode, hold down the 

B

B

B

B

B

 button for about two

seconds.

The second hand will move to READY, and signal reception will
start.

To interrupt reception

Press any button. This will cause the watch to return to the Timekeeping Mode.

When reception is successful

The watch will terminate reception and adjust the current time. Next the second hand will move to
GET.

When reception is not succesful

The second hand will move to NG (No Good), without adjusting the time setting.

After the second hand is pointing at GET or NG, the watch will return to the Timekeeping Mode if you
press any button or if you do not perform any operation for about one or two minutes.

Hand Operation During Signal Reception

Second Hand ..................... The second hand moves to READY when the reception operation starts,

indicating that the watch is getting ready to receive. It points to WORK
while actual reception is in progress.

Hour and Minute Hands ... The hour and minute hands continue to operate normally.

Note that the second hand does not move during signal reception.

To check the result of the last signal receive operation

In the Timekeeping Mode, press the 

B

B

B

B

B

 button. This

enters the Receive Result Mode.

If the watch was able to perform a successful signal receive
operation since midnight, the second hand will move to GET. If
the watch has been unable to receive any signal successfully,
the second hand will move to NG.

To return to the Timekeeping Mode, press the 

B

 button twice.

The watch will also return to the Timekeeping Mode if you do not
perform any operation for about one or two minutes.

Calibration Signal Reception Precautions

Auto reception can be performed while the watch is in the Timekeeping Mode only.

If the hands become misaligned for some reason, they may not indicate the correct time, even if the
time calibration signal is received normally. If this happens, use the procedure under “Adjusting Home
Positions” to adjust the home positions of the hands and the date.

Pressing any button while auto reception is in progress will cause reception to stop.

This watch is designed to adjust its current time setting in accordance with the calibration signal
transmitted in Japan only. It operates like a standard (non-radio controlled) watch outside of the range
of the receivable time calibration signal transmitters.

When the watch is unable to receive the time calibration signal for some reason, timekeeping accuracy
is within 

±

20 seconds per month.

Proper reception may be impossible if there is something blocking the signal.

The watch’s calendar shows dates up to the year 2099. Attempting a receive operation after that
causes an error.

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.

In a location where there is
radio interference (construction
site, airport, etc.)

Near mountains

Inside a vehicle

(automobile, train, plane, etc.)

Next to a household appliance or
office equipment (TV, speaker,
fax, computer, cell phone, etc.)

Among or near buildings

Near high-voltage lines

READY

9 o’clock
side

Or

GET

Summary of Contents for 3707

Page 1: ...efficiency Charging Guide Starting from a full charge the watch should be able to continue operating for about five months without further charging under the conditions described below Daily Use All time values are approximate Signal reception 6 minutes Making sure the watch is regularly exposed to light ensures stable operation 1 hour 3 hours 4 hours 37 hours 16 hours 78 hours Timekeeping Restore...

Page 2: ... minutes To perform manual receive In any mode hold down the B B B B B button for about two seconds The second hand will move to READY and signal reception will start To interrupt reception Press any button This will cause the watch to return to the Timekeeping Mode When reception is successful The watch will terminate reception and adjust the current time Next the second hand will move to GET Whe...

Page 3: ...f second hand alignment is correct it should point directly at 12 o clock If the second hand is pointing at 12 o clock Advance to step 3 If the second hand is not pointing at 12 o clock Press the B button to move the second hand clockwise until it points at 12 o clock Each press of the B button advances the second hand by one second Holding down the B button for about two seconds advances the seco...

Page 4: ... button operation for about two or three minutes the watch will exit the manual setting mode and normal hand movement will resume Pressing the A button and the B button at the same time in the manual setting mode will cause the hands to move to the original unadjusted time setting Then the watch will return to the Timekeeping Mode 2 Use the operation described below to move the hands clockwise To ...

Page 5: ...Sep Aug Jul Apr Jun May Nov Dec Oct Forward 6 Press the A A A A A button This will cause the second hand to move to the ten s digit of the year setting 7 Press the B B B B B button to increase the ten s digit setting by one You can set the year within the range of 2000 to 2099 Forward 10 20 30 90 80 70 40 60 50 00 8 Press the A A A A A button This will cause the second hand to move to the one s di...

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