How A Radio-Controlled Watch Works; Calibration Signal - Casio 2730 Operation Manual

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 received using
built-in antenna.
Transmitter Long-wave

Calibration Signal

Watch decodes
received data and
Signal Data converts it to time
data.
Decode
Time Data
Time is adjusted
Cesium
according to time
Atomic Clock
Internally
Watch
data.
After the watch receives the time calibration 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.
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.
Among or near buildings Near high-voltage lines
Inside a vehicle Next to a household appliance
(automobile, train, plane, etc.) or office equipment
(TV, speaker, fax, PC,
mobile phone, etc.)
In a location where there is
radio interference
(construction site, airport, etc.) 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.
Operation Guide 2730
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.
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.)
• Manual receive (You initiate reception using a button operation.)
• If reception is not successful for any of the normal auto receive
times shown above, auto receive is performed one more time at
5:00 a.m.
• 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 it
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.
Reception Range
This watch is designed to receive the standard time calibration signal of Japan (JJY) or of the United States (WWVB). The signal that is
received depends on the current Home City setting.
• For information about selecting a Home City, see "Setting the Time and Date Manually".
Home City
Either the Mt. Otakadoya signal (40kHz) or the Mt. Hagane signal (60kHz)
TYO
Fort Collins, Colorado signal
LAX, DEN, CHI, NYC
Transmitter Location
1000km
Mt. Otakadoya
500km
(40kHz)
500km
Mt. Hagane
(60kHz)
1000km
• 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, the season, the time of day, can even make reception impossible even when you are within range of
the transmitter.
• Best reception is possible late at night.
Time Required for Reception
Signal reception takes anywhere from about two to six minutes.
• Note that when "AT" is specified as the frequency selection mode,
signal reception can take up to 12 minutes.
• See "Specifying the Transmitter Selection Mode" for more
information.
Triggering Reception Manually
In the Timekeeping Mode, hold
down the D D button for about D D D
two seconds until the watch
beeps.
• This indicates that manual receive
has started. Ongoing reception is
indicated by the icon and the
receive indicator.
Stopping Signal Reception
Press the D D D D button. D
• All other buttons besides D are disabled during signal reception.
When reception is successful
The watch terminates reception and adjusts the current time. Next
it beeps and then displays the date and time the adjustment was
performed.
• The icon on the display also indicates successful signal reception.
• Following successful reception, the analog hands adjust
automatically to the digital time.
When reception fails
The watch does not adjust its current time setting, and displays
"ERR" instead.
• The display also returns to the normal timekeeping screen
automatically if you do not perform any operation for about one
or two minutes.
Transmitter
Transmitter Location
3000km
1000km
Fort Collins
• 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.
Receive Icon
Receive Icon
The receive indicator cycles from
"Unstable" through "Stable" as
shown below while reception is in
progress. How far it cycles depends
on the signal strength. Keep the
watch in a location where reception
isstable when it is in progress.
Unstable Stable
• Even under optimum reception conditions, it can take about 10
seconds for reception to stabilize.
• Use the receive icon 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.
Analog Hands and Signal Reception
Second Hand
This hand moves to the 12 o'clock position when reception starts.
• It resumes normal movement after reception is complete.
• Pressing a button to stop reception causes the second
hand to move to the seconds count as kept by the digital
display and resume normal operation.
Hour and Minute Hand
These hands continue to operate normally.
Note that the second hand does not move while signal
reception is in progress.
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