Casio 4390 Manual page 21

• Signal reception may not be possible up to the distances noted below during certain
times of the year or day. Radio interference may also cause problems with reception.
Mainflingen (Germany) or Anthorn (England) transmitters: 500 kilometers (310
miles)
Fort Collins (United States) transmitter: 600 miles (1,000 kilometers)
Fukushima or Fukuoka/Saga (Japan) transmitters: 500 kilometers (310 miles)
Shangqiu (China) transmitter: 500 kilometers (310 miles)
• Even when the watch is within the reception range of the transmitter, signal
reception will be impossible if the signal is blocked by mountains or other geological
formations between the watch and signal source.
• Signal reception is affected by weather, atmospheric conditions, and seasonal
changes.
• See the information under "Signal Reception Troubleshooting" (page E-31) if you
experience problems with time calibration signal reception.
E-19