I am just wondering why Casio doesn't use the on-board GPS atomic clock for atomic time keeping?The GPS system consists of a constellation of 24 orbiting satellites. Each satellite has an on-board atomic clock, providing a highly accurate timing reference to within a few nanoseconds of UTC.
The current earth positioned atomic clock is very limited in reception to certain perimeters only. The most being 3000km radius at Fort Collins, Colorado USA. It is also effected by weather , atmospheric condition, seasonal changes, mountain or other geological formations.
I think the use of GPS atomic clock will be fair to all Casio users all over the world. Though the GPS signal can't travel through metal and brickwork but it can penetrates glass and plastic. The time will automatically be calibrated in the open or by putting the watch close to the window.