Japan recently launched the first of three QZSS navigation satellites. These are to complement the current American GPS satellites. QZSS is meant to overcome the interference (to GPS signals) from the many mountains and tall buildings in Japan. When all three of the four ton QZSS satellites are operational, Japanese GPS users will get a signal 99.8 percent of the time, rather than the current 90 percent. While QZSS broadcasts a similar signal, special receivers will be required to use the QZSS signals.