The Quasi-Zenith Satellite System (QZSS), developed by Japan, provides a regional satellite navigation service in East Asia and Oceania. QZSS was designed to provide position service in urban canyons and mountainous environments. Although QZSS is primarily an augmentation and complementary system to GPS, it also has the potential to operate in stand-alone mode providing a regional service, however with diminished positioning performance.Nevertheless, the system has the capability to be extended to a fully operational, high-performance Japanese regional system in the future.
In October 2002, a GPS/QZSS Technical Working Group was established for a joint specification of the QZSS signals to guarantee interoperability with GPS. At the beginning the system was developed by the Advanced Space Business Corporation (ASBC) team,including Mitsubishi Electric Corp., Hitachi Ltd., and GNSS Technologies Inc. In 2003, the conceptual study phase has been started. When in 2007 ASBC collapsed, the work was taken over by JAXA together with Satellite Positioning Research and Application Center (SPAC), established in February 2007 and approved by the Ministers associated with QZSS research and development.The Initial Phase Operation started in September 2010 with the launch of the first quasi-zenith satellite, Michibiki, has been completed by summer 2011, with all functions of the satellite and the ground segment confirmed.In 2011 the Government of Japan has decided to accelerate the QZSS deployment in order to reach a 4-satellite constellation by the late 2010s, while aiming at a final 7-satellite constellation in the future.
As GPS, QZSS is a CDMA system with a different ranging code f
or each satellite.The Quasi-Zenith Satellites (QZS) transmit L1C/A compatible with the GPS L1C/A signal at the frequency of 1575.42 MHz, which means QZSS applies for the L1C/A signal,the same ranging code modulation as GPS. The PRN codes are assigned in coordation with GPS. Furthermore, the same navigation message, as specified by GPS, is modulated on the L1C/A signal.
QZSS also includes additional signals that will not be supported in Signal Studio:
L1C (its ranging codes and navigation messages are in accordance with GPS L1C's )
L1-SAIF (Submeter-class Augmentation with Integrity Function) signal
L2C ( a replica of GPS L2C component)
L5I (a replica of GPS L5C component)
L5Q (a replica of GPS L5C component)