Positioning, Navigation, and Timing (PNT) Satellites
Japanese PNT Satellites (QZSS)
Japan’s Cabinet Office continues to operate all four satellites of QZSS (also known as Michibiki), the country’s PNT constellation. QZSS is a regional PNT system solely catering to . . .
After seven years of single-satellite operations for the Quasi-Zenith Satellite System (QZSS), Japan’s PNT constellation, the Japan Aerospace Exploration Agency (JAXA) launched . . .
In 2010, the Japan Aerospace Exploration Agency (JAXA) launched a single positioning, navigation, and timing (PNT) satellite as a start for its Quasi-Zenith Satellite System (QZSS). Japan has not launched other satellites into the QZSS constellation since. Japan’s 2016 share of the world’s operational PNT satellites was ##%. The country plans to…
The Japan Aerospace Exploration Agency (JAXA) launched the ## satellite of its Quasi-Zenith Satellite System (QZSS) in September 2010, and continued to operate and run tests on it during 2014. Japan’s urban canyons and mountainous regions present challenges for receiving the relatively weak signals from PNT satellites such as GPS. The inclined orbit of QZSS, in combination with its dwell time over Japan, gives PNT receivers in Japan a better chance of receiving a PNT signal.
Japan already employs a ##-satellite GPS-augmentation system called MSAS, which stands for the MTSAT (Multi-functional Transport Satellite) Satellite-based Augmentation System. The Japan Aerospace Exploration Agency (JAXA) is also creating the Quasi-Zenith Satellite System (QZSS), consisting of ## to ## quasi-GEO satellites that will address navigation issues specific to Japan’s geography. While these will be at similar altitudes as traditional GEO satellites, they will not actually be fixed over the Equator like typical FSS satellites.
Japan is creating the Quasi-Zenith Satellite System (QZSS), consisting of ## or ## satellites in a quasi-zenith orbit, and ## satellites in GEO to be operated by JAXA. This network will supplement its signals with those of the GPS network and, by using a tailored GEO orbit, will provide improved positioning performance in urban and mountainous regions. These GEO satellites will not be fixed over the Equator like typical FSS satellites but will regularly move north and south in relation to the Equator, making them easier to be seen from those areas where line-of-sight visibility to GPS can be difficult.
The complete constellation is planned to be in place by 2011, though no launches had been conducted by the end of 2009. Japan’s Quasi-Zenith Satellite System (QZSS) will consist of ## GEO satellites operating over Japan and surrounding areas. While these satellites are geosynchronous, orbiting the Earth once per day, they are not stationary as are FSS satellites. They are inclined-GEO satellites, meaning that they move in a north-south “figure eight” pattern as observed from a single point on the Earth.
Japan’s Quasi-Zenith Satellite System will supplement GPS coverage over areas of Japan that prove difficult with GPS alone. The first launch is expected in 2010.
The first launch of Japan’s Quasi-Zenith Satellite System (QZSS) is scheduled for 2009. QZSS uses ## geosynchronous satellites in orbital planes designed to have observed elevations of 60 to 70 degrees over Japan. These observed elevations will avoid interference from urban canyons or mountains.
Japan is developing the Quasi-Zenith system, a regional augmentation of the GPS signal, with a 2008 planned launch.