GPS is a misnomer, it should be JPS, Japan Positioning System, nothing global to see here folks. It is unfortunate that the article does not stress that this system is only useful in Japan; especially with the conclusion that many nations will be watching the results given the "range of promised applications [range of use, certainly not geographic range] and relatively low cost." That being said I am interested to see how the experiment with atomic clockless birds goes. One of the most overlooked features of GPS is time transfer.
Well, only sort of: GPS is the initialism for a specific system (and QZSS provides corrections for that particular system's satellites, among other things), not a generic term for global navigation satellite systems. Had it said "Japan’s Plan for Centimeter-Resolution GNSS", it would have been different. Europe has EGNOS, which is similar (and was recently granted €1.3 billion for upgrades), the US has WAAS, and India has something similar too [1][2].
Yes. India has GAGAN (GPS Aided Geo-Augmented Navigation)[1][2] to augment GPS accuracy, similar to EGNOS and WAAS. Apart from this, there's IRNSS (Indian Regional Navigational Satellite System)[3], which is an indigenous satellite navigation system independent of GPS.
"Well only sort of" what? Yes, "GPS is the initialism for a specific system" and G is the initial for Global. The G in GNSS is also global so I am not sure how that is any different. The article is titled "Japan's Plan for Centimeter-Resolution GPS" and then goes on to describe a system that is anything but global.
GNSS is a generic term for globally available satellite navigation system. GPS is a GNSS implemented and maintained by the USA. Japan is planning to launch thier own satellites as part of QZSS program, to augment this GPS coverage over Japan. GPS receivers in Japan can make use of these "local" sats along with American sats for more accurate positioning.
