Can the cooperation of the four global navigation systems achieve seamless coverage of global positioning 100%?

Global navigation satellite system (GNSS), also known as global navigation satellite system, is a space-based radio navigation and positioning system, which can provide users with all-weather three-dimensional coordinate, speed and time information anywhere on the earth's surface or near-earth space. Include one or more satellite constellations and their augmentation systems required to support a specific task.

At present, the four major navigation systems in the world are the global positioning system (GPS) of the United States, GLONASS of Russia, Galileo of the European Union and BDS of China. GPS is a medium-range circular orbit satellite navigation system. It can provide accurate positioning, speed measurement and high-precision time standard for most areas (98%) of the earth's surface.

Personally, I think this 100% seamless coverage is such an absolute answer, and it changes in real time, but at present it is basically global coverage.

Thumbnail of global satellite navigation system