What is the fine-grained topic of the following text: While GPS and Glonass are fully functional global systems, the Chinese and the Japanese systems offer regional coverage and Europe’s Galileo is yet to be operational.India will formally join the select group of nations owing such system once IRNSS is declared operational after checking the systems – space (satellites), ground (ground stations) and the user-end signal receivers. Only return the topic.
Global Navigation Satellite Systems