Satellite Navigation System Upgrades, Buildouts Move Forward
Monday, May 02, 2016 | Comments
The world’s satellite navigation systems have undergone upgrades and new launches during the past several years. The four major positioning systems — Europe’s Galileo, China’s BeiDou, Russia’s GLONASS, and the U.S. GPS systems — all have been bolstered with updated satellites that provide longer service, updated functionality and interoperability with other navigation systems. In addition, regional systems are progressing in Japan and India.

The systems are expected to play an increasing role in future services and tools that affect public-safety and mission-critical communications.

Coverage provided by Europe’s Galileo system is increasing after the European Space Agency (ESA) launched the ninth and 10th satellites to its planned constellation of 30 satellites in medium earth orbit, including 24 active satellites and six spares. The satellites were launched in September 2015 and underwent in-orbit testing before beginning live broadcasts earlier this year. A Galileo control center in Oberpfaffenhofen, Germany, tested command-and-control functions, while a control center in Fucino, Italy, tested navigation messages to users.

“This is the first recurrent launch of Galileo full operational capability satellites from an in-orbit test point of view,” said ESA’s Christian Lezy. “All tests were conducted in a seamless manner in parallel with the ongoing routine operations of the rest of the fleet.”

ESA launched satellites 11 and 12 in December, and those satellites are still undergoing in-orbit testing. Satellites 13 and 14 are in the pre-flight stage and awaiting launch. Production on the remaining satellites is ongoing.

The Galileo system is a collaboration of the European Space Agency (ESA) and the European Commission (EC) to build an independent satellite positioning system under civilian control. The system is expected to be interoperable with other satellite navigation systems, including GPS.

China has been busy filling out its constellation of 21 planned satellites that will make up its BeiDou navigation system. In February, China launched its 21st BeiDou satellite into space from the Xichang Satellite Launch Center in Sichuan Province. Chinese media reported that the satellite is entering a testing phase and is already successfully transmitting signals back to earth.

The first 16 satellites in the constellation focused coverage on China and neighboring regions. The second phase, which includes five satellites to date, is expected to expand coverage worldwide. The new satellites are testing intersatellite crosslinks and a new navigation signaling system.

“Our new intersatellite crosslink system, featuring strong disturbance resistance and high-level privacy, is the core technology to compete with other countries’ navigation networks,” said Lin Baojun, the satellite’s chief designer. “The new satellite will fully verify our technology.”

China began development of the BeiDou system in 2000 and expects the completed constellation to include 35 satellites in both geostationary and nongeostationary earth orbits by 2020.

Russia’s Global Navigation Satellite System (GLONASS) has a long history dating back more than three decades. The Soviet Union launched 43 GLONASS satellites by 1991, and the Russian Federation continued development of the system during the 1990s. The system was fully operational in 1995 with 24 satellites in orbit.

A period of financial instability prevented the Russian Federation from maintaining an ongoing launch schedule required to keep the system operational. However, by 2001, the system had only six operational satellites.

A modernization and renewal effort on GLONASS began in the early 2000s and the system was restored to 24 satellites in 2011. In December 2015, the system was declared officially completed. Russia continues to launch satellites to replenish GLONASS satellites, including a launch of a Soyuz rocket carrying the 51st GLONASS satellite in early February. Newer generation satellites with longer service life are being developed and are expected to launch in the next couple of years.

The U.S. GPS system also has been undergoing a modernization effort aimed at replacing aging equipment and introducing new capabilities. The U.S. Air Force successfully launched the 12th and final IIF category satellite in February aboard an Atlas V 401 rocket.

“This is a significant milestone for GPS, the 50th GPS satellite to be delivered on-orbit,” said Lt. Gen. Samuel Greaves, Space and Missile Systems Center (SMC) commander and Air Force program officer for space. “The GPS IIF satellite performance has been exceptional and is expected to be operational for years to come.”

The next phase, GPS III, is underway. The SMC released a request for proposals in January for GPS space vehicles.

Regional Systems
India and Japan both are working toward launching regional satellite navigation systems. India’s system will consist of three satellites in geostationary orbit (GEO), four satellites in geosynchronous (GSO) orbit and two standby satellites on the ground. Satellite launches were expected to occur over the past few months, and the system is planned to be operational in June. The system is expected to provide civilian navigation and positioning services, as well as an encrypted service for use by the military and authorized users.

Japan’s Quasi-Zenith Satellite System (QZSS) — also known as Michibiki — is expected to integrate with GPS and make up for deficiencies that occur because a limited number of GPS satellites are visible over Japan at a given time. The system is expected to have four satellites in orbit by 2018, three of which will be visible at all times from locations in the Asia-Oceania regions. These satellites and the visible GPS satellites will ensure eight or more positioning satellites are always available, increasing location accuracy.

Japan is planning additional satellite launches to create a seven-satellite constellation that will further increase the number of always-visible satellites and improve location capabilities in urban and mountainous regions that are affected by multipath, obstructions and terrain.

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