The Relative and the Absolute: A MOSA Path to Complementary Position, Navigation, and Time Information for GPS

Published in Military Embedded Systems

The use of a modular open systems approach (MOSA) will benefit the effort to integrate alternative position, navigation, and timing (PNT) technologies into platforms. In addition, a MOSA can increase competition and innovation while reducing the use and associated costs of proprietary systems.

The U.S. military has become increasingly dependent on data provided by GPS satellites. The GPS constellation consists of 31 medium-Earth orbit satellites that provide the military with its primary source of position, navigation and timing (PNT) information. PNT data is used to determine location, ascertain orientation, and plan routes, while enabling the fusion of intelligence, surveillance, and reconnaissance (ISR) data. Beginning in the 1970s, the Navy was the first to use GPS; later, during the Persian Gulf War in 1991, GPS use was expanded to ground vehicles. Today, it’s estimated the Army has 500,000 GPS receivers in use.

With such a valuable system in place, it is not surprising that GPS is under threat. In 2020, a congressional defense task force reported that GPS could be a single point of failure for the U.S. military. Adversaries are actively developing electronic warfare (EW) capabilities, such as GPS jammers and spoofers, as well as ground-based antisatellite weapons. Access to continual GPS data requires a clear line of sight between the platform and the satellites, which is not always possible in urban combat situations. The U.S. Department of Defense (DoD) recognizes the threat posed by the possible loss of this critical battlefield infrastructure. Consequently, the Pentagon is now upgrading the GPS system: Under the GPS III program, the U.S. Space Force is developing and deploying new satellites that use M-Code, a stronger military navigation signal that gives users superior capabilities including better defense against jamming.

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