GPS Modernization: DOD Continuing to Develop New Jam-Resistant Capability, but Widespread Use Remains Years Away, Report to Congressional Committees [open pdf - 8MB]
From the Highlights: "DOD has been developing the capability to use its more jam-resistant military-specific GPS [Global Positioning System] signal for 2 decades. The Air Force launched the first GPS satellite capable of broadcasting the M-code [military code] signal in 2005, but is only now completing development of the software and other equipment needed to use it. The GPS modernization effort spans DOD and the military services, but an Air Force program office is developing M-code cards for eventual production and integration into weapon systems. The National Defense Authorization Act for Fiscal Year 2016 included a provision that the Air Force provide quarterly reports to GAO [Government Accountability Office] on next-generation GPS acquisition programs, and that GAO brief congressional defense committees. Since 2016, GAO has provided briefings and reported on various aspects of GPS. This report discusses DOD's progress and challenges (1) developing M-code receiver cards, and (2) developing receivers and taking other steps to make M-code-capable receivers available for fielding. GAO reviewed schedules and cost estimates for the Air Force's MGUE [Military GPS User Equipment] programs; military service and DOD M-code implementation data; and test and integration plans for aircraft, ships, and ground vehicles. GAO also reviewed strategies for continued access to microelectronics and interviewed officials from the MGUE programs, military services, and DOD, and representatives from microelectronics developers."
Government Accountability Office: https://www.gao.gov/