GPS III to boost accuracy, security

The Air Force is on track to deliver in August 2016 the first of a series of advanced GPS satellites that promise to vastly improve the accuracy, reliability and security of the global positioning system constellation used by the military and civilian users, according to Air Force Col Steven Whitney, director of the Global Positioning Systems Directorate within Air Force Space Command's Space and Missile Systems Center.

Most of the GPS satellites in orbit have surpassed their operational design life and need more advanced capabilities to meet the military's changing requirements for position, navigation and timing (PNT) services as well as advanced anti-jamming capabilities. As a result, the Air Force and Lockheed Martin are developing the next-generation satellite system, known as GPS III, to sustain and modernize the constellation.

GPS III will deliver three times better accuracy, provide up to eight times improved anti-jamming capabilities and extend spacecraft life to 15 years, 25 percent longer than the satellites launching today, according to Lockheed Martin. Moreover, GPS III's new L1C civil signal also will make it the first GPS satellite interoperable with other international global navigation satellite systems.

At the end of December, the GPS III space vehicle one (SV 01) completed thermal vacuum testing, where it is was subjected to simulated harsh space environments. Successful completion of this testing is critical as it will help validate the design and manufacturing processes for all follow-on GPS III satellites, Mark Stewart, vice president of Lockheed Martin's Navigation Systems mission area, said when SV 01 entered testing last summer.

"Our work is not done after the first satellite," Whitney said. "Our joint team has laid out detailed schedules for satellites two through eight to keep a steady production flow." Lockheed Martin is under contract to build eight GPS III satellites at its GPS III processing facility near Denver, a factory specifically designed to streamline satellite production.

Whitney said the Air Force is negotiating to purchase two additional satellites, SV 09 and SV 10. Furthermore, on Jan. 8, SMC released a solicitation seeking proposals for the GPS III Space Vehicles 11+ Phase 1 Production Readiness Feasibility Assessment contract. The initial phase of this strategy is to research whether there is sufficient competition for production-ready satellites. Based on the results of that research, the Air Force will determine what type of procurement process should be in place to purchase production-ready satellites, Whitney said.

GPS III SV11+ will use the current GPS III SV01-08 requirements baseline with the addition of a redesigned Nuclear Detonation Detection System government furnished equipment (GFE) hosted payload, a search and rescue/GPS GFE hosted payload, a laser retro-reflector array GFE hosted payload, unified S-band compliance capability, and a regional military protection capability. No changes are allowed to the GPS next generation operational control system (OCX) or Military GPS User Equipment (MGUE) interfaces.

The aggressive launch campaign

"The Department of Defense—specifically, the Air Force—develops and operates the GPS system, which consists of three segments: space, which comprises a constellation of PNT satellites orbiting the earth—currently, approximately 40; ground control, which primarily consists of software and operates the satellites as well as monitors and corrects signal data; and receivers, which help civil and military users employ GPS signals to determine their location," according to a September 2015 GAO report on development of OCX and MGUE. For about the past eight years, the Air Force has been in the process of modernizing all three segments to enhance GPS performance and security.

"We currently have 40 active satellites with 31 of those operational," Whitney said.

The most recent launch was on Oct. 31, 2015. Now 11 of the 12 GPS 11F satellites are in orbit. The final satellite of that family goes up on February 3," Whitney said. (Editor's note: After the interview, the launch was rescheduled to February 5.)

Adding GPS III satellites to the constellation eventually will boost the number of satellites to 24 with M-code capability.

M-code offers new capabilities

M-code is a new signal that is designed to improve both the security and anti-jamming properties of military navigation using GPS, and will be an integral capability in the GPS III family of satellites.

"M-code itself offers advanced anti-jamming and spoofing," Whitney said. It is a modernized signal, which is built to provide intense wave forms and higher power without interfering with existing signals, he noted.

M-code also has advanced cryptography capabilities similar to the modern, crypto methods used in cell phones.

Anti-jamming and spoofing capabilities are critical in today's environment in which threats to military GPS have evolved and improved at a rapid pace — from a proliferation of small-scale commercial jamming devices that can readily be purchased on eBay to large-scale military anti-access/area-denial capabilities, Army MAJ Christopher Brown, assistant program manager Dismounted PNT within the Army's Assured PNT program, told C4ISR & Networks in an interview last year.

Search and rescue payload from Canada

In addition to the anti-jamming capabilities, GPS III eventually will offer a search and rescue capability hosted on the satellites. "Search and rescue is a hosted payload provided by Canada. We are putting that payload on the satellite and it will come with future generations of satellites number 11 and beyond," Whitney said.

Canada's Department of National Defense announced last July that the department will provide the U.S. Air Force' with 24 search and rescue repeaters. Provided by Canada's Medium Earth Orbit Search and Rescue satellite project, the repeaters will significantly cut down on the time it takes to detect and locate a distress signal from an hour to about five minutes, according to Canadian officials.

As the Air Force works on the GPS constellation to offer vastly improved PNT and security to military and civilian users, actions are needed to improve ground control system development and user equipment readiness, according to the GAO report.

"OCX is the key to enabling the full GPS capability that both the military and civilian communities depend on, from command and control of the satellite constellation including the new GPS III satellites, to allowing military receivers to take advantage of M-code signals for more robust war fighting capability, to enabling advanced civil GPS signals. However, by any measure, OCX development has been mired in development difficulties resulting in steady cost growth and schedule delays," the report states.

The Air Force now needs OCX block 1 to be operational by late 2019 to launch and incorporate GPS IIIs into the constellation, the report states.

Going forward

The GPS ground control segment is being modernized under the OCX program, with Raytheon as the prime contractor, and military receivers are being developed under the MGUE program, utilizing three prime contractors.

Whitney noted that the GPS III program has had technical challenges in the past that are well-documented. The first GPS III satellite was originally expected to be available for launch in April 2014, but development problems delayed its initial launch, the GAO report states.

"Bottom line is GPS is the world's global utility, it will be here when you need it," Whitney said.

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