DOD races against time to keep GPS up and running

By: William Jackson
December 13, 2017

William Jackson
William Jackson

The current iteration of the Global Positioning System (GPS)—first launched by the Defense Department in 1973 and fully operational since 1995—is proving to be more durable than expected and is forecast to remain operational until June of 2021. But all things come to an end, and as the solar arrays on the current constellation of satellites degrade so will the signals relied upon by military, commercial and civilian users around the world.

Modernizing GPS while sustaining the current capability requires new satellites to replace the existing ones that are near the end of their expected operational life and developing a ground control system for both existing and new satellites.

Congress approved funding for the next generation of the system, GPS III, in 2000. But program delays have left the DOD racing against the clock to field the next generation of satellites, ground stations and receivers while keeping the current system operational, according to a new report from the Government Accountability Office.

The Air Force expects to launch six new satellites by June 2021, but things are moving more slowly on the ground.

“DOD is relying on a high-risk acquisition schedule to develop a new ground system, known as OCX, to control the broadcast of a modernized military GPS signal,” GAO reported. The OCX program has been delayed by five years, and the Air Force has an interim program to modify the current ground system to deliver a limited encrypted signal for the military, called M-code.

Getting the equipment to use that M-code signal could be more problematic. DOD has begun testing receiver cards for the new signal, but additional work is needed to make M-code work with more than 700 weapon systems that use GPS. Only 28 weapons systems are fully funded for upgrading to the new M-code, and 72 are partially funded, for a total of $2.5 billion. The rest have not been funded. “The cost will increase by billions when as yet unfunded weapon systems are included,” GAO said, and there is no timeline for deploying the new receiver cards.

GPS has become so common in our cars and smart phones that many might have forgotten that the Global Positioning System began as a military program to provide positioning and navigation for weapons systems and troops in the field. It was opened to civilian use in the 1980s. Ground-based receivers get precise time signals from a number of satellites and use them to compute the receiver’s location. Current civilian signals are accurate to about 5 meters without additional refinement. Military users get more accurate results.

GPS was pretty much by itself for more than 15 years, but new systems have begun coming online:

  • GLONASS—The Russian satellite positioning system, which became fully operational in 2011 with 24 satellites in orbit, is the only other fully operational global system. It has an accuracy of 4.5 to 7.4 meters.
  • Galileo—The European Union’s system began operation in 2016 and is expected to be fully operational in 2020. It now has 30 satellites in orbit and has an accuracy of 1 meter for public use and 1cm for military and paying commercial customers.
  • BeiDou—China’s navigation system now covers Asia and the West Pacific region and is expected to be fully operational in 2020. It has 22 satellites in orbit and an accuracy of 10 meters for public use and .1 meter for military.
  • IRNSS—Is India’s regional system, with seven satellites. It is accurate to with 10 meters for public use and .1 meter for military.
  • QZSS—Is a Japanese regional system to augment GPS signals for accuracy from .01 to 1 meter. It has three satellites.

With plans in place for DOD to begin launching GPS III satellites and to fix up the current ground control system to deliver the new M-code signals, the DOD’s major challenge now is in getting GPS III ground receivers, GAO said.Once USAF develops the receiver cards, acquisition and upgrading across DOD will be complex. As yet, “DOD does not have an organization assigned to collect test data, lessons learned, and design solutions so that common design solutions are employed to avoid duplication of effort,” GAO said. “DOD therefore risks paying to repeatedly find design solutions to solve common problems because each program office is likely to undertake its own uncoordinated development effort.”

DOD said it plans to put an organization in place to coordinate data and lessons in designing and deploying receivers.