Jam-Resistant GPS Technology Deployment Delayed

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GPS may seem like everyday technology, but it depends on military systems that continue to evolve to meet defense needs. The US Department of Defense has worked for decades to develop a jam-resistant GPS capability for the military called M-code. This requires satellites to broadcast the M-code signal, control systems on the ground, and equipment that can receive it.

Modernized satellites are in space but receiver equipment needed for weapons systems to make use of the signal is delayed, in some cases by years, causing ripple effects. Due to receiver delays, for example, DOD is no longer planning to use this technology in some new aircraft.

So while the DOD continues to develop new jam-resistant capability, widespread use remains years away due to the complexity of the technology, states a Government Accountability Office report published recently at gao.gov. 

According to the report, M-code-capable receiver equipment includes different components, and the development and manufacture of each is key to the modernization effort. These include:

• Special M-code application-specific integrated circuit chips
• Special M-code receiver cards, being developed under the Air Force Military GPS User Equipment (MGUE) programs
• The next generation of GPS receivers capable of using M-code signals from GPS satellites 

DOD will need to integrate all the components into different types of weapon systems. Integration across DOD will be a considerable effort involving hundreds of different weapon systems, including some with complex and unique integration needs or configurations.

The Air Force is almost finished — approximately one year behind schedule — developing and testing one M-code card for testing on the Marine Corps Joint Light Tactical Vehicle and the Army Stryker vehicle. However, one card intended for use in aircraft and ships is significantly delayed and missed key program deadlines. The Air Force is revising its schedule for testing this card.

GAO added that the DOD initially intended to incorporate the M-code receiver into F/A-18 fighter aircraft, MH-53E helicopter and AV-8B strike aircraft but terminated plans due to delays.

DOD has been developing the capability to use its more jam-resistant military-specific GPS signal for 2 decades. The Air Force launched the first GPS satellite capable of broadcasting the M-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, according to the report.