Eroding the Jamming Threat to Military GPS
Alex Cerruti, Daniel Shultz, John W. Betz, The MITRE Corporation
Alternate Number 1
This paper compares performance in jamming of modernized military GPS with currently fielded systems, demonstrating that completing and fielding current GPS programs of record will make the new military GPS user terminals highly resistant to jamming. For more than a decade, the Space Force’s Space and Missile Systems Center has been executing a set of programs designed to counter threats to the use of military GPS. As these programs mature, it is important to understand how effective they will be against jamming, and to postulate how adversaries might then react.
While current operational military terminals use the original military signal, the P(Y)-signal, the Military GPS User Equipment (MGUE) program is developing chipsets forming the basis for terminals that primarily use the modernized GPS military signal, the M-signal. The M-signal design has many features that terminals can exploit for enhanced robustness against jamming. MGUE exploits these features while also implementing sophisticated and robust processing techniques enabled by modern digital electronics. This greater jamming tolerance in MGUE is complemented by the higher received M-signal power provided by the GPS Block III satellites, with even greater power from regional military protection (RMP) on the GPS Block IIIF satellites.
This paper introduces the use of Tolerable Jamming Power (TJP) as a replacement for J/S, the ratio of received jamming power to signal power, to effectively assess the combination of receiver processing and signal power on jamming resistance. It then shows the TJP of various representative legacy P(Y)-signal terminals operating in different modes. The TJP of MGUE is then compared for signals from GPS Block III and GPS Block IIIF satellites. The significant improvement in TJP translates into the ability to operate much closer to jammers and can be further improved as needed by using anti-jam antenna systems.
It is thought that adversaries would react to this increase in TJP by further increasing their jamming power. This paper identifies and evaluates the available adversary courses of action to recover the jamming capability that has been eroded by M-signal and provides an assessment of the ability of the program of record to sufficiently counter the current and projected jamming threat to military GPS.
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