With GPS jammers proliferating, the Army wants to enable its missiles to ignore fake signals.
The Army is looking for "novel techniques, which use existing antenna configurations or minor changes to the vehicle's RF front-end, to determine direction-of-arrival of malicious interference sources (i.e., trackable spoof signals) on a missile platform (potentially extendable to other platforms)," according to the Small Business Innovation Research solicitation.
The solution must "generally realizable, or available, hardware and assets on missile platforms to achieve an on-board mitigation routine for interference signals," the Army said. "The available hardware may include on-board CSAC (chip scale atomic clocks), a FRPA antenna and, potentially, one multiple-element CRPA antenna+module (with available covariance estimation). Software approaches are encouraged, but minor hardware upgrades may be considered."
The Army points to newly developed algorithms that would enable a missile to detect jammers and determine their location, such as Multiple Signal Classification (MUSIC). These algorithms focus on unique characteristics of jammers. "For example, trackable interference, aka spoofers, likely generate the entire GPS-like constellation and transmit from a common point; thus, these signals generate exogenous constellation-wide delay (i.e., in a bend-pipe versus line-of-sight RF transmission). Other defining characteristics of a malicious interference may include increased energy (i.e., jammers), clock drift/offset coloring, inter-satellite interference, etc."