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Radio Direction Finding Obfuscation


TECHNOLOGY AREA(S): Electronics 

OBJECTIVE: Develop novel methods and materiel solutions for protecting existing Army radio systems from commonly employed RF radiolocation direction finding systems. Intent is employ techniques that can introduce sufficient spatial uncertainty into target radiolocation systems accuracy as to make their use problematic for the purpose of employing indirect fires against the protected transmitter, while not significantly degrading host radio performance 

DESCRIPTION: The Army is in the process of deploying tactical wideband networking mobile radio systems to lower echelons of the force, which has led to exposing a larger number of data networking radios to adversarial electronic warfare threats, including radio direction finding (DF). At the same time, the Army is entertaining upgrades to our narrowband voice and data systems deployed at the very lowest echelons. Traditional high-assurance Low Probability to Intercept (LPI) / Low Probability to Detect (LPD) techniques cannot defeat modern digital signal processing receivers, and come at significant cost in terms of operational utility, performance and/or spectral resources. The desired solution at completion will employ novel techniques at the physical layer or higher to introduce sufficient uncertainty into the target radiolocation systems as to make these systems unusable for providing targeting for indirect fire. Low Probability to detect solutions are desirable, but not required. Typically, an RMS position error of 300-500m or greater would be sufficient to render a tactical DF system ineffective for cueing indirect fire. Solutions can encompass current Army radio waveform modifications as well as transmission chain modifications appropriate for installation in Army vehicle platforms. There have been little to no commercially published reports of radio location obfuscation techniques being implemented or tested. Target radio platforms include narrowband VHF (30-80 MHz) radios such as SINCGARS, wideband UHF (225-450 MHz) and L-band (1350-1390, 1755-1850 MHz) radios, including HMS Rifleman, Manpack, and MNVR Radios. Target waveforms include SINCGARS, Wideband Networking Waveform, and Soldier Radio Waveform. Target radiolocation techniques include but are not limited to Time Difference Angle of Arrival (TDOA), Amplitude comparison, and Correlative Interferometry. 

PHASE I: The Phase One deliverable will be a comprehensive white paper describing: • Explore potential methods of accomplishing the goal of modifying existing tactical radio systems to be resistant to common radiolocation techniques/systems that would be implemented on a tactical ground vehicle or aircraft. • Perform trade analysis to determine best alternative technique/approach, balancing performance, suitability to platform, and cost. • Perform analysis of potential host radio waveform software changes and/or hardware packaging approaches suitable for use on Army radio platforms. 

PHASE II: • Develop and demonstrate a prototype solution for Army radios that employ wideband networking waveforms. • Phase Two deliverables will include: o Prototype solution suitable for use with Army vehicle mounted radios o Demonstration of the prototype with existing Army radio systems o Test report detailing solution performance against common threats o Product documentation detailing functions and operations of the prototype Monthly Progress reports. The reports will include all technical challenges, technical risk, and progress against the schedule. o A baseline approach and schedule for phase III. 

PHASE III: • Develop and demonstrate a radio direction finding obfuscation solution that operates with both current narrowband and wideband tactical radio waveforms, and is suitable for deployment in vehicular, manpack and handheld tactical radios platforms. • Phase III military application can include an applique that can be applied to existing Army tactical radio platforms or integrated into the radio platform itself. Future PM Tactical Radio (PM TR) radio system acquisitions are envisioned to be acquired though both and developmental software defined radio (SDR) programs and commercial NDI procurement programs, so both applique and commercial licensing options would be available depending on the technology solution selected. • Commercial application would similarly encompass both a standalone applique product for commercial radio solutions (e.g. law enforcement, personal protection, etc.), and/or license opportunities for inclusion into commercial radio products, dependent on the technology solution proposed. 


1: Army Techniques Publication (ATP) 6-02.53 TECHNIQUES FOR TACTICAL RADIO OPERATIONS JAN 2016



4:  Analysis of Wireless Geolocation in a Non-Line-of-Sight Environment, Y. Qi, H. Kobayashi and H. Suda, IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 5, NO. 3, MARCH 2006

5:  A Non-Line-of-Sight Error Mitigation Algorithm in Location Estimation, Pi-Chun Chen, Wireless Communications and Networking Conference, 1999 WCNC 1999 IEEE 0-7803-5668-3


KEYWORDS: VHF Radio, UHF Radio, L-Band Radio, Radiolocation, Electronic Warfare, Electronic Protect, Digital RF, Signal Processing, WIN-T, WNW, SRW, SINCGARS 

Richard Greel 

(443) 395-8436 

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