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Session A2: Cooperative Space-Based Sources: Experimentation

Results from Prototype Agile Navigation Aid (PrANA) on-the-Wire and Over-the-Air Transmissions
Andrew Cochrane, Jim Aarestad, COSMIAC at The University of New Mexico; Alex Hostick, ARES Corporation
Location: Room 1-3
Alternate Number 1

Since the electronics industry has evolved to provide cheap commercial off-the-shelf (COTS) hardware
that provides a highly available platform for developing GNSS receiver disruption technology [1][2][3], there is
a need to develop ever more sophisticated techniques for coping with navigation signal interference. Solutions to
the problem of navigating through GNSS interference have been implemented using technological approaches
including controlled reception pattern antennas (CRPAs)[4], alternative modulation techniques[5], signals of
opportunity[6] and other alternative navigation techniques. But PrANA aims to mitigate interference through
modularity and waveform agility.
Implemented from Logan Scott’s Frequency Spatial Polarization Time (FSPT) waveform proposal[7], a
real-time transmitter for PrANA (pronounced “piranha”) signals has been created on an Software Defined Radio
(SDR) type platform and a post-processing, software-based receiver has been implemented in python[8]. The
PrANA waveform improves navigation signal resilience by providing comprehensive modularity. A PrANA
signal plan may be updated over time, providing a framework for employing agile navigation signals.
Lab tests combine PrANA signals with simulated jamming environments, on-the-wire, enabling
characterization the potential for efficacy of jamming mitigation. These experiments explore fundamental limits
of tracking with respect to integration period, energy allocation and processing gain with and without
interference filtering. Sensitivity of PrANA to manufactured interference as parameterized by various signal plan
metrics is measured for a small sample of signal plans. Lab tests also provide a reference for signal quality
comparable to recordings of over the air transmissions.
Over-the-air field tests and tuning of the post-processing receiver demonstrate that PrANA can be
tracked successfully in a contested environment, enabling future implementations to provide data or timing
information critical in aiding navigation equipment through RF contested environments. Results include analysis
of the behavior of the signal tracking loop under the influence of interference, the limits the waveform as
transmit power is adjusted and shows what problems can arise from poorly regimented development.
The field tests also reveal myriad challenges associated with selection of transmission equipment,
transmitter programming, recording receiver selection, user interface, data storage, and slow post-processing.
This effort exemplifies the difficulties in fielding prototype equipment.
[1] Ferreira, Renato, et al. Effective GPS Jamming Techniques for UAVs Using Low-Cost SDR Platforms.
Wireless Personal Communications. Issue 115. 2020.
[2] Anonymous Author. Low Cost and Portable GPS Jammer. http://phrack.org/issues/60/13.html. Phrack
Magazine. Issue #60. 2002.
[3] Nardi, Tom. Teardown: Mini GPS Jammer. https://hackaday.com/2020/09/08/teardown-mini-gps-jammer/.
Hackaday. 2020.
[4] Goldblatt, Scott, et al. Modular Antijam GPS Receiving System for Dismounted Forward Observers. Joint
Navigation Conference 2023. Institute of Navigation. San Diego, CA. 2023
[5] Dafesh, Phillip A. BPSK vs BOC. Joint Navigation Conference 2023. Institute of Navigation. San Diego, CA.
2023
[6]Bruckner, Dean, et al. Single-Mission Geolocation and Use of Ground-based GPS Jammers as Signals of
Opportunity for Sequenced UAV Navigation: Simulation and Field Test Results. Joint Navigation Conference
2023. Institute of Navigation. San Diego, CA. 2023
[7] Scott, Logan. The FSPT Waveform, the Smorgasbord Defense. Joint Navigation Conference 2022. Institute of
Navigation. San Diego, CA. 2022.
[8] Cochrane, Andrew, et al. Agile New Signal Development and Demonstration. Joint Navigation Conference
2022. Institute of Navigation. San Diego, CA. 2022.
Approved for public release; distribution is unlimited. Public Affairs release approval #AFRL-2024-0325.

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