Challenges and opportunities with positioning, navigation, and timing (PNT)

Dr. Ronald Polcawich, QIS-PNT ERP Engineer & Army LNO to OUSD(R&E)/RDER, US Army Combat Capabilities Development Command (DEVCOM), Army Research Laboratory, presented on challenges and opportunities with assured, trusted, and resilient positioning, navigation, and timing (PNT) at the SEMI, USA, MEMS & Sensors Executive Congress (MSEC) 2022.

PNT solution today is reliant on satellite-based navigation, such as GPS. However, there are shortfalls with national PNT service. We need assured and real-time PNT in physically impeded environments (e.g., indoors, multi-story buildings, urban canyons, and underground facilities. Sufficient accuracy and integrity in electromagnetically-impeded environments including operations during spoofing, jamming, and natural and unintentional interference.

We need higher accuracy with integrity (especially for future highway and rail applications). Timely notification (as short as 1 second in some situations) when PNT information is degraded or misleading, especially for safety-of-life applications or to avoid collateral damage and user equipment space, weight, and power considerations). We also need high-altitude/space position and orientation, including real-time high accuracy position and orientation (<10 milliarcseconds).

User access to timely geospatial information (e.g., terrain, conditions along route) for efficient and effective navigation. Timelier PNT modeling and simulation capabilities depicting and analyzing impeded conditions to determine impacts, as well as the capability to predict impacts in urban environments. PNT services, including supporting IT infrastructure, and supply chain are protected from cyber threats. There should be ability to accurately locate the sources of intentional and unintentional interference in a timely manner. National PNT capabilities that are over-dependent on GPS provide insufficient resilience and survivability when GPS services are not available or are untrusted (e.g., spoofed).

New opportunities
Numerous challenges create opportunities for alternative and complementary approaches. Complementary solutions are required to augment complex national PNT systems. By 2025,
GPS-quality PNT should be available. We need to maintain GPS-quality PNT (10m, 10ns error) for long-duration missions in contested environments. By 2030+, we will have precision PNT. It will enable precision beyond GPS and classical limits (<1m, <1ns error) to enable transformational capabilities such as distributed, co-ordinated effects.

Mid-term S&T focus upto 2025 is on resilience. We can preserve access, provide complementary sensors, and ensure trust of existing signals and data. Far-term S&T focus from 2030-20450 is on precision. Precision localization and synchronization will be through QIS and photonic sensing.

QIS-PNT ERP research thrusts are on positioning, navigation and timing. For positioning, we need better, smaller inertial measurement units that hold position for longer durations between position updates. Better, smaller positioning sensors (optical, gravimeters, magnetometers, etc.) that provide georeferenced position without external inputs. And, precision techniques to measure distance relative to another position.

For navigation, smaller anti-jam antennae for use by dismounted soldiers, and group 2 or 3 UAS. We need distributed processing, sensing, threat detection and multi-agent systems. Robust sensor fusion using stochastic filters and adaptive sensor modeling can enable self-calibration, self-healing, self-initialization, etc. AI/ML algorithms can detect compromised and erroneous PNT data at sensor or system.

For timing, we need better, smaller clocks that hold time for longer durations between updates. We need enabling technologies for low-SWaP, deployable clocks, and precision techniques to synchronize time relative to other clocks that are difficult to detect and interrupt.

Quantum information science can look at the exploration of quantum-based approaches to improve measurement precision and quantum control. The long-term ARL approach is to push beyond classical limits using building blocks of novel sensing and distributed entanglement, including strong light-matter interfaces, solid-state clocks, gravimeters, and magnetometers.

There are several opportunities in PNT. For positioning — precise position and minimize position drift, we can have material choices, integrated photonics, integrated calibration and compensation approaches, manufacturing and assembly, and quantum-based approaches.

For navigation – with uninterruptable access to and ensure trust and authenticity, we can have advanced antennae, robust, adaptive sensor fusion, AI/ML for trust and authentication, etc. For timing — for extended holdover and precision synchronization, we can have material choices, heterogenous integration for short- and long-term drift minimization, and AI/ML for calibration and compensation.