By Dominick Acquista
Global navigation satellite systems (GNSS) have been around since the 1960s. Originally created for the military, the technology was eventually repurposed to be used by everyday civilians. The earliest versions of these systems were based on the Doppler effect and used radio waves to transmit signals. As GNSS became increasingly viable, the technology was updated, leading to various iterations of the system, such as GPS, which is still the most widely used navigation system.
Unfortunately, due to the extent to which military personnel and civilians rely on GNSS, they have become a target for disruption by bad actors. GNSS radio waves are vulnerable to both jamming and spoofing — disruptive techniques that overpower GNSS signals with noise and deceive receivers by sending counterfeit signals in hopes of masking the position and relative time of a target. In addition to the intentional mischief that can plague the systems, GNSS is susceptible to signal degradation merely when the location of the satellite is obscured.
A stand-alone version of the Laser Velocity Sensor (LVS). Courtesy of Advanced Navigation.
“The world is evolving, and navigation must evolve with it,” said Chris Shaw, CEO and cofounder of Advanced Navigation. “GPS is disturbingly vulnerable to challenging environments, harsh weather conditions, and cyberattacks with rising threats of jamming and spoofing. The question isn’t if GPS will fail, but when. Operators need to build resilience now.”
Using this philosophy as an impetus, Advanced Navigation employed its space-grade Laser Unit for Navigation Aid to develop a terrestrial adaptation called the Laser Velocity Sensor (LVS). Integrating it with a strategic-grade fiber optic gyroscope (FOG) inertial navigation system (INS) resulted in a functional GNSS alternative with a software-fused hybrid architecture that the company said can deliver precision and reliability even in the most challenging environments.
The problem with GNSS
While GNSS is generally effective, it remains vulnerable to interference — not only from military adversaries and malicious actors, but also from natural and human-made obstructions. For example, urban environments, underground structures, bridges, dense forests, and other physical obstructions can make it difficult for signals to pass through, rendering the time-sensitive and precision uses of the technology in these settings somewhat dysfunctional and driving the demand for situational awareness of assured positioning, navigation, and timing (APNT).
The LVS-integrated fiber optic gyroscope (FOG) inertial navigation system (INS) was inserted into a car for its ground tests. It uses three infrared lasers to measure a vehicle’s ground-relative 3D velocity. Courtesy of Advanced Navigation.
“To provide reliable navigation in GNSS-denied environments, APNT technologies integrate multiple sensors for robust state estimation,” said Lyle Roberts, head of photonics at Advanced Navigation. “At the core of these systems are inertial sensors, or an INS, which consists of an inertial measurement unit and a processor
that integrates the [inertial measurement unit] data to compute position and attitude.”
Generally constructed using microelectromechanical systems (MEMS)-based accelerometers and gyroscopes, INS will experience drift over time. This can be stabilized by the replacement of MEMS devices with FOG-based INS, but this adaptation does not account for its ability to calculate velocity, which is needed to maintain continual navigational accuracy over prolonged periods. Unfortunately, conventional methods used to calculate velocity also do not solve this problem and are subject to limitations.
“For example, visual-inertial odometry — which uses cameras and [inertial measurement unit] data to estimate motion through feature tracking — is effective in structured environments but struggles against unreliable visual references and poor lighting conditions. … Wheel-speed sensors — which measure the forward velocity for ground vehicles — require continuous ground contact and are subject to wheel slip,” Roberts said.
Advanced Navigation’s FOG INS, which is sensitive enough to detect the Earth’s rotation, uses the LVS for this purpose. The LVS projects infrared lasers to measure a vehicle’s ground-relative 3D velocity with high-accuracy and long-term stability, performing reliably on both ground and airborne platforms. The laser platform requires a clear line of sight of a surface, such as the ground or a stationary object, for it to be effective. But unlike GNSS, where a change of environment is necessary to overcome limitations, these challenges can be overcome with the integration of higher-powered lasers or a larger telescope.
The LVS can even enhance navigation resilience by detecting GNSS spoofing, comparing its independent velocity measurements against GNSS-derived velocity.
LVS validation
To validate the accuracy and resilience of the LVS hybrid system, Advanced Navigation conducted a series of real-world driving tests with an automobile in Australia. Across five trials, the system delivered high performance with an average error per distance traveled of 0.053%, compared with a GNSS reference.
At the starting point, GNSS on the INS was disabled in the state estimation process, forcing the system into dead-reckoning mode (estimating position based on the last-known location and velocity). Real-time kinematic positioning GNSS was logged separately as a reference. This approach allowed for a direct comparison between the computed dead-reckoning solution and a trusted position reference.
During the tests, when passing through a tunnel, the results showed that the global navigation satellite system (GNSS) lost coverage of the vehicle, while the system using INS and LVS was able to keep track of the vehicle’s position. Courtesy of Advanced Navigation.
The hybrid system was also tested on a fixed-wing aircraft combined with a tactical-grade INS, demonstrating a final error per distance traveled of 0.045% over the course of a low-altitude flight over 545 km. These results demonstrate the system’s ability to improve navigation performance of the INS in GNSS-denied or contested scenarios.
While the global navigation satellite system is generally effective, it remains vulnerable to interference — not only from military adversaries and malicious actors, but also from natural and human-made obstructions.
All the data was processed using the company’s AdNav OS Fusion software, which uses algorithms to interpret and filter sensor data. The software is designed to dynamically weigh the input of each sensor, enabling it to adjust in real time based on reliability scores, environmental conditions, and operational context. This ensures continuous state estimation even when signals are lost, degraded, or distorted. This inertial-cantered, multisensor approach delivers a step-change in GNSS-denied navigation performance, compared with traditional methods.
From validation to the real world
While the LVS’ companion product, Laser Unit for Navigation Aid, is set to be demonstrated aboard Intuitive Machines’ Nova-C lander as part of NASA’s Commercial Lunar Payload Services program, LVS itself is beginning to see use on Earth. Namely, the LVS-integrated FOG INS was recently demonstrated in a live-streamed trial at the Callio Pyhäjärvi underground test mine in Pyhäjärvi, Finland, which was hosted by Australian mining and metals company BHP through its innovation team, Think & Act Differently (TAD).
The demonstration was part of the Deep Mining Open Call, launched in September 2024 by TAD, with the aim of identifying organizations with capabilities that could be applied to deep underground mining. Advanced Navigation will collaborate closely with TAD during the next few months to develop the hybrid navigation system in relation to real-world deep mining environments.
Aside from mining, Advanced Navigation is currently discussing the implementation of the LVS in the fields of defense, aerospace, robotics, and autonomous systems. The company is also contemplating ways to use the technology for underwater navigation in the future.