Category: GNSS

DHS S&T releases new tool to strengthen GNSS for critical infrastructure

The Department of Homeland Security’s Science and Technology Directorate has released a new tool designed to help protect critical infrastructure that relies on GNSS: The GNSS Test Vector Suite and Distribution Methodology.

The GNSS Test Vector Suite and Distribution Methodology, now available on GitHub, is designed to help infrastructure operators assess and improve the resilience of their positioning, navigation and timing (PNT) systems. These systems are essential for sectors such as energy, transportation and telecommunications, and are vulnerable to disruptions from natural events, technical failures or cyber threats.

The tool suite provides standardized test scenarios and simulated data, allowing users to evaluate how their equipment responds to challenges such as signal interference or spoofing. By generating and converting simulated data into signals that mimic real-world GNSS systems, the tool enables independent testing of devices and systems for conformity to resilience standards.

“Accurate and precise Positioning, Navigation, and Timing information is vital to the nation’s critical infrastructure and is the backbone of the many services we depend on daily, from keeping our lights on to ensuring planes land safely,” said Julie Brewer, DHS acting under secretary for science and technology. “This new toolset gives people responsible for safeguarding these systems a way to independently test and strengthen them, ensuring our nation’s infrastructure is more secure against potential disruptions.”

The release of the GNSS Test Vector Suite supports Executive Order 13905, which seeks to protect essential PNT services across critical industries.

Additional information about the PNT Program is available on the DHS Science and Technology website.

The GNSS Test Vector Suite can be accessed through the PNT GitHub page.

May 22, 2025
SpaceX details Starlink’s role in enhancing US PNT resilience amid FCC inquiry

SpaceX has submitted reply comments to the Federal Communications Commission (FCC) detailing how its Starlink low-Earth orbit (LEO) satellite system currently provides, and could further support, positioning, navigation, and timing (PNT) services. The filing is part of the FCC’s ongoing Notice of Inquiry (WT Docket No. 25-110), which seeks to promote resilient and diverse PNT capabilities across the United States in response to vulnerabilities associated with the nation’s reliance on GPS, such as the risks of jamming and spoofing.

The FCC’s initiative, titled “Promoting the Development of Positioning, Navigation and Timing Technologies and Solutions,” aims to explore both space-based and terrestrial alternatives to ensure the continuity of critical PNT functions for national security, public safety, and economic stability. The agency is soliciting input from stakeholders on technologies that could complement or serve as alternatives to GPS, with a focus on robustness, geographic coverage and resilience to interference.

In response, SpaceX noted in its comments: “One opportunity stands out as a particularly ripe, low-hanging fruit: facilitating the rapid deployment of next-generation LEO satellite constellations that can deliver PNT as a service alongside high-speed, low-latency broadband and ubiquitous mobile connectivity.”

SpaceX also states that it has already been working on a PNT system for its cellular Starlink service, which is currently in public beta and is set to launch through T-Mobile in July. SpaceX outlines several technical features of the Starlink system that they argue are relevant to PNT applications.

Starlink Architecture and Features

SpaceX also noted that Starlink terminals can already provide nanosecond-level timing accuracy and meter-level positioning by using time-of-arrival measurements from its satellites. These capabilities allow the network to support precise timing applications, such as cellular network synchronization, without relying on external GPS sources. Timing signals are derived from the LEO constellation and synchronized through Starlink’s broadband infrastructure.

The filing highlights the Starlink system’s architecture, which includes thousands of satellites in low Earth orbit for global coverage and short signal travel times. SpaceX points to its phased-array user terminals, which use directional antennas to enhance signal integrity and mitigate interference. The company also notes that Starlink employs end-to-end encryption, making its timing and positioning information less susceptible to spoofing or tampering. According to SpaceX, Starlink is already in commercial use by a variety of customers and has been tested by U.S. military and civilian users in environments where traditional GNSS signals are degraded. The company emphasizes that these capabilities have been demonstrated under real-world conditions, not just in theory.

A Layered Approach to PNT

Addressing the FCC’s interest in a “layered” approach to national PNT resilience, SpaceX positions Starlink as one of several complementary solutions to enhance national PNT resilience. The company argues that using diverse, independently operated systems — both satellite and terrestrial — can provide redundancy and reduce dependence on any single technology or spectrum band.

SpaceX also responds to concerns from other stakeholders about whether Starlink qualifies as a PNT system, reiterating that the system was developed independently of government funding and can scale rapidly due to SpaceX’s vertically integrated manufacturing and launch model.

SpaceX confirms that Starlink operates in Ku- and Ka-band spectrum allocated for broadband services and is not proposing new spectrum allocations for PNT-specific use. It asserts that PNT functionality can be delivered within existing allocation.

May 19, 2025
FCC opens door to GPS alternatives, but risks undermining its greatest strength
On March 27, the Federal Communications Commission (FCC) unanimously approved a Notice of Inquiry (NOI) to explore GPS alternatives, amid escalating threats to security and system resiliency. The move signals growing federal concern about the reliability of space-based navigation and timing infrastructure amid rising global interference and spoofing incidents.

But while the FCC’s broad consideration of alternative technologies is a welcome step forward, its framing also risks weakening one of GPS’s most important defenses: the growing adoption of multi-constellation strategies across the commercial sector.

Rising Threats, Broader Mandates

The FCC’s decision follows the release of the International Air Transport Association’s (IATA) latest safety report, which documented a 175% increase in GPS interference and a 500% rise in spoofing attacks year-over-year. These incidents pose critical challenges to aviation safety, emergency services, telecommunications, and countless other sectors that rely on Positioning, Navigation, and Timing (PNT) services.

Against this backdrop, the Commission’s vote reflects a bipartisan sense of urgency. The NOI invites public comment on a range of technologies that could serve as complements or alternatives to GPS, including low-Earth orbit (LEO) satellites, terrestrial signals, and enhanced end-user devices. This broad framing is encouraging and acknowledges the multifaceted nature of PNT resilience.

A Multi-Layered Approach to PNT

The FCC’s focus on diversification — across space-based, terrestrial, and user-level technologies — is not only prudent, but essential. Enhancing national security and system redundancy requires more than a single backup solution. It demands layered resiliency that integrates complementary modalities into a cohesive ecosystem.

It is very encouraging that the NOI outlines a wide array of candidate technologies that could play a role in improving the U.S. PNT infrastructure. These range from inertial navigation systems and time transfer services to novel terrestrial radio signals and commercial LEO constellations. By casting a wide net, the FCC opens the door to innovation and allows market forces to contribute meaningfully to PNT modernization.

Commercial Reality vs. Government Narrative

However, the FCC’s discussion notably underplays a key reality: few commercial technologies today rely solely on GPS. The commercial PNT landscape has already moved beyond single-source dependency, with the vast majority of systems integrating multiple GNSS constellations (such as GPS, Galileo, BeiDou and GLONASS) alongside additional sensor and signal data to ensure robust coverage and accuracy.

This multi-constellation approach is arguably the single most powerful tool we have to strengthen the resilience of GPS-dependent systems. By allowing receivers to pull data from multiple GNSS sources, users gain spatial and signal diversity, enabling them to cross-check signals, reject spoofed or erroneous data, and maintain accurate position and timing even in degraded environments. It’s important to remember that a device can’t selectively use GNSS networks depending on the user’s geography. If U.S. device makers disable BeiDou and GLONASS, then anywhere in the world that receiver goes it will be less performant and competitive. In recent field tests, we found that disabling the BeiDou constellation decreased a device’s positioning accuracy by 30% to 40%.

This accuracy and resilience are especially important in sectors like aviation, autonomous systems, and emergency response, where signal fidelity and redundancy can be life-saving. Multi-constellation GNSS use isn’t theoretical: it’s already the industry standard.

The International Tightrope

Despite this, key elements of the NOI, as well as comments during the meeting, reflect a growing U.S. government skepticism toward the inclusion of foreign GNSS systems, especially BeiDou and GLONASS. While geopolitical caution is understandable, overly rigid restrictions on international signals could do more harm than good.

These systems are not merely foreign-owned alternatives. They are integral components of the modern GNSS environment. Many U.S. commercial devices — ranging from smartphones to augmented reality, fleet tracking systems, drones, and more — already leverage multiple GNSS sources by default. Future technologies such as autonomous vehicles, robotics and urban air mobility will also require multiple GNSS signals to function. Prohibiting or restricting their use could mean rolling back years of progress in signal resilience, not to mention stymying future technologies, and all for a speculative and largely unquantified national security risk.

While there are some valid concerns about adversarial control over PNT infrastructure, the FCC must weigh these carefully against the real, measurable benefits of an open and interoperable GNSS ecosystem. An overcorrection risks introducing new vulnerabilities in the name of mitigating others. In reality, the more vulnerable elements of the threat surface are GNSS receivers and mobile networks, particularly 5G systems, where user location is actually determined and tracked. Unlike the largely speculative and technically unproven threats tied to adversarial GNSS constellations, there are well-documented cases of compromised receivers and nation-state exploitation of mobile infrastructure – the very reason several countries have banned Chinese 5G providers. The FCC should focus on these clear and active risks, rather than reacting to theoretical scenarios that experts argue are not technically feasible.

Innovation at Risk

There is a significant opportunity at this moment. The NOI rightly identifies emerging technologies that can enhance U.S. resiliency, including advanced chipsets, LEO-based positioning, crowd-sourced signal verification, and next-generation timekeeping tools.

However, that innovation cannot thrive in isolation. If the U.S. limits the ability of domestic systems to take full advantage of all available GNSS sources, it will undermine both resiliency and competitiveness. Even worse, it could widen the gap with foreign alternatives, especially China’s BeiDou system, which is already surpassing GPS in both accuracy and global coverage. GNSS has always thrived on multi-national cooperation and the opportunity of soft power influence. Both of which are diminished by exclusion, which is likely why there have not been bans by other countries to date.

A Path Forward

The FCC is right to prioritize this issue. It is urgent for the U.S. to build a more robust and secure PNT infrastructure in the face of these mounting threats. But its long-term success will depend on whether or not it embraces the full complexity of the PNT landscape.

This means supporting:
- Open, multi-constellation GNSS access for commercial users.
- A flexible, layered approach that integrates space, terrestrial, and user-level technologies.
- Public-private collaboration to accelerate innovation and deployment.
- Clear regulatory guidance that balances national security concerns with commercial realities.
The future of secure and reliable PNT lies not in isolating GPS, but in augmenting it through interoperability, diversity, and resilience at every layer of the system.

If the FCC’s inquiry can steer the country in that direction, it will be a pivotal moment not just for GPS, but for the entire space-based infrastructure upon which modern life depends.
May 14, 2025
GNSS/GPS signal integrity in autonomous systems: Key issues and solutions

Question: What are the main challenges facing GNSS/GPS-based autonomous solutions in terms of signal integrity, jamming and spoofing, and how are these being addressed?

Answer: Outside of the military, interference is the most common threat to GNSS, with the dominant source being cellular transmission harmonics. It is commonly addressed with out-of-band filters. Non-terrestrial networks (NTN), like Global Star uplink at 1.6 GHz, are gaining traction in more mobile and wearable devices to fill gaps in cellular availability. However, it can create coexistence issues for devices for concurrent L1 GNSS reception during NTN uplink.

In military cases, while intentional interference is effective, the increasing number of GNSS bands to cover requires more transmission power. Modernized GNSS signals with wider bandwidth signals require more jamming power, which risks detection by radiofrequency emission satellite systems such as Hawkeye 360. The frequency of spoofing events will likely continue to increase and spill over into civilian domains.

Thanks to the increasing number of test ranges being made available to commercial GNSS developers, anti-spoofing technology is making some gains, at least in the high-end systems used for autonomous GNSS.

Q: What are the most impactful use cases and sectors benefiting from recent advancements in autonomous solutions?

A: Ride sharing and transport are the likely winners in exploiting the cost savings of driverless systems with autonomous navigation. The past 15 years’ investments in the development of augmented navigation systems — mainly lidar and vision-based — are finally paying off as we see Waymo in service, and soon Uber and Tesla in commercial deployments. Still, these systems depend solely on GNSS as the absolute positioning system, used for navigation in non-urban environments, but also fallback in certain cases where the sensors are problematic, as well as system calibration.

Agriculture, being one of the first segments to exploit autonomous solutions, can still see incremental gains as GNSS corrections systems move RTK from local to regional, allowing some monthly service margin improvements. High-precision consumer products like robotic lawn mowers will be enabled with similar infrastructure. Data services are a key part of infrastructure, for communication as well as precision navigation enablement. Companies such as Swift Navigation, Point One Navigation and RxN networks are expanding their networks and competing with the likes of Trimble and Hexagon.

May 13, 2025
NextNav proposes a GPS complement and backup in the lower 900 MHz band

A year after NextNav shared a new vision for the Lower 900 MHz band, the Federal Communications Commission (FCC) collected additional comments seeking to bolster positioning, navigation and timing (PNT) resilience by exploring terrestrial and space-based technologies, including NextNav’s, that could complement and back up GPS. The FCC’s PNT Notice of Inquiry (NOI) is a level set on PNT issues, and seeks to engage stakeholders across government and industry to advance a “whole-of-government approach” to building resiliency to safeguard America’s critical infrastructure, national security and public safety.

We caught up with NextNav’s Vice President of Regulatory Affairs, Renee Gregory, to hear more about how the company is thinking about a terrestrial complement and backup to GPS. Its technology is one of the solutions being discussed within the FCC and the broader industry.

Why is it important to create a complement and backup to GPS? 

Renee Gregory: GPS is an incredible technology that underpins national security, public safety and American commerce. However, GPS signals have physical limitations indoors and in urban canyons (i.e. big cities), plus the signals are vulnerable to intentional spoofing, jamming and unintentional interference. With GPS contributing more than $1 trillion to the U.S. economy since its inception, and a potential outage costing $1.6 billion per day, relying on a single system leaves us exposed. As Rear Admiral USN (ret.) David Simpson recently wrote, “If GPS goes down, critical infrastructure fails and our nation plunges into chaos.”

What is the Federal Government doing about the problem?

Gregory: Leaders, from President Donald Trump to Chairman Ted Cruz and Senator Ed Markey, have all advocated for the government to take action to ensure that a resilient PNT system of systems is in place. During President Trump’s first term, he signed an Executive Order establishing a comprehensive national policy to promote the responsible use of PNT services to strengthen critical infrastructure resilience. Earlier this year, the FCC adopted a NOI to promote the development of PNT technologies and solutions. It marked an important acknowledgment by the FCC of the seriousness of GPS vulnerabilities and limitations. It also reinforced the need for a system-of-systems approach that includes terrestrial PNT.

What should our readers know about the NOI?

Gregory: NextNav fully supports the FCC’s focus on resilient PNT. The FCC’s stated goal in the NOI is to build a record on specific actions the FCC can take to incentivize and support industry efforts to develop resilient and secure PNT technologies and solutions. The FCC intends to focus its efforts on utilizing its authority over non-Federal use of spectrum to rapidly support PNT solutions that could serve as complements or backups to GPS. NextNav has urged the FCC to enable at least one future-proof option that relies on market forces to deliver a terrestrial, wide-scale PNT solution that is broadly available to critical infrastructure, public safety, and consumers, and has a clear path to incorporation in consumer devices, like the smartphones we all use every day.

What is the solution NextNav is proposing?

Gregory: NextNav has a proven track record of providing accurate, reliable vertical location information to support first responders. Building on that legacy, NextNav’s next-generation 5G-based 3D PNT solution will leverage preexisting 5G networks and network capabilities, as well as the established and vibrant 5G device ecosystem, to enable a broadly available, widescale terrestrial complement and backup to GPS in partnership with one or more mobile network operators with experience in deploying newly-available spectrum and services within a relatively short period of time. This partnership model will rely on market forces and not taxpayer funding. NextNav brings not only its expertise in PNT technology but also its extensive spectrum licenses in the Lower 900 MHz band to address the critical need for resilient PNT.

What are other technologies under consideration in the NOI?

Gregory: The FCC is considering a range of terrestrial and space-based technologies as part of a system-of-systems approach to resilient PNT. Because different technologies and deployment models bring different strengths — and different weaknesses — truly resilient PNT requires multiple layers of redundancy and both space and terrestrial-based technologies. There is no single solution. We need an all-of-the-above approach.

Is NextNav trying to replace GPS? 

Gregory: No. NextNav’s efforts to develop a complement and backup to GPS will not diminish the role of GPS, which will remain vital to national and economic security.

Is NextNav asking for new spectrum to enable its terrestrial PNT solution?

Gregory: Some opponents have suggested that NextNav is asking the FCC to give it 15 megahertz of spectrum, but that’s simply not true. After acquiring extensive spectrum licenses at auction and in the secondary market, NextNav is the largest licensee in the lower 900 MHz band and is one of only two active geographic license holders in that band, which is today dedicated to terrestrial positioning services. In 2024, NextNav reached a commercial agreement to acquire the remainder of the licenses from the only other active geographic licensee in the band.

NextNav is suggesting a reconfiguration of the existing licensing scheme to ensure that the lower 900 MHz band can support next-generation 5G-based 3D PNT solutions that require multiple 5 MHz blocks of spectrum, for a total of one more megahertz than the amount of spectrum currently dedicated for geographically-licensed terrestrial positioning services. To enable this band configuration, and the availability of a terrestrial PNT complement and backup, NextNav has proposed a “swap” in which NextNav will return all its current and pending license holdings in exchange for a 15 MHz nationwide license, consistent with the technical characteristics of 5G networks.

How much does this plan cost?

Gregory: The market-based NextNav solution will not require any taxpayer funding or legislation.

What about those opposed to NextNav’s proposal?

Gregory: NextNav is focused on solving an urgent national security problem by enabling a complement and backup to GPS to advance resilient PNT. While some parties have raised objections based on claims of interference to current uses of the Lower 900 MHz band, they have not provided detailed technical analyses to support their claims that NextNav would interfere with their operations, or offered solutions beyond suggesting that the FCC reject NextNav’s proposal. Simply opposing one proposal without offering credible, fact-based solutions undermines the FCC’s goal of building a resilient, system-of-systems approach.

As a leader in PNT innovation, NextNav is looking forward to working closely with the Chairman, Commissioners and broader stakeholder community to accelerate the deployment of resilient PNT, building important redundancies into a system we rely on every day. 

May 12, 2025
Sierra Space demonstrates resilient GPS technology for US Space Force

Sierra Space, a commercial space and defense technology company, has successfully completed another demonstration of its resilient GPS (R-GPS) technology for the U.S. Space Force. This achievement marks the third major milestone for the program, which is designed to enhance the resilience of GPS infrastructure against threats such as jamming and spoofing. The recent demonstration included early integration of R-GPS satellite technology using FlatSat flight software and hardware subsystem testing, as well as successful communication with ground software systems.

The R-GPS effort is part of a broader initiative by the U.S. Space Force’s Space Systems Command to develop smaller, more cost-effective GPS satellites. Sierra Space was awarded a Quick Start contract in September 2024 to produce design concepts for these satellites, aiming to rapidly bring advanced technology to the national security space sector. The company’s progress comes just six months after the program’s inception, highlighting its ability to accelerate technology development in response to evolving defense needs.

GPS technology is integral to both civilian life and military operations, supporting applications that range from smartphone navigation to critical defense activities. As adversarial threats become more sophisticated, the need for resilient GPS systems has grown. The R-GPS program addresses this by planning to augment the existing GPS architecture with a network of smaller satellites, which would provide additional layers of security and rapid deployment capabilities.

The latest testing milestone demonstrated the flow of commands and telemetry between Sierra Space’s ground software and a ground stations service provider, establishing that the technology can operate effectively between orbit and ground-based facilities. The FlatSat testing format, where satellite components are evaluated while laid out flat, allowed for early integration of flight software and hardware subsystems.

May 9, 2025
NVS-02: Navigation signals from transfer orbit

NVS-02 is a second-generation navigation satellite of the Indian regional navigation satellite system NavIC. It was launched on Jan. 28, 2025, but could not reach its designated orbit due to a malfunction of a valve of the thrusters. Thus, the satellite is still in its transfer orbit. As of April 2025, the NVS-02 perigee is about 190 km, whereas the apogee is 37,400 km above the Earth’s surface. The inclination is about 21° and the eccentricity is 0.74. The groundtrack of NVS-02 is illustrated in Figure 1 and currently has a repeat cycle of about six days.

As of today, starting on Feb. 19, 2025, a decent number of receivers of the International GNSS Service are tracking the L5 signal of NVS-02 with the pseudo-random noise number I11. The L5 tracking of dedicated stations on individual days is indicated by different colors in Figure 1. Although the groundtrack has global coverage, no stations in Northern and Southern America have tracked I11 so far. The tracking is limited to periods when the satellite is near the apogee with altitudes between 23,000 km and 37,400 km and visible from the Indian Ocean region. During these periods, indicated in pink in Figure 1, the transmitter is active and the antenna is roughly pointing toward Earth.

Figure 2 shows the carrier-to-noise density ratio (C/N0) of the NVS-02 L5 signal tracked by a Septentrio PolaRx5 receiver at the German Space Operations Center (GSOC) of the German Aerospace Center (DLR) in Oberpfaffenhofen, Germany. Sudden drops in the C/N0 occur at about 8°, 28°, 46° and 52°. Here, the line of sight to the satellite is at the edge of the transmit antenna main lobe with a significantly lower gain, introducing the drop in signal power and, finally, the loss of lock.

Figure 2: Elevation-dependence of the carrier-to-noise density ratio of the NVS-02 L5 signal at Oberpfaffenhofen, Germany. (All figures provided by the authors)

The spectral flux density of NVS-02 in the L5, L1 and S band is shown in Figure 3. The L-band spectra have been measured with GSOC’s 30 m high-gain antenna in Weilheim, Germany. As the feed of this antenna is limited to the L band, the S band spectrum has been recorded with a 5 m dish antenna of DLR’s Institute of Communication and Navigation.

Figure 3: Spectral flux density of NVS-02 in the L5 (top), L1 (middle) and S band (bottom). (All figures provided by the authors)

The peak in the L5 spectrum at the center frequency of 1176.45 MHz is related to the civil Standard Positioning Service and introduced by a Binary Phase Shift Keying (BPSK) modulation with 1 MHz bandwidth. The two broader peaks with an offset of 5 MHz from the center frequency are caused by a Binary Offset Carrier (BOC) signal of the Restricted Service with a bandwidth of 2 MHz. Sidelobes of that signal are visible at the center frequency ±15 MHz and ±25 MHz.

For the L1 band, a Synthesized Binary Offset Carrier (SBOC) is used. It consists of two BOC signals with 1 MHz bandwidth and offsets of 1 MHz and 6 MHz, respectively. The two mainlobes of the BOC (1,1) component are visible at 1575.42±1 MHz, and the mainlobes of the BOC (6,1) component at 1569 MHz and 1581 MHz. The same type of signals, as in L5, are transmitted on the S band carrier with a center frequency of 2492.028 MHz. Due to its different location in a less remote area, compared to the 30 m antenna in Weilheim, the 5 m antenna in Oberpfaffenhofen suffers from pronounced interference with other signals in the S band; the most prominent peak can be seen at 2480 MHz, several smaller and sharper peaks over the whole frequency range shown in the lower plot of Figure 3. Possible causes of these interferences are WiFi and civilian and military radiocommunication services.

Although NVS-02’s mean orbit height is steadily decreasing due to the atmospheric drag around the perigee, the satellite will stay in orbit for at least a decade. However, navigation signal transmission might stop at any time due to operational constraints or unfavorable conditions in the non-nominal orbit.

May 8, 2025
Balboa Geo demonstrates PNT system in GPS-denied environments
Balboa Geo, in partnership with the Texas A&M Engineering Extension Service (TEEX) and the George H.W. Bush Combat Development Complex (BCDC), completed a rigorous field testing campaign of its POINTER system, a “dual-use,” real-time alternative positioning, navigation and timing (A-PNT) technology designed for GPS-denied, degraded and disrupted environments, including indoor, subterranean and obstructed urban settings.

The POINTER field test plan, led by Balboa Geo’s Andrew Aubrey, Ph.D., with technical support from TEEX and Texas A&M Professor Stacey Lyle, Ph.D., RPLS, involved 130 tests across seven challenging testing and training venues located at TEEX and the BCDC.

Test venues included:
- A three-story concrete structure with 10-inch-thick, rebar-reinforced concrete walls
- A compartmentalized steel-hulled ship with three decks reaching approximately 25 ft high
- A steel shipping container (CONEX)
- A simulated collapsed structure and rubble pile composed of steel, concrete, and a 90° tunnel network
- A simulated industrial oil refinery with processing equipment and complex, elevated steel piping
- A six-story steel training tower with metallic siding throughout
- The BCDC military-grade subterranean tunnel network, featuring a main tunnel at about 10 ft deep and a heavily shielded segment with Faraday cage properties simulating greater depth
Rigorous test design and real-time A-PNT data collection

The POINTER field test plan deployed a Base Station Laptop (BX) and a single Transmitter (TX) emitting an omni-directional Magneto-Quasistatic (MQS) field outside each venue. Two Receivers (RX) were introduced at various internal locations to capture multiple “XYZ” axis measurements within each GPS-denied setting. Tests were repeated to validate reproducibility, with highly precise measurements taken where possible for ground truth position references.

The BCDC military-grade tunnel network testing consisted of “normal” and “inverted” configurations. The “inverted” test consisted of placing the TX at depth within the tunnel network, with the BX and RX units located externally.

Highlights of the summary results and key findings:
- MQS field penetration and position location were achieved at all seven test venues.
- Real-time, three-dimensional distance measurements were obtained for all 130 tests.
- The mean positional uncertainty across all venues was 12.62 cm.
- Positional uncertainty ranged from 2.5 cm to 36 cm, depending on venue complexity, receiver location, and transmitter-receiver distance.
- Vertical measurements at the concrete structure showed uncertainties as low as 2.5 centimeters at a distance of about 11 m, and up to 24 cm at about 30 m.
- The POINTER system demonstrated penetration into and out of the BCDC military-grade tunnel network, including the shielded portion, indicating flexibility and performance in challenging subterranean environments.
May 6, 2025
NAL Research, VectorNav collaborate on solution for GNSS/GPS-denied environments

NAL Research and VectorNav Technologies — two U.S.-based leaders in assured position, navigation, and timing (APNT) solutions — are joining forces to develop and produce Iridium STL (satellite time and location)-aided inertial navigation systems (INS) designed to meet the increasing demand for resilient PNT in GNSS-denied environments.

Both companies will be exhibiting and discussing the collaboration during the SOF Week Exposition in Tampa, Florida, May 5–8, NAL Research (#3005) and VectorNav (#1941).

Operators of uncrewed systems, in particular, can benefit from implementing an INS solution that leverages NAL’s Iridium STL-enabled APNT receivers to maintain critical operations in areas where GPS/GNSS signals are denied or degraded.

For such applications, VectorNav is leveraging its VN-210E GNSS-aided INS, which combines a tactical-grade IMU with an L1/L2 GNSS receiver in a miniature, board-mount package. Designed for maximum modularity, the VN-210E hosts VectorNav’s tightly coupled INS and includes four serial ports that enable simultaneous integration with multiple external PNT-aiding sources, such as NAL Research’s ALTM Gen2 Mini Iridium STL receiver. When paired, the system provides a high-rate and continuous position, velocity and attitude solution — even in dynamic applications and in GNSS-denied environments.

“This complete offering delivered through our high velocity collaboration with VectorNav will deliver dynamic innovation to the emerging APNT market,” said NAL Research President Robert Bills. “Our partnership streamlines our customers’ implementation of alternative APNT sources. We look forward to helping government and enterprise users achieve operational success by enabling the ability to rapidly implement highly accurate and reliable navigation solutions.”

NAL Research and VectorNav will continue to focus on co-developing product solutions that combine VectorNav’s industrial and tactical-grade INS with NAL Research’s Iridium STL receivers. Future offerings will focus on reducing SWaP-C (size, weight, power and cost), increasing environmental resilience, and supporting MIL-STD compliance for defense and aerospace applications.

“The demand for robust APNT solutions, manufactured at scale and capable of supporting dynamic autonomous systems, is growing rapidly — particularly in the critical maritime domain,” said Jakub Maslikowski, VP of business development for VectorNav. “This collaboration with NAL Research will help to realize the emerging LEO satellite PNT capability and strengthen the U.S. and allied nations’ resilience when operating in contested environments.”

May 1, 2025
Q-CTRL demonstrates quantum navigation system as GPS backup

A team of researchers at Q-CTRL, a quantum infrastructure software company based in Sydney, Australia, has completed a successful demonstration of a new quantum navigation system called Ironstone Opal. The group described the system’s operation and performance in a paper posted to the arXiv preprint server.

GPS technology is widely used for navigation in both civilian and military vehicles and aircraft. However, the increasing reliance on GPS has highlighted its vulnerability to outages, which can leave drivers stranded, force pilots to rely on outdated methods and complicate the deployment of military assets. These concerns have driven efforts worldwide to develop robust backup systems or alternatives to GPS.

Q-CTRL’s Ironstone Opal is designed as a backup navigation system and, according to the research team, can deliver accuracy up to 50 times greater than existing GPS backup systems in certain scenarios. The system leverages quantum sensors that are highly sensitive to variations in the Earth’s magnetic field. Because the magnetic field differs depending on geographic location, these sensors can precisely determine an object’s position by reading the field and using artificial intelligence-based software to generate geographic coordinates similar to those provided by GPS.

The research team shared that unlike conventional systems, Ironstone Opal is passive, meaning it does not emit signals that could be detected or jammed by adversaries. The system’s software is designed to filter out noise from vehicles or aircraft carrying the sensors, and the hardware is compact enough for installation in cars, trucks, UAVs and aircraft.

Field trials conducted by Q-CTRL included both ground vehicles and aircraft. The results showed that Ironstone Opal outperformed a high-end inertial navigation system, a standard GPS backup, by up to 50 times in ground tests and by at least 11 times in airborne tests. These trials demonstrated the system’s ability to maintain high accuracy under a range of environmental conditions, altitudes, and maneuvers, with positioning uncertainty as low as 0.01% of the total distance traveled in the best cases.

Q-CTRL’s approach combines proprietary quantum magnetometers with advanced denoising and map-matching software, allowing the system to detect subtle magnetic “landmarks” in the Earth’s structure. The technology is designed to be resilient, unjammable, and suitable for integration into a wide range of platforms, including autonomous vehicles and commercial aircraft.

April 29, 2025
Beyond Gravity supplies high-power antenna for ESA mission

On April 29, the European forest satellite “Biomass” was launched into space from Kourou aboard a European Vega-C rocket operated by Arianespace.

The company Beyond Gravity, based in Zurich, Switzerland, supplied several key products for this mission. Its high-power antenna and navigation receiver will provide the satellite’s precise position in orbit. Also, the satellite will be protected by the company’s thermal insulation.

The European Space Agency’s (ESA) “Biomass” mission will measure forest biomass and will observe the state and development of forests and advance our knowledge of the carbon cycle. Knowing the amount of carbon bound up in forest biomass will sharpen our understanding of climate change and its likely effects on the global carbon cycle. The satellite will orbit Earth at an altitude of 666 kilometers. The mission’s expected lifetime is at least 5.5 years.

“Forests are the green lungs of our planet, providing us with oxygen and storing carbon dioxide,” said Oliver Grassmann, Executive Vice President Satellites at Beyond Gravity. “With the environmental satellite Biomass, we are learning more about the importance of forests to our climate system. Contributing to the functioning of such a groundbreaking climate satellite with key products, like various antennas, our navigation receiver and our multi-layer thermal insulation is a great honor and extremely inspiring for all our colleagues.”

The Biomass mission will feature a new high-power antenna from Beyond Gravity that serves the data downlink needs of new Earth-observing satellites as they gather ever larger quantities of environmental data. The antenna has the size and shape of a large ice cream cone. While more and more Earth observation data from satellites is gathered, the satellite itself becomes smaller. Thus, there was a clear need for a smaller, more powerful data downlink antenna.

The X-band helix antenna design was developed for ESA by Beyond Gravity’s site in Gothenburg, Sweden. Beyond Gravity also provided the S-Band TTC (telemetry, tracking and command) antenna, which acts as a communication and control antenna for the satellite.

A new antenna from Beyond Gravity for data downlink will serve Biomass. It was developed through an ESA General Support Technology program contract with Beyond Gravity in Sweden. (Photo: ESA, Beyond Gravity)

Precise in-orbit position determination. The satellite’s position in space is determined to within centimeters using technology from Beyond Gravity’s site in Vienna, Austria. The more accurate the positioning, the more accurate the data provided by the satellite.

The receiver can process both GPS and Galileo signals. Beyond Gravity’s navigation receivers determine the position of approximately 25 satellites in space. The Beyond Gravity site in Tampere, Finland, produced the Reflector Deployment Interface Unit.

Multi-layer thermal insulation from Beyond Gravity made out of several layers of ultra-thin special polyimide foils will keep the satellite’s instruments at the required operating temperature despite the harsh thermal environment in space. Nearly every European ESA satellite is protected by thermal insulation from Beyond Gravity, which is designed and produced at the company’s sites in Austria. Beyond Gravity also produced the Eddy Current Damper, which is part of the spacecraft’s solar array wing and is providing the damping to slow down the deployment and prevent shocks at deployment completion.

April 29, 2025
Satellite Safety Alliance urges reversal of FCC Ligado Order

A new letter protesting the Federal Communications Commission’s (FCC) Ligado Order marked the fifth anniversary of the controversial decision.

In the letter, the Satellite Safety Alliance (SSA) and 93 companies and organizations stated the need for the Ligado Order to be overturned by President Trump and Congressional leadership.

“The proposed network is designed to inappropriately use spectrum reserved for satellite communications, causing significant interference to other services,” the SSA stated. Interference with GPS is a major concern of the group.

The letter urges the president and the chairs and ranking members of the House and Senate armed services and commerce committees to work with the FCC on granting petitions for reconsideration that will help prevent the building of Ligado’s terrestrial wireless network.

“Ligado’s network would threaten a wide range of critical government and commercial services, including military communications, private satellite communication, GPS, agriculture, aviation, weather forecasting, and more,” the SSA stated.

“For over two decades, Ligado and its predecessors have tried and failed to build a

terrestrial network that wouldn’t harm GPS, national security, and other critical interests,” commented the SSA. “The FCC’s Ligado Order has faced unprecedented opposition, including from 14 federal agencies and over 90 organizations representing huge swaths of the economy — from aviation and agriculture to science and manufacturing. Rarely does any issue garner

agreement from such a wide and divergent group of constituencies.”

Congress found through independent analysis that the Ligado Order poses unacceptable risks of interference to GPS, satellite communications, weather forecasting, and other services, the SSA explained. “Countless federal staff hours and resources have gone to reviewing, debating, and litigating this issue. It is past time the FCC put the issue to rest by granting the pending petitions for reconsideration.”

Copies of the letters are availble here.

April 28, 2025