Photo: NextNav

The Federal Communications Commission (FCC) has issued a public notice seeking comment on NextNav’s filing to reconfigure the Lower 900 MHz band (902 to 928 MHz band).

This action comes in response to NextNav’s April 2024 filing, which proposes a comprehensive restructuring of the band to enable the deployment of a 5G terrestrial positioning, navigation, and timing (PNT) network.

NextNav’s proposal aims to create a 5 MHz uplink in the 902-907 MHz band paired with a 10 MHz downlink in the 918-928 MHz segment. This reconfiguration is designed to complement and serve as a backup to GPS while also freeing up spectrum for 5G broadband services.

NextNav CEO Mariam Sorond said the spectrum band reconfiguration complements GPS to continue location mapping and tracking services and national security needs. “Our plan creates abundance from scarcity in this band by unleashing much-needed spectrum for wireless technology. These common-sense solutions can benefit consumers and our national interests at no cost to taxpayers,” Sorond said.

However, the FCC’s public notice raises several questions regarding the protection of incumbent users, including federal radiolocation systems, industrial, scientific, and medical (ISM) equipment, and unlicensed Part 15 devices. The Commission seeks input on how these existing operations would be safeguarded under NextNav’s proposal.

Comments are due Sept. 5, 2024. Following this comment period, the Commission will review the feedback to develop proposed rules for the potential reconfiguration of the Lower 900 MHz band.

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The warning came in a four-page memo to the Deputy Secretaries of Defense and Transportation from retired Admiral Thad Allen, Chair of the advisory board. The memo was nominally a report of the board’s April 2024 meeting in Colorado Springs.

The overwhelming majority of Allen’s message, though, dealt with GPS and U.S. PNT being vulnerable, the importance of PNT to the nation’s safety and security and the failure of the government to do the things it said it should and would do. It says:

“America’s continued over-reliance on GPS for PNT makes critical infrastructure and applications vulnerable to a variety of well-documented accidental, natural and malicious threats.

…our conclusion is that PNT, in general, and GPS, in particular, have not been accorded their rightful prominence in the national policy agenda.

Simply put, the Board believes that the 20-year-old framework for GPS governance and the current policy statements establish neither the priority that the system deserves nor sufficiently clear accountability for its performance.”

The reason for this was assessed to be that the leadership and governance structure established by 2004’s NSPD-39 and confirmed in 2021’s SPD-7 was not working.

Allen gave a recent policy document on critical infrastructure as an example. All critical infrastructure sectors use PNT, and most depend on it.

“These findings were reinforced just earlier this year by the release of the National Security Memorandum on Critical Infrastructure Security and Resilience (NSM-22, April 30, 2024). We were surprised to discover that GPS is nowhere mentioned in that important document.”

While not mentioned in the memo, PNT was also not mentioned in national cybersecurity documents issued last year. This is despite timing being essential to the operation of IT systems, and time and location data being key elements in many applications.

Allen’s memo also emphasized that the real issue is not about GPS, but overall national PNT capability. He went so far as to say, “Space Policy Directive 7 (SPD-7), U.S. Space-based PNT Policy, must be revisited and the term ‘space-based’ should be removed from its title” (emphasis added).

Reinforcing this message, the following table comparing U.S. and Chinese national PNT systems was included in the memo.

“The Board believes it is time to take a fresh look at our approach to PNT governance and establish a clear strategy for re-establishing an unquestioned position of leadership for the United States. To be successful, such a strategy requires a governance structure characterized by clearer authority and accountability. Ideally, the administration should propose legislation to Congress that would support this goal with a clear mandate (authorization) and resources (appropriations) adequate to the task.”

As part of his report of the April meeting, Allen’s memo reaffirmed the board’s nine recommendations from January of last year and added three more:

• Direct the U.S. Space Force to establish a way for “good enough” monitoring of GPS L5 signals using existing capabilities and set L5 signals healthy subject to a “use at your own risk” caveat, just as is done with L2C today. We recommend establishing a deadline of September 2024.
• Direct federal Chief Information Officers to acquire and install multifrequency dual-system (GPS-Galileo) receivers to complement GPS use. The Department of Transportation and the Department of Homeland Security should actively encourage critical infrastructure users to adopt multifrequency dual-system (GPS-Galileo) receivers.
• Assign a lead agency and single individual with clear responsibility and authority for the end-to-end prompt detection, characterization, and removal of significant sources of interference to GNSS in the United States.

Allen’s memo comes on the heels of a similar warning to United States leaders about the nation’s vulnerability to GPS disruptions. On July 18, the

National Security Space Association published a report titled “America’s Asymmetric Vulnerability to Navigation Warfare: Leadership and Strategic Direction Needed to Mitigate Significant Threats,” which cited several national PNT shortfalls from the Federal Radionavigation Plan as significant concerns.

Two of that paper’s key findings are:

“Long-standing lack of progress on issues important to U.S. national, homeland, and economic security,” and

“Focused leadership, properly empowered and resourced, is essential to the national PNT strategy’s success.”

It warned that significant disruption to GPS “…could have cascading effects which unravel America’s socioeconomic fabric…”

<p>The post Experts to PNT leaders: “It’s not working!” first appeared on GPS World.</p>

Personnel from the Australian Joint Precision Navigation and Timing Directorate, Joint Capabilities Group and Joint Navigation Warfare Center align GPS test equipment in the JNWC anechoic chamber at Kirtland Air Force Base, N.M., in preparation for a GPS resilience test April 15, 2024. This combined effort not only enhances GPS navigation resilience but also exemplifies the power of international cooperation in addressing security threats. As the world faces evolving challenges, partnerships like these remain essential for maintaining an edge in contested environments. (U.S. Air Force photo by Senior Airman Spencer Kanar)

The Australian Department of Defense has collaborated with the Joint Navigation Warfare Center (JNWC) to enhance the resilience of GPS devices in contested environments. The JNWC’s mission is to ensure positioning, navigation and timing (PNT) superiority for the Department of Defense and its partners. This joint effort aimed to test the performance of GPS devices under simulated jamming conditions.

Personnel from the Australian Joint Positioning, Navigation and Timing Directorate worked with JNWC experts to evaluate the Defense Advanced GPS Receiver (DAGR), a crucial device used by U.S. and allied forces for navigation across land, sea, and air. The testing took place in an anechoic chamber designed to replicate contested and limited GPS conditions, providing insights to improve the device’s resilience.

The JNWC, recognized for its expertise in navigation warfare, created optimal conditions for this assessment. The specialized chamber allowed them to test the DAGR’s performance in a jamming environment, generating data that can inform the device’s warfighting effectiveness. The team explored solutions such as antennas that enhance jamming resilience, and the findings will be shared with coalition partners to strengthen collective space resilience.

The collaboration serves as a model for international cooperation in addressing security threats, enhancing GPS navigation and timing resilience for allied forces.

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Under this contract, CACI will provide 24/7 operations support, joint and operational planning, adversary positioning, navigation and timing (PNT) capability assessments and other tasks to enhance joint force, DOD combatant commander, interagency and allied NAVWAR requirements.

“Adversary PNT capabilities rapidly evolve, putting our warfighters and national security operations at risk around the world,” said John Mengucci, CACI president and CEO. “CACI’s experts comprehensively understand multi-domain PNT threats and advise combatant and joint force commanders on how to swiftly respond to NAVWAR threats and operational requirements.”

PNT is critical to U.S. national security and NAVWAR. This includes deliberate defensive and offensive actions to ensure and prevent PNT use through space, cyber and electronic warfare. The contract represents new work for CACI, with mission experts supporting global NAVWAR reach-back operations via the Joint NAVWAR Operations Center (JNOC). These experts will assist combatant commanders in operating in PNT-disrupted, denied and degraded areas by conducting operational field assessments, war gaming scenarios, modeling and simulating threats and more.

<p>The post CACI provides PNT support to US Space Command first appeared on GPS World.</p>

Photo: tifonimages / iStock / Getty Images Plus / Getty Images

Describing a dangerous “asymmetric vulnerability to navigation warfare” a recent paper from the National Security Space Association (NSSA) calls for a wide variety of actions to mitigate the threat. The most important, “Focused leadership, properly empowered and resourced…”

The nineteen-page paper, in some ways, reads like a primer on GPS and positioning, navigation and timing (PNT), providing background and context for policymakers unfamiliar with the technology and the United States’ broad dependence upon it.

“Long-standing lack of progress on issues important to U.S. national, homeland, and economic security.”

The lack of focused leadership, according to the paper, is evidenced by long-standing failures to follow through on a variety of mandates from senior leadership over the course of the last 20 years. Quoting from the Federal Radio Navigation Plan, it cites persistent shortfalls in national capability as including:

• Assured, real-time PNT in physically impeded environments (e.g., indoors, urban canyons, underground facilities).
• Sufficient accuracy and integrity in electromagnetically impeded environments — including operations during spoofing, jamming, and natural and unintentional interference.
• Higher accuracy with high integrity; timely notification/alarming when PNT performance is degraded or misleading, especially for safety-of-life applications or to avoid collateral damage.
• Ensuring PNT services, including supporting information technology (IT) infrastructure and supply chain are protected from cyber threats
• Ability to accurately locate sources of intentional and unintentional interference in a timely manner.
• Insufficient resilience and survivability when GPS services are unavailable or untrusted.

“American society has been transformed by the availability of GPS.”

The paper describes four decades of GPS being incorporated into virtually every technology and used by every critical infrastructure. It calls the harm to society should it be lost “incalculable.” It also notes that the operation of many space systems that support critical infrastructure and/or critical national applications is itself dependent upon GPS for proper operation.

The military utility and advantages brought by GPS are also discussed. These include:

• Its role as the lynchpin for precision strike.
• Enabling “… the maneuver, synchronization, and massing of effects from dispersed forces.”
• PNT to achieve information and decision superiority over an adversary.

“Merely the threat of disrupting GPS services might be enough to impact U.S. national security and foreign policy.”

The paper says recent actions by and ongoing threats from adversaries of the United States are a critical concern.

Electronic warfare (EW) and cyber attacks by Russia, China, Iran, and North Korea demonstrate the ease and effectiveness of such vectors, as well as the seriousness of the threat.

As one example, Russia’s impending launch of a nuclear-armed anti-satellite weapon has the potential to both destroy or damage GPS satellites nearby and interfere with radio communications. NSSA recently published a paper on the Russian nuclear ASAT threat.

A potentially even more serious threat would be if Russia should deploy a nuclear-powered directed energy or electronic warfare weapon. Such a device would be “reusable” and could threaten an even larger number of space platforms or, in the case of an EW device, both space-based and terrestrial receivers.

“GPS blackmail”

The paper posits that the United States’ overdependence on GPS is so great that it could be subject to “GPS blackmail.” It suggests that this may already have occurred.

Prior to Russia’s invasion of Ukraine, it destroyed a defunct satellite with a ground-based missile, creating thousands of pieces of debris. Shortly thereafter, state-sponsored TV announced that Russia would destroy all 32 GPS satellites if NATO “crossed its red line.” Despite 90,000 Russian troops massing along the border, “U.S. officials decided against sending certain military equipment to Ukraine to avoid provoking Russia.”

“…could have cascading effects which unravel America’s socioeconomic fabric…”

NSSA warns that U.S. “critical infrastructures, national essential functions, and military forces could be at grave risk.” Among the impacts of a major GPS disruption, it counts:

• Loss of U.S. political prestige and influence.
• Degradation of the informational element of national power (IT and telecommunications).
• Severe socioeconomic implications. “given the integration of GPS into critical infrastructures and their interdependencies, lengthy disruption just of the power grid, for example, could have cascading effects which [would] unravel America’s socioeconomic fabric…”
• Harm to national and homeland defense. Leadership is needed to perform national essential functions.

While the paper makes several specific recommendations for actions by various departments, it also identifies national-level leadership as key:

“The United States must rapidly develop and implement a comprehensive, whole of nation, strategy to redress its asymmetric vulnerability to Navwar and restore U.S. leadership in space-based and terrestrial PNT. … Focused leadership, properly empowered and resourced, is essential to the national PNT strategy’s success.”

The NSSA paper “America’s Asymmetric Vulnerability to Navigation Warfare: Leadership and Strategic Direction Needed to Mitigate Significant Threats” was sponsored by the Resilient Navigation and Timing Foundation and can be accessed here.

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Mike O’Connor

Satelles, which developed the Satellite Time and Location (STL) system, recently became part of Iridium, which already owned a large share of the company. I spoke with Michael O’Connor, previously Satelles’ CEO, who is now Executive Vice President of Iridium’s PNT Division.

Besides the ownership change, has anything changed in your organization?

What was the Satelles business is now part of the broader Iridium company. We’ve been partnered very closely with Iridium since the genesis of Satelles more than a decade ago. It really made strategic sense to become a part of Iridium. The industry is clearly at an inflection point. We don’t have to look too far to understand that the mainstream is catching on to the things that you have been writing about for years. Now, people are realizing what’s actually happening. Various users — especially those near conflict areas — are starting to truly experience jamming and spoofing events. The world is starting to recognize that there’s a need for solutions. The U.S. Department of Transportation has just come out with a complementary PNT plan. They put out a request for a quotation recently to engage the industry.

Companies like ours, and others in the industry who have been developing solutions to this problem for many years, will finally start to see traction with customers. We just signed an agreement with L3 Harris to roll out GNSS augmentation or complementary PNT for the Federal Aviation Administration (FAA) to networks. Not just industry, but also the U.S. government is now taking steps to implement the resilience that’s needed to protect critical infrastructure. So, the timing is good.

Does being now fully part of Iridium give you any additional access to the company’s satellite network?

We will be rolling out, over time, some additional capabilities and expanded service areas. We will be announcing ways in which, by integrating the companies, we can expand more quickly into new geographic areas, providing additional signal coverage in areas where Satelles had not previously been able to do so. As Satelles, we were very focused on timing and national critical infrastructure. Iridium’s business lines align with some of the directions in which Satelles was already intending to grow in any case — such as maritime, internet of things (IoT) and possibly even someday aviation. There are areas where we will be able to expand our reach much more quickly than we ever would have been able to do as a standalone company.

STL makes indoor positioning possible because the signal is much stronger due to Iridium’s satellites’ much lower orbit than that of GPS satellites, correct?

Exactly right. It’s really about the signal power. Part of it is being closer to Earth, part of it is that we are on a channel that was dedicated to paging, back when people had pagers on their belts and was designed with a higher power signal than the Iridium satellites’ two-way voice and data channels. Additionally, we’ve designed the signal itself to also have some coding gain. So, all those things ultimately increase the receive sensitivity of a receiver by about 30 dB, which makes the signal 1,000 times stronger.

In the mix of complementary PNT options and systems, what are your system’s strengths?

There is no single silver bullet solution to complementary PNT. We can offer our solution, but different applications have different needs, for sure. What Iridium offers with the Iridium STL service is a system that’s available today to protect critical infrastructure — we’ve been delivering this to customers, we have thousands of users; it’s available globally — we effectively have a global license, a global capability, a global satellite constellation. We also have the distinct advantage of a high-power signal that can reach places where GNSS cannot. So, we focus on applications for which we can offer some unique value. A lot of that is based on the underlying Iridium satellite network. A long time ago, Iridium secured global rights for the L-band spectrum. Besides being in LEO, the network has inter-satellite links that enable it to cover the whole world from a finite, manageable set of ground monitoring sites.

Because of all these aspects of its network, Iridium can offer something unique in the industry. Other solutions have different advantages and disadvantages. There is a breadth of solutions across the industry. All these entities are trying to solve the same important problem. Different users of PNT and different users who have a need for complementary PNT will see the advantages and disadvantages of different solutions out there. So, we like that there’s a thriving ecosystem of solution providers.

Iridium Communications will provide its Satellite Time and Location (STL) service to more than three dozen L3Harris-operated communications network backbone nodes and a similar number of Federal Aviation Administration (FAA) facilities throughout the United States. (Image: Iridium)

Regarding markets, end users and user applications, what’s your focus?

Our focus today is very much around timing and national critical infrastructure. We are in that market today, but it is one where we also see the greatest growth. We already have several partners who are selling products into those markets — including Adtran Oscilloquartz, VIAVI and Safran — and products available today. That market is just starting to recognize the need for complementary PNT and accelerate its adoption.

Our primary focus today is making those customers successful with our solutions. Looking at new market opportunities, we are exploring the next products and markets we will pursue, but it is likely to be in an area that overlaps with those in which Iridium already has great partners and customers to which we can provide additional value. Maritime is a good example. Aviation may be a longer sales cycle. It would be speculating as to what that next big market will be because right now we are very focused on that initial market.

As far as timing for critical infrastructure — cell phone towers, electrical distribution, data centers, etc. — are your boxes replacing the previous ones or sitting next to them?

They can do either. The products that our partners offer include GNSS plus STL, so it can replace the GNSS-only solution in those systems. A lot depends on the customer and the application, of course. Our partner would provide a solution that includes GNSS plus STL; it typically would replace a GNSS-only solution and provide resilience by having a complementary PNT capability.

The solutions we’re providing to the FAA are not on-aircraft solutions. They are ground infrastructure solutions that keep the integrity of the ground networks, which are of course Safety of Life critical to the operation of our national airspace. We are providing the timing solution for the FAA within that data center infrastructure.

<p>The post Iridium focuses on timing and critical infrastructure first appeared on GPS World.</p>

Photo: Safran Federal Systems

GNSS — delivering up to millimeter accuracy from 20,200 km in space with a received signal of one tenth of one millionth of one billionth of a Watt — is, in Arthur C. Clarke’s famous definition, “indistinguishable from magic.” Yet, in addition to the inherent errors in the transmission, propagation, and reception of their signals, GNSS are increasingly challenged by jamming and spoofing attacks, especially in and near conflict zones.

For that reason, as any regular reader of this magazine knows, combating jamming and spoofing and building resilience in positioning, navigation, and timing (PNT) systems has been a constant theme of many of our articles and industry news items for years.

The U.S. National Space-Based Positioning, Navigation and Timing Advisory Board has been focusing on how to “protect, toughen and augment” GPS, with the third word referring both to enhancements to GPS and to the “provision and use of alternate sources of PNT that complement, back up, or replace (partly or entirely) use of GPS.”^(*)

For this cover story, I discussed complementary sources of PNT with executives from four companies that design, produce, and/or operate them. They cover a wide range of complementary PNT technologies. Read the exclusive interviews below: 

• Iridium owns and operates a constellation of satellites in low-Earth orbit (LEO) and has global rights for L-band spectrum. This enables it to operate the Satellite Time and Location (STL) system developed by Satelles before it recently became part of Iridium. STL protects critical infrastructure by providing a timing signal that is independent of GNSS constellations and 1,000 times stronger than the GPS signal.
• Spirent Communications’ latest simulation system brings together GNSS and a wide range of other PNT systems. It simulates L-band, S-band, alternative navigation signals, signals of opportunity and emulated inertial outputs. It focuses particularly on the new and emerging LEO constellations, including Xona Space Systems’ PULSAR signals, and enables users to inject new signals via I/Q data files.
• SpacePNT has developed an FPGA-based hardware/software/firmware spaceborne GNSS receiver technology specifically targeting the fast-growing New Space satellite market. The company’s innovations include a precise orbit determination algorithm that can process signals from the Galileo High Accuracy Service and from geostationary orbit (GEO) satellites.
• VIAVI Solutions has developed a system that aggregates signals of opportunity, as well as Iridium LEO and Inmarsat GEO sources; weighs and cross-verifies them; then converts the output to the legacy GPS L1 signal and feeds it to a GPS receiver. It can also aggregate a stand-alone cesium clock.

(*) From Dr. John Betz’s presentation on “Augmenting GPS for Critical Infrastructure” at the April 24, 2024, meeting of the PNT Advisory Board.

<p>The post PNT without GNSS: Exclusive interviews first appeared on GPS World.</p>

Photo: GPS IIIF

The European Union Aviation Safety Agency (EASA) has updated its Safety Information Bulletin (SIB) to address the growing number of GNSS outages and disruptions.  

This updated advisory, SIB No. 2022-02R3, highlights the increasing sophistication and impact of GNSS jamming and spoofing, which have become significant concerns for aviation safety. 

The bulletin is directed at competent authorities, Air Traffic Management/Air Navigation Services (ATM/ANS) providers, air operators, aircraft and equipment manufacturers and organizations involved in the design or production of ATM/ANS equipment. It aims to inform these stakeholders about the risks and necessary precautions related to GNSS interference. 

Since February 2022, there has been a notable increase in GNSS jamming and spoofing, particularly in regions surrounding conflict zones and other sensitive areas such as the Mediterranean, Black Sea, Middle East, Baltic Sea and the Arctic, reports the EASA. These interferences can disrupt the accurate reception of GNSS signals, leading to various operational challenges for aircraft and ground systems. 

Tackling jamming and spoofing  

The bulletin addresses jamming and spoofing. Jamming involves intentional radio frequency interference that prevents GNSS receivers from receiving satellite signals, rendering the system ineffective or degraded, while spoofing involves broadcasting counterfeit satellite signals to deceive GNSS receivers, resulting in incorrect positioning, navigation and timing (PNT) data. Jamming typically results in immediate and noticeable effects, whereas spoofing is more difficult to detect and poses a higher safety risk. 

Some symptoms of suspected GNSS spoofing include incoherence in navigation position, abnormal differences between ground speed and true airspeed, time and date shifts and spurious Terrain Awareness and Warning System (TAWS) alerts. These disruptions can lead to significant operational issues, such as re-routing or diversions, loss of Airborne Collision Avoidance System (ACAS) and misleading surveillance data. 

EASA recommends several measures to reduce the risks associated with GNSS interference. These measures include establishing coordinated procedures between authorities, ATM/ANS providers and airspace users. The agency also suggests utilizing complementary PNT infrastructure and encourages users to implement a process to collect and report information on GNSS degradation. 

Specific recommendations 

For air operators:  

• Train flight crews to recognize and respond to GNSS interferences. 
• Promptly report any GNSS anomalies. 
• Assess operational risks and maintain alternative navigation procedures. 

 For ATM/ANS providers:  

• Establish monitoring and reporting processes for GNSS degradations. 
• Ensure ground navigation infrastructure supports non-GNSS procedures. 
• Provide navigation assistance and maintain communication coverage in case of GNSS jamming or spoofing. 

For manufacturers:  

• Assess the impact of GNSS interference on products and guide users. 
• Support operators with instructions for managing GNSS-related issues. 

 Stakeholders are urged to implement the recommended measures to mitigate the impact of GNSS jamming and spoofing on aviation safety. 

For further details, read the full EASA Safety Information Bulletin and visit the EASA website for updated information on affected regions. 

<p>The post EASA updates advisory on navigation interference first appeared on GPS World.</p>