Receiver evolution yields new options

Photo: CHC Navigation

Change from one generation of GNSS receivers to the next is generally evolutionary, not revolutionary. As with other technologies, it follows a feedback loop between end-user requirements and technical advances. Additionally, GNSS receivers can now take advantage of four full GNSS constellations, two regional ones, and a plethora of corrections/augmentation services — and increasingly must be able to counter jamming and spoofing.

To get the perspective of GNSS receiver manufacturers on these issues, I asked four questions to the following company representatives:

• Joel Korsakissok, president, Syntony GNSS
• Gustavo Lopez, senior market portfolio manager, Septentrio
• Rachel Wang, product manager, surveying and engineering division, CHC Navigation
• Farrokh Farrokhi, founder and president, etherWhere
• Stephen Ching, core segment manager, Hexagon’s Autonomy & Positioning division

For longer versions of their responses, as well as responses from additional companies, visit here.

Question: What is currently the best way to take full advantage of the large number of GNSS satellites — four full constellations and two regional ones — and of the many corrections/augmentation services?

Korsakissok: Many satellites in view means greater precision in urban areas, where the view of the sky is partially masked, better resilience to adversity (jamming, spoofing, constellation disruption) and, more generally, greater precision even with a clear view of the sky, thanks to local augmentations. Users working on autonomous vehicles are asking for these advantages, with the goal of achieving a certified and secured system. Technically, to have an optimal usage of this multiplicity of satellites and signals, a receiver should be able to make a fix, even with one or two satellites of each constellation in view, as we do at Syntony. Practically, because of the heritage, it is not so often the case: Many receivers, even today, make a position, velocity and time (PVT) calculation with GPS first and then use the other signals to improve it.

Lopez: To fully leverage all GNSS constellations and regional systems, it is essential to utilize multi-constellation and multi-frequency receivers that significantly enhance accuracy and reliability. These advanced receivers not only improve performance by accessing a broader range of satellite signals but also ensure consistent positioning in challenging environments, such as urban areas with tall buildings or rural regions with obstructed views of the sky.

Septentrio’s antarx is a rugged GNSS/INS multi-frequency smart antenna. (Photo: Septentrio)

Some GNSS manufacturers limit signal usage due to inadequate hardware that cannot track multiple signals and their desire to reduce costs (e.g., CPU power or the number of signal tracking components). Effectively tracking multiple signals and constellations necessitates a robust hardware architecture as well as efficient algorithms that can operate optimally in compact embedded systems to fully leverage all available signals in space. At Septentrio, we prioritize maximizing all available signals to deliver the best possible performance for users while ensuring that our solutions remain valuable and accessible for a variety of applications.

Utilizing multiple GNSS signals not only enhances accuracy, availability, and reliability but also improves resilience and GNSS security, offering crucial protection against jamming and spoofing — issues that are becoming increasingly critical for many applications. Moreover, manufacturers must prioritize compatibility with various correction systems, which provide real-time data to improve positional accuracy further. Ensuring that receivers can seamlessly integrate with multiple correction services allows for smooth adoption across diverse market applications, catering to the unique needs of different industries.

To meet market demand, Septentrio has developed the Agnostic Corrections program, enabling customers to select from a range of well-established and affordable correction services. This approach offers flexibility and access to key service providers in the industry. Since these services support various signals, the advantage of our receivers is key to accommodate the wide array of signals and format messages used by these correction services.

At Septentrio, optimizing these elements is central to our vision and strategy for GNSS core technology. By focusing on performance, reliability, and compatibility, we aim to deliver innovative solutions that meet the evolving demands of the market while maintaining our commitment to excellence in GNSS technology. This strategic approach not only enhances the user experience but also positions Septentrio as a leader in the GNSS field.

Wang: To fully benefit from commercial PPP corrections, receivers must be capable of receiving signals from all GNSS constellations and frequency bands, and support SBAS and L-band services. On the software side, optimizing GNSS satellite utilization involves feeding the navigation filter with a wide range of observations from each available constellation. This, combined with adaptive interference mitigation algorithms and receiver autonomous integrity monitoring (RAIM) techniques, can greatly enhance the robustness and resilience of GNSS solutions in challenging environments such as urban canyons, interference, and spoofing.

Farrokhi: Regional services are categorized as augmentation systems. They are offered through both satellites and terrestrial systems. Satellite-based augmentation systems include but are not limited to SBAS, WAAS, AGNOS, MSAS, GAGAN, NavIC and QZSS. Terrestrial augmentation systems include but are not limited to GBAS, and GLS. Correction services include but are not limited to RTK and PPP.

Supporting these regional and correction services along with multi-band support increases the complexity of the receiver hardware and associated firmware. It is important to note that not every application or use case requires all these different services. For instance, asset tracking utilizing battery-operated tags do not require correction services or L5 acquisition. Low-power operation and simplicity of the GNSS receiver is key to longevity of operation in such applications.

The selection of correction service is highly dependent on the type of communication pipe supported by the hardware. For instance, L-band capability is required for satellite-based correction services, whereas LTE is needed for terrestrial based services.

Ching: I think one of the best ways is to embrace all the available signals on hand. What that means is with the luxury of redundancy, the system can select the best signals to use into the position estimation algorithm. Our OEM7 uses multiple constellations (GPS, GLONASS, Galileo, BeiDou, QZSS and NavIC) and multiple frequency bands (L1, L2, L5 and E6).

Q: Are the requirements for different end user applications — for example, surveying vs. fleet tracking — still very different or are they converging as capabilities increase?

Cerber CRPA Receiver with four-channel antenna and Constellator CRPA simulator. (Photo: Syntony)

Korsakissok: In a way, everybody is benefiting from better precision year after year, using the standard open signals; related to that, we can say that the solution capabilities are converging. A bit. However, we do not see everybody converging toward a “high precision real-time PVT every time everywhere.” Bringing 20-cm precision to a truck-tracking application is nice, but nobody will ever want to pay for this, if it is not relevant for how they use the application. Conversely, for precision agriculture, precision mining and autonomous vehicles, it will always be required, and they will be able to pay for the precision, when associated with reliability, in order to achieve the targeted level of safety.

Lopez: Although GNSS technology has evolved significantly in recent years due to the growing demand for accuracy across new applications, the requirements among different applications remain highly varied. Some may need centimeter-level precision, while others are satisfied with accuracy within 10 centimeters. Survey-grade applications still demand millimeter-level accuracy, while certain autonomous systems may only require 1 to 10 centimeters of precision. Additionally, the environments in which these applications operate vary, such as a surveyor working in unobstructed ground conditions versus a drone navigating through complex airspaces, where jamming, signal availability, and interference can affect performance.

The increasing number of applications that rely on accuracy has resulted in diverse requirements across the board. This is why customers seek more flexible GNSS receivers to balance availability, accuracy, and reliability based on the specific use case. There’s a broad spectrum of needs — not only in GNSS performance (accuracy, time to fix, reliability) but also in security (anti-jamming, anti-spoofing, cybersecurity) and hardware design. For example, some users need compact solutions for small form-factor devices, while others prefer robust systems that can endure harsh environmental conditions. A surveyor, focused on achieving high accuracy, may not need the same GNSS resilience required by critical infrastructure or autonomous systems, where safety mechanisms are crucial.

As more prosumer and innovative applications advance, their needs differ from those of industrial or critical-use cases. At Septentrio, we offer solutions that fill the gaps when lower-end options fall short, attracting customers dissatisfied with third-party products that fail to meet their needs. Septentrio also provides enclosure solutions with stringent environmental protection requirements, including water resistance, humidity control, vibration tolerance, and corrosion resistance.

While GNSS technology continues to advance and become more sophisticated, we also see that the gap between different applications is narrowing. Fleet tracking, for instance, is beginning to benefit from more precise positioning and the ability to use multiple GNSS constellations for autonomy — features traditionally reserved for high-precision applications such as surveying. The cost of high-precision GNSS receivers is also decreasing, making advanced features more accessible across various industries.

However, this increased autonomy introduces new demands, such as top performance and safety in complex environments, and seamless integration with sensor fusion and other ecosystems. Traditional GNSS receivers used for basic fleet tracking will not meet the needs of these advanced use cases, even if they remain part of the same vehicle or platform.

In summary, despite a trend toward the convergence of GNSS capabilities that enhance accuracy, the core requirements of these applications remain distinct, challenging the industry to develop more universally applicable solutions.

Wang: From our point of view, while GNSS performance is steadily improving, manufacturers still need to strike a balance among cost, accuracy, and availability to meet the diverse requirements of different user applications. In surveying, for example, accuracy is the top priority, while in transient control, integrity and availability are more critical. Although GNSS capabilities are increasing and some convergence of requirements is occurring, significant differences remain, necessitating careful design and optimization by manufacturers to address these varying needs.

Farrokhi: The requirements for surveying, for instance, do not apply to the rest of the market. For surveying, extreme accuracy is a must, hence utilizing RTK services and the cost of the solution is usually high. On the other hand, asset tracking, for instance, can benefit from high sensitivity, low power, low cost and cloud processing to reduce power consumption in the asset tracking device.

Generally speaking, the GNSS market falls into the following categories:

• Low power, low cost — such as asset tracking
• High precision — e.g., surveying and agriculture
• High precision, with high reliability — such as ADAS
• High speed, high G — in defense applications
• Anti-jamming and anti-spoofing — such as in avionics and defense

etherWhere’s next generation hardware solution enables the convergence of all these disparate applications onto one hardware platform by utilizing flexible software and cloud processing.

Ching: Ultimately, regardless of applications, users want the reported positions that are accurate with trustworthy quality indicators. As capabilities increase, I expect more requirements to converge. For example, both surveying and fleet-tracking applications need to operate during ionospheric scintillations. Having a robust positioning solution in both applications is essential. Hexagon | NovAtel released updated firmware (versions 7.09.01 and 7.09.02) in April 2024 to increase ionospheric resilience.

Q: What is the best way to integrate complementary sources of PNT — such as LEO satellites and ground-based systems — into end user hardware and software, to maximize resilience during GNSS disruptions or outages?

Korsakissok: Such integration will be eased for all the new sources that can be acquired with the same RF stages, meaning mostly L-band as of today. SBAS has paved the way and emits at the same carrier frequency as the classic GNSS. U.S. and European low-Earth orbit positioning, navigation and timing (LEO-PNT) projects have included such signals in L-bands, and other telecom constellations can also be used that way (Inmarsat, Iridium, etc.). Because of this, all these L-band extensions to classical GNSS will be the first in line on everybody’s roadmap. When C-band signals will be emitted by GNSS constellations, then telecom ones could also be easily integrated. However, that will take many years.

Lopez: To enhance resilience during GNSS disruptions or outages, integrating a multi-layered approach with complementary sources of positioning, navigation, and timing (PNT), such as LEO satellites and ground-based systems, into end-user hardware and software is crucial. While GNSS technology will remain essential, the combination with other technologies such as inertial sensors and sensor fusion will become increasingly important as these solutions become more available.

Although alternative PNT mechanisms can bolster resilience, the strengths and protections at the core of GNSS are vital for many applications, especially since GNSS manufacturers possess the expertise to address jamming and spoofing effectively. This layered security approach resembles the “onion model” in cybersecurity — adding more security layers enhances protection against disruptions.

While LEO technology is advancing, its full value for PNT may take a few more years to materialize. In the meantime, other sensor technologies, such as inertial navigation systems (INS), already provide significant benefits in the absence of GNSS or in the most difficult conditions to GNSS.

etherWhere’s EW6181 multi-GNSS receiver. (Photo: ehterWhere)

At Septentrio, we are committed to developing products that invest in sensor fusion technologies (GNSS/INS), and we actively participate in key LEO programs that promise substantial improvements in resilience and other PNT aspects, including GNSS corrections and enhanced multipath mitigation for optimal performance in challenging environments. We view this evolution as critical to our product roadmap and consider it a strategic priority for our company.

Wang: The foundation of an effective positioning system is robust hardware that supports the integration of multiple PNT sources. Building on this multi-source signal base, a set of advanced algorithms is necessary to selectively use the signals and filter out interference, enabling the seamless fusion of these sources and achieving superior performance. Moreover, redundant and backup filters are crucial for maintaining the robustness of the positioning solution, particularly during GNSS disruptions or outages.

Farrokhi: etherWhere’s next-generation solution supports LEO constellations such as Xona Space to enhance location tracking and provide resilience and redundancy. LEO satellites signal strength is higher than GNSS satellites due to their lower orbit and as such provide better link margin. The key to ubiquitous adoption is in a well-integrated single chip solution at lower power consumption.

Ching: Complementary sources of PNT must be proven to provide a consistent improvement in positioning performance, beyond what GNSS alone can provide. For example, increasing availability is not helpful if the quality indicators cannot be trusted. The integration must be an overall benefit to the user, in terms of ease of use, positioning performance and reliability. Our team is already leading the market and working with key stakeholders and partners to provide PNT beyond GNSS as we announced in previous years.

Q: What are the key innovations in your latest receiver or generation of receivers?

Korsakissok: Syntony is well-known to have one of the first full SDR embedded receivers, working in multi-frequency and multi-constellation mode. Thanks to that, we were able to be the first to demonstrate the coupling with XONA, at ION GNSS in 2022, and have been chosen by the European Space Agency (ESA) for their own LEO PNT: Flexibility and ease of modification are the major advantage of full SDR, versus ASICS.
Today, our SDR receiver is embedded in cars, trains, UAVs, launchers and satellites, but also in trucks for underground mining, together with our SubWAVE solution. Not to mention our CRPA version, which is capable of state-of-the-art anti-jamming level, completed by exclusive anti-spoofing mitigation, as we can compare, directly inside the receiver, the direction of arrival of all GNSS signals with the ephemeris, avoiding retaining and tracking the ones that are spoofed.

Lopez: This year, Septentrio has achieved notable advancements in GNSS receiver technology by enhancing resilience against jamming and spoofing and by launching the AntaRx product line. It offers high-precision performance, a durable design, and versatility for industrial applications, such as construction and mining. With advanced anti-jamming and anti-spoofing across all products, plus the AntaRx — which is an all-in-one GNSS, antenna, and sensor fusion solution — we remain committed to delivering the most reliable positioning in the most challenging environments.

Lopez: In response to evolving market demands and guided by our strategic vision, Septentrio has made significant advancements in GNSS receiver technology, focusing on two major pillars: resilience and performance.

Resilience: Septentrio has established a reputation for providing robust GNSS solutions thanks to our AIM+ technology, and we remain committed to enhancing resilience across our product line. Our latest innovations have significantly improved our receivers’ ability to detect and mitigate spoofing attacks. These enhancements have been validated through rigorous testing, including recent GNSS jamming tests conducted in Norway (see Norway results here), as well as field applications where our receivers have successfully operated in contested environments, particularly within drone applications. This continued focus on resilience ensures that our customers can rely on our technology even in challenging conditions where signal integrity is paramount.

AntaRx Product Portfolio: This year, we proudly launched the AntaRx product line, specifically designed to meet the rigorous demands of industrial applications such as construction, mining, and robotics. The AntaRx series offers a variety of configurations, including single-frequency, dual-frequency, and inertial variants (GNSS/INS), providing unparalleled flexibility for a wide range of use cases (see more about this product here).

What sets the AntaRx apart is its exceptional high-precision GNSS performance combined with core reliability. This product line is compatible with various correction services, allowing users to achieve optimal accuracy regardless of their operational environment. Moreover, the AntaRx features advanced anti-jamming and anti-spoofing technologies, which are critical for ensuring the integrity of positioning data in areas where interference is prevalent.

In addition to its technological innovations, the AntaRx is designed with ruggedness in mind. It is built to withstand harsh environmental conditions, making it suitable for deployment in demanding industries. The user-friendly interface simplifies operation and enhances the user experience, ensuring that both seasoned professionals and newcomers can easily integrate the technology into their workflows.

Furthermore, the AntaRx incorporates sophisticated sensor fusion capabilities, combining GNSS with inertial data to enhance overall positioning accuracy and reliability. This integration is particularly beneficial in environments where GNSS signals may be obstructed or unreliable. The careful design of the AntaRx, which includes an integrated antenna and GNSS components, significantly improves multipath mitigation, further ensuring optimal performance even in challenging conditions.

In summary, Septentrio’s commitment to innovation is evident in our latest GNSS receiver developments. By focusing on resilience and advanced capabilities, particularly with the launch of the AntaRx product line, we aim to provide our customers with the most reliable and high-performing GNSS solutions tailored to meet the diverse demands of various industries. As technology continues to evolve, we will remain dedicated to enhancing our products to meet the future challenges of positioning, navigation, and timing.

Wang: Our newest product, the RS10, leverages cutting-edge technologies to achieve seamless integration of GNSS with SLAM, vision, and INS. This fusion has resulted in the RS10 delivering enhanced accuracy and reliability while providing an exceptionally efficient solution for the surveying and mapping industries. By combining these complementary technologies, we’ve made a significant leap forward in advancing the performance and capabilities to benefit geospatial professionals.

Farrokhi: At etherWhere, we have innovated on multiple fronts to address different use cases.

These innovations include:

• AccuWhere Cloud to address the requirements for low-power, battery-operated asset trackers.
• Hybrid Constellation to address the simultaneous processing of the four GNSS constellations along with LEO signals of opportunity (SOP) to provide resilience and redundancy.
• ArrayNav adaptive multi-antenna system for anti-jamming applications such as avionics and also applications that require elimination of multipath such as autonomous driving.

Ching: In addition to the latest firmware update announcement to combat ionospheric scintillation, Hexagon | NovAtel also rolled out the latest office software version (NovAtel Application Suite v 2.0) for providing the next-level GNSS interference monitoring insight to users to make informed decisions to maintain robust positioning. In parallel, NovAtel has been developing the functional safety positioning engine and correction services that meet ISO 26262 standard as we anticipate the automotive world not only needs a positioning solution that is accurate and resilient, but is also safe to use.