Cover photo: Topcon
Lay of the GNSS Land
Top receiver manufacturers discuss what’s on the horizon for GNSS receivers. The companies reveal recent and upcoming innovations, how to combat spoofing and jamming, fusing GNSS with other sensors, and the impact of increasing accuracy both for professional surveyors and consumers.
With regard to jamming and spoofing, the preferred approach is a combination of monitoring, detection and filtering. However, shielding, the use of IMUs and other third-party sensors, and advances in processing algorithms also help mitigate interference. In a few years, hopefully, encrypted or “watermarked” signals will substantially reduce this problem.
IMUs and other sensors are now routinely integrated with GNSS receivers, with their outputs fused. This trend is largely propelled on the demand side by the needs of the emerging market for autonomous vehicles and on the supply side by smaller, cheaper and more accurate IMUs and lidar scanners. Meanwhile, developments in algorithms have improved the modeling of errors to correct for the inherent tendency of IMUs to drift. Additionally, digital cameras, lidar and other industry-specific sensors are increasingly common, especially for collision avoidance in human-machine interactions.
In surveying, the use of all constellations and frequencies, as they become available, is an industry trend. Costs will continue to drop as the growth in the adoption of GNSS solutions enables manufacturers to take greater advantage of economies of scale. Precise point positioning (PPP), which benefits greatly from the growth in GNSS constellations, is now giving real-time kinematic (RTK) positioning a run for its money. Available applications enable Android mobile devices to achieve centimeter accuracy, while innovations continue in core positioning algorithms.
In the world of mobile consumer devices, dual-frequency, multi-constellation GNSS chipsets are increasingly prevalent. As increased accuracy fuels expectations for even higher accuracy, precision positioning may become the norm in the consumer space, and new applications for these devices may emerge. Already, crowdsourcing the monitoring of both GNSS signals and interference helps improve accuracy for everyone, in a positive feedback loop.
Other notable trends include the introduction and expansion of 5G data networks, the increased use of satellite-based correction services, and continued efforts to develop precise positioning for indoor areas.
Topcon
Jamming and Spoofing. “We continue to develop and deploy patented technology to detect spoofing,” said Alok Srivastava, director, product management. “We already have cutting edge GNSS antenna technology to provide stellar support for interference rejection and filtering.” All Topcon end products have this advanced antenna and filtering technology.
Sensor Fusion. “Topcon has been using inertial systems for decades for a variety of positioning applications — such as machine control, mobile mapping, and agriculture,” said Srivastava. “In recent years, advancements in IMU technology have progressed to where the size and cost of these sensors are at levels to be utilized at a larger scale. For example, the recently released Topcon HiPer VR takes advantage of inertial technology to improve productivity in real time with our Topcon Integrated Leveling Technology (TILT), which compensates for mis-leveled field measurements out of plumb by as much as 15 degrees.”
Surveying. Topcon continues to invest in its core positioning algorithms to innovate such features as quartz lock loop, advanced multi-engine platform, and VHD heading technology into its positioning engines, Srivastava said. “We also produce solutions such as our Millimeter GPS and Hybrid Positioning innovations, which are designed around improving accuracy, higher reliability, and greater flexibility by converging positioning technologies.”
Consumer Devices. “GNSS in consumer devices and other commercial systems is used to aid other positioning sensors,” Srivastava said. “So, it may not be in the best of interest to offer that level of accuracy from GNSS alone.”
Other Challenges. Precise indoor positioning is a requirement of the vertical construction industry. “Topcon’s combined optical instrument takes a unique approach to solve that problem by integrating a compact laser scanner with a fully featured robotic total station,” Srivastava said.
Photo: CHC Navigation
CHC Navigation
Jamming and Spoofing. CHCNav is currently taking a twofold approach to GNSS interference, said François Martin, vice general manager, International Division. “As a GNSS system integrator, we focus our design around strong electromagnetic shielding and sealed isolation chambers.” Additionally, he pointed out, the advanced filtering of GNSS signals and an antenna patch produce optimal interference mitigation.
Sensor Fusion. Integrating interference-free, high-dynamic IMUs instead of MEMS has brought the full benefits of tilt compensation to users, Martin said. The latest development in algorithms dramatically obviated the need for the annoying process of initializing GNSS IMU receivers and boosted the availability of GNSS RTK in demanding environments.
Surveying. The fast adoption of GNSS solutions by large user segments has reduced costs by enabling a sizable manufacturing economy of scale, Martin pointed out. “Tighter combination of embedded technologies such as GNSS and connectivity modules are sustaining that cost reduction process.”
Consumer Devices. “The emergence of dual frequency multi-constellation GNSS chipsets supports the development of untapped user segments, but the position accuracy repeatability remains an issue,” Martin said. “The integration of GNSS chipset and high-performance helical antennas, as precision add-on modules, onto rugged Android cell phone and tablets is creating a prosumer-grade centimeter to decimeter accuracy answering to a wide range of mobile workforce applications.”
Other Challenges. A growing number of positioning and navigation applications require the fusion of technologies to increase productivity, Martin said. “The integration of advanced tightly integrated positioning algorithms, scanners, IMUs, HDR cameras, IoT and cloud-based connected solutions are a clear trend.” However, their adoption by a large user base remains limited by their current price point.
Photo: Septentrio
Septentrio
Jamming and Spoofing. “Recent developments in receiver-antenna combinations maximize the benefits of anti-jamming techniques,” said Gustavo Lopez, market access manager. Third party sensors, such as IMUs, also help mitigate interference, he pointed out. “Septentrio’s advanced receiver technology such as AIM+, a standard feature on all the company’s products, bring not only real time monitoring but also jamming/spoofing mitigation. Galileo and GPS have clear roadmaps bringing signal authentication in order to avoid spoofing.”
Sensor Fusion. Smaller IMUs with higher grade performance now on the market are enabling new use cases in autonomous applications, said Lopez. Other important elements are a new generation of compact high-performance sensors and the growing importance of multi-sensor technology “to provide even higher levels of positioning integrity.” He cited Septentrio’s AsteRx-i family of products as an example of GNSS/INS integrated solutions.
Surveying. As an example of Septentrio’s survey-specific products, which “continuously benefit from advanced developments being rolled out in our platform,” Lopez cited the Altus NR3.
Consumer Devices. The increasing positioning accuracy of cell phones, Lopez pointed out, “has spurred innovations such as PPP and the use of mobile phone measurements,” as well as “other purposes, such as interference detection and crowdsourcing.”
Other Challenges. “Sensor fusion is a key element in positioning and orientation,” Lopez said. “Easy integration is a key element in this trend. Also, integrity in error reporting and positioning will be required as well as reliable raw measurements which can be integrated with other sensors. This drives the requirement for receivers capable of running customer proprietary software. Another important element will also be the possibility of running positioning algorithms on a third-party processor.”
Photo: Hemisphere GNSS
Hemisphere GNSS
Jamming and Spoofing. “Hemisphere’s new Lyra II ASIC platform used in our Phantom and Vega series positioning and heading boards,” said Miles Ware, director of marketing, “introduces new technology and filtering methods to identify and mitigate known and unknown interference sources that typically have an adverse effect on GNSS performance.”
Sensor Fusion. “Advancements in IMU integration and sensor fusion,” Ware said, “will continue to be a key focus for Hemisphere to support the growth and adoption of the expanding autonomous vehicle and application marketplace. The positioning and heading technology offered in our Vega 28 will be a core component for autonomous marine, machine control, and agriculture solutions for new and emerging markets.”
Surveying. “Access to modern and future signals like BeiDou Phase III, ALTBOC and BS-ACEBOC significantly enhance GNSS accuracy, especially in challenging environments where satellite visibility is compromised by the topography and or the structures present,” Ware pointed out. “Survey solutions that can not only track but also use all the available GNSS measurements in their RTK solution will have a substantial advantage in the market.”
Consumer Devices. “As mobile phones and consumer devices continue to adopt hardware designs that can access the latest GNSS signals,” Ware said, “the opportunities for solutions where high precision measurement engines can be hosted within mobile devices opens up a new realm of solutions that can leverage the high accuracy positioning performance found in Hemisphere technology and products. We see this as a very exciting and emerging area.”
Other Challenges. Ware pointed to “leveraging GNSS technology to further support environmentally friendly transportation solutions and sustainable agriculture,” for which GNSS continues to be an integral component.
Photo: Unicore
Unicore Communications
Sensor Fusion. “We are implementing GNSS with different level IMUs, including low-cost and high-end, targeting automotive, intelligent driving, and robot application scenarios,” said Gao Jingbo, marketing director. “The algorithm can also integrate with the already-existing sensors on the platform, such as IMUs, cameras and odometers. The solution can be done on the GNSS side, with high information synchronization accuracy, or processed on the platform.”
Surveying. Products with Unicore boards inside can provide centimeter- to millimeter-level positioning accuracy, said Jingbo. “Unicore’s high precision boards and modules can track all frequencies of all satellite systems. The UGypsophila RTK technology can make the most of the observation data of all frequencies in all systems even without the observations of the base station in the RTK solution, thus greatly improving the usability, reliability and accuracy of RTK.” The company is now also working to reduce the dimensions and cost of its products, Jingbo pointed out. “With Unicore’s single GNSS SoC on board, the UB4B0M and UM4B0 modules are making affordable high-end high precision surveying possible.”
Consumer Devices. Algorithms and hardware are ready now to implement PPP+RTK in cell phones, Jingbo said, and this increase in positioning accuracy will enable many more applications. “We have rich experience in high precision GNSS, but the antenna might be a challenge. Our new generation 22 nm GNSS SoC features low power consumption and support of sensor fusion. Additionally, true point technology by Rx-Networks (also a BDStar company) can provide sub-meter data service, which also enables users to access centimeter-level accuracy location data through their mobile phones and wearable technologies, without increasing the demand for processing power.”
Photo: Trimble
Trimble
Jamming and Spoofing. “Trimble’s latest GNSS receivers leverage our seventh-generation Maxwell technology, which implements hardware- and software-based techniques to detect and mitigate spoofing,” said Stuart Riley, vice president, GNSS Technology. “In addition, Trimble continues to improve the robustness of our GNSS receivers with advances in processing algorithms and hardware enhancements such as the integration of inertial technology.”
Sensor Fusion. “For many years, IMUs have been widely used in Trimble agriculture and Applanix products,” Riley said. “Over the past few years, we’ve created a new line of lower-cost inertially integrated board-level GNSS receivers. We have also integrated inertial components into survey and construction products, including tilt compensation in the Trimble R10, R12 and SPS986 receivers. Trimble also combines its GNSS solutions with optical, laser, lidar and other sensors.”
Surveying. Trimble’s GNSS products, Riley pointed out, range from GIS handhelds to high-performance mobile mapping systems.
Consumer Devices. “The Trimble Catalyst system uses Android-based smartphones or tablets to run an application that includes a software-defined GNSS receiver,” Riley said. “The recently introduced SiteVision system builds on this ecosystem and integrates Google’s ARCore platform with precision GNSS to provide an augmented reality solution for a variety of professional applications.”
Other Challenges. To address signal masking and multipath, Trimble has “continued to improve performance in difficult environments with products such as the Trimble R12 receiver, which provides sophisticated multipath mitigation and an advanced precision processing engine.” Riley said, “Trimble’s RTX Correction Services, delivered via satellite, enable users to achieve RTK speed and accuracy nearly anywhere on the planet without the need for local reference stations.”
Photo: NovAtel
NovAtel
Jamming and Spoofing. “The RF environment is at best crowded and at worst hostile,” said Sandy Kennedy, vice president of innovation, Hexagon’s Positioning Intelligence division. “The NovAtel OEM7 generation of receivers was launched in 2016, with interference detection and mitigation as key features on every variant. Protecting authenticity, availability, and precision for multifrequency measurements is the challenge going forward — in all segments of the system: constellation management and SIS, antenna, receiver design and processing in FW/SW.”
Sensor Fusion. In the last three years, Kennedy pointed out, IMU manufacturers have made significant improvements in the performance offered in smaller, cheaper IMUs. “At the same time, new methods to improve error modelling (to control positioning errors) have been added to the NovAtel SPAN product line, especially in SPAN Land profile. Extended GNSS outages are easily handled now.”
Surveying. “PPP has become a strong competitor to RTK, as convergence times have decreased, and this will continue in service offerings like Terrastar-X from NovAtel,” Kennedy said.
Consumer Devices. The devices, Kennedy said, offer “the tantalizing promise of quality measurements from a common utility device with huge computing horsepower and data connectivity built in! It’s fun to watch, and we shall see if accuracy is truly addictive enough to fuel development for general use of precision positioning.”
Other Challenges. “In the past 20 years, users have moved from awe and wonder that centimeter-level positioning is possible — to utter contempt when it is not,” Kennedy said. “This will continue, with an added requirement of integrity and functional safety. Continuously available positioning within a usable protection level is a requirement for autonomous vehicles.”
Look for part 2 in our February issue.