How do we ensure that GPS is protected from harmful interference?
By J. David Grossman, guest columnist
J. David Grossman
Debates in Washington over harmful interference and the coexistence of divergent services are raging. Nowhere are the differences more apparent than when comparing radio navigation services such as GPS to radio communications systems used in wireless communications networks.
How do we ensure that a satellite-based radionavigation service like GPS, which by design operates below the ambient noise floor, is protected from harmful interference? The International Telecommunications Union’s (ITU) definition of harmful interference provides a starting point, by defining harmful interference as a level that “endangers the functioning of a radionavigation service.”
With this foundational definition, the internationally established criterion of a 1-decibel (dB) increase in the noise floor, otherwise known as the 1-dB standard, provides the answer, offering a readily identifiable, objective and predictable metric.
The 1-dB standard uses a 1-dB increase in the noise floor as the distinction between the onset of interference that can be detected by a GPS receiver and harmful interference. (This can be reliably measured by a 1-dB decrease in the carrier-to-noise ratio, C/N0, reported by the receiver). Thus, the 1-dB standard provides a definitive way to protect GPS receivers from harmful interference. Adherence to this standard helps ensure that systems operating in an adjacent spectrum band do not interfere with GPS.
Why use the 1-dB standard instead of other metrics? The 1-dB standard is based upon well-understood GNSS engineering considerations and is associated with quantifiable changes in the overall noise to which GNSS receivers are subject, with equally well-understood effects on receiver operation. (The 1-dB standard enables system designers and spectrum regulators to carefully assess interference from various sources and analyze their net effect on GNSS receivers).
It also has been adopted internationally and has a long and well-established proven history of protecting GPS operations from harmful interference in both international and domestic regulatory proceedings.
So-called “alternatives” to 1 dB, which may be appropriate in the context of radio communications systems, fail to recognize that the accuracy, integrity and reception (availability) of GPS signals used by a receiver can be degraded by interfering noise in ways not immediately apparent to an end user. This means that the effects of degraded service of GPS signals can still be detrimental well before the user loses position accuracy or experiences complete loss of position.
Additionally, C/N0 is computed at the entry point of a GPS receiver, such that a 1-dB decrease serves as an early warning of interference potentially becoming harmful. Other metrics, computed further downstream, may be indicative of harmful interference already occurring.
GPS has become a fundamental part of our lives and is an integral engine of the U.S. economy, creating new jobs, and unlocking innovation. Maintaining the 1-dB standard ensures that the GPS success story and American innovation will continue for decades to come.
What are the key technical criteria in matching GNSS receivers and antennas from the same or different manufacturers? For what uses does it matter most?
John Fisher. (Photo: Orolia)
“For fixed-pattern antennas, it’s fairly simple: RF + DC to power the antenna. Most vendors are compatible. The challenge is more for controlled radiation pattern antennas (CRPA). Power requirements vary greatly, and performance can be improved with a two-way data exchange between the CRPA and receiver, but there is no industry standard yet for this interface. An example: tilt angles from the receiver’s IMU can greatly aid beam pointing.” John Fischer Orolia
Ellen Hall
“Antenna selection is exceptionally critical for our military and high-precision users. The platform and environment are the primary drivers of these antenna requirements. In general, SWaP (size, weight and power) is at the forefront of all criteria. As operational plans are developed, requirements for a single or multi-element array, element gain, and noise figure must be considered.” Ellen Hall Spirent Federal Systems
Members of the EAB
Tony Agresta Nearmap
Miguel Amor Hexagon Positioning Intelligence
Thibault Bonnevie SBG Systems
Alison Brown NAVSYS Corporation
Ismael Colomina GeoNumerics
Clem Driscoll C.J. Driscoll & Associates
John Fischer Orolia
Ellen Hall Spirent Federal Systems
Jules McNeff Overlook Systems Technologies, Inc.
Terry Moore University of Nottingham
Bradford W. Parkinson Stanford Center for Position, Navigation and Time
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. (See part 2 of this feature here.)
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.”
A version of the NeQuick G algorithm using a new coding approach is now available for download on the GSC website. This version is the result of intensive recoding by engineers at the EU’s Joint Research Centre.
GNSS signals traveling through the ionosphere can be significantly delayed by the electrical charges in this atmospheric layer before reaching the users’ terminal. To compensate for this delay in the signal, Galileo receivers integrate a dynamic model of the ionosphere composition known as the NeQuick G model.
Receiver manufacturers will now be able to benefit from a version of the NeQuick G correction algorithm that implements a new coding approach.
Rigorous testing
The JRC concluded its work recently after successful rigorous testing in the framework of the gLAB tool (GNSS software suite from the Universitat Politecnica de Catalunya). This version of the code has been designed to be highly modular, rendering it more legible for a potential programmer with no specific knowledge about signal propagation in the ionosphere. A library has been also developed to enable its quick integration into existing applications.
This software will be released as free and open source software under the terms of the European Union Public Licence (EUPL), version 1.2.
The open-source code is now ready to be implemented on single-frequency platforms and can be used on a global scale without limitation under the EUPL. This freedom should contribute to a wider adoption of the NeQuick G model at user level.
We used to divide GPS receivers into consumer grade, resource grade and survey grade. Have these categories been replaced by a continuum of GNSS capabilities?
Clem Driscoll
“In the U.S. commercial telematics market, GPS remains the primary source of location data, with very little reliance on other GNSS networks. A bigger issue is the generation of cellular networks used to transmit GPS data, with 3G network sunsets pending and 5G on the horizon. As autonomous commercial vehicles become closer to a reality, multiple GNSS networks and differential techniques will become essential. These solutions are currently in development.” Clem Driscoll
C.J. Driscoll & Associates
Greg Turetzky
“No. These categories still define important hardware distinctions (such as antenna) and required correction services that define the achievable specifications. Although they all have correlators, they have very different architectures; however, resource and survey have a blurrier line.” Greg Turetzky
Consultant
Members of the EAB
Tony Agresta Nearmap
Miguel Amor Hexagon Positioning Intelligence
Thibault Bonnevie SBG Systems
Alison Brown NAVSYS Corporation
Ismael Colomina GeoNumerics
Clem Driscoll C.J. Driscoll & Associates
John Fischer Orolia
Ellen Hall Spirent Federal Systems
Jules McNeff Overlook Systems Technologies, Inc.
Terry Moore University of Nottingham
Bradford W. Parkinson Stanford Center for Position, Navigation and Time
Raytheon Company’s GPS Next-Generation Operational Control System program, known as GPS OCX, completed final qualification testing of the system’s modernized monitor station receivers, which are now ready to be installed around the world starting in August.
GPS OCX is the enhanced ground control segment of a U.S. Air Force-led effort to modernize America’s GPS system.
“The modernized receivers give GPS OCX the ability to receive and decrypt all GPS III military and civil signals, a critical capability the current system doesn’t have,” said Dave Wajsgras, president of Raytheon Intelligence, Information and Services. “Monitor station receiver installation keeps us on track for full system delivery by our June 2021 contractual deadline.”
The modernized receivers will measure and monitor legacy military and civilian signals sent by the current GPS satellite constellation plus the new signals sent by the next-generation GPS III.
The receivers will also feed correction models at the master control station, giving U.S. Air Force satellite controllers the information necessary to make key adjustments to maximize accuracy.
Feature photo: GPS ground antenna at Schriever Air Force Base, home of the 50th Space Wing. (Photo: Raytheon)
By Urs Niesen, Jubin Jose, Xinzhou Wu, Qualcomm Technologies Inc.
Emerging automotive applications require reliable but at the same time low-cost positioning solutions. In this paper, we present such a solution by fusing the measurements from several consumer-grade sensors using a tightly coupled centralized filter.
The sensors used are a single-frequency GNSS receiver providing GPS and GLONASS pseudoranges and GPS carrier-phase measurements, a micro-electro-mechanical (MEMS) inertial measurement unit (IMU), a monocular camera, wheel-speed and steering-angle sensors.
We also employ vehicular constraints, integrated as pseudo-measurements. The centralized fusion architecture allows sensor cross-calibration and improves outlier detection. The filter runs in real time on the target platform, producing pose estimates at 30 Hz. Through extensive experimental evaluations, we demonstrate positioning accuracies of sub-meter 95-percentile horizontal errors even in GNSS-challenged deep-urban scenarios.
Conflicting Requirements. Accurate positioning is a requirement for several emerging vehicular applications such as advanced driver-assistance systems (ADAS) and autonomous driving. Positioning solutions for these applications face two competing constraints. To be technically viable, the computed position estimate needs to be reliable in scenarios ranging from open sky to deep urban, with less than 1-meter 95-percentile horizontal error as an often-mentioned target. To be economically viable, the system needs to be built from consumer-grade components.
We reconcile these conflicting requirements by fusing measurements from several low-cost sensors into a single pose estimate using one centralized extended Kalman filter (EKF). A multi-constellation single-frequency GNSS receiver provides GPS pseudorange and carrier-phase measurements and GLONASS pseudorange measurements. These are combined in a tightly coupled integration architecture with a consumer-grade MEMS IMU used to produce the reference navigation solution.
Tight integration enables outlier rejection directly for the raw GNSS measurements. This is crucial in deep-urban scenarios, since many or most raw GNSS measurements could be outliers in these conditions. We use a monocular camera and vehicular sensors, providing four wheel-speed measurements and a steering-angle measurement, as additional aiding sensors.
Constraints. Finally, vehicular constraints are integrated as pseudo-measurements. These sensors have very different noise sources and failure modes, which allows cross-calibration and improves failure and outlier detection. Given the tightly coupled integration in a single EKF, the filter state is quite large and can reach more than 100 dimensions. Despite its size, we are able to run the filter in real time and on target, producing pose outputs at a rate of 30 Hz.
We report the result of extensive experimental evaluations in different scenarios ranging from open sky with good satellite visibility to deep urban with long stretches of no or only limited satellite visibility. In each of these scenarios, we obtain the target accuracy of sub-meter 95% horizontal positioning error.
We show that, in the benign open-sky scenarios, GPS and IMU sensors are sufficient to achieve the target accuracy. However, in challenging deep-urban scenarios, all the integrated sensors are required to attain reliable sub-meter positioning performance.
Sensors and Components. We use Qualcomm SiRFstarV 5e B02 GNSS chipset, a low-cost commercial GNSS product, connected to a NovAtel GPS-702-GG dual-frequency GPS+GLONASS Pinwheel antenna, the only component not consumer-grade, to separate impact of a specific antenna on performance. We plan to evaluate low-cost antennas in the future. We use a TDK InvenSense low-cost MEMS 6-axis IMU (MPU-6150) and a vehicle interface with vehicle sensors through the controller area network bus. Accurate timestamping for tightly coupling sensor measurements is provided by a custom sensor sync board. The processor is a Qualcomm Snapdragon 820 automotive platform for real-time computation. (Qualcomm SiRFstar and Qualcomm Snapdragon are products of Qualcomm Technologies, Inc. and/or its subsidiaries.)
The NavIC Indian constellation is now supported in NovAtel’s latest firmware release for its OEM7 series of GNSS receivers.
The 7.05.04 firmware release for OEM7 provides the following benefits:
Users can achieve a single point position accuracy of 2.5 m (rms) using NavIC L5 signals (from the Indian Regional Navigation Satellite System) with GPS L1 on the newly available JSN model.
Access to the L5 frequencies on the OEM7600 and OEM7720 provides triple-frequency capabilities to unlock the potential of GPS L5, Galileo E5a and AltBOC, Beidou B2a and NavIC L5.
A full listing of all changes in this release are included in the “What’s New” document included in the firmware download package. Visit this page to download the latest firmware for a specific platform. Visit NovAtel’s documentation portal for the OEM7 reference manual.
Guest column by Peter Fairhurst, Director, Product Line Management, Product Center Positioning, u-blox
Peter Fairhurst, Director, Product Line Management, Product Center Positioning, u-blox. (Photo: u-blox)
A new generation of GNSS hardware and pioneering new correction data services are enabling cheaper, more compact and truly scalable high-precision GNSS solutions, ready for the mass market.
High-precision GNSS as employed by specialized markets for more than a decade isn’t aren’t suitable for mass-market autonomous vehicles or other mainstream use cases. As well as being big, heavy and expensive, traditional high-precision GNSS systems don’t scale, which is a critical shortcoming when you consider this capability may very soon need to be built into every car that gets built.
To overcome these challenges, we’re seeing two complementary things coming to market: a new generation of GNSS hardware, and pioneering new correction data services. These two key facets combine to enable cheaper, more compact and truly scalable high-precision GNSS solutions, ready for the mass market.
A new generation of GNSS correction service forgoes the two-way link between customer device and the correction data service that is a hallmark of traditional high-precision GNSS corrections. Instead of sending each device its own, location-specific GNSS correction data, the new-generation services create a real-time model of relevant errors across their entire territory. They broadcast this over satellite and/or the Internet for customer devices to pick up.
Transmitting modeled GNSS error data to receivers across an entire region – as opposed to maintaining a two-way link with each and every device – opens the door to large-scale, mass market applications of high-precision GNSS
The shortcomings of traditional high-precision positioning
Correction data has long been key to high-precision GNSS services. In traditional applications, the customer’s positioning device detects its approximate location and sends this information to its correction service provider. This provider uses a network of base stations to monitor GNSS errors, comparing the readings calculated from the satellite signals to the stations’ known, fixed positions. It uses these insights to send the customer’s device tailored correction data, based on its location.
The technology has successfully been used to provide centimeter-level accuracy in surveying, agriculture and machine control, but annual subscriptions of sometimes more than $1000 per device mean it’s remained confined to specialized markets.
Moreover, traditional correction data services typically only operate in one country, or even one state. While this may not be an issue in some applications (such as localized agriculture), there are other use cases where limited range is a major problem. Imagine, for example, that you regularly need to travel across a state or national boundary in your (semi-) autonomous vehicle, or carry out remote UAV-based surveying in another country: maintaining your high-precision positioning capability is likely to mean roaming contracts and other extra costs.
The other issue with these traditional services is scalability. They use two-way cellular communication to pass data back and forth between the customer device and the correction data provider. And while this works when device density is relatively low, if this number grew to thousands or even millions of end-user pieces of kit trying to access the correction data service, current cellular infrastructure would struggle to deliver the required reliability. Particularly in safety-critical applications, where losing access to the correction data service could put lives at risk, this is unacceptable.
Image: u-blox
Recent developments in high-precision positioning
The new generation of GNSS correction services, creating and broadcasting a real-time model of relevant errors across their entire territory, over satellite and/or the internet for customer devices to pick up, opens the door to large-scale, mass-market applications of high-precision GNSS. Technology using State Space Representation (SSR) is one flavor of these new-generation GNSS correction data services.
Japan has led the way in GNSS error-broadcasting, using the L6 signal of its QZSS satellite network as a proving ground for mainstream use of the approach. Although it’s currently only available within Japan, the Centimeter Level Augmentation Service (CLAS) is generating a lot of interest across the automotive, agricultural and machine-control industries. Mitsubishi Electric, for example, used the CLAS service to field-test its autonomous driving system.
In China, Qianxun Spatial Intelligence Inc. is pioneering a different technique. Instead of broadcasting the data, Qianxun SI is leveraging its special access to the Chinese GNSS reference base stations to push the boundaries of what’s possible using the traditional technique. It provides tailored correction data services to customers including individuals, system integrators and original equipment manufacturers (OEMs). While it’s been a success in China, the approach is less appealing to OEMs who ship worldwide, because it requires their clients to arrange their own, local GNSS correction data.
Another important advance has been the rise of multi-band GNSS receivers, which enhance standalone positioning accuracy, thereby delivering a better customer experience in a variety of use cases. However, even multi-band receivers can’t achieve the centimeter-level accuracy that mobile robotics and autonomous vehicles need: these devices will always need to be complemented by some form of correction service.
Continent-wide GNSS correction data
Particularly in Europe, where there’s a lot of cross-border travel and economic activity, the simplicity of continent-wide GNSS correction services would offer enormous value. Sapcorda, for example, a recently launched joint venture between Bosch, Geo++, Mitsubishi Electric and u-blox, is creating a next-generation GNSS correction data service with coverage on a global scale (Europe, North America, etc), building on the lessons learned in Japan.
Sapcorda will broadcast right across the continent, using cellular networks as well as over satellite links. Customers won’t be tied to a specific GNSS manufacturer. Data will be distributed in an open format, so that device-makers can create exactly the solutions their customers want.
Having access to GNSS correction services continent-wide has the potential to transform high-precision positioning into a mainstream offering, supporting various IoT applications, as well as drones and (semi-) autonomous vehicles.
Addressing the remaining challenges
High-precision GNSS correction services that target the mass market are still relatively new, with different suppliers pursuing different business models. Trimble’s service, for example, doesn’t use an open correction-data format, and is only compatible with devices using its own GNSS receivers. The benefit of this is that it can deliver a seamless, fully integrated solution, with complete interoperability across the Trimble product range (provided the region in question has good coverage). OEMs with customers is geographically broader markets will need to weigh this up against the benefits of global coverage provided by a range of correction-data suppliers offering open-format data.
As we touched on earlier, in safety-critical applications where location-accuracy is essential, any correction data service must be up to the task. This includes ensuring data broadcasts aren’t crowded out when cellular networks become saturated. To this end, u-blox has been working with the 3GPP body to create appropriate standards that can ensure the service meets the required service level agreements.
Lastly, although there’s now country-wide coverage in both China and Japan, Sapcorda is now attempting to provide continent-wide high-precision services. If it’s a success, it could overcome the challenges of national boundaries and country-based cellular providers. It’s as yet unclear how existing correction-data-service suppliers will respond.
Customer satisfaction is paramount
For high-precision GNSS services to achieve mainstream success, they not only need to offer wide coverage and be truly open, but must facilitate innovation and ensure they can broaden the appeal of this capability beyond being a niche specialism. Like in any industry, customer satisfaction is essential if the technology is to achieve this.
Complexity that arises as a result of state boundaries, national borders, conflicting regulations or subscriptions, must be shielded from the end user and dealt with upstream. This is already happening in some areas, where device-makers are partnering with correction data service providers, enabling them to bundle the service cost into the device cost that the end user pays.
A revolution in positioning
As well as helping to realize some of the automated navigation solutions currently under development, new-generation high-precision GNSS services are driving a seismic shift across the whole industry.
The rise of innovative, high-precision GNSS technology, combined with business models that promise to make high-precision a mass market reality, mean the coming years will be tremendously exciting. By disrupting the existing market, the new technology will mean lots of new opportunities for those ready to grasp them.
Peter Fairhurst joined the Product Strategy team in the Product Center Positioning at u-blox AG in 2015. He is responsible for the development of industrial markets, with a specific focus on unmanned systems and mapping solutions. Prior to u-blox, he was part of the Product Management group at Leica Geosystems AG, where his focus was on high-precision GNSS surveying technology.
Fairhurst holds a bachelor degree in Mathematics & Computer Sciences and doctorate degree in satellite geodesy from Newcastle University and an MBA diploma from the University of Strathclyde.
Mountainous areas present special problems for surveyors, overcome by the expanded availability of multi-GNSS. (Photo: Trimble)
Today’s GNSS satellites transmit on three or more carrier frequencies. The quality of the data in these signals from GPS, BeiDou, Galileo, GLONASS and QZSS reveals the expected measurement precisions. This article explores the noise of the range residual and ionospheric residual to indicate the oncoming capabilities.
Today, four GNSSs transmit various codes on various carrier frequencies: the USA’s GPS, Russia’s GLONASS, Europe’s Galileo and China’s BeiDou. Most of the carrier phase and pseudorange data are available using civilian GNSS receivers. Improvements in signal quality as well as reliability of the satellites are foreseen through the generations, as well as the introduction of new signals, such as L1C, L2C, L5 carrier and codes, and M-codes, on top of the existing L1-C/A code and the P(Y) code on both L1 and L2. Improvements are also seen in boosting the transmitting power.
This article investigates the use of two approaches to analyze the relative noise in the various carrier phase and pseudorange observable for GPS, BeiDou, Galileo, GLONASS and Japan’s Quasi-Zenith Satellite System (QZSS) augmentation. Two approaches analyze the relative noise in the observables: the range residual and the ionospheric residual. Both techniques can also be used to detect cycle slips.
Range Residual
UAV survey operations benefit from multi-GNSS receivers. (Photo: Septentrio)
The range residual is simply the change from one epoch to the next in the difference in the range calculated using the pseudorange and the range calculated by the carrier phase on a specific frequency. The pseudorange values are scaled using the wavelength to an equivalent range in units of the carrier’s cycles rather than meters. Equation 1 illustrates the range residual between the pseudorange ρ on a specific carrier frequency and the carrier phase observable φ, using the wavelength λ of the carrier to scale the pseudorange. The values of these observables are compared between adjacent epochs.
RR = (p/λ) – φ (1)
Two adjacent epochs are used, as then the integer ambiguity value, as well as the ionospheric and tropospheric errors, and satellite and receiver clock errors are the same, or negligibly different at such small (<1 s) epoch intervals. Therefore, these are all canceled out, and the resulting value is the measurement receiver and observable noise. The pseudorange observable will be significantly noisier than the carrier phase observable, therefore this method is a good way to calculate the measurement noise for the pseudoranges.
Ionospheric Residual
Surveyors work the Berezitovy mine in the North Amur region of Russia. (Photo: Javad GNSS)
If the carrier waves traveled only through a vacuum, then a phase observation from a specific satellite to a specific GNSS receiver could be scaled and converted to an equivalent phase measurement on another frequency using the frequencies of the carrier waves. However, as the signal passes through the ionosphere, systematic errors that are frequency dependent are introduced, so it is not possible to directly convert from one carrier phase value to another for a specific range measurement. The error is known as the ionospheric residual, and this will change slowly over time as the satellite passes overhead and the ionosphere being passed through changes, and also as the ionosphere slowly changes its characteristics over time, mainly due to the sun’s activities.
Equation 2 shows the calculation, using L1 and L2 carrier phase readings and corresponding frequencies, used to calculate the ionospheric residual. Again, the difference in the ionospheric residual values between adjacent epochs is used, as in the same way as the range residual values, external noise sources are eliminated.
(2)
Results
The results presented here are a subset of a much larger set. Figure 1 illustrates the range residuals for L1 and L2 as well as the L1L2 ionospheric residual for PRN32 (Block IIA satellite).
Figure 1. L1 range residual (left) L2 range residual (center) and L1L2 ionospheric residual (right) for GPS PRN32 (Block IIA) satellite. (Charts: Authors)
Figure 2 illustrates the L1 and L5 range residuals and the L2 (C-code) L5 ionospheric residual for PRN01 (Block IIF satellite).Both figures’ data are for the complete passing of the satellites from horizon over and back down again.The data for PRN32 is all that exists in the datafile, as this satellite only transmits L1 CA code and P(Y) code, as well as L2 P(Y) code, and corresponding carrier values.
Figure 2. L1 range residual (left) L5 range residual (center) and L2 (C code) L5 ionospheric residual (right) for GPS PRN01 (Block IIF) satellite. (Charts: Authors)
PRN01 is a block IIF satellite, and data for L1 CA code, L2 P(Y) code as well as L2 C-code, L5 code, and corresponding carrier phase values are recorded in the datafile.The block IIF satellites can result in four range residual values and five ionospheric residual combinations.Figure 2 only illustrates three of these combinations.The data were obtained from the Curtin University GNSS repository on Sept. 1, 2015, gathered at a 1-Hz epoch interval; 29,908 epoch of data were gathered for PRN32, and 26,073 epochs for PRN01.
It can be seen from these figures that the L1 range residuals are similar in characteristics for both PRN01 and PRN32.The values are noisy at the start and the end of the time series, indicating that the CA code is more prone to noise at low elevations.Comparing these to the L2 (PRN32) and L5 (PRN01) range residuals, we can see that both the L2 and L5 range residuals are not as prone to low elevation noise. Also, the two L2 and L5 range residuals are visually similar in characteristcs.By comparing the L1L2 and L2L5 ionospheric residuals (Figure 1, right, and Figure 2, right), we can see that the L1L2 combination is slightly noisier than the L2L5, in particular at low elevation angles.
If we compare BeiDou ionospheric residual results, we can see the comparison of noise on the three ionospheric residual combinations, B1B2, B1B3 and B2B3, as well as the results from the three types of satellite orbits, ie MEO, IGSO and GEO. Figure 3 illustrates the ionospheric residual results for PRN07 (IGSO) for the three frequency combinations, from data gathered on a static pillar located on top of the University of Nottingham Ningbo China’s Science and Engineering Building.
Figure 3. Ionospheric residual results for BeiDou PRN07 (IGSO) for combinations B1B2 (left), B1B3 (center), B2B3 (right). (Chart: Authors)
Figure 4 illustrates the ionospheric residual results for PRN01 (GEO) for the three frequency combinations.
Figure 4. Ionospheric residual results for BeiDou PRN01 (GEO) for combinations B1B2 (left), B1B3 (center), B2B3 (right). (Chart: Authors)
Figure 5 illustrates the ionospheric residual results for PRN12 (MEO) for the three frequency combinations. Here it can be seen that the B2B3 combination is generally less noisy than the B1B2 and B1B3. In addition to this, it can be seen that when the MEO and IGSO satellites are at lower elevation angles, the observables also become noisier. The GEO satellites have a constant elevation angle, and do not experience this phenomenon.
Figure 5. Ionospheric residual results for BeiDou PRN12 (MEO) for combinations B1B2 (left), B1B3 (center), B2B3 (right). (Charts: Authors)
Detailed Results
The data, gathered on a single GNSS receiver located at the University of Curtin’s GNSS research center, was downloaded in BINEX format and converted into RINEX 3.02 format using RTKLIB software. Software was developed by the authors in Matlab in order to interrogate the data files and implement the range residual and ionospheric residual algorithms. RINEX 3.02 format was chosen due to its compatibility with multi-GNSS and multi-frequencies.
Industrial UAV applications such as construction draw benefits from multi-GNSS receivers’ capabilities. (Photo: Skycatch, Swift Navigation)
Results are presented for both ionospheric residual and range residual results for various GNSS. These results have been calculated with varying elevation mask angles, ranging from 0° to 55° at 5° intervals. The RMS values of the resulting ionospheric residuals and range residuals were calculated and plotted against the respective elevation mask angle for each satellite and frequency combinations. This illustrates the influence of the elevation mask angle used on the results.
Typically, tens of thousands of epochs of data were used for every plotted point in the following figures. Further to this, not only are the results for the various frequencies and frequency combinations for the various GNSS illustrated, but also the various satellite types, MEO, GEO and IGSO, and various satellite Blocks for GNSS. GPS Block IIA (PRN04 and PRN32), Block IIR (PRN14), Block IIR-M (PRN31) and Block IIF (PRN01, PRN26, PRN25) data were all analyzed. Thus, the comparison of the various frequencies within each satellite system are illustrated, as well as the variations by comparing the various satellite constellation types and the various generations of GPS satellites.
Surveying accuracy is critical to roadway construction. (Photo: Leica Geosystems)
The BeiDou data illustrated are MEO (C12, C14, C11), IGSO (C09, C10, C07) and GEO (C01, C02). The data used were gathered on Sept. 1, 2015, in order to include GPS Block IIA satellites (PRN04 and PRN32). PRN32 was retired in June 2016, and PRN04 was taken out of active service in November 2015, but the satellite was reactivated in March 2018, this time broadcasting PRN18.
Figure 6 illustrates RMS of the range residual results for GPS (a), BeiDou (b), Galileo (c), GLONASS (d) and QZSS (e) respectively. These figures have been drawn so that the y-axis ranges are the same for each, hence illustrating the relative values.
Figure 6A illustrates the range residual results for GPS. It can be seen that the L1 CA code results are the noisiest, with PRN14 being the noisiest, followed by PRN31, PRN26, PRN01, PRN04, PRN25 and PRN32. It can also be seen with these results that lower elevation angle mask increases the noise level. Both the L2 and L5 code results are less noisy.
Figure 6A. RMS range residual results for GPS. (Chart: Authors)
Looking at the detail, the L5 code results is less noisy than the L2 and affected less than the L1 results by the changes in elevation mask angles used. Interestingly enough, the data file includes both the L2 P(Y) code and L2C code results. L2C only exists on the Block IIR-M and Block IIF satellites. The L2C code results are generally noisier than the L2 P(Y) code.
Figure 6B illustrates the results for the range residuals for the BeiDou satellites. Here it can be seen that the B1 code is affected more by low elevation mask angles than B2 and B3. It can also be seen that both the geostationary satellites’ B1 results stand out, with satellite C02 being noisier than C01. The B2 and B3 values for both these GEO satellites are bunched up with the majority of the other results towards the middle of the figure. The pairs of B2 and B3 results for the GEO satellites are close to each other in values, and the pairs of B2 and B3 results for the other satellites are also close to each other.
Figure 6B. RMS range residual results for BeiDou. (Chart: Authors)
It can also be seen that the range residual results for BeiDou are generally less noisy than than GPS, in units of cycles.
Similarly, for Galileo, Figure 6C, the E1 results are worst, and affected more by low elevation masks. Again, generally the Galileo results are seen to be improved over GPS. The GLONASS results, Figure 6D, illustrate that the L1C results are generally noisier, and then the L1P, followed by L2C and L2P. PRN09 is also consistently generally noisier than PRN10. Finally, Figure 6E illustrates the results for QZSS. Again, L1C is the noisiest and affected most by low elevation mask angles.
Figure 6C. RMS range residual results for Galileo. (Chart: Authors)Figure 6D. RMS range residual results for GLONASS. (Chart: Authors)Figure 6E. RMS range residual results for QZSS. (Chart: Authors)
Figure 7 illustrates the ionspheric residual results for the same satellites as Figure 6. This time, however, the resulting ionospheric residual values are calculated using pairs of data from the same satellite on different carrier frequencies. The range residual results compare the code and carrier from specific satellites and frequencies.
Figure 7(a) shows that the ionospheric residual results are affected by low elevation masks, and that the L1L2CW (L1 CA code and L2 P(Y) code available on all the satellites) combinations are the noisiest, followed by L2L5WX (L2 P(Y) code and L5 code available on Block IIF satellites, PRN 26, PRN01, PRN25), followed by L1L2CX (L1 CA code and L2 C code available on Block IIF and Block IIR-M satellites, PRN31, PRN26, PRN01 and PRN25), followed by L1L5CX (L1 CA code and L5 code, Block IIF satellites, PRN01, PRN25, PRN26) and finally the least noisy were the L2L5XX results (L2 C code and L5 code available on Block IIF satellites, PRN26, PRN25 and PRN01).
Figure 7A. Ionospheric residual results for GPS. (Chart: Authors)
Figure 7(b) illustrates the BeiDou ionospheric residual plots, illustrating that satellite C14 is much noisier for all three combinations of B1B3, BB1B2 and B2B3 in that order. The B1B2 combinations for the satellites are generally the noisiest, and then the B1B3 and B2B3 combinations are intertwined. The Galileo results again illustrate that the E1 combinations are generally noisier, and again we see the effect of low elevation angle masks, Figure 7(c). Generally, however, the Galileo results are less noisy than GPS, as are the BeiDou results.
Figure 7B. Ionospheric residual results for BeiDou. (Chart: Authors)Figure 7C. Ionospheric residual results for Galileo. (Chart: Authors)
The GLONASS results are again generally the noisiest, and again PRN09 is noisier than PRN10, with the L1P combinations being noisier, Figure 7(d). Figure 7(e) for QZSS shows that there are generally two groups of results. The upper set consists of L1L2ZX, L1L5ZX, L1L2XX, L1L5XX, L1L6ZX and L1L6XX from highest to lowest noise respectively. The lower, less noisy, group consists of L1L2CX, L1L5CX, L2L5XX, L2L6XX, L1L6CX and L5L6XX from highest to lowest noise respectively. Further details about the various codes and carrier values can be found in the RINEX 3.02 manual produced by the IGS.
Figure 7D. Ionospheric residual results for GLONASS. (Chart: Authors)Figure 7E. Ionospheric residual results for QZSS.(Chart: Authors)
Conclusions
A surveyor checks an urban construction project. (Photo: Topcon)
These preliminary results illustrate that there are differences in the noise values for various GNSS, frequencies as well as satellite generations and orbit types. It can be seen that generally L1, B1 and E1 have noisier results, and are affected moreso by low elevation mask data, and hence multipath. It can also be seen that newer generations of satellites do indeed produce better quality data.
Some specific satellites produce lower quality data such as GLONASS PRN09 and BeiDou C14. This could be due to multipath produced at the satellite.
Today roughly 100 GNSS transmit data, and typically users can gather data from 30 to 50 at any time. Positioning requires nowhere near this number of satellites, therefore decisions are needed as to which satellites and which data to use in a positioning solution. Our findings imply that our approach could be used in such decision-making in GNSS processing software, helping the software to choose the optimum satellites to draw from in a positioning solution.
Acknowledgments
This work described in this article was first presented at the FIG 2018 conference held in Istanbul, Turkey. The authors acknowledge the use of data supplied from the Curtin University GNSS Centre.
Manufacturers
The GNSS receiver used is a Trimble NET R9, and the antenna is a Trimble TRM 59800.00 SCIS choke ring antenna. A ComNav K508 GNSS receiver supplied some of the BeiDou results.
GETHIN WYN ROBERTS is an associate professor at Fróðskaparsetur, the University of the Faroe Islands. He is past Chairman of the FIG’s Commission 6, Engineering Surveys, and previously held posts at the University of Nottingham both in the UK and in China. He holds a Ph.D. in engineering surveying and geodesy from the University of Nottingham.
CRAIG M. HANCOCK is an associate professor in Geodesy and Surveying Engineering and the head of the Department of Civil Engineering at the University of Nottingham, Ningbo, China as well as the head of the Geospatial and Geohazards Research Group. He holds a PhD from the University of Newcastle Upon Tyne.
XU TANG is a research fellow at the University of Nottingham, Ningbo, China. He holds a PhD from Nanjing University.
TDK’s booth at the Consumer Electronics Show (CES) is in South Hall 3, Booth #30306, and offers a look at sensors, passive components and more from TDK and its group companies. (Photo: TDK)
TDK Corporation has launched its InvenSense Coursa Drive software, an inertial-aided positioning solution for autonomous vehicle platform developers.
A high-performance extension of the InvenSense Positioning Library (IPL) that has provided sensor-aided positioning to more than 50 million devices worldwide, Coursa Drive enhances inertial-only vehicle positioning to <0.2 percent of distance traveled. These precise levels of accuracy are critical to maintaining decimeter lane-level vehicle positioning in challenging GNSS/perception system environments.
Coursa Drive’s inertial navigation system (INS) calibrates using absolute position inputs from either high-accuracy GNSS receivers or from perception-based systems (camera, radar, lidar) with high-definition (HD) maps.
In real time, Coursa Drive provides high-rate, 100 Hz delta positions and orientation to the autonomous vehicle (AV) system, complementing the lower-rate position references from GNSS and perception systems.
For improved system fault-tolerance, Coursa Drive can provide decimeter position precision for short periods when the GNSS or perception systems are uncertain or unavailable.
For non-real-time applications such as HD map creation and maintenance, Coursa Drive’s offline mode reprocesses INS data at two to three times higher accuracy than real-time mode, providing HD map companies alternative position references to verify HD map accuracy, even without GNSS, for up to 60 seconds.
“Coursa Drive delivers vehicle dead reckoning accuracy equivalent to high-end systems costing thousands of dollars,” said Mike Housholder, senior director of the TDK InvenSense Location Software and Services Business. “Our cost-effective software solution will help AV platform and Tier 1 vehicle manufacturers scale beyond prototype vehicles to high-volume mass production.”
Coursa Drive provides autonomous vehicle platform developers with maximum flexibility for system integration. The solution is platform agnostic and can operate on Cortex-M4F-class microcontrollers, or higher, and supports most dual-frequency GNSS receivers. The Coursa Drive API specifications are available upon request.
Coursa Drive is thoroughly tested and characterized using the InvenSense line of automotive-grade IMUs, including the IAM-20680 and IAM-20680HP, as well as several industrial grade IMUs. Coursa Drive is available now for select early partners and customers.
TDK and its group companies offering a comprehensive portfolio of sensors, electronic components and solutions for mobile, wearables, AR/VR, automotive, IoT and industrial applications will be at CES 2019, showcasing the Coursa Drive solution, along with additional innovative sensor solutions, in Booth #30306, Las Vegas Convention Center, South Hall 3, Jan. 8-11, Las Vegas.
Main applications
Level 2 to Level 5 advanced driver-assistance systems (ADAS)
Robotaxis
Trucking
Precision agriculture
Key features
World’s first high-precision inertial-aided positioning software for AVs
Inertial-only decimeter precise positions provided during short GNSS or perception system outages/uncertainties
High-rate, 100 Hz position and orientation updates supplied to the AV system
GNSS-agnostic software solution offers flexible integration for full-stack AV solution providers
Unique offline mode further enhances accuracy by two to three times for HD map building and maintenance applications.
A roundup of recent products in the GNSS and inertial positioning industry from the December 2018 issue of GPS World magazine.
OEM
Combination antenna
Long-range connectivity
Photo: Molex
The Molex highly compact 2.4/5-GHz combination GPS/Wi-Fi ceramic antenna is designed to be a cost-competitive solution covering the full GNSS band, 1.561 to 5.85 GHz. The triple-band ceramic antenna has Wi-Fi HaLow compatibility and is interference-resistant, supporting larger but lower (900-MHz) frequency ranges than 2.4/5-GHz connections. It also operates with lower power over longer ranges than 2.4/5-GHz Wi-Fi. Advanced Wi-Fi applications the internet of things, connected cars, smart homes and smart cities.
The MSB1054 multi-receiver module requires no external components, meeting needs of smartwatches, fitness trackers, logistics and navigation. Its Flash memory saves navigation data to optimize performance and provide a hot start. The ability to receive signals from several satellite systems significantly reduces the time to first fix. The module provides a built-in RF-front end (SAW filter, low-noise amplifier) as well as a temperature-compensated crystal oscillator (TCXO), so no external component is required other than an antenna. It measures 5.8 × 6.2 × 1 millimeters and uses 3.4 mA current in low-power mode, such as for tracking.
The GE310-GNSS is an internet of things (IoT) module with GSM/GPRS, multi-constellation satellite positioning and Bluetooth functionality in a 270-millimeter-squared form factor. It meets European demand for GSM/GPRS compact form factors and is part of Telit’s migration-support program that helps customers leverage 2G’s low cost and broad coverage while preparing for 4G and 5G. The GE310 enables OEMs and system integrators in asset management, utilities and telematics to meet the strong demand for low-cost, highly compact devices without tradeoffs in performance, reliability and functionality, particularly in regional markets such as Europe, where 2G is forecast to remain in strong growth in number of IoT connections for many years.
With multi-sensor fusion positioning and orientation
Photo: Unicore
The CLAP-B multi-GNSS/MEMS integrated inertial navigation board features a miniaturized high-performance inertial measurement unit (IMU) on a compact high-performance GNSS board. The high-accuracy GNSS positioning coupled with a high-precision gyro and accelerometer provides stable, continuous 3D position, velocity and attitude, as well as original acceleration and angular velocity measurements, even in GNSS-denied environments. CLAP (Concurrent Localization & Attitude Pilot) technology is a high-precision multi-sensor fusion positioning and orientation technology developed by Unicore. The board is compact, light weight and has low power consumption. It is designed for ease of integration and mass production, and is suitable for autonomous driving, smart surveying and UAVs.
The UNI-GR1 RTK GNSS receiver offers highly accurate heading and positioning output. It can be connected to any device through Wi-Fi, mobile data, radio, USB or serial cable. It simultaneously tracks GPS L1/L2/L5, GLONASS L1/L2, Galileo E1/E5a/E5b and Beidou B1/B2/B3 on 432 channels. The receiver has a built-in level, a LED ring driven by a nine-degrees-of-freedom inertial measurement unit. Users can configure numerous settings such as real-time kinematic, or begin surveying immediately with a smartphone or laptop.
Dynamic tilt functionality has been added to the Trimble SPS986 GNSS smart antenna. The dynamic tilt upgrade allows for faster data collection to enable construction surveyors to create larger digital terrain models faster and with improved accuracy. It can capture higher accuracy measurements on steeper slopes from a moving vehicle and more accurate volume measurements to save time and money on material planning. The dynamic tilt measurement mode also auto-measures antenna height. From inside the vehicle, contractors can set the height of the antenna and quickly interrogate surface models using the real-time 3D surface display in Trimble Siteworks field software.
The Skycatch Edge1 is an on-premise data processing and GNSS base station optimized for the Skycatch Explore1 and DJI Phantom 4 RTK drones. Field teams can fly a drone, process the data and receive centimeter-level data output in 30 minutes or less, directly to a tablet, without the need for internet or cellular connectivity. 2D maps and 3D point clouds can be shared from the tablet. The Edge1 includes built-in WiFi, LTE and reliable sub-5-centimeter accuracy, and delivers high-quality data output. It is also capable of running deep learning algorithms to extract more insights from collected data in near real time.
Drone surveying software Virtual Surveyor now eliminates the need for clients to use third-party applications to prepare data for processing. Version 6.1 handles on-the-fly projections that previously required a separate software package to set the data in the proper coordinate system. It bridges the gap between UAV photogrammetric processing applications and engineering computer-aided design (CAD) packages. The software generates an interactive onscreen environment with UAV orthophotos and digital surface models where the surveyor selects survey points and breaklines to define the topography, creating highly accurate topographic products for CAD input up to five times faster than otherwise possible. Surveyors can drag and drop all kinds of files into Virtual Surveyor: points, raster, vectors and point clouds. The point clouds are converted to a DSM for manipulation and processing, dramatically accelerating the time required to generate the CAD model.
Includes Efficiency Gap Measure to explore redistricting problems
Screenshot: Mapitude
Maptitude for Redistricting is a professional tool for political redistricting. Maptitude provides measures and reports that support the creation of fair and balanced districts, and regularly enhances the software. Maptitude was used to democratize redistricting in California and is used by redistricters from independent commissions, non-profits, and civil rights groups, to the courts and political parties.
Stockpile measurements are up to 80% more accurate
Photo: DJI
The DJI Mavic 2 Pro drone is now part of the Kespry stockpile measurement solution for mining and aggregates companies. Kespry’s stockpile measurement solution produces data up to 80% more accurate than manual measurement. All of the survey data is stored in a central cloud application, accessible for analysis by the entire team. Large aggregates and mining companies can standardize and capture stockpile data across all their sites in the Kespry platform, while using Kespry 2s or DJI Mavic 2 Pro drones.
Designed for next-generation automotive applications
Image: Quectel
The automotive-grade C-V2X module AG15 features the Qualcomm 9150 C-V2X chipset paired with Quectel LTE module AG35. It is designed to meet the telematics and vehicle-to-everything (V2X) connectivity requirements of autonomous driving and road safety. It features a built-in multi-constellation high-precision GNSS (GPS/GLONASS/BeiDou/Galileo/QZSS) receiver with additional support from satellite-based augmentation systems (SBAS) and Qualcomm 3D dead-reckoning technology, which improves positioning accuracy and speed while simplifying customer designs. It is designed to allow low-latency, highly reliable and highly dense data exchange between vehicles and their surroundings, enabling effective information sharing among road users to avoid collisions, thus improving automotive safety, automated driving and traffic efficiency.
The SPC58 Chorus H microcontroller (MCU) line can run multiple applications concurrently to allow more flexible and cost-effective vehicle electronics architectures. The line is designed for high-end body, networking and security applications such as gateways, body-control modules, battery management and ADAS safety systems. The line has three high-performance processor cores, more than 1.2-MB RAM and powerful on-chip peripherals. The MCU securely delivers updates over the air for vehicle powertrain, body, chassis and infotainment features. With high security and large on-chip code storage, ST’s Chorus automotive microcontroller is a gateway/domain-controller chip capable of handling major OTA updates securely. Two independent Ethernet ports provide high-speed connectivity between multiple Chorus chips throughout the vehicle and enable responsive in-vehicle diagnostics.
The VBOX 3i RTK is a real-time-kinematic-enabled version of the VBOX 3i dual antenna that can be used in conjunction with an RTK differential base station to obtain ±2-centimeter positional accuracy in real time at 100 Hz. The data logger combines the advantages of a twin antenna GPS setup with GLONASS satellite tracking. It can be used in vehicle tests where positional accuracy and repeatability are of key importance, such as lane departure testing, distance to a fixed object or precise mapping. The VBOX 3i RTK comes with the VBOX manager, a display enabling users to change dynamic modes and filter settings, set up slip angle data and define antenna locations.
The StarLink TrackerWi‑Fi advanced vehicle-tracking device combines u-blox GNSS, 4G and Wi-Fi technology, eliminating the need to equip vehicles with a separate mobile Wi‑Fi hotspot. StartLink is suitable for applications for connected cars, telematics, vehicle diagnostics, fleet management, vehicle security, usage-based insurance, and rental and leasing service companies. With the Wi‑Fi hotspot, users can tap into cellular 4G to transfer telematics data to the fleet manager and send real-time data to the driver’s smart device or infotainment system.
The Notilo Plus team with the iBubble. (Photo: Notilo Plus)
Notilo Plus has launched iBubble, a fully wireless, autonomous and intelligent underwater drone that can be used for search-and-rescue operations, naval or underwater infrastructure maintenance, and subsea patroling. iBubble can accompany divers for up to an hour and down to 197 feet depth, enabling superior underwater imaging. The remotely operated vehicle (ROV) was designed using a patented underwater localization technology, which is mainly based on acoustic signal transmission and image recognition (video tracking). By combining these technologies, iBubble is able to locate precisely its target underwater and shoot stable footage. The iBubble is equipped with an obstacle avoidance system, real-time image recognition, a stabilization system and direct surface control.
Anafi Work is an ultra compact tool for professionals, helping them make informed decisions using the drone’s aerial insights. Anafi Work includes the advanced Anafi drone equipped with an innovative imaging system, a 4K/21MP camera with a 180° vertical orientation, allowing users to capture images of inaccessible areas.The drone operates for 1 hour and 40 minutes with its 4 USB-C smart batteries. It can be transported anywhere in a compact shoulder bag. Professionals can create 3D models of buildings, quickly and easily, using a one-year subscription to Pix4Dmodel.
The Riegl VQ-480 II and VQ-580 II are designed for airborne applications at mid-altitudes for use on both manned and unmanned aircraft. The new Mark 2 designs of previous models improve both performance and user-friendliness. Both offer a measurement rate of up to 1,250,000 measurements/second and a 75-degree field of view of suitable for corridor mapping, city modeling and applications in agriculture and forestry. Weighing approximately 10kg, they are ready for integration into helicopters and unmanned UAVs with a higher payload capacity. The VQ-480 II and VQ-580 II are prepared for smooth GNSS/IMU integration, offer interfaces for up to five optional cameras, and are have built-in and removable storage.The VQ-480 II works at a laser wavelength of 1550 nm; the VQ-580 II at the1064 nm wavelength suited to measure on ice and snow.
DroneNode is a portable, compact and inconspicuous counter-drone jamming device that law enforcement can use at large outdoor events without raising public concern (it is not yet authorized for use in the U.S.) It can simultaneously jam 2.4 GHz, 5.8 GHz and GNSS L1 and L2 bands up to one kilometer, causing drones to return to their point of origin or land. It is also effective against swarm attacks. Emergency broadcasts, cellphone communication and other dedicated channels are unaffected.
Skydio R1 users now have the ability to follow cars. New modes include Car Follow, improved Lead Mode, and other improvements throughout the system, which is built on top of the Skydio Autonomy Engine. The engine operates 13 cameras, enabling it to map and understand the world in real time, allowing it to be fully autonomous and independently capture video footage. Its Nvidia Jetsonl AI runs neural networks that trained for the Car Follow feature on datasets of automobile images.
