The tech press and broad public media have both made much ado about a November market report from the European GNSS Agency (GSA). Most accounts have focused on a GSA prediction of an installed base of 7 billion GNSS-enabled devices worldwide by 2022, and nearly every account has replicated the GSA math to trumpet “almost one for every person on the planet.”
Oh Hosanna. We (will) have reached holy ground at last.
Other than asserting that this bonanza “has the potential to deliver additional significant benefits, not measured in this report, especially in terms of time and fuel savings, as well as efficiency gains,” neither the GSA itself nor any pundit’s account of the report that I have seen ventures to speculate on how this might actually change daily human life. Hopefully ‘twill not be on the order of how cell phones have affected society, communication, and interaction; read tweeting and social-network stress. But knowing what little we do about human nature, this possibility is not at all to be discounted.
Allow me to walk the plank out into left field long enough to quote from a 2009 NBC News Science report titled “Is Twitter evil?” “Researchers probing the workings of the brain have found that it takes longer for feelings of social compassion and admiration to register on our neural circuits — and they worry that the rapid-fire effect of texting and tweeting could have ‘potentially negative consequences’ for our moral fiber.”
Could total, global, continuous, pervasive location-awareness in the palm of everyone’s hand possibly lead down a similar path? I’m sure that cell-phone enthusiasts also promised vast, billionish-plus benefits, with absolutely no downside, three decades ago.
If I can pry myself back from Nostradamus mutterings — and I am sure you are glad that I have now done so — the GNSS Market Report Issue 3 contains a great deal of data worth considering.
Said document foresees compound annual growth rates (CAGRs) for “GNSS core” and “GNSS-enabled” revenues increasing by 9 percent through 2016 and 5 percent through 2020, to attain €350 billion ($478 billion) per year. Of the 2022 total, GNSS core revenues will comprise about €100 billion (US$137 billion).
To further differentiate “core” and “enabled,” this from the report’s early Market Definitions section:
“This market report primarily considers the core GNSS market. For multi-function devices, such as smartphones, the core market includes the value of GNSS functionality only (rather than the full device price) and service revenues directly attributable to GNSS functionality (e.g. data downloaded by smartphones to use Location-Based Services).
“For multi-function devices, a correction factor is taken into account, for example:
• GNSS-enabled smartphone: only the value of GNSS chipsets is counted, estimated at 1% of the price.
• Personal Navigation Devices (PNDs): 100% of retail value since GNSS is the key enabler.
• Aviation: the value of the GNSS receiver inside the Flight Management System is taken into account.
• Precision agriculture system: the retail value of the GNSS receivers, maps, and navigation software is counted.
“The Executive Summary also presents results for the enabled market. The enabled market represents the services and devices enabled by GNSS, and includes the core market. For the enabled market, the entire retail value of the smartphone is included.”
The 72-page report breaks out market segments, focusing in turn on: location-based services (LBS), road, aviation, rail, maritime, agriculture, and surveying. The weight of the report, as you might guess by the necessity of reaching that 7 billion figure, falls primarily on LBS, a heading that for the GSA encompasses “smartphones, tablets, digital cameras, laptops, fitness and people-tracking devices, and mobile-data revenues.”
What’s good for the mass market must surely be good for satellite makers and operators around the world, as they attempt the jump from one to many systems. That’s the underlying but unstated premise of the report. “Multi-constellation receivers become widely available on the market” trumpets the Executive Summary headline on page 8. In what is certainly the money pitch for the Prague-based, European Union-funded agency, “Galileo is recognised as a valuable element in multi-constellation systems, and it is already present in more than 30% of receiver models, well ahead of its full operational capability.”
Nevertheless, GLONASS is the second GNSS constellation choice of receiver manufacturers after GPS.
For BeiDou, the researchers will only venture that “Several equipment manufacturers, particularly those based in Asia-Pacific, have started to offer BeiDou-enabled models.”
More than 70 percent of models on the market are GPS-SBAS capable (SBAS comprising WAAS, EGNOS, and MSAS) and this penetration will grow further.
In a final provocative note (neither final nor provocative from the GSA’s point of view, although I confess it causes me a vague unease), the four-fold increase in the number of GNSS devices will be “largely driven by increased penetration in regions outside Europe and North America.”
Production of the report relied on “advanced forecasting techniques together with a validation process with market experts.”
Lest you feel unfairly treated by my curmudgeonly take, here is some actual data generated by and taken from the report.
Global GNSS Market Size, from GNSS Market Report 2013 Issue 3Installed Base of GNSS Devices by Region, from GNSS Market Report 2013 Issue 3GNSS capability in receivers, from GNSS Market Report 2013 Issue 3
Rohde & Schwarz extends the functionality of the R&S SMBV100A vector signal generator by adding BeiDou/Compass capability to its integrated GNSS simulator. With the R&S SMBV-K107 option, the GNSS simulator now covers the BeiDou standard as well as the GPS, Galileo and GLONASS satellite navigation systems.
The new option allows users to generate real-time scenarios with up to 24 BeiDou satellites. R&S SMBV-K107 supports all possible BeiDou orbits and can therefore even simulate satellites that are not yet in orbit. It also supports hybrid scenarios with GPS, Galileo or GLONASS satellites. A software update makes it easy to upgrade existing GNSS simulators for BeiDou. No hardware modifications are required.
The R&S SMBV100A permits users to quickly define their own satellite scenarios to test GNSS receivers under diverse conditions. A wide range of options are available for simulating realistic effects such as signal obscuration and multipath propagation. These scenarios can now be configured for BeiDou as well.
This inexpensive solution is one of the few on the market that does not require an external PC for testing receivers and components of satellite-based navigations systems, the company said. In addition to GNSS signals, the R&S SMBV100A can simulate mobile radio, wireless and radio standards, allowing users to test several functions with a single instrument.
The new R&S SMBV-K107 option is now available from Rohde & Schwarz.
Qualcomm Incorporated has announced that its subsidiary, Qualcomm Technologies, Inc., is enhancing location precision in smartphones and tablets initially in China with support for China’s BeiDou Satellite Navigation System.
Supporting the BeiDou constellation within Qualcomm IZat location solutions increases the number of satellites that Qualcomm-based devices can access to provide greater position location accuracy. Qualcomm is collaborating with Samsung to launch the first wave of BeiDou enhanced consumer smartphones, demonstrating the commitment of the companies to provide technology that delivers optimum performance for location-based services within China and globally.
Powered by the Qualcomm Snapdragon 800 processor (MSM8974), the Samsung Galaxy Note 3 (WCDMA 3G version SM-N9006 & TD-LTE 4G version SM-N9008V) uses the industry’s first, integrated tri-band location platform to provide more accurate and responsive location data to mobile users. It does so by concurrently processing signals from multiple satellite networks. Armed with this capability, users will have more enjoyable experiences using their location-based services, even in the most challenging of environments.
Leveraging Qualcomm IZat location solutions, Samsung will be able to deliver an optimal user experience with quick and accurate location information and services in China. Historically, this has been a challenge in some locations, especially in urban canyons, where devices may suffer from low visibility to satellites blocked by tall buildings that obstruct the signals. Bringing BeiDou-enabled phones to China means the Galaxy Note 3 has access to more satellites, which increases location accuracy. This ultimately improves customers’ pedestrian navigation, speeds local searches and enhances other location-based services.
Qualcomm’s mobile chipsets feature interoperability with existing constellations, which use tri-band hardware integration to deliver improved location capabilities in an optimal way, with enhanced accuracy, and with no additional increase in power consumption. In Snapdragon and Gobi™ chipsets, global positioning support is built into the modem and RF chips, enabling the location signals to be processed in the modem, instead of waking up the apps processor, thus saving power without sacrificing location accuracy.
“This industry-first implementation of BeiDou in a smartphone underscores Qualcomm’s leadership in the location industry. More than 3 billion devices which feature Qualcomm’s location technology have shipped to date and the introduction of BeiDou is the latest step to evolve our technology,” said Amir Faintuch, president, Qualcomm Atheros. “We see BeiDou’s support being an important factor for OEMs in China, and globally as well. With this new location enhancement, we believe our customers can bring greater differentiation with advanced performance, applications and services.”
PCTEL, Inc. announced the launch of its next generation multi-band GNSS antennas for global timing and precision tracking applications at the ION GNSS Conference being held this week in Nashville, Tennessee.
The new antennas, which are designed for use with GPS, GLONASS, BeiDou, and Galileo systems, are being showcased along with other PCTEL antennas at the PCTEL booth in the Exhibit Hall, Booth 318/320. All models of the new antennas are available for sale.
Equipment providers for carrier network timing, precision agriculture, and global asset tracking applications need a single antenna solution for global deployment. PCTEL’s new GNSS1-TMG-26N and GPS-LB12GL-MAG antennas address global compatibility issues for two of the industry’s most crucial applications.
For critical timing applications for macro and small cell deployments, PCTEL has developed the GNSS1-TMG-26N antenna. The GNSS1-TMG-26N is a fixed mount network timing antenna covering GPS, GLONASS, Beidou, and Galileo system frequencies in one single unit, making it a true global solution.
PCTEL’s GPS-LB12GL-MAG antenna is designed for precision agriculture.
For global precision navigation applications, PCTEL has developed the GPS-LB12GL-MAG to cover GPS L1, GPS L2, GLONASS, and L-BAND constellations. The GPS-LB12GL-MAG’s multi-band coverage addresses the precision market in the USA as well as differential correction signals needed across Europe and Asia.
“PCTEL will meet the GNSS market requirements for our global customers while maintaining PCTEL’s high standards for quality and performance,” said Jeff Miller, president of PCTEL Connected Solutions. “We understand that our products need global compatibility to support our customers around the world. We are proud to showcase our design excellence in this highly technical area,” added Miller.
By Steffen Thoelert, Johann Furthner, and Michael Meurer
Future positioning and navigation applications of modernizing and newly established GNSSs will require a higher degree of signal accuracy and precision. Thus, rigorous and detailed analysis of the signal quality of recently launched satellites, including the discovery of any possible imperfections in their performance, will have important implications for future users.
Global navigation satellite systems achieved amazing progress in 2012, with major milestones reached by the various navigation and augmentation systems, bringing new satellites and satellite generations into orbit. Since the complexity of the satellites and also the requirements for a precise and robust navigation increase consistently, all of the newly available signals of the existing or emerging navigation satellite systems must be analyzed in detail to characterize their performance and imperfections, as well as to predict possible consequences for user receivers.
Since the signals are well below the noise floor, we use a specifically developed GNSS monitoring facility to characterize the signals. The core element of this monitoring facility is a 30-meter high-gain antenna at the German Aerospace Center (DLR) in Weilheim that raises GNSS signals well above the noise floor, permitting detailed analysis. In the course of this analysis, we found differences in the signal quality in the various generations of the Chinese navigation satellite system BeiDou, differences which influence the navigation performance.
This article gives an overview of new navigation satellites in orbit. For selected satellites, a first signal analysis reveals important characteristics of these signals. The data acquisition of these space vehicles was performed shortly after the start of their signal transmission to get a first hint about the quality and behavior of the satellites.
For more detailed analysis, these measurements should be repeated after the satellites become operational. Then the acquired high-gain antenna raw data in combination with a precise calibration could be used for a wider range of analyses: signal power, spectra, constellation diagrams, sample analysis, correlation functions, and codes to detect anomalies and assess the signal quality and consequently the impact at the user performance.
Measurement Facility
In the early 1970s, DLR built a 30-meter dish (Figure 1) for the HELIOS-A/B satellite mission at the DLR site Weilheim. These satellite missions were the first U.S./German interplanetary project. The two German-built space probes, HELIOS 1 (December 1974–March 1986) and HELIOS 2 (January 1976–January 1981), approached the Sun closer than the planet Mercury and closer than any space probe ever. Later, the antenna supported space missions Giotto, AMPTE, Equator-S, and other scientific experiments.
Figure 1. 30-meter high-gain antenna.
In 2005, the Institute of Communications and Navigation of the DLR established an independent monitoring station for analysis of GNSS signals. The 30-meter antenna was adapted with a newly developed broadband circular polarized feed. During preparation for the GIOVE-B in-orbit validation campaign in 2008, a new receiving chain including a new calibration system was installed at the antenna. Based on successful campaigns and new satellite of modernizing GPS and GLONASS, and GNSSs under construction — Galileo and COMPASS — the facility was renewed and updated again in 2011/2012.
This renewal included not only an upgrade of the measurement system itself, but also refurbishment of parts of the high-gain antenna were refurbished.
The antenna is a shaped Cassegrain system with an elevation over azimuth mount. The antenna has a parabolic reflector of 30 meters in diameter and a hyperbolic sub-reflector with a diameter of 4 meters. A significant benefit of this antenna is the direct access to the feed, which is located within an adjacent cabin (Figure 2). The L-band gain of this high-gain antenna is around 50 dB, the beam width is less than 0.5°. The position accuracy in azimuth and elevation direction is 0.001°. The maximum rotational speed of the whole antenna is 1.5°/second in azimuth and 1.0°/second in elevation direction.
Figure 2. The shaped Cassegrain system: (1) parabolic reflector of 30 m diameter; (2) hyperbolic sub- reflector with a diameter of 4 meter; (3) sub-reflector; (4) Cabin with feeder and measurement equipment.
Measurement Set-up
The antenna offers another significant advantage in the possibility to have very short electrical and high-frequency connection between the L-band feeder and the measurement equipment. As mentioned earlier, the challenge for future GNSS applications is the high accuracy of the navigation solution. Therefore, it is necessary to measure and then analyze the signals very accurately and precisely. To achieve an uncertainty of less than 1 dB for the measurement results required a complete redesign of the setup, which consists of two main parts:
paths for signal receiving and acquiring the measurement data;
calibration elements for different calibration issues.
The path for receiving the signal and acquiring the measurement data consists of two signal chains, each equipped with two low-noise amplifiers (LNAs) with a total gain of around 70 dB, a set of filters for the individual GNSS navigation frequency bands, and isolators to suppress reflections in the measurement system. With this setup it is possible to measure right-hand circular polarized (RHCP) and left-hand circular polarized (LHCP) signals in parallel.
This provides the capability to perform axial ratio analysis of the satellite signal, and consequently an assessment of the antenna of the satellite. Using the switches SP01 and SP02, the measurement system is also able to acquire data from two different bands at the same time. This enabless investigations concerning the coherence between the signals in post-processing.
The signals are measured and recorded using two real-time vector signal analyzers with up to 120 MHz signal bandwidth. Both analyzers are connected to a computer capable of post-processing and storing the data. Additional equipment like digitizers or receivers can be connected to the system using the splitter III outputs, where the unfiltered RHCP signals are coupled out after the first LNA. A high-performance rubidium clock is used as reference signal for the whole measurement equipment. In front of the first LNA of each chain, a signal can be coupled in for calibration issues.
Control Software. Due to the distance of the antenna location from the Institute at Oberpfaffenhofen (around 40 kilometers) it was necessary to perform all measurement and calibration procedures during a measurement campaign via remote control. A software tool was developed which can control any component of the setup remotely. In addition, this software can perform a complete autonomous operation of the whole system by a free pre-definable sequence over any period of time. This includes, for example, the selection of the different band-pass filters, the polarization output of the feed, and the control of the calibration routines.
After the measurement sequence, the system automatically copies all data via LAN onto the processing facility, starts basic analysis based on spectral data, and generates a report. Sophisticated analysis based on IQ raw data is performed manually at this time.
Absolute Calibration
To fulfill the challenge of highly accurate measurements, it is necessary to completely characterize all elements of the measurement system, which comprises the antenna itself and the measurement system within the cabin after the feed. An absolutely necessary precondition of the calibration of the high-gain antenna is a very accurate pointing capability. The pointing error should be less than 0.01° concerning antennas of this diameter.
Furthermore, it is important to check long-term stability of these characterizations and the influences of different interference types and other possible error sources. This has to be taken in to account, when it comes to a point where the value of the absolute calibration has the same range as the summed measurement uncertainties of the equipment in use.
Antenna Calibration. High-accuracy measurements require not only the correct antenna alignment but also accurate power calibration of the antenna. To determine the antenna gain, well known reference sources are needed. These could be natural sources like radio stars or artificial sources like geostationary satellites.
Standard reference signal sources for the calibration of high-gain antennas are the radio sources Cassiopeia A, Cygnus, and Taurus. All these radio sources are circumpolar relative to our ground station, and therefore usable for calibrations at all times of the year. A further advantage of these calibration sources is the wide frequency range of the emitted signals. Thus, contrary to other signal sources (like ARTEMIS satellite L band pilot signal) the antenna gain can be calibrated in a wide bandwidth. With the help of the well-known flux density of the celestial radio sources and using the Y-method, the relation between the gain of the antenna and the noise temperature of the receiving system, or G/T, can be measured. Measuring the noise figure of the receiving system, the antenna gain can finally be calculated.
System Calibration. The measurement system calibration behind the feed is performed using wideband chirp signals. The chirp is injected into the signal chains via coupler I and II (Figure 3). The calibration signal is captured by the two vector signal analyzers. In the next step, the signal is linked via the switches directly to the analyzers, and the chirp signals are recorded as reference again. It has to be taken into account that more elements are in the loop during the chirp recordings compared to the receiving chain. These are the link between the signal generator and the couplers and the direct path to the analyzers.
Figure 3. Measurement setup overview.
To separate the receiving chain from the additional elements within the wideband calibration loop, two more measurements are needed. The injection path from the signal generator to the couplers and the direct paths are characterized by network analyzer (NWA) measurements. Based on the chirp and NWA measurements, the transfer function of the system is calculated to derive the gain and phase information. To determine the calibration curve over the frequency range from 1.0 GHz to 1.8 GHz, a set of overlaying chirps with different center frequencies is injected into the signal paths and combined within the analysis. Figure 4 and Figure 5 show the results of the wideband calibration of gain and phase.
Figure 4. Gain of the measurement system after the feed over 14 hours.Figure 5. Phase of measurement system.
Is it enough to determine the gain only once? If we assume that there is no aging effect of the elements, and the ambient conditions like temperature are constant, the gain should not change. In reality the behavior of the system is not constant. Figure 6 shows the temperature within the cabin during a failure of its air conditioning system. Figure 7 shows the corresponding gain of the measurement system during the temperature change in the cabin of about 5° Celsius. Clearly, it can be seen that the gain changed around 0.2 dB.
Figure 6. Cabin temperature increase during outage of the air condition concerning measurements shown in Figure 7.Figure 7. Gain variations of the measurement system based on temperature variations in the cabin (see Figure 6).
This example shows the sensitivity of the system to changes in environmental conditions. Usually the measurement system is temperature-stabilized and controlled, and the system will not change during data acquisition. But every control system can be broken, or an element changes its behavior. For this reason, the calibration is performed at least at the beginning and at the end of a satellite path (maximum 8 hours).
Measurement Results
Here we present selected results from the European Galileo and the Chinese BeiDou navigation systems.
Galileo FM3 and FM4. In October 2012, the third and fourth operational Galileo satellites, FM3 and FM4, were launched into orbit. Signal transmissions started in November and in December, respectively. Both satellites provide fully operational signals on all three frequency bands, E1, E5, and E6. The measurement data of both satellites were captured in December 2012, shortly after the beginning of the signal transmission. Figure 8 shows the spectra of both satellites for El, E5, and E6 bands. The quality of the transmitted signals seems to be good, but for the El signal of FM4 satellite, minor deformations of the spectra are visible.
Figure 8. Measurement results of Galileo IOV FM3 & FM4: El, E5 and E6 spectra.
Figure 9 shows the results of the IQ constellations both for FM3 and FM4 concerning each transmitted signal band. The constellations and consequently the modulation quality of each signal are nearly perfect for the FM3 satellite. The IQ constellation diagrams of FM4 show minor deformations in each band. What impact these imperfections create for future users has yet to be analyzed. Both satellites were at the time of measurement campaign still in the in-orbit test phase and did not transmit the final CBOC signal in the E1 band. It could be expected that especially the signals of the FM4 will be adjusted to become more perfect.
Figure 9 Measurement results of Galileo IOV FM3 & FM4: E1, E5, and E6 – IQ Constellation.
BeiDou M6. BeiDou satellites transmit navigation signals in three different frequency bands, all are located adjacent to or even inside currently employed GPS or Galileo frequency bands. The center frequencies are for the B1 band 1561.1 MHz, B3 band 1268.52 MHz, and B2 band 1207.14 MHz.
In 2012, China launched six satellites: two inclined geostationary space vehicles and four medium-Earth orbit ones, concluding in September (M5 and M6) and October 2012 (IGSO6). There have been further BeiDou launches in 2013, but these satellites’ signals are not analyzed here.
Figure 10 displays calibrated measurement results from the Beidou M6 satellite. The spectra of the B2 and B3 band of the Beidou M6 satellite are clean and show no major deformation. Within the B1 spectra, some spurious results, especially on top of the side lobes, are obvious. This behavior has to be investigated more in detail to determine their origin. The IQ diagrams, which visualize the modulation quality, show also no major deformation. Only within the B3 signal, a marginal compression of the constellation points can be seen, which points to a large-signal operation at the beginning of the saturation of the amplifier of the satellite.
Figure 10. BeiDou M6 satellite signal spectra and IQ constellations at B1, B2 and B3 band
Conclusion
Reviewing the quality of the presented measurements, signal analysis, and verification on GNSS satellites, the use of the 30-meter high-gain antenna offers excellent possibilities and results. Regarding the calibration measurements of the antenna gain and measurement system, the variances are in the range of measurement uncertainty of the equipment.
The sensitivity of the measurement system concerning ambient conditions was exemplarily shown based on the gain drift caused by a temperature drift. But the solution is simple: stabilize the ambient conditions or perform calibration in a short regular cycle to detect changes within the system behavior to be able to correct them.
Based on this absolute calibration, a first impression of the signal quality of Galileo FM3 and FM4 and the BeiDou M6 satellites were presented using spectral plots and IQ diagrams. Only minor distortion could be detected within the Galileo FM4 and Beidou M6 signal; these distortions may be negligible for most users. Concerning FM4 and FM3, both satellites were in the in-orbit test phase during the data acquisition. The signal quality may have been changed during their stabilization process in orbit, or the signals have been adjusted in the meantime. Thus, it would be interesting and worthwhile to repeat the measurements and perform detailed analysis to assess the final satellite quality and consequently the user performance.
Acknowledgments
The authors wish to thank the German Space Operation Centre for the opportunity to use the high-gain antenna. The support of colleagues at the DLR ground station Weilheim for the operational and maintenance service over recent years is highly appreciated. This work was partly performed within the project “Galileo SEIOT (50 NA 1005)” of the German Space Agency, funded by the Federal Ministry of Economics and Technology and based on a resolution by the German Bundestag. Finally, the support of DLR’s Centre of Excellence for Satellite Navigation is highly appreciated.
This article is based on the paper “GNSS Survey – Signal Quality Assessment of the Latest GNSS Satellites” presented at The Institute of Navigation International Technical Meeting 2013, held in San Diego, California, January 28–30, 2013.
Steffen Thoelert received his diploma degree in electrical engineering at the University of Magdeburg. He works in the Department of Navigation at German Aerospace Centre (DLR), on signal quality assessment, calibration, and automation of technical processes.
Johann Furthner received his Ph.D. in laser physics at the University of Regensburg. He works in the DLR Institute of Communication and Navigation on the development of navigation systems in a number of areas (systems simulation, timing aspects, GNSS analysis, signal verification, calibration processes).
Michael Meurer received a Ph.D. in electrical engineering from the University of Kaiserslautern, where he is now an associate professor, as well as director of the Department of Navigation at DLR.
A few months ago I wrote in the magazine’s Out in Front column about the surprising abundance of BeiDou-centric papers to be presented at the upcoming ION GNSS+ conference, to which I very much look forward — both the abundance and the conference as a whole. With GLONASS encountering stormy weather of late, and Galileo plugging steadily along but not quite making up time, it seems increasingly possibly that the first GNSS of choice may constitute GPS+BeiDou, if certain spectrum questions can be worked out. News of an advance in Australia further heralds this likelihood.
Researchers at Curtin University in Perth, Western Australia, have put forth a method integrating GPS and BeiDou signals, in an effort particularly aimed at urban canyons. In Australia at least, the visibility of BeiDou’s five geostationary and five inclined geosynchronous orbit satellites hovering above the Asia-Pacific region can bring added punch to any receiver experiencing skyviews obscured by skyscrapers. The same problem occurs in open-pit mines, said Curtin University professor Peter Teunissen. Open-pit mines are a very big thing in Australia.
For those surprised to find this flying Dutchman, the inventor of the LAMBDA method for GNSS carrier phase ambiguity resolution, popping up in Australia, it appears he has a secondary appointment at Curtin University. He remains based, as he has for 20 years, at the Delft University of Technology in the Netherlands, where he is head of the Department of Earth Observation and Space Systems.
I wish I had a secondary appointment somewhere.
“By combining GPS with Beidou,” announced Teunissen and colleagues at the Cooperative Research Centre for Spatial Information, “we are making use of Beidou’s 14 new satellites that cross our sky at a high angle, increasing satellite availability, improving positioning capability and ultimately creating a system that is perfect for both urban and mining environments.”
Beidou of course has a ways to go to achieve its fullness at 35, perhaps as soon as 2020. Combining all and sundry GNSS, more than 100 GNSS satellites are expected to be operational by 2016, so algorithms making use of multiple signals and systems have moved to the fore. As we well know.
“The emergence of new GNSSs, together with the linking of different systems, has enormous potential for improving the accuracy, integrity and efficiency of positioning worldwide, enabling much more reliable data,” Teunissen added.
Precise positioning services could boost Australia’s gross domestic product by $13.7 billion by 2020, according to a recent report by a consultant for the Department of Industry, Innovation, Climate Change, Science, Research and Tertiary Education. (Maybe that’s where I should seek my secondary appointment; they’ve got a lot on their plate.)
In January of this year, Teunissen’s Curtin University group and Dr Dennis Odijk, from the Western Australian School of Mines (WASM), also announced a methodology integrating GPS with Galileo signals. Both projects were funded by the Australian Space Research Program.
The NavX-NCS GNSS multi-frequency simulator now supports China’s BeiDou-2 navigation satellite system. BeiDou support is a key enhancement in software update V.1.9 for the NavX-NCS GNSS multi-frequency simulator product line, by IFEN andWORK Microwave.
Leveraging new features and functionalities, users have the flexibility to support a wide range of constellations, frequencies, and channels for research and development of GNSS safety and professional applications, as well as system integration and production testing of mass-market applications, such as automotive satellite navigation, mobile-phone applications, chipsets, and handheld personal navigation devices, the companies said.
By enabling real-time simulation of second-generation BeiDou satellite signals, also referred to as BeiDou-2, NavX-NCS expands a user’s GNSS signal capability beyond GPS, Galileo, GLONASS, and SBAS constellations.
“Through a simple software update, NavX-NCS customers can automatically generate signal capabilities for phase two of the BeiDou constellation,” said Dr. Günter Heinrichs, head of customer applications, IFEN GmbH. “Adding BeiDou-2 support to our NavX-NCS simulator comes at the perfect time given the recent release of the BeiDou-2 ICD specification, which outlines interface control requirements for BeiDou-2 B1 satellite signals within the B1 frequency band.”
A powerful new multi-user functionality enables the simulation of up to four different users, or one user with up to four antennas, in different locations simultaneously, IFEN said. Possible use scenarios include simulating a static user such as a reference station at the same time as a roving user, or simulating multiple docking maneuvers on an oil rig. In addition, the NavX-NCS GNSS simulators now include a new 6DOF functionality that makes it possible to simulate six degrees of freedom (three dimensions of space plus yaw, pitch, and roll). This allows even more true-to-life simulations of ships, airplanes, and cars. A new monitoring widget makes it easier to monitor the current state of simulation.
Optimized to perform advanced lever arm calculations, the NavX-NCS GNSS simulators ensure accurate navigation for users. In simulation environments where the antenna is not located in the center of the moving object, such as the external of an airplane wing, lever arm calculations compensate for the fact that acceleration and GPS measurements are not made at the same point. By calculating the lever arm measurement between the PAR antenna and GPS position reference for every epoch of observation, this new feature guarantees that the most accurate signal simulation is achieved.
The NavX-NCS GNSS simulators are available in Professional and Essential versions, both now optionally Export License-Free (LF), speeding up the approval process and delivery time to users abroad. With the Export LF version, users can now limit the simulated user velocity of their simulator equipment to 600 meters per second, eliminating the need for an export license. If an export license should be applied for and be granted later on, it is also upgradeable to a full version meaning the simulation of higher user velocities will be available.
All NavX-NCS GNSS simulators feature up to nine L-band frequencies and 108 channels, offering users more than twice the number of channels compared with standard GNSS simulators. The platform includes a two-year maintenance contract, the broadest range of frequencies and satellite navigation systems per chassis, as well as the flexibility for users to easily install software updates when they become available.
By Oliver Montenbruck, Chris Rizos, Robert Weber, Georg Weber, Ruth Neilan, and Urs Hugentobler
GPS IS ALMOST 40 YEARS OLD. While mass consumer use of GPS began only within the past decade or so, GPS was “born” during the Labor Day weekend of 1973, when about a dozen military officers and industry analysts under the leadership of Brad Parkinson met to consolidate the concept for a single satellite-based navigation system for the U.S. Department of Defense. Their proposal for NAVSTAR GPS was approved on December 22, 1973. The first satellite to be launched under the GPS program, on July 14, 1974, was the Naval Research Laboratory’s Navigation Technology Satellite (NTS) 1. NTS-2 followed, with a launch on June 23, 1977. These satellites carried payload components similar to those to be used on the subsequent GPS Block I or Navigation Technology Satellites. The first Block I satellite was launched on February 22, 1978, and was followed by nine others. With the launch of the Block II and IIA Operational Satellites and with 24 satellites on orbit, Initial Operational Capability was declared on December 8, 1993. Following testing, Full Operational Capability (FOC) was announced on July 17, 1995.
Whether in reaction to the development of GPS or simply to fulfill the requirement for a system with similar capabilities for its armed forces, the former Soviet Union developed the Global’naya Navigatsionnaya Sputnikovaya Sistema or GLONASS. The first GLONASS satellite was launched on October 12, 1982. By early 1996, a fully populated FOC constellation of 24 satellites was in orbit, but the number of operational satellites dwindled to a handful due to lack of financial support. Eventually the needed funds started flowing again and on December 8, 2011, FOC was again achieved and subsequently maintained.
With the announcement of FOC and the removal of the accuracy-limiting policy of Selective Availability on May 2, 2000, widespread consumer use of GPS took off.
And now GPS is approaching middle age. And like for some humans approaching that milestone desirous of change, a GPS renewal or modernization is under way. New civil and military signals are being transmitted by the Block IIR-M and IIF satellites along with the legacy signals pioneered by the Block I satellites. And new GNSS signals are now coming from the satellites orbited for the Chinese BeiDou Navigation Satellite System, the Japanese Quasi-Zenith Satellite System, and Europe’s Galileo, as well as those from satellite-based augmentation systems. Although it will be some years before full constellations will be transmitting these signals, scientists and engineers are already monitoring and analyzing the new signals to learn how best to use them and how to integrate subsets of them for a wide variety of applications in positioning, navigation, and timing.
In this month’s column, we learn the details of the effort established by the International GNSS Service to support the study of these new signals: the Multi-GNSS Experiment.
“Innovation” is a regular feature that discusses advances in GPS technology andits applications as well as the fundamentals of GPS positioning. The column is coordinated by Richard Langley of the Department of Geodesy and Geomatics Engineering, University of New Brunswick. He welcomes comments and topic ideas. To contact him, see the “Contributing Editors” section on page 4.
Over the past four decades, GPS has evolved from a primarily military navigation system into an indispensable tool not only for society at large, but also for geodetic research and global monitoring of the Earth. And within the past decade, the world of satellite navigation has experienced dramatic changes. With GLONASS, a second GNSS has achieved full operational status; GPS is introducing modernized civil and encrypted navigation signals; and a variety of new navigation constellations are being built up in Asia and Europe.
As of early 2013, Europe has successfully launched a total of four Galileo In-Orbit Validation (IOV) satellites, which are undergoing testing in parallel to the build up and verification of the ground segment. The satellites routinely transmit signals at four frequencies (E1, E5a, E5b, and E6) and offer a variety of publicly accessible pilot and data signals. As a unique feature, Galileo enables tracking of the alternative binary-offset-carrier (AltBOC) signal in the combined E5a+E5b band, which offers superior noise and multipath performance.
Meanwhile, the Chinese BeiDou Satellite Navigation System (BDS; formerly known as Compass) has completed the first stage of its system deployment and declared a regional navigation service for the Asia-Pacific region operational. A total of 14 functioning satellites have been launched so far, which includes five satellites in geostationary orbit (GEO), five satellites in inclined geosynchronous orbit (IGSO), and four in medium-altitude Earth orbit (MEO). These satellites transmit signals in three frequency bands (B1, B2, B3), and tracking of the corresponding open service (OS) signals is already supported by a variety of GNSS receivers. With the release of a B1 OS Interface Control Document (ICD) at the end of 2012, the BeiDou navigation message has become publicly accessible, and users throughout the Asia-Pacific region can now benefit from BeiDou as a supplementary or stand-alone navigation system.
The Japanese Quasi-Zenith Satellite System (QZSS) has, so far, only launched a single satellite but recent political decisions have paved the way for the build up of a mini-constellation of IGSO and GEO satellites. Aside from a high level of compatibility with GPS, QZSS has introduced new signals such as the modernized L1 Civil (L1C) signal and the L-band Experiment (LEX) signal (also known as L6) for high-precision point positioning in the E6 band. Along with this unique set of navigation signals, QZSS provides innovative service features such as the L1 Sub-meter-class Augmentation with Integrity Function (L1-SAIF or L1S) message. Also, QZSS precedes GPS in offering the new Civil Navigation (CNAV) message on L2C and L5, as well as the CNAV2 message on L1C. Long before their planned use in GPS, these messages are now broadcast on a routine basis and contain novel information such as inter-frequency corrections and Earth-orientation parameters.
Last, but not least, GPS has now a total of four Block IIF satellites in orbit that transmit an operational L5 signal for aviation users (and others) and which fly a new generation of highly stable rubidium clocks. While neither L2C nor L5 are transmitted by a full constellation, users and investigators can gradually familiarize themselves with these new signals that will enable encryption-free dual-frequency navigation services for aeronautical and other civil applications.
Within the International GNSS Service (IGS), more than 200 worldwide agencies have, for many years, pooled resources and permanent GNSS station data to generate precise GNSS products in support of Earth science research, multidisciplinary applications, and education. So far, this service has been restricted to two systems — namely, GPS and GLONASS. In recognition of the rapidly evolving GNSS landscape, the IGS has set up the Multi-GNSS Experiment (MGEX) to explore and promote the use of new navigation signals and constellations. It will enable an early familiarization with new GNSS, identify and overcome relevant challenges, and prepare use of emerging navigation systems in routine IGS products. MGEX comprises the build-up of a new network of sensor stations, the characterization of the user equipment and space segment, the development of new concepts and data processing tools, and the generation of early data products for Galileo, QZSS, and BeiDou. MGEX is coordinated by the IGS Multi-GNSS Working Group (MGWG), which interacts closely with other IGS entities, such as the RINEX WG, the Antenna WG, the Data Center WG, and the Infra-structure Committee.
The article starts out with a description of the MGEX network that formed the starting point and initial focus of the overall MGEX project. Following a description of system characterization activities, the current status of multi-GNSS data products and ongoing efforts for the development of new standards for multi-GNSS-related work within the IGS are presented.
Network
Following a call-for-participation released in the summer of 2011, the build up of a new international network of multi-GNSS sensor stations was initiated and has grown substantionally in a short time. By the end of 2012, the MGEX network had comprised approximately 50 stations supporting at least one of the new navigation systems (Galileo, BeiDou, and QZSS) in addition to the legacy GPS, GLONASS, and SBAS systems. At last count, the network now includes 75 stations.
The bulk of the stations is provided by IGS partners such as Bundesamt für Kartographie und Geodäsie (BKG), Centre National d’Etudes Spatiales (CNES), Deutsches GeoForschungsZentrum (GFZ), Deutsches Zentrum für Luft- und Raumfahrt (DLR), Geoscience Australia (GA), the Geospatial Information Authority of Japan (GSI), Institut National de l’Information Géographique et Forestière (IGN), and the Swedish National Land Survey (Lantmaeteriverket, LMV), that have upgraded existing sites with new, multi-GNSS-capable receivers and antennas or started to deploy new multi-GNSS networks (such as the COperative Network for GNSS Observation (CONGO) or CNES’s REseau GNSS pour l’IGS et la Navigation (REGINA) network).
As shown in FIGURE 1, the present set of MGEX stations exhibits almost global coverage, even though a concentration in Europe and a reduced coverage in the Americas and the western Pacific are obvious. However, this situation is expected to improve soon with announced contributions from Geoscience Australia, the Multi-GNSS Monitoring Network (MGM-net) of the Japan Aerospace Exploration Agency (JAXA), and other stations. While most MGEX sites support tracking of Galileo satellites, only a subset of stations provides data for QZSS and BeiDou. In particular, the regional BeiDou constellation (that is, the GEO and IGSO) satellites are not well covered by the current network.
Figure 1. Distribution of MGEX stations supporting tracking of QZSS (blue), Galileo (red), and BeiDou (yellow) as of June 2013.
Further MGEX sites are encouraged and the nomination of sites is still possible through the MGEX submission form under the provision of relevant improvements to the capabilities, coverage, and homogeneity of the overall network.
In terms of equipment, five basic receiver types and seven basic antenna types are employed at the MGEX stations (see TABLES 1 and 2). Observation types provided by the individual receivers have been compiled from summary reports generated by the Astronomical Institute of the University of Bern (AIUB) as part of their routine monitoring of RINEX 3 observation files from MGEX stations.
Table 1. Receiver types in use within the MGEX network (status as of June 2013). Observation types for Galileo (E), BeiDou (C), and QZSS (J) are based on RINEX 3 observation codes as reported in the submitted data files (frequency bands: 1=L1/E1, 2=L2/B1, 5=L5/E5a, 6=E6/B3, 7=E5b/B2, 8=E5ab; signals: C = C/A-code, I = data, Q = pilot, X = data+pilot). They do not necessarily indicate the full tracking capabilities supported by the receivers but rather the observations made available to MGEX users from the respective stations.Table 2. Antenna types employed within the MGEX network (as of June 2013).
Note that no common standard has yet evolved in terms of supported signals and observation types. This causes certain restrictions for data analysis and product generation. As an example, Galileo orbit and clock products will (at least initially) be based on E1/E5a observations due to a limited coverage of E5b and E5ab tracking.
Selected sites (such as UNB and USNO) offer multiple receivers in short- or zero-baseline configurations to facilitate equipment characterization. Further such installations will be added to the MGEX network at the time of the proposed extensions.
While all stations contribute data to offline archives hosted by the Crustal Dynamics Data Information Service (CDDIS), IGN, and BKG for the MGEX project, a selected subset also supports real-time analyses (see FIGURE 2). All real-time streams utilize the Networked Transport of RTCM via Internet Protocol (NTRIP), which has emerged as a standard for real-time GNSS data exchange. A dedicated MGEX caster is hosted by BKG in Frankfurt, where native raw data streams received from the individual sites are converted and encoded in the RTCM3 Multiple-Signal-Message (MSM) format.
Figure 2. Distribution of MGEX real-time stations supporting tracking of QZSS (blue), Galileo (red), and BeiDou (yellow) as of June 2013.
RTCM3-MSM will enable a harmonized framework for multi-GNSS real-time operations and ensure a seamless conversion to the RINEX3 offline data format. The new MGEX NTRIP caster provides a basis to gain early experience with the new MSM format and facilitates a timely adaptation of user software. This is further supported through freeware software modules for data conversion provided by BKG.
System Characterization
While a systematic quality control of the MGEX data has not yet started, first performance assessments of both the ground and space segment have been reported in the literature (see Further Reading). Overall, the measurement quality of the employed multi-GNSS receivers is found to be comparable or even superior to established GPS reference stations. A high performance is, in particular, obtained for unencrypted signals with high chipping rates and bandwidths such as the GPS/QZSS L5 and Galileo AltBOC.
By way of example, FIGURE 3 illustrates the elevation-angle-dependency of pseudorange errors for BeiDou tracking with a Trimble NetR9 receiver as used at numerous MGEX stations. Aside from the expected variation of receiver noise, the analysis reveals a systematic code bias that varies by 0.4-0.6 meters from horizon to zenith and can best be attributed to spacecraft internal multipath.
Figure 3. Code noise and elevation-dependent biases for BeiDou tracking.
An interesting opportunity for system characterization is provided by triple-frequency observations (GPS+QZSS L1/L2/L5, BeiDou B1/B2/B3, Galileo E1/E5a/E5b) made available by a subset of the MGEX network. A thermal variation of inter-frequency biases has earlier been identified for the GPS Block IIF satellites, but a high level of consistency is demonstrated for QZSS, BeiDou, and Galileo (see FIGURE 4).
Figure 4. Triple-frequency combination of Galileo IOV-3 observations.
Products
While the newly established MGEX network forms a mandatory prerequisite for multi-GNSS work within the IGS, the MGEX campaign supports a wider range of activities, which are now being established. Foremost, the generation of orbit and clock products for the new constellations is promoted in coordination with new and established IGS analysis centers.
Initial Galileo IOV products have been provided by CNES/CLS, CODE, and GFZ since mid-2012, and a combined Galileo+QZSS product has been added by Technische Universität München (TUM). Aside from the MGEX network, some of these solutions make complementary use of proprietary multi-GNSS networks to compensate existing coverage limitations and achieve an improved product quality.
TABLE 3 compares selected MGEX orbit products for the Galileo IOV satellites, while FIGURE 5 shows a time series of the difference between the TUM and CODE orbit products for IOV-1 (E11).
Table 3. Inter-comparison of selected MGEX orbit products for the Galileo IOV satellites. (IOV-1 (E11), DOY 323-329, 2012). Orbit differences (mean ± standard deviation) in radial (R), along-track (T) and cross-track (N) directions are provided in the upper right cells, 3D RMS position differences in the lower left. All values are in units of meters.Figure 5. Difference of MGEX Galileo IOV-1 (E11) orbit products from TUM and CODE for DOY 232-239, 2012 (R: radial direction, T: along-track direction, N: cross-track direction).
TABLE 4 shows the residuals of Galileo IOV-1/2 satellite laser ranging measurements (mean ± standard deviation) relative to the GNSS-based orbit products (days of year (DOY) 323-329, 2012).
Table 4. Satellite laser ranging residuals (mean ± standard deviation) for Galileo IOV-1/2 orbit products (DOY 323-329, 2012). Units are centimeters.
FIGURE 6 shows a time series of the differences between TUM orbit products for QZS-1 and precise ephemerides computed by the Japan Aerospace Exploration Agency (JAXA) for DOY 027-033, 2013. It demonstrates consistency at the 0.5-meter level, which already represents an important accomplishment, given the sparse subset of QZSS-capable MGEX stations available at the time. Further improvements are expected as the MGEX network continues to grow.
Figure 6. Comparison of TUM MGEX orbit products of QZS-1 with precise ephemerides of JAXA for DOY 027-033, 2013.
Concerning the Chinese BeiDou system, which has now reached initial operational capability for a regional service, early orbit and clock determination results have been reported by various Chinese and European researchers using data from dedicated regional sensor station networks. An effort will be made to promote the extension of the BeiDou tracking capabilities within the MGEX network and to make MGEX-only or mixed network-based orbit and clock products for BeiDou accessible to a wider user community through the MGEX data centers.
Given the late public availability of Galileo and BeiDou broadcast navigation messages, the MGEX orbit and clock products constitute a significant promotion for the early use of all available navigation systems. Aside from initial positioning experiments, they provide a basis for the in-depth characterization of both the space and user segment, and, it is hoped, will facilitate an improved interaction with system providers. Early applications of MGEX multi-GNSS products and observations have, for example, been reported at conferences and in journals (see Further Reading).
Standardization
In support of MGEX, the Multi-GNSS WG interacts closely with other IGS working groups to coordinate data formats, processing standards, and applicable models for use in multi-GNSS work. Examples include necessary RINEX 3 and RTCM3 extensions for full support of new GNSS signals and tracking modes as well as the rapidly growing set of diverse broadcast navigation data.
Another focus of current work addresses the proper modeling of antenna offsets and phase patterns for receiver and satellite antennas, along with documentation of constellation-specific spacecraft coordinate systems and attitude modes. This work is performed in close coordination with the IGS Antenna WG. Among others, conventional antenna phase center offsets (see TABLE 5) have been agreed upon, which will enable consistent processing of MGEX observations until the release of official information by the Galileo and BeiDou program offices.
Table 5. Conventional antenna offsets from the spacecraft center of mass for processing Galileo IOV and BeiDou observations. All values refer to the spacecraft coordinate system. Units are meters.
Public Outreach
As a central point for exchange of MGEX-related information with the user community, a dedicated website has been established at the IGS Central Bureau (see FIGURE 7). The new website provides an overview of available MGEX data and products with direct links to the respective archives at IGS data and product centers. Furthermore, users are provided with up-to-date information on the status of the emerging navigation satellite systems as well as recommended parameters (such as antenna offsets) for harmonized and consistent processing of MGEX observations.
Figure 7. Homepage of the IGS Multi-GNSS Experiment at http://igs.org/mgex.
Through individual members, the Multi-GNSS WG is represented on other boards and bodies such as the International Committee on GNSS, the International Association of Geodesy, and the Multi-GNSS Asia project.
Summary and Conclusions
As part of its continued effort to provide the highest quality data and products for all satellite navigation systems, the IGS has initiated the Multi-GNSS Experiment. MGEX supports early work with new signals and constellations. It enables a timely preparation of IGS analysis centers as well as the user community to expand from GPS/GLONASS towards full multi-GNSS processing.
Within the first year of MGEX, substantial progress has already been made. In particular, a global network of multi-GNSS receivers has been established in parallel with the existing core IGS network and by upgrading existing sites with new multi-GNSS equipment. The MGEX network forms the backbone for all other activities, such as system characterization and product generation. Aside from offline data provisions, a substantial fraction of MGEX stations are already offering real-time data streams, which paves the way for a rapid extension of the upcoming IGS real-time pilot service to Galileo and possibly other constellations. A limited number of analysis centers have already started to provide orbit and clock products for Galileo and/or QZSS as a basis for precise positioning applications. In addition to initial positioning experiments, they will provide a basis for the in-depth characterization of both the space and user segment, and help facilitate an improved interaction with system providers.
Upcoming activities will focus on the systematic incorporation of the BeiDou navigation satellite system. While BeiDou is the third constellation to reach an operational system status after GPS and GLONASS, it is not well covered by the current MGEX tracking network. Along with the targeted incorporation of BeiDou-capable reference stations (particularly in the Asia-Pacific region), the generation and provision of related orbit and clock products will be promoted to facilitate a timely use of BeiDou by the geodetic community.
Subject to active participation by a sufficient number of analysis centers, the MGEX project will eventually transition into an IGS pilot project offering operational data products of Galileo, QZSS, and BeiDou within the next few years.
OLIVER MONTENBRUCK is the head of the GNSS Technology and Navigation Group at DLR’s German Space Operations Center. He chairs the IGS Multi-GNSS Working Group and coordinates the MGEX Multi-GNSS Experiment.
CHRIS RIZOS is a professor at the University of New South Wales, Sydney, Australia; president of the International Association of Geodesy; co-chair of the Multi-GNSS Asia Steering Committee; and a member of the executive and governing board of the IGS.
ROBERT WEBER is an associate professor at the Department of Geodesy and Geoinformation, TU Vienna, and former chair of the IGS GNSS Working Group.
GEORG WEBER is the scientific director in the Department of Geodesy at the German Federal Agency for Cartography and Geodesy (BKG). He is a member of the IGS Real-time Working Group and the Radio Technical Commission for Maritime (RTCM) Services Special Committee (SC) 104 on Differential Global Navigation Satellite Systems (DGNSS).
RUTH NEILAN is the director of the Central Bureau of the IGS, vice-chair of the Global Geodetic Observing System Coordinating Board, and co-chair of Working Group D, Reference Frames, Timing and Applications, of the United Nation’s International Committee on GNSS.
URS HUGENTOBLER is a professor at the Institute of Astronomical and Physical Geodesy, TUM, Munich. He is the chair of the IGS Governing Board.
FURTHER READING
• The IGS MGEX Campaign
“The IGS MGEX Experiment as a Milestone for a Comprehensive Multi-GNSS Service” by C. Rizos, O. Montenbruck, R. Weber, G. Weber, R. Neilan, and U. Hugentobler in Proceedings of The Institute of Navigation 2013 Pacific PNT Meeting, Honolulu, Hawaii, April 23 –25, 2013, pp. 289–295.
“Multi–GNSS Working Group” by O. Montenbruck in International GNSS Service Technical Report 2012, edited by R. Dach and Y. Jean and published by the IGS Central Bureau, April 2013. Pp. 163–170.
“IGS M-GEX – The IGS Multi-GNSS Global Experiment” by R. Weber, U. Hugentobler, and R. Neilan in Proceedings of the 3rd International Colloquium on Scientific and Fundamental Aspects of the Galileo Programme, Copenhagen, 31 August – 2 September, 2011.
“Initial Assessment of the COMPASS/BeiDou-2 Regional Navigation Satellite System” by O. Montenbruck, A. Hauschild, P. Steigenberger, U. Hugentobler, P. Teunissen, and S. Nakamura in GPS Solutions, Vol. 17, No. 2, April 2013, pp. 211–222, doi: 10.1007/s10291-012-0272-x.
“Orbit and Clock Determination of QZS-1 Based on the CONGO Network” by P. Steigenberger, A. Hauschild, O. Montenbruck, C. Rodriguez-Solano, and U. Hugentobler in Navigation – Journal of The Institute of Navigation, Vol. 60, No. 1, Spring 2013, pp. 31–40.
• RTCM and NTRIP Formats
Differential GNSS (Global Navigation Satellite Systems) Services, Version 3, RTCM 10403.2, published by Radio Technical Commission for Maritime Services, Arlington, Virginia, February 1, 2013.
“The RTCM Multiple Signal Messages: A New Step in GNSS Data Standardization” by A. Boriskin, D. Kozlov, and G. Zyryanov in Proceedings of ION GNSS 2012, the 25th International Technical Meeting of The Satellite Division of the Institute of Navigation, Nashville, Tennessee, September 17–21, 2012, pp. 2947–2955.
“Networked Transport of RTCM via Internet Protocol (Ntrip) – IP-Streaming for Real-time GNSS Applications” by G. Weber, D. Dettmering, H. Gebhard, and R. Kalafus in Proceedings of ION GPS 2005, the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation, Long Beach, California, September 13–16, 2005, pp. 2243–2247.
I recently attended the Fourth China Satellite Navigation Conference (CSNC, held May 15–17 in Wuhan, China), as an invited speaker and panelist. I had attended the third CSNC last year in Guangzho, and as expected this year’s was a little bigger and a little better. The Chinese GNSS industry is growing quickly, as evidenced by the more than 2000 attendees with as many as 10 simultaneous sessions at some times, with more than 200 presentations over three days, and nearly 150 exhibitors on the show floor. The conference is mainly attended by Chinese, but they are working hard to attract an international audience by providing simultaneous translation of all presentations, and dual-screen projection for slides in English and Chinese if the author chooses.
I couldn’t possibly see everything, so I chose to spend most of my time in a series of sessions on industrial policy, regulations, standards, and intellectual property. I thought those sessions would provide the most unique information this conference had to offer. I expected to hear a lot of standard or official position statements without much audience discussion, but I was pleasantly surprised by the level of information from personal experience that the speakers offered and the amount of lively debate that often followed the presentations. The simultaneous translation was essential and not only allowed me to follow but created the opportunity for multi-language Q&A which allowed more complex questions to be asked.
I was particularly interested in understanding what changes were going to occur since the full release of the BeiDou Interface Controld Document (ICD) in December. One thing I noticed right away is that the term Compass has pretty much gone away. The official name, and what everyone used in their presentation, is BDS. I am not quite sure I follow the methodology, but it’s an abbreviation for the BeiDou Satellite System. I would certainly recommend to anyone meeting with Chinese business associates that you appear very up to date by using BDS instead of Compass in all your presentations, oral, written or PowerPoint.
The changing of the official name is just the first ripple in what I expect will be a wave of changes in the BDS industry (see, I learn fast). One of the most interesting talks was given by Hua Xu, whose affiliation was given in the English program as “BDS specific policies and regulations expert team, ex-director of the policy and regulations Division of Development and Reform Commission.” His talk was entitled “Thoughts of perfecting China’s BDS Industry System Construction.” He related several interesting anecdotes about the history of the satellite program, going back many years, all the way to the Cultural Revolution of the 1970s. As an example of how different the Chinese setting is for legal issues, he told us that in China, if a car hits a pedestrian, the car driver has to pay damages regardless of fault, because since he is driving the car, and the car damaged the pedestrian, he must accept responsibility. Mr. Xu spent more time talking about how China’s GNSS industry must grow in terms of industrial capability, intellectual property, and mass production, and how the government is encouraging that growth.
To date, that growth has been very rapid, as embodied by a vast array of small companies focusing on domestic Chinese applications of BDS, in particular in survey and mapping and in search and rescue. The growth impetus now moves to the automotive sector, where there is continued investment by both the national government and regional governments to promote the use of BDS in transportation projects involving trucks, taxis, and government vehicles. Some may view this as protectionist, due to the approved vendor lists and subsidies that are provided, but I think it is just a natural effort to create local centers of excellence and jobs in a new technology; this process occurs all over the world. The companies that are in this business are the 150 or so who exhibited on the CSNC show floor, and they are the little tigers of my title.
Most of the names of the little tigers are not that familiar outside of China: unicore, BDstar, Olinkstar, and many more. They have developed their own GPS+BDS chips and are selling them in moderate quantities of thousands for domestic customers. At CSNC, they presented lots of results that clearly show the advantages of multi-GNSS (GPS+BDS) within today’s BDS regional coverage area. Furthermore, the accuracy and time-to-first-fix performance of their solutions is comparable to the overall market. However, as market needs in China grow from thousands of units to millions of consumer devices, the little tigers are not quite ready yet to support the Lenovos (computers), HTCs (smartphones) and Huaweis (mobile phones and tablets).
But China wants to see BDS in all those consumer devices, to demonstrate to the world the benefit of BDS; hence the ICD was released in December. The ICD release opened the gate to China’s domestic market that previously was solely hunted by the little tigers. The wolves were waiting at the gate and they have charged in. Broadcomm, CSR, Trimble, NovAtel, and others have already publicly announced BDS support in their mainstream products, in the first few months following the release.
This was the topic of the discussions in CSNC that were most revealing for a foreigner like me to hear. I was ready to ask the tough question of what the future holds in the consumer market, because I figured no one else would. But much to my surprise, the moderator of the session put up a slide that translated to: “B1 ICD was released while Regional System is officially operational, will affect domestic BDS receiver industry? Pros? Cons?” (See opening photo.)
The ensuing discussion was quite lively but polite on both sides of the issue. Would subsidies continue for domestic suppliers? How could local companies hope to attract investment to scale up with international competition? Where could Chinese companies carve out intellectual property to protect their inventions? What could that government really do without running afoul of the World Trade Organization?
Many more questions were raised than answers arrived at, and I think most of the really interesting discussions took place away from the microphones and the simultaneous translation. So I cannot provide them for you.
Even without answers, the act of discussion was enlightening. I think the fact that these discussions are happening in public forums indicates the growth and transformation of Chinese society. There were finance people, engineers, businessmen, government regulators, all debating a difficult topic.
I don’t know the answers, but the little tigers know that the wolves are coming. And they are not running in fear. The openness of the internal debate within China indicates that the little tigers are working on a new plan, and no one should assume that the wolves are going to win. The competition in the domestic Chinese market — the very largest market, by far, of any in the world — is going to be very interesting over the next few months and years.
Greg Turetzky is a principal engineer at Intel responsible for strategic business development in Intel’s Wireless Communication Group focusing on location. He has more than 25 years of experience in the GNSS industry at JHU-APL, Stanford Telecom, Trimble, SiRF, and CSR. With this issue, he joins GPS World’s Editorial Advisory Board.
The statements, views, and opinions presented in this article are those of the author and are not endorsed by, nor do they necessarily reflect, the opinions of the author’s present and/or former employers or any other organization the author may be associated with.
The chief designer of the BeiDou Navigation Satellite System said China will advocate the use of the system, which will be compatible with new devices, “so that Beidou can function properly and independently even if something goes wrong with the GPS.”
Sun Jiadong, chief designer of BDS and an academician of the Chinese Academy of Sciences, made his comments in an interview with The Beijing News, as reported by the Chinese government’s website.
He added that this compatibility is the only way to ensure the protection of national information. “Safety issues abound in economic areas,” said Sun. “Ordinary people may have few concerns about the security of information but it is of vital significance.”
The development of Beidou also largely depends on the government’s involvement. “Even though the enterprises spare no effort in developing the system, the products they make would not be available for mass production, which will in turn be reflected by the prices. The government has to promote the research and development of the system,” Sun said. Sun cited the governments of Beijing, Shanghai, and Guangzhou as examples of local governments that were effectively helping to develop the BDS.
The use of Beidou could go beyond basic navigation functions and extend to the civilian market. It would take longer for the BDS to be available for civilians, said Sun. The use of Beidou on mobile phones relies on the development of a small and power-efficient chip. Otherwise the phone cannot be used.
When asked about when and how the cost of developing the BDS will be recovered, Sun reiterated that Beidou was developed to ensure the security of national information, and not to make profits.
The Beidou global navigation system will be available by 2020 with the launching of more than 30 satellites.
The K501 GNSS OEM board by ComNav is a GPS+BeiDou small-sized OEM board. K501 has advanced dynamic acquisition ability and high-accuracy carrier phase calculating. By using the GPS+BeiDou dual system high-dynamic processing engine, work in difficult environments is easier and RTK positioning accuracy can reach the centimeter level. The hardware size, interface, and data command are compatible with major brand OEM boards.
The K501 GNSS OEM board by ComNav
Features include:
GPS L1/L2+BeiDou B1/B2 dual satellite system calculating
Configurable GPS/BeiDou single-system positioning and GPS+BeiDou dual-system positioning
Compatible with other major brands on physical size, interface and data command
Directly export PJK coordinate
Supports short, middle and long baseline, RTK working distance can reach 50 KM
Easy to customize, can satisfy different kinds of demands
China’s icebreaker Xuelong, or Snow Dragon,returned to Shanghai April 9 after successfully completing China’s 29th Antarctica scientific expedition. As a high-accuracy GNSS solutions provider, ComNav supplied a GPS+BeiDou GNSS receiver for this expedition. This was the first time that the ComNav GNSS receiver worked in such an extreme environment.
The reliable performance of the receiver impressed the expedition team. “The fast-searching satellites speed and the accurate positioning result saved us lots of time in the extreme cold field,” said one team member. It was the first time that a BeiDou receiver was used in the Antarctic, according to ComNav.
The research vessel left the southern port city of Guangzhou on November 5, 2012, for Antarctica. It covered 29,000 nautical miles over its 156-day southern voyage, among which 6,000 nautical miles were in ice regions. A total of 239 researchers on board completed 53 research tasks on biology, ecology, geophysics, ocean, climate, environment and glacier, and engineering construction missions.
