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Trimble Announces New Precision Products, RolleiMetric Acquisition, and Saab JV


Trimble
has announced its new GNSS reference receiver — the Trimble NetR8 — for precise scientific and network infrastructure applications. The NetR8 reference receiver has 76 channels and supports GPS L1, L2, L2C and L5 signals as well as GLONASS L1/L2 signals.

Four additional channels are dedicated to tracking space-based augmentation systems
(SBAS), including Wide Area Augmentation System (WAAS) in North
America, European Geostationary Navigation Overlay System (EGNOS) in
Europe, Multi-functional Satellite Augmentation System (MSAS) in Japan,
Omnistar services and others.

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By Glen Gibbons
August 24, 2008

Agricultural and Energy Prices Driving GNSS Products and Services

From the perspective of consumers, the yearlong rise in commodity prices — from oil and natural gas to corn and wheat — has clouded the economic outlook. But for producers, including many GNSS manufacturers and service providers, those clouds have silver linings.

Recent financial reports from companies active in agricultural and natural resource markets bear this out. GNSS products used to guide and control equipment are in heavy demand as are real-time differential correction services, particularly those using global satellite-based systems.

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By Glen Gibbons
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July 6, 2008

GPS Southern Africa Conference and Exhibition

The GPS Southern Africa Conference and Exhibition – the first of its kind in Africa – takes place from 20 August to 22 August 2008 at the Indaba Hotel, Fourways, Johannesburg.

The conference will highlight the many new applications of GPS technology across the board and the penetration of GPS in transport, safety and security, mining, government, and mining.

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By Inside GNSS
June 19, 2008

Real-time Kinematic with Multiple Reference Stations

Multiple reference station RTK (real-time kinematic) is a complex, yet natural extension of single reference station RTK. Single reference station RTK actively and dynamically measures GNSS measurement errors, most notably satellite orbit, troposphere, and ionosphere errors.

Multiple reference station RTK (real-time kinematic) is a complex, yet natural extension of single reference station RTK. Single reference station RTK actively and dynamically measures GNSS measurement errors, most notably satellite orbit, troposphere, and ionosphere errors.

These measurement errors are characterized by their spatial correlation. To this end, in single reference station RTK, the errors are assumed to be constant everywhere around the reference station. In reality however, because the errors are not constant, the quality of these error estimates degrade as a function of distance and can reach an unacceptable level for ambiguity resolution after tens of kilometers.

One approach to ensure an acceptable level of measurement error over a wide geographic region is to deploy many reference stations, each operating independently. Once this infrastructure is in place, users select the reference station that will provide them with the greatest reduction of measurement errors and apply the corresponding corrections in the traditional single reference station RTK approach.

Unfortunately, the decision of which reference station to use can be problematic especially when the user is located between reference stations with nearly equally spacing. The estimated measurement errors at each of the reference stations may be different but the user is forced to discretely choose one or the other.

The solution to this problem is multiple reference station RTK. Instead of choosing the solution from one reference station or another, the multiple reference station solution allows users to combine the estimated measurement errors at each of the reference stations and smoothly transition from the errors at one reference station to another.

The multiple reference station solution is not only better because of the ease of use when transitioning between reference stations but also because the smooth combined solution is more likely to represent the user-observed measurement errors. This provides an even further reduction of user measurement errors, relative to the single reference station case.
. . .
The main advantage of multiple reference station RTK stems from the improved user performance. However, the improvement in performance can also be analyzed in an opposite manner, namely, as a way to increase the spacing between reference stations while still achieving the same level of performance. The performance improvement depends on many factors, including the variability of the measurement errors in the region and the ability to successfully resolve network ambiguities.

Multiple reference station RTK is more robust against station outages because a network solution can still be calculated even if individual reference station data is missing. However, due to the current trend of sparse network station spacing, the absence of any individual reference station would likely cause pockets within the network with less than desirable performance. Even under these conditions, the network solution is still more likely to provide a solution better than that from a single reference station.

This improvement comes at a cost of increased complexity and infrastructure. The data from all of the network reference stations must be collected in a central location for processing and then redistributed to network users. The cost of maintaining a processing center and data communication links for each reference station may be significant, depending on the number of reference stations and the country and region in which the network is located.

(For the rest of Paul Alves’ answer to this question, including figures and graphs, please download the complete article using the pdf link above.)

GNSS Solutions is a regular column featuring questions and answers about technical aspects of GNSS. Readers are invited to send their questions to the columnist, Prof. Mark Petovello, Department of Geomatics Engineering, University of Calgary, who will find experts to answer them.

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May 27, 2008

Topcon Draws on GNSS Expertise to Build Leadership

Recent leadership appointments at Topcon Positioning Systems (TPS) reflect the company’s efforts to expand its focus from being a vendor of equipment for surveying, civil engineering, and construction to a broad-spectrum provider of positioning solutions drawing heavily on GNSS-based technologies.

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By Glen Gibbons
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April 7, 2008

The Art of ARTUS–A Second-Generation Galileo/GPS Receiver

Creation of new global navigation satellite systems and modernization of existing ones is introducing many new signals across a wide swath of RF spectrum now and in the near future. These developments are accompanied by a growing need to design new GNSS receivers that can work with new signal structures on an increasing number of frequencies.

Europe’s Galileo program has supported a number of activities intended to promote innovations in receiver design, such as prototype Galileo user equipment, reference receivers, and so on.

Creation of new global navigation satellite systems and modernization of existing ones is introducing many new signals across a wide swath of RF spectrum now and in the near future. These developments are accompanied by a growing need to design new GNSS receivers that can work with new signal structures on an increasing number of frequencies.

Europe’s Galileo program has supported a number of activities intended to promote innovations in receiver design, such as prototype Galileo user equipment, reference receivers, and so on.

One such activity is a project named ARTUS (Advanced Receiver Terminal for User Services), 50 percent of which is financed by funds allocated by the Galileo Joint Undertaking (GJU). A consortium of four companies is leading the ARTUS project (see "Acknowledgments" below)

ARTUS supports the development of receiver technologies to aid the research and development activities for Galileo “professional” receivers. These efforts are designed to facilitate the availability of Galileo professional receiver prototypes and antennas at an early stage.

ARTUS provides Galileo/GPS navigation capability. All three Galileo frequencies (L1, E6 and E5a/E5b) are supported as well as the GPS L1, L2 and L5 (L5=E5a) frequencies.

The receiver supports any BPSK (GPS-C/A, Galileo E5a and E5b (sideband tracking), AltBOC (E5ab), Galileo L1-B/C (BOC(1,1)) as well as BOCc(15,2.5) (E1-A / E6-A); GIOVE-A transmits BPSK (E5a/E5b/E6) and BOC(1,1) (E1).

Although the receiver can track the modulations foreseen for the PRS, it cannot generate the corresponding codes. One can, however, do performance measurements using periodic substitute codes.

Although not initially planned, the consortium has decided to also implement the GPS L2 band for commercial reasons. The unit performs the measurements and processes the raw data to provide an RTK solution.

The Artus design will also form the basis for a breadboard development of the next generation RIMS receivers. This development will be conducted in the frame of an ESA contract lead by IFEN with NemeriX and Euro Telematik as subcontractors.

This article describes the design and operation of the second-generation ARTUS receiver with a particular focus on innovations in four key areas: antenna, RF front-end, digital baseband processing, and navigation software.

Although originally intended to focus primary on tracking Galileo and GPS signals, the flexible design of ARTUS also allows it to receive and track signals from the Russian GLONASS system and China’s Beidou.

After discussing the receiver design and operation, we will briefly describe some of the results of testing using combinations of laboratory GNSS signal simulators, signals-in-space, and simulated signals generated in the German Galileo Test Bed (GATE). . .

Conclusion
The ARTUS GNSS receiver described in this article offers a rich flexibility for various configurations of signals on different RF bands. The high performance antenna in conjunction with a flexible RF front-end design offers excellent performance on all currently available GNSS signal bands, including the upcoming Galileo system.

With the availability of up to 120 channels, the receiver is well equipped for future navigation systems; however, it can also be configured in a version with only 20 or 40 channels for tracking the currently available GPS (L1 and L2) alone.

The modular concept, applied even for the firmware of the baseband processor FPGAs, allows easy adaptation of the algorithms developed for the ARTUS receiver or fast implementation of new algorithms. And if the IP protocol is used, any user interface can easily connect — even remotely — to the receiver — whether for navigation or monitoring purposes.

The ARTUS project is now in its qualification phase. Further developments aim for the commercialization of the receiver.

(For the complete article, including figures, charts, and images, please download the PDF version at the link above.)


Acknowledgments

ARTUS was developed in the framework of a GJU 50 percent–funded project, contract GJU/05/2414/CTR/ARTUS. These activities have been taken over by the European GNSS Supervisory Authority (GSA). This support is gratefully acknowledged. IFEN served as the principal contractor for ARTUS.

The consortium members involved in the ARTUS receiver development are ifEN (overall system design and baseband processing), NemeriX (analog RF-front-end), Roke Manor Research (antenna and RF splitter), Leica Geosystems and inPosition (RTK software). In essence the ARTUS design is based on previous receiver developments carried out by IFEN in the frame of the German Galileo Test Bed (GATE).

GATE is being developed on behalf of the DLR (German Aerospace Center, Bonn-Oberkassel) under contract number FKZ 50 NA 0604 with funding by the BMWi (German Federal Ministry of Economics and Technology). DLR kindly gave its permission to publish the preliminary test results.

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Network Adjustment SW

NovAtel’s Waypoint Products Group offers the GrafNav/GrafNet Version 8.10 software, a high-precision GNSS post-processing package that supports raw data from most available GNSS receivers. Using data from both a roving station and as many as eight base stations, centimeter-level positions can be computed, according to the company. For applications in which base station setup is difficult or not desired, precise point positioning (PPP) is offered, which uses downloadable GPS clock and orbital corrections to compute solutions accurate to between 5 and 40 centimeters.

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By Inside GNSS
April 3, 2008

2008 ESRI Survey & Engineering GIS Summit

GPS Wing Commander David W. Madden will keynote ESRI’s Survey & Engineering GIS Summit in San Diego during the plenary session on Saturday, August 2. Col. Madden is responsible for the multinational, multiservice development of all GPS space, satellite, and ground segments.

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By Inside GNSS
March 10, 2008

Europe Readies Galileo Procurement

Having transformed the Galileo program into a fully public procurement, European agencies have announced a schedule that would lead to contracts for the €3.4-billion project by the end of 2008. And non-European companies may be involved in providing certain components and services to the effort.

The plans were revealed in presentations by high-ranking figures from the European Commission (EC) and European Space Agency (ESA) speaking at the Munich Satellite Navigation Summit in Germany, February 19–21.

In comments at the conference, Jacques Barrot, EC Vice President and commissioner for transport and energy, and Giuseppe Viriglio, ESA director of telecommunications and navigation, indicated that they hope to see invitations to tender (ITTs, essentially, requests for proposals) to be issued July 1.

Deadline for tenders would follow within a few months, followed by a review of bids and contract awards in December. Identification of prospective bidders and requests for information will precede the ITTs, activities that will probably begin within the next few weeks.

The EC and ESA still need to complete a “delegation agreement” that would outline the responsibilities and principles under which ESA would act as the prime contractor — the procurement agent and design authority that will oversee the engineering work and contracts under which the ground and space infrastructure would be built. It will receive an estimated €195 million for that role.

ESA will set up a new Galileo directorate, Viriglio said, to handle its responsibilities. The European Commission will act as the Galileo program manager, taking on additional staff to handle the work, according to Paul Verhoef, head of the Galileo Unit in the EC’s Directorate-General for Transportation and Energy. The ESA directorate would have about 30–40 staff members and the EC Galileo unit would gain about 35 persons to handle program management, according well-informed sources.

The procurement contract schedule will have to be met in order to have a chance to meet the goal of Galileo having a fully operational capability (FOC) by 2013.

The acquisition is divided into six “work packages”: system engineering support, completion of ground mission infrastructure, completion of ground control facilities, launchers, satellites (26 in batches of 10–12, 6–8, and 6–8), and operations.

No company or consortium of companies may bid for more than two of the six packages. The prime contractors must subcontract at least 40 percent of the work to companies not affiliated with them.

In the program’s clearest statement of interest in gaining from the GNSS-related experience of other countries, Viriglio underlined the possibility for European industries “to rely on non-European sources for certain components and services in case of demonstrated substantial advantages in terms of quality and costs, taking account of the strategic nature of the European GNSS programs and of the EU security and export control requirements.”

ESA Takes the IOV Reins. Meanwhile, ESA has already taken over as prime contractor for the in-orbit validation (IOV) phase of the program after a billion-euro contract with European Satellite Navigation Industries (ESNI) was terminated in December. IOV includes construction and launch of four full-fledged Galileo satellites in 2009–2010 to form a mini-constellation for additional validation testing before the other 26 spacecraft are launched in 2011–13.

All the other IOV contracts will be retained as will the associated technical baseline, said Viriglio. European officials still need to figure out how they will cover an estimated $350-million overrun in IOV caused by delays, unexpected security costs, a change in the Open Service signal design as a result of the 2004 EU-US agreement on interoperability of GPS and Galileo, and dependence on a single customer (ESNI).

European officials repeatedly emphasized that the €3.4 billion was the most that they would spend on implementing Galileo, and that competition for contracts would take place under European Union (EU) rules rather than ESA procurement policy, which allocates 90 percent of funds to businesses based on the contributions from the member states in which they are located.

The calculation of $3.4 billion is based on cost estimates by ESA, drawn primarily from industry proposals and earlier studies and concession negotiations under the Public Private Partnership (PPP) concept, which was discarded last year. The largest portion of the costs would be for the space segment — building and launching satellites — estimated at €1.6 billion; the ground segment, €400 million; operations, €275 million; and systems engineering support, €150 million.

Members of aerospace companies that will probably compete for the contracts were less optimistic in their estimates of whether $3.4 billion will be enough.

Galileo has one satellite in orbit, the so-called GIOVE-A, which launched in December 2005 and will reach the end of its design life in March, although its builder, Surrey Satellite Technology Ltd., predicts that it will continue operating at least through the end of 2008. A second, larger spacecraft, GIOVE-B, is now scheduled for launch on April 26 from the Baikonur space center in Kazakhstan.

More than €2.6 billion has been spent on Europe’s satellite navigation program to date, mostly by the EC and ESA. This includes €133 million for the definition phase, €1.5 billion for the IOV phase, €520 million for the European Geostationary Navigation Overlay Service (EGNOS), and €480 million for Galleo-related projects financed through the EU’s Framework R&D programs. EGNOS is a satellite-based augmentation system that will be integrated into the Galileo infrastructure and operations over the next few years.

Who Calls the Shots? A new regulation regarding financing, governing structure, and procurement procedures for Galileo will be taken up by the European Council in April. But now that the funding and acquisition process have been largely resolved, the outstanding issue facing the Galileo program is governance, that is, the matter of political direction and control of the system’s implementation.

Now that the funding and acquisition process have been addressed, the outstanding issue facing the Galileo program is governance, that is, the matter of political direction and control of the system’s implementation. That, in turn, will have a substantial effect on whether the program is able to stay on schedule and within budget.

Until the abandonment of the PPP, that issue had seemed fairly clear. The European GNSS Supervisory Authority (GSA), a Community agency with a executive board made up of directors from the EU member states, would sign and monitor a contract with a private consortium to build and operate Galileo under a 20-year concession.

Now, however, the GSA has lost that primary supervisory role and has come under pressure from both the EC and the European Parliament, which approved the €3.4-billion Galileo program budget last November.

The 2004 EC Council regulation that created the GSA also assigned it other responsibilities: market development of the Galileo operational phase, GNSS-related research, technical certification of the components and services of the Galileo system, management of Galileo security aspects, coordinating radio frequency activity, and managing the agreement with an EGNOS service provider.

The EC would clearly like to bring the GSA back under its direct control, either as a separate but subsidiary entity or by absorbing key technical staff members into the Galileo Unit headed by Verhoef. “What we need is the expertise of the GSA, either directly or through a transfer to an EC office,” Verhoef said at the Munich conference.

Two related approaches are now under consideration: retaining a GSA, separately or within the EC, and restructuring it as a GNSS Security Agency that would handle GNSS security issues and, perhaps, technical certification of the Galileo system being built under the supervision of ESA. ESA would take over most or all of the GSA’s technical responsibilities and the EC Galileo Unit, as program manager, would acquire most of the rest.

Parliament Joins the Fray. In late January, Parliament weighed in with a proposal before the Industry, Research, and Energy (ITRE) Committee that would abolish the GSA, turn responsibility for ensuring the Galileo system’s security requirements over to a new Committee on European GNSS Programs, and establish an Interinstitutional Monitoring Group (IMG) consisting of representatives of the parliament, the European Council’s Presidency, and the EC.

The proposed actions amending the EC’s draft regulation for deployment and commercial operation of Galileo were tentatively approved at a January 30 committee meeting. A final vote on the regulation as a whole by the committee and, later, by the full parliament had not taken place as Inside GNSS went to press.

Parliament clearly feels emboldened by the fully public procurement of Galileo for which the legislative body must approve a budget. In a plenary session at the Munich Summit, Etelka Barsi-Pataky, a member of the European Parliament, noted that “Galileo is a Community project, fully funded from the public budget — taxpayer money.

“We need very strong political control of the project,” she said, noting that in the 11 years since the EC submitted its first communication on satellite navigation, “We have produced a ton of paper, a lot of studies, a lot of discussion. What we need now is to build an operating system.”

Although a “substitute” rather than a full member of the ITRE Committee, Barsi-Pataky is the Galileo rapporteur, the person appointed by parliament to investigate an issue or a situation and report back to it.

By Inside GNSS
March 9, 2008

GPS-IMU

SRI International (SRI) has recently addressed the requirements of pointing systems for a variety of maneuvering platforms. These platforms include airborne systems (unmanned aerial vehicles, aircraft), land vehicles (tanks, HUMVEES), and marine vessels.

SRI International (SRI) has recently addressed the requirements of pointing systems for a variety of maneuvering platforms. These platforms include airborne systems (unmanned aerial vehicles, aircraft), land vehicles (tanks, HUMVEES), and marine vessels.

Our primary goal was to obtain 0.1-degree pointing accuracy. To achieve this, we considered several design options. A stand-alone navigation grade inertial measurement unit (IMU) seemed too expensive and heavy but has a clear advantage by being more immune to GPS outages. A magnetic compass–based solution appeared too problematic due to calibration and accuracy issues.

After other design trades were reviewed, we limited the path forward to tactical grade IMUs combined with GPS. Several different IMUs were then evaluated for integration into a flexible software package previously developed at SRI for position and attitude tracking of large parachute pallet loads.

A secondary goal was to establish a truth system to verify pointing accuracy of the developed system. The criteria that we set for the truth system were approximately 0.06 degree for kinematic applications and 0.02 degree for static applications. Moreover, we wanted all biases between the units under test and the truth system to be less than 0.01 degree.

Providing truth at this level of accuracy presents difficulties, however. Optical systems can easily attain this level of accuracy for static tests but are difficult for dynamic tests.

A stand-alone GPS attitude system works well for kinematic tests, but the static accuracy requirement would need too long of a baseline to be portable. Ultimately, a hybrid system was developed using both optical and GPS methods.

The first part of this article presents the component analysis and differences for the MEMS IMU versus the tactical grade unit. Then we discuss the design and architecture for the system and the associated GPS/INS navigation processing software. Next we discuss implementation differences for the various components.

Following those sections, we consider the truth systems developed at SRI. Finally, we discuss the tests performed, truth data analysis methodology, and results.

This SRI initiative has led to the implementation of GPS/IMU systems on a variety of platforms. . .

Conclusions
With suitable dynamics, both varieties (fiber-optic and MEMS) of IMU/GPS combinations were capable of providing an azimuth to within at least 0.06° 1 σ. Furthermore, the Allan variance analysis accurately predicted the azimuth drift performance of the IMU systems.

Additional testing on the FOG units showed azimuth to be determined faster and more accurately with RTK data than with L1 data. The telescopic sight proved to be a convenient way of testing for static cases. The long-boom GPS attitude system, coupled with averaging, appears to give very good testing accuracy during dynamics.

Acknowledgment: We wish to thank Patrick Weldon of Honeywell for lending us on short notice the MEMS unit used in our tests.

(For the complete article, including figures, graphs, and additional resources, download the PDF version at the link above.)

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