Let’s all remember, brevity is the soul of wit.

GPS III Flexible Signal Generator. With completion of the Delta Preliminary Design Review for the GPS III satellites, Lockheed Martin and the U.S. Air Force announced that “an innovative new waveform generator permits the addition of new navigation signals after launch to upgrade the constellation without the need to launch new satellites.”

IGS Real-Time Service. The International GNSS Service, a worldwide federation of agencies involved in high-­precision GNSS applications, announced the launch of its Real-­Time Service (RTS). The RTS is a global-scale GNSS orbit and clock correction service that enables real-time precise point positioning and related applications requiring access to IGS low-latency products. The RTS is offered in beta as a GPS-­only service for the development and testing of applications.

QZSS Will Grow to Four. The Japanese government has ordered three navigation satellites from Mitsubishi Electric Corp. to expand the Quasi-Zenith Satellite System, currently orbiting the sole Michibiki. QZSS augments GPS navigation signals for users in the Asia-Pacific region. NEC Corporation has been awarded a contract for the QZSS ground control segment.

Real-Time PPP with Galileo. Fugro Seastar AS achieved this task within a week of all four Galileo satellites being activated. Fugro is now generating Galileo orbit and clock corrections, which can be used in conjunction with the Fugro G2 decimeter-level corrections associated with its GPS/GLONASS PPP service.

BeiDou Ground System Approved. The BeiDou Ground-Based Enhancement System (BGBES), a network of 30 ground stations, an operating system, and a precision positioning system, was approved by a Chinese government evaluation committee. The system is expected to improve BDS positioning accuracy to 2 centimeters horizontal and 5 centimeters vertical via tri-band real-time precision positioning technology, and to 1.5 meters with single-frequency differential navigation technology.

CNAV Test on GPS L2C and L5. The U.S. Air Force Space Command announced that CNAV capabilities on the GPS L2C and L5 signals will be tested in June. The civilian navigation message to be carried by modernized GPS will have similar data to the existing NAV message, but its structure will be different, with increased message bandwidth for greater information density. L2C and L5 users and receiver manufacturers are encouraged to review the test plan, provide comments, and participate in the evaluation process.

GPS at the Smithsonian. Brad Parkinson’s presentation, “GPS for Humanity — The Stealth Utility,” is now available as video on UStream.The talk helped introduce the new Smithsonian National Air and Space Museum exhibit, “Time and Navigation: The Untold Story of Getting from Here to There,” which is now open and free to the public in Washington, D.C.

Launch, deploy, and operate “22 satellites in less than 3 years.” That’s two satellites every three months, leading to a four-at-once launch in 2014. And that’s the challenge that Europe and the European Space Agency (ESA) now face.

This pointed call to action during the opening plenary of the European Navigation Conference (ENC) came from Didier Faivre, director of Galileo Programme and Navigation Related Activities at ESA. It was the only somber note sounded during the keynote speeches, which otherwise paraded the stirring recent accomplishments of the Galileo In-Orbit Validation (IOV) phase. IOV now concludes, and Galileo’s operational phase opens.

The ENC takes place in Vienna, Austria this week (April 23–25), hosted by the Austrian Institute of Navigation. Privately and informally, a handful of knowledgeable conference attendees expressed confidence that OHB System can furnish the completed satellites, at least, according to schedule. OHB System is the prime contractor for  construction of 22 Full Operational Capability (FOC) Galileo satellites and is responsible for developing the satellite bus and for integrating the satellites. Surrey Satellite Technology Ltd. (SSTL) is developing and constructing the navigation payload and  assisting OHB with final satellite assembly.

“Using only European tools and means, European ground infrastructure deployed on European territory, our conception, machine and design, is totally validated,” stated Faivre, referring to the recent Galileo-only positioning fix by ESA. The March 12, 2013, event marks “the end of the beginning,” and culminates 12 years of intense work at all levels of European industry.

“Europe is at par with GPS” with performance as expected. “I hope that soon our U.S. colleagues will be jealous of our performance,” Faivre stated, implying yet again the persistent Galileo claim that the system will be more accurate than GPS. He returned to this theme with reference to Fugro’s accomplishment of real-time precise point positioning at the centimeter level.

He acknowledged that “It’s a technological competition with the United States, Russia, and China,” even though all may be friendly and collegial.

In that competitive light, “the success of Galileo will be measured by the number of users,” and not by the number of satellites, or the degree of accuracy, or the strength of the signal.

Previously, the ENC audience had heard from Ingolf Schädler that “Europe has closed the gap with the technological superpowers,” in what “may be the most complex invention ever of mankind, the system of navigation that is GNSS.” He also made a proud reference to Austrian-produced signal generators aboard Galileo’s orbiting IOV satellites. Schädler is the deputy director general of innovation for the Austrian federal Ministry for Transport, Innovation and Technology.

“We have reached cruising speed,” announced the third keynote speaker, Carlo des Dorides of the European GNSS Agency (GSA). He was referring explicitly to the re-positioning of the GSA headquarters from Brussels to Prague, but the remarks reverberated to the Galileo program as a whole.

David Blanchard, deputy head of unit, EU Satellite Navigation Programmes for the European Commission, quoted an unnamed U.S. publication: “With the capability to make a position fix from four signal-broadcasting satellites, we can now say that Galileo has truly arrived.”

That statement appeared in the May 2013 GPS World, an issue of the magazine that was distributed in conference bags to all attendees at the ENC.

Blanchard then shifted the focus slightly from Galileo, to Galileo together with the European Geostationary Navigation Overlay Service (EGNOS), Europe’s satellite-based augmentation service that also broadcasts GPS corrections. “We have to make sure that all the capabilities afforded by EGNOS are realized.” He also made strong references to the EGNOS Data Access Service (EDAS).

Blanchard cited a current ongoing study that shows that 6 to 7 percent of European gross domestic product (GDP) is dependent upon GNSS.

“A gold mine within arm’s reach of European industry” was how Gard Ueland, head of Galileo Services, characterized the present situation. “Development of European downstream market is crucial; it also has to bring more benefits to European society.” Galileo Services will host a workshop of  industry stakeholders in late October, at the OHB System premises in Bremen, Germany. Watch GPS World Events calendar and news for an announcement with specific dates.

Having attained altitude and cruising speed, the Galileo program must now shift to warp speed to hit its goals on time: 18 satellites in orbit by the end of 2014, and a total of 26 by the end of 2015. Early services by the end of 2014, and full services in 2016. Stable, continuous services, as Blanchard emphasized.

Better go to overdrive.

The April 18 webinar is free, but you must register beforehand. A downloadable file of the webinar will be available roughly one week afterwards, in case you miss the live presentation. Speakers include Khaled Dessouky from TechnoCom Corporation, a company that supervised the trials; Ganesh Pattabiraman from NextNav and Norm Shaw from Polaris Wireless, two companies whose technologies underwent rigorous testing in the trials; and Greg Turetzky from CSR, a company closely involved in the process.

Testing Overview

Conducted by the Communications Security, Reliability, and Interoperability Council (CSRIC) of the Federal Communications Commission (FCC), Working Group 3 (WG3), the tests trialled thousands of attempted location fixes in four representative morphologies (dense urban, urban, suburban, rural) and various building types.

The massive R&D movement focus on consumer-level applications, that is, cell phones, but this work will also ultimately affect professional and high-precision uses of GNSS. Those involved in machine control for warehousing, industrial assembly, indoor and even underground mapping, construction both above- and underground, underground mining, utility work, and even forestry will find this of particular interest — any activity in areas where sky-view is limited or negligible.

Test Fixture (cart) used during indoor testing.

Today, well more than half of mobile phone calls are made inside buildings. The number of emergency calls roughly parallels that, and both figures are only projected to rise. The FCC has a clear mandate to bring E-911 capability to indoor calls.

The 2001 regulations governing such emergency calls required that both landlines and cellphones should provide the location of callers to within specific accuracy levels. Location information was to be sent transparently to public safety answering points (PSAPs), to dispatch fire/rescue/police personnel to the source the 911 call, and not just to the right street address, but to the right floor of a multi-storied building. That’s the driver for all this.

Widespread application of successful technology/ies meeting the indoor requirement, once determined, is the key to significant revenue for many parties, not least of them GNSS manufacturers and location-based services (LBS) providers.

GPS and augmented GPS technologies were only part of the cellphone solution, and other implementations included use of the cell signal itself along with an extensive database which can contain amongst other things signal attributes and network asset locations.

The WG-3 Locations Based Services (LBS) sub-group set about finding what technologies exist, how well they work and how they could be applied to E-911. Click here for the full report.

In the tests, Polaris Wireless used an RF pattern-matching/fingerprinting technique, Qualcomm used a hybrid assisted-GPS (A-GPS)/advanced forward link trilateration (AFLT) system, and NextNav used wireless beacon technology.

WG3 selected the San Francisco Bay Area for the Stage-1 Indoor Test Bed. The methodology centered on indoor testing in sample buildings within the most common wireless use environments, called morphologies: dense urban, urban, suburban, and rural.

Dense urban: Bldg. 2: One Front Street, San Francisco, California.

Urban: Bldg. 18: Super 8 Motel on O’Farrell St., San Francisco, California.

Suburban: Bldg. 8: 861 Shirley Avenue (house), Sunnyvale.

Rural: Bldg. 13: Gilroy Gaits, Beige Stable Building, Hollister, California.

Polygons surrounding areas containing 19 buildings were selected; the distribution of buildings tested was 6 dense urban, 5 urban, 6 suburban and 2 rural. 75 test points were selected by TechnoCom within these 19 buildings. Statistically significant samples of stationary test calls were placed from each test point using multiple test devices for each of the 3 location technologies under test by NextNav, Polaris Wireless, and Qualcomm.

More than 13,000 valid test calls were collected across the test points for each of the three technologies. Broad, representative wireless industry participation in the test bed meant that Polaris’ results were aggregated over AT&T’s and T-Mobile’s networks; Qualcomm’s results were aggregated over Sprint’s and Verizon’s networks; and NextNav operated essentially as a standalone overlay location network.

A certified land surveyor provided indoor ground-truth accuracy to compare test-call locations. The certified accuracy was +/-1 cm horizontal and +/-2 cm vertical.

The test results show the location-performance attributes under test: horizontal location accuracy, vertical accuracy, yield, time to first fix (TTFF), and reported uncertainty.

NextNav Summary Indoor Accuracy Statistics.

Polaris Summary Indoor Accuracy Statistics.

Qualcomm Summary Indoor Accuracy Statistics.

Dense Urban Environment

Satellite signals (in this instance, GPS) have, of course, significant challenges in penetrating large buildings. Consequently, AGPS fall-back modes, such as AFLT, were experienced frequently. Accuracy degraded as expected when GPS fixes were not attained. While a surprising proportion of hybrid fixes were experienced, even at test points where one would not expect a satellite signal to penetrate, the quality of the hybrid fixes was in general significantly degraded compared to GPS fixes.

RF finger-printing experienced its best performance in the dense urban setting. This is probably a combination of a confined environment that could be extensively calibrated and many RF cell sites and handoff boundaries that could be leveraged in creating a good RF fingerprint map of the dense urban center.

The best observed performance in the dense urban setting was that of the dedicated terrestrial (beacon) location system — a new infrastructure. However, due to multipath, location fixes that may be relatively close in absolute distance (for example, 40 meters away) are often located in a building across the street, in a neighboring building, or even across a few blocks from the test point.

Urban Environment

Each individual test building in the urban morphology produced different challenges, and the three technologies under test met them in varying degrees.

A major-league baseball stadium created a situation where AGPS fallback fixes could be very far away due to the exposed RF propagation outside the structure in which the test points were located. Stadium structure created challenges to RF fingerprinting at some test points.

A convention center created in some cases an environment that was deep indoors but with very strong cellular signal from cell sites inside the building. This made the beacon-based location system perform poorer than in most other test points, since attenuation to different directions in the outside world was particularly strong in those scenarios. AGPS and RF fingerprinting relied on the cell sites inside the structure to create adequate location fixes.

An older building of comparatively heavy construction, with a large atrium in its middle, produced widely varying results based on distance from windows or the atrium. Again, the phenomenon of apparent location in a building across the street was seen for both NextNav and Qualcomm. RF fingerprinting fixes appeared to cluster about the larger reflectors in this urban corner of San Francisco, which happened to be mostly across the streets from the target building.

A motel building demonstrated the unique challenge with indoor location: absolute distances (like 50 or 150 meters) which may have meant much in assessing outdoor performance mean less for the indoors, since emergency dispatch to the wrong building or even the wrong block could be easily encountered at those distances. A location across the street is certainly better than one a few or many blocks away but it may still leave some human expectations unmet.

A tall condominium building in a (non-dense) urban downtown San Jose created relatively poor AGPS performance, uneven beacon system performance, and RF fingerprinting performance that degraded with the height of the test point. All of the above factors related to each of the urban buildings, combined with a generally lower cell site density for fall back (than in dense urban), resulted ultimately in an aggregate urban performance that is slightly worse than the dense urban performance.

Suburban Environment

The effect of smaller buildings with lighter construction and more spacing between buildings quickly became evident. Outstanding GPS performance, almost as good as outdoors, can be achieved inside single-story homes. Similarly outstanding performance is achieved on average by the beacon-based location technology under similar circumstances. RF fingerprinting appears to suffer from performance degradation compared to more dense morphologies in the city.

The AGPS performance predictably changes as the suburban buildings become bigger and higher. The terrestrial beacon-based network continues to perform well in the larger suburban. RF finger-printing shows some enhancement relative to the smaller suburban buildings, but still shows most of the location fixes along the roads, highways or reflecting buildings.

Rural Environment

Large one-story structures with metal roofs limited the available number of satellite signals available for trilateration. In these cases more hybrid fixes were experienced with a concomitant increase in the spread of the location fixes about the true location. The performance of the beacon-based network was less impacted by the metallic roof (since that roof had more impact on sky visibility rather than on side visibility towards terrestrial beacons). Consequently the performance was somewhat better than for AGPS. The performance of the beacon-based network would of course depend on the density of its deployed beacons covering the rural area, which was sufficient in the case of the rural test polygon.

RF finger-printing showed reduced performance relative to the suburban environment due to the large spacing between surveyed roads (where calibration is done) and the rural structures as well as the lower density of cell sites.

Conclusion

Finally, the report concludes: “Stage-1 of the test bed contained in the end only three technologies to test. With the complexity of the task at hand, this created a good learning opportunity for both CSRIC WG3 members and the test house. However, there are a number of technologies that are either in use for location based services (LBS) or that are emerging which should be evaluated for their potential to contribute to the improvement of indoor wireless E911.

“Indoor wireless E911 is a critical public safety issue that will only increase.”

One key factor that the report does not at all address is relative cost of implementing these respective solutions. The same can be said for timeline. While some observers have concluded that “NextNav came out on top,” this solution in particular can be presumed to face much greater challenges for full or nationwide implementation than the other two, which rely largely on already existing infrastructures.

Another round of E-911 test-bed activities will ensue once funding and management issues are resolved. See CSRIC WG 3 LBS Subgroup member Greg Turetzky’s “Expert Advice” column from GPS World for perspective and a forward look.

Once again, for an up-close and personal look at the CSRIC Bay Area indoor tests, register beforehand here for Thursday’s webinar, April 18. A downloadable file of the webinar will be available roughly two weeks afterwards, in case you miss the live presentation.

My acquaintance with the system began in July 2000, when I joined the staff of GPS World and received my first assignment, editing an article about GPS-bearing carrier pigeons in the sister publication Galileo’s World, from founding editor Glen Gibbons. We published Galileo’s World quarterly from 2000 to 2002, chronicling the ups and downs, forward steps and back, of the European GNSS. Unless you counted EGNOS — really telecom satellites with a piggyback SBAS payload — Galileo had no space vehicles as yet, but did encompass plenty of political and financial maneuvering, rhetoric, market projections, international negotiations, and technical blueprints. In short, the stuff of news. For application stories in the magazine, we filled with European uses of GPS, all of which would eventually integrate Galileo as well.

In 2002, a UK-based travel agency of the same name began to assert its legal possession of the name Galileo, and sent a cease-and-desist shot across the bows to the corporate ownership of the two magazines, and to the European Union. The EU felt it had sufficient legal clout or standing of some kind, for it neither desisted nor renamed its space program. But our counsel at the time instructed us to quietly fold up our tent and steal away. The impending battle wasn’t worth our stake.

And so Galileo’s World sadly ceased publication. Not for lack of interest, or support, or commitment. But because of someone else’s greed or turf belligerence in a completely unrelated market. Such is the way of the global economy.

We have covered every step of Galileo’s way, technically, economically, and politically, in the pages of GPS World. Occasionally we ponder calling ourselves GNSS World, or even PNT World. But the brand, like the satnav system it is named after, is just so strong, it would be foolhardy to walk away from it, at this point in time at least.

We continue to support European satnav progress at each successive stage. And so we say yet again: Welcome, Galileo!

Measurements of individual Galileo horizontal position fixes performed for the first time using the four Galileo satellites in orbit plus the worldwide ground system between 1000 and 11:00 CET on Tuesday 12 March 2013, showing an overall horizontal accuracy over ESTEC in Noordwijk, the Netherlands, of 6.3 m.

Galileo Logs First Autonomous Fix; Galileo over Canada (By James T. Curran, Mark Petovello, and Gérard Lachapelle); and Indoor Nav: Early Steps towards FCC Standards

Galileo Logs First Autonomous Fix

Entitling its release “From Orbit with Love,” the European Space Agency (ESA) announced March 12 that the four current satellites of the Galileo constellation achieved their first autonomous position fix. The feat was replicated by the NavSAS group of Politecnico di Torino, by GNSS manufacturer Septentrio, and by a University of Calgrary team as the four satellites appeared over North America.

The obtained accuracy lies in the 10-meter range, according to ESA, adding that this fulfills expectations, considering the infrastructure is only partly deployed. The fix was obtained by ESA’s Netherlands navigation lab, using the four satellites, launched in October 2011 and 2012, and the Galileo programme’s ground infrastructure: control centers in Italy and Germany and a global network of ground stations.

With only four satellites for the time being, the full Galileo constellation is visible at the same time for a maximum two to three hours daily. This frequency will increase as more satellites join the constellation in orbit, along with extra ground stations coming online, for Galileo’s early services to start at the end of 2014.

With the validation testing activities under way, users might experience breaks in the content of the navigation messages being broadcast, said ESA. In the coming months the messages will be further elaborated to define the offset between Galileo System Time and Coordinated Universal Time (UTC), enabling Galileo to be relied on for precision timing applications, as well as the Galileo to GPS Time Offset, ensuring interoperability with GPS.

NavSAS Confirmation. Almost simultaneously with the ESA announcement, the NavSAS group of Politecnico di Torino and Istituto Superiore Mario Boella in Turin, Italy, also achieved a position fix using the signals of the four In-Orbit Validation satellites (PFM, FM2, FM3, FM4). NavSAS researchers computed the positions using full software receivers developed by the team.

Septentrio, Too. Septentrio became the first receiver manufacturer to report an autonomous real-time position calculation using Galileo IOV satellites with its own standard commercial receiver. The company based in Leuven, Belgium announced on March 12 that it performed  standalone position calculated from in-orbit navigation messages using a standard PolaRx4 GNSS receiver equipped with commercially released firmware.

This achievement was followed by a further Septentrio release stating performance of what it believes to be the first 4-constellation PVT by a standard commercial receiver, on March 12 at approximately 10:35 UTC.

The milestone in all three accounts is that it is Galileo-only real-time positioning. Galileo positioning in post-processing mode was described by authors from the Technische Universität München and the German Space Operations Center, in a GPS World account, February 2012 issue.

Galileo over Canada

By James T. Curran, Mark Petovello, and Gérard Lachapelle

Within a day of activation over Europe, Galileo satellites were visible over North America. The PLAN Group of the University of Calgary captured and processed signals from Galileo PRN 11, 12, and 19 on E1B/C. The PLAN software GSNRx  simultaneously tracked GPS L1 and GLONASS L1 for combined solutions in real time.

The Galileo navigation message on E1B stated that the satellite health status is flagged as E1BHS=3 meaning “Signal Component currently in Test” and the data validity status is flagged as E1BDVS=1 meaning “Working without guarantee.” Current Galileo-ready commercial receivers may automatically discard measurements from a satellites broadcasting such messages. Parsing the received words in the I/NAV message, more than 50 percent were of type 0, although all words (types 0 to 10) were decoded at some point during the test.

Figure 1. 2D position errors.

Data was collected using a roof-mounted NovAtel 702GG antenna and an in-house two-channel digitizing front-end clocked by a high quality OCXO, in addition to a three-channel National Instruments front-end for post-processing. The two-channel intermediate frequency data was streamed live to a laptop computer for real-time processing with GSNRx. The GPS and GLONASS signals were tracked using a Kalman-filter-based tracking strategy while the Galileo signals were tracked using a specialized data-pilot algorithm.

Pseudorange and Doppler observations were extracted from the tracking strategies at a rate of 2 Hz. Single-frequency single-point position solutions were then computed for each of the three systems, each of the three pairs of systems and for the full combined Galileo-GLONASS-GPS. In the case of the three-satellite Galileo solution, the height was held fixed. Figure 1 shows 2D position errors with respect to antenna ITRF coordinates. Departures of the solutions involving GLONASS are likely due to orbital biases, given location of Calgary with respect to GLONASS ground stations.

Figure 2. Pseudorange residuals.

Next, by fixing the known position in the solution and solving only for the three clock biases, accurate pseudorange residuals were computed and are shown Figure 2. Galileo PRN 19, launched a year later than PRN 11 and 12, exhibits larger residuals, perhaps attributable to ephemeris or orbital errors. The overall results show very good consistency of the Galileo results and the PLAN Group equipment and GSNRx receiver.

Indoor Nav: Early Steps towards FCC Standards

The Federal Communications Commission (FCC) on March 14 released two reports from its Communications Security, Reliability, and Interoperability Council (CSRIC): the “Indoor Location Test Bed Report,” and “Leveraging LBS and Emerging Location Technologies for Indoor Wireless E9-1-1.”
They report on Bay Area tests of technology from NextNav, Polaris Wireless, and Qualcomm, in four representative morphologies (dense urban, urban, suburban, rural) and various building types. They are available online, via www.gpsworld.com/csric, are the subject of an Expert Advice column (see page 10), and will be more fully discussed in May issue.  For now, this summary from the first-named report:

“Seven location vendors/technologies began the process to demonstrate their performance indoors through the common test bed, but only three completed the process. Of these three, two technologies (AGPS/AFLT and RF Fingerprinting) are already in common use for emergency services, while the third (metropolitan beacons) is not yet commercially available. However all technologies tested demonstrated relativity high yield and various levels of accuracy in indoor environments.

“Significant standards work is required for practical implementation of many emerging location technologies for emergency services use.

“Many positioning methods require handset modifications. Integration of these modified handsets into the subscriber base, once the location technology is commercially available, will take years to complete.

“Progress has been made in the ability to achieve significantly improved search rings in both a horizontal and vertical dimension. However, even the best location technologies tested have not proven the ability to consistently identify the specific building and floor, which represents the required performance to meet Public Safety’s expressed needs. This is not likely to change over the next 12–24 months. Various technologies have projected improved performance in the future, but none of those claims have yet been proven through the test bed process. It is hoped that such technologies would be tested and validated in future test bed campaigns.”

An April 16 GPS World Webinar covers this topic with test participants. Registration is free.

The questions that candidate speakers are asked to address (given further on in this column) read like a primer on modern signal design, and suggest the complexity of issues dealt with at this very high technical level. The depth and level of detail at which the session organizers seek input reveal — what? That such issues are truly not yet determined by U.S., Chinese, Russian, and European system operators? This is impossible to know, outside government circles, and could easily be doubted by cynical minds. Yet the organization of such a workshop hints that at least some, if not many, such delicate matters remain in flux and under discussion.

The organizers seek three speakers each in four main topic areas. They emphasize that they are trying to involve only those who design GNSS receivers, not users, service providers, or product integrators.

High-Precision Code is for products with sub-decimeter accuracy that use wide area correction signals such as from OmniSTAR or StarFire.

High-Precision Phase is for products with sub-cm accuracy that use terrestrial correction signals to resolve carrier phase ambiguities.

Medium Precision is for products with sub-50 cm accuracy, which often are single-frequency receivers using local correction signals.

Consumer Applications are for chipsets embedded in consumer products.

If you want to participate, in person, by Internet, or by recorded PowerPoint presentation, you can contact the workshop organizers via GPS World magazine, by emailing editor@gpsworld.com. Please indicate the topic that best fits your presentation. If you are not selected to speak, you are welcome to submit a paper or presentation that will be given to each signal provider.

Specific questions that candidate speakers are asked to address include:

Supported applications: What types of applications do your receivers (or receiver designs) support?

Increase in noise floor: Do you see a threat to GNSS receivers due to many more GNSS signals centered at 1575.42 MHz?

Whether you see a threat or not, do you prefer all new CDMA signals at L1 to be centered at 1575.42 MHz, or have some of them elsewhere, e.g., at 1602 MHz?

Given that most GNSS providers plan to eventually transmit a modernized signal at 1575.42 MHz, what is your long-term perspective on whether you will continue to use C/A? Why and How?

CDMA and FDMA: Once there are a large number of good CDMA signals, will there be continuing commercial interest in FDMA signals? Why or why not?

Compatibility: Do you prefer signals in different L1 frequency bands for interference mitigation rather than at one center frequency for interoperability? Why?

What to do about misbehaving signals: If a satellite’s signals do not meet quality standards, should they:

• Be set unhealthy?
• Transmit with a nonstandard code?
• Transmit with reduced signal power (reduce interference)?
• Be switched off?
• What combination of the above?

To assure only good signals, should GNSS providers agree on minimum international signal quality standards and agree to provide only signals meeting the standard?

E5a and E5b: Given that L5/E5a will be transmitted by most GNSS providers, do you intend to use the E5b signal? If so, for what purpose?

Frequency steps: For your applications, are small satellite frequency steps (Δf) a problem?

If so, what interval between frequency steps and what Δf magnitude would be excessive?

Interoperable use: Assuming signal quality is acceptable from every provider, would you limit the number signals used by provider or by other criteria? What criteria?

Is having more signals inherently better or do you think there should be a limit?

Will the marketplace force you to make use of every available signal?

For best interoperability, how important is a common center frequency? How important is a common signal spectrum?

Another common open-service signal: Will you provide tri-lane capability in the future? Why?

If so, do you prefer a common middle frequency or the combined use of L2 (1227.6), B3 (1268.52), and E6 (1278.75) if B3 and E6 open access is available?

Would you prefer a common open signal in S Band? In C Band? Why?

Precision code measurements: Does a wider satellite transmitter bandwidth help with multipath mitigation?

What minimum transmitter bandwidth would you recommend for future GNSS signals in order to achieve optimum code precision measurements?

Added GNSS or SBAS messages: Would you recommend GNSS or SBAS services provide interoperability parameters:

• System clock offsets
• Geodesy offsets
• ARAIM parameters
• Others

Should they be provided by other means so as not to compromise TTFF or other navigation capabilities?

Signal coherence: For your applications and for each signal, what amount of drift between code and carrier over what time frame would be excessive?

For your applications and for two or more signals in different frequency bands, e.g., L1 and L5 (when scaled properly), what amount of relative drift in code and carrier between the signals would be excessive?

Spectrum protection: Should the international community strive to protect all GNSS signal bands from terrestrial signal interference?

System geodesy: Do the current differences (~10 cm) in geodesy pose a problem for your users? Why or why not?

If geodesy differences are a problem, what is the preferred method of compensation:

• Published values (e.g., on websites)
• Satellite messages

System time: Do you want each system to cross-reference the other’s time (e.g., with a GGTO type of message) or compare itself to a common international GNSS ensemble time? To what precision?

Will your future receivers calculate a time offset between systems based on signal measurements or use only external time offset data?

What is the preferred method of receiving time offsets: Satellite messages, Internet messages, or internally calculated?

Further information and background on the April 26 session can be downloaded at http://www.mediafire.com/?cegvqb9l8ya1c.

The timed agenda for the April 26 meeting follows, showing both Hawaii Standard Time (HST) and Coordinated Universal Time (UTC), provided because some presenters will speak from remote locations using GoToMeeting over the Internet. Another option for presenters is to provide a PowerPoint file with embedded audio.

HST/UTC        Topic                        Presenter

9:00/19:00     Welcome and Introduction     Working Group Co-Chairs

9:25/19:25     Welcome and Introduction     Xiaochun Lu

9:35/19:35      Framing the Presentations    Tom Stansell

9:50/19:50     Certified Avionics           TBD

10:15/20:15     High Precision Code #1       TBD

10:40/20:40    Break

10:5520:55     High Precision Code #2       TBD

11:20/21:20     High Precision Code #3       TBD

11:45/21:45     High Precision Phase #1      TBD

12:10/22:10     High Precision Phase #2      TBD

12:35/22:35     Lunch

13:35/23:35    High Precision Phase #3      TBD

14:00/0:00     Medium Precision (~GIS) #1   TBD

14:25/0:25     Medium Precision (~GIS) #2   TBD

14:50/0:50     Medium Precision (~GIS) #3   TBD

15:15/1:15    Break

15:30/1:30     Consumer Applications #1     TBD

15:55/1:55     Consumer Applications #2     TBD

16:20/2:20     Consumer Applications #3     TBD

16:45/2:45     Summary                      Tom Stansell

16:55/2:55     Summary                      Xiaochun Lu

17:05/3:05     Conclusion       Working Group Co-Chairs

17:25/3:25     End

Paul Flament

A Constellation of 18 by 2015, Rising to 26 by the End of That Year

An Interview with Paul Flament

Paul Flament is the European Commission Programme Manager and Head of the EU Satellite Navigation Programme Unit.

A Belgian civil engineer specialized in telecommunications, he previously worked  for 11 years in the European Space Agency, for space missions control centers and for the design and development of telecommunication satellites. After obtaining a master’s degree in European Studies, he joined the European Commission in 1998.

On the occasion of this special Europe/Galileo issue of the magazine, he speaks to GPS World readers regarding the present and promising future of the European GNSS.

Alan Cameron (AC): Can you recap for us briefly the upcoming satellite launch schedule that will take Galileo to Initial and then to Full Operating Capability?

Paul Flament (PF): It’s very simple. The first two in-orbit validation satellites were launched in October 2011, the next two on October 12, 2012. Satellites 5 and 6 will be launched in September of this year, aboard a Soyuz launcher from Kourou, and numbers 7 and 8 will follow in December.

Then, in 2013 we will see three Soyuz launches of two satellites each. We do not have the precise launch dates yet, but they are likely to be in April, June, and September. In December 2014, we expect to have the first launch using the Ariane 5 launcher, which is capable of deploying four satellites in one go. This means that by the end of 2014 Galileo will have deployed 18 satellites in orbit.

In 2015, there will be two Ariane 5 launches, one in the middle of the year, one at the end, each carrying four satellites. This will bring the total number of satellites to 26 by the end of 2015.

I am doubly confident of this constellation deployment schedule. First, at the technical level: The European Commission (EC) together with the European Space Agency (ESA) is following very closely all the industrial activities. The satellites in production now are with OHB. We have people in Bremen, where the OHB facilities are located, following this very closely. If there are technical issues, we take them up straight away with those concerned, the moment they appear. We also have monthly meetings with Jean-Jacques Dordain, the director general of ESA, and we make a careful tour of all the dates and conditions.

Secondly, there are no unknowns from the budget point of view. Except for the cost of the Ariane 5 launchers, the costs of deployment are already covered. And the EU’s member states have agreed on a budget of €6.3 billion for the next seven years. Budget should not be an issue.

Just recently, on March 12 of this year, we were for the first time able to calculate positions with the four Galileo satellites already in the sky. They pass overhead every so often, depending on geometry of orbit. This is an important technical milestone, even if this does not provide you a service as such. It demonstrates that the capability is there and that the mission part of the system works.

In terms of services, we want to be able at a certain point in time to start offering a guaranteed service. Our objective is October 2014. We will then have a constellation of 14 satellites. On the basis of that constellation, taking some margins, we will guarantee a minimum service of eight operational satellites. That service, in combination with GPS and other systems like GLONASS, will be something that users can start counting on. We will guarantee that at least eight satellites will be in operation from that moment onward.

We will probably translate this number of satellites into a performance-level guarantee. But for the moment it will be based on the number of satellites.

The fact is that we are populating the constellation, and very quickly we will have 26 satellites in orbit. That leads us to the Initial Operational Capability (IOC) phase: With those 26 in the sky we will guarantee a service based on 22 operational satellites.

The target constellation is one of 30 satellites. We don’t know yet for sure when this will be achieved. That will depend on when the last batch of satellites are ordered, and we are still discussing that. But we have an obligation to have deployed 30 satellites by the end of 2020. Then we will guarantee a service based on 24 satellites, with two spares per orbital plane.

AC: What is foreseen as the market readiness to adopt and use Galileo at that time? What companies are taking the lead in designing, manufacturing, and selling combined GNSS receivers?

PF: We believe that market trends go towards multi-constellation receivers. We already see that in some iPhones with GLONASS capability. We already see in the professional market segment that there are some companies providing Galileo capabilities, taking advantage of E1 and E5 for GPS and Galileo.

In the mass market, we also believe many companies will start to build up the multi-signal capability. Companies like STMicroelectronics are working on that. I have asked the European GNSS Agency (GSA) to provide figures. Out of a list more than 60 receiver manufacturers, at least 50 percent of them have at least one product that incorporates European Geosationary Navigation Overlay Service (EGNOS) capabilities. Of those same 60 companies, 30 percent already also have products incorporating Galileo capabilities: STMicro, Septentrio, NovAtel, Leica Geosystems, IFEN, Japan Radio, and others.

We believe that it is important to have continuous interaction with receiver manufacturers so that they understand the benefits of Galileo. EC Vice President Antonio Tajani is devoting a lot of attention to that. We build Galileo, but we do it for users. We have to make sure manufacturers understand the benefits. Discussions with them started in December in London when Mr. Tajani met with a set of CEOs of receivers manufacturers. He promised to meet with them every six months. We are also meeting with them on March 19 to provide information on calendars.

AC: What other European Commission programs will rely on initial or full Galileo capability to fulfill their mission?

PF: As of today, there is no obligation to use Galileo, no mandatory regulation imposing the use of it. There are some initiatives, like the Intelligent Transport Directive, which recommend but do not impose making use of EGNOS and Galileo. Or eCall, which in case of a car accident automatically contacts the rescue services. This will be required in all new cars starting 2015. These systems rely on satellite navigation for positioning. We also have digital tachography to measure the times of driving and rest of truck drivers. This will become a requirement as from 2018, and also relies on satellite navigation.

We also see initiatives by member states to put in place GNSS-based road-pricing systems. Germany has taken a lead in this. The European Union (EU) is trying to harmonize these road-pricing systems across national borders, with programs like Eurovignette and the Interoperability Directive.

In other modes, like aviation, you already have EGNOS. With landing procedures in place based on EGNOS, the system has become a reality.

In Europe we have the common agricultural policy, providing subsidies to farmers. As these are based on field sizes and crops, they need to be controlled, and using EGNOS and Galileo will help achieve more precise measurements.

AC: The Galileo Open Service Signal In Space Interface Control Document (OS SIS ICD) Issue 1 is described as being “subject to evolution.” Can you predict when a further iteration (Issue 2) will appear, and what changes it may contain?

PF: The present version of the ICD is still applicable. It correctly reflects the structure of the messages broadcast by Galileo. The statement you quote refers to the evolution of the document because as you remember there has been a debate about a safety-of-life (SOL) service that is multi-constellation and multi-regional. Since the initial concept of SOL on Galileo was changed in the last two years, some capacity onboard the satellites has been freed. We would like to use that for something else, keeping the backward compatibility for receivers. This will allow us to put in place, for example, a mechanism to improve the tracking performance and availability. Also authentication and higher accuracy for professional markets could be implemented, while maintaining the options for future advanced receiver-autonomous integrity monitoring (RAIM). That explains why we are still working on the evolution of the document. The next version of the ICD will be published in due time.

AC: Can you talk about progress towards increasing the EU share of the GNSS global market — currently 20 percent, but with the objective to reach 33 percent, as in other high-tech sectors? How might this be done?

PF: It is important for us in building Galileo that users benefit in having a second constellation. Satisfying users is the key. It also gives us some sort of independence from GPS, which would otherwise be the sole-source GNSS in the world. We would like our European companies to be more proactive and not to be limited to 20 percent share of the market. Everyone would.

We have our traditional research programs, like the Seventh Framework Programme (FP7). The next installment of the EU’s research programs will be called Horizon 2020, and it will make available budget devoted to the development of applications, receivers, and so on. Whether that will allow European companies to gain market share will depend on their proactivity, their innovation, and market-oriented strategies. That is their responsibility.

We are also active in things like the Galileo Masters, which tries to help small-to-medium enterprises (SMEs) who have good business ideas, young entrepreneurs or scientists with good GNSS-related innovations.

On top of that, we are starting studies to see how we can secure the market uptake of Galileo, not simply to help European industries, but to see that manufacturers and downstream applications developers understand the benefits of Galileo. By the end of the year, we should have created a better understanding by manufacturers and users of the full potential of using Galileo.

AC: Are there any other issues or concerns that you would like to bring to the attention of GPS World readers and the global GNSS community?

PF: I would like to briefly focus on EGNOS. For us it is important that this service will stay for a long time. We promised this to the aviation sector. The EU is finalizing its budget for the period 2014 to 2020, and this will allow us to continue to operate and improve EGNOS. Our objective is that it will augment Galileo as well as GPS, using the dual-frequency approach. That’s a real plus at the regional level for Europe. Its main customer will remain the aviation sector, although it is also widely used in precision farming, tracking and tracing, and so on.

Secondly, we are working on the continuous evolution of the system. We all know that satnav is an evolving domain. It takes time to build satellites and to improve technology. The Mission Evolution Road map that has been developed by experts will be presented to member states later this year.
Finally, we will be organizing the annual European Space Solution conference in Munich in November this year, and in mid-2014 in Prague. We are also hosting the International Committee on GNSS (ICG), which will take place in Prague in November 2014. For us, the location in Prague is symbolic since the European GNSS Agency (GSA), which will be our exploitation entity, is also located there.

Within a day of their initial activation over central Europe on March 12, Galileo satellites were visible over North America. The PLAN Group of the University of Calgary was successful in capturing and processing the signals from these satellites as they emerged. Galileo PRN 11, 12, and 19 were found and tracked on E1B/C. The PLAN software GSNRx was also able to track simultaneously GPS L1 and GLONASS L1 and produce combined position solutions.

Examining the Galileo navigation message transmitted on the E1B signal, it was found that the satellite health status is flagged as E1B_HS=3 meaning Signal Component currently in Test, and the data validity status is flagged as E1B_DVS=1 meaning Working without Guarantee. Current Galileo-ready commercial receivers may automatically discard measurements from a satellites broadcasting such messages. Parsing the received words in the I/NAV message, it was noted that more 50 percent of them were of type 0, although all words (types 0 to 10) were decoded at some point during the test.

Data was collected using a roof-mounted NovAtel 702GG antenna and an in-house two-channel digitizing front-end clocked by a high quality OCXO and also a three-channel National Instruments front-end for post-processing. The two-channel intermediate frequency data was streamed live to a laptop computer for real-time processing with GSNRx. Two RF channels were processed, the first centered at 1574.0 MHz with an IF bandwidth of 10.0 MHz, for the GPS L1 C/A and Galileo E1B/C signals and the second centered at 1602.0 MHz again with a bandwidth of  10.0 MHz, for the GLONASS L1 OF signals. The GPS and GLONASS signals were tracked using a Kalman-filter-based tracking strategy while the Galileo signals were tracked using a specialized data-pilot algorithm.

Figure 1. Scatter plot of the north and east position

Pseudorange and Doppler observations were extracted from the tracking strategies at a rate of 2 Hz. A 2D horizontal plot of the combined GPS & GLONASS and the combined Galileo, GLONASS & GPS single-frequency single-point solutions is presented in Figure 1.

Figure 2: Skyplot of the Galileo satellites.

The pseudorange residuals are plotted against time for each PRN tracked from each of the three systems in Figure 3. It is apparent that the addition of the three Galileo observations contributes to a reduction in bias and standard deviation in the horizontal directions, showing an excellent functioning of the Galileo satellites and PLAN Group equipment and software.

Figure 3. Pseudorange residuals are plotted against time for each PRN tracked from each of the three systems.

Figure 4. A screenshot of the receiver processing the data.

Contact: Dr. James T. Curran

Email: James.T.Curran at ucalgary.ca