The ASTRA 5B is installed in preparation for launch Friday, March 21. (Photo credit: Arianespace)
The launch of the satellite ASTRA 5B, which will become part of the European Commission’s European Geostationary Navigation Overlay Service (EGNOS), is scheduled for Friday, March 21, according to satellite company SES. It will be launched into space from the European Space Centre in French Guiana on board an Ariane 5 ECA rocket between 19:05 p.m. and 20:02 p.m. local time (23.05 – 00.02 CET; 18.05 – 19.02 EDT).
ASTRA 5B will carry a hosted L-band payload for EGNOS. It will also extend transponder capacity and geographical reach over Eastern Europe and neighboring markets for DTH, direct-to-cable, and contribution feeds to digital terrestrial television networks.
ASTRA 5B was built by Airbus Defence and Space (formerly Astrium) in Toulouse, France, using a Eurostar E3000 platform. The multi-mission satellite will be located at 31.5 degrees East.
“The launch of ASTRA 5B will be the 39th launch of an SES satellite on board a European Arianespace launch vehicle,” said Martin Halliwell, chief technology officer of SES. “Our long-standing relationship is based on this proven track record and shows the continuous confidence we have in Arianespace and our commitment to Ariane as a launch vehicle. We look forward to a successful mission with this longstanding launch partner.”
Plans to harness Galileo and other satnav systems for next-generation satellite augmentation systems for aviation and other high-performance uses took a significant step forward at the latest gathering of worldwide operators and experts, reports the European Space Agency.
Satellite augmentation systems combine additional ground stations and satellite transponders to sharpen satnav accuracy and reliability across given geographical regions — based on the U.S. GPS for now, but with plans to move to a multi-constellation design additionally employing Europe’s Galileo, China’s BeiDou, and Russia’s GLONASS systems in the post-2020 era.
The 26th Satellite Based Augmentation Systems (SBAS) Interoperability Working Group (IWG) took place in New Delhi, India on February 5–7.
The 26th SBAS Interoperability Working Group (IWG) was introduced by V. Somasundaram, board member of the Airport Authority of India.
Among its achievements was to converge on a standard message definition for one of the channels — known as L5 — of the planned second-generation SBAS systems, which will utilize dual-frequency, multi-constellation signals.
“Two solutions had been put forward, one by ESA based on work by European industry and one from the U.S. Federal Aviation Administration and Stanford University,” explains ESA’s Didier Flament, co-chair of the IWG.
“A single definition coordinated between both bodies has been presented, combining the benefits of both solutions. The formal IWG review and approval loop has now been started with the objective of finalizing it for September’s IWG meeting.
“The aim is to have it ready to submit to the official international SBAS standardization bodies — the International Civil Aviation Organization and the Radio Technical Commission for Aeronautics — as soon as October.”
The meeting also marked the significant progress made by Indian’s own SBAS system GAGAN, which underwent its final stability test last summer, followed by its safety certification in December.
At this point GAGAN was declared certified for non-precision approach users , followed by its safety-of-life service being formally offered to civil aviation users on 14 February.
GAGAN has been jointly undertaken by the AAI and the Indian Space Research Organisation, intended to provide improved accuracy, availability and integrity necessary to enable users to rely on satnav signals for all phases of flight – from en route as well as approach to all qualified airports within the GAGAN service area.
SBAS services worldwide
EGNOS is an operational precursor to Europe’s Galileo global satnav system.
GAGAN is the fourth certified SBAS to enter servicer worldwide. Europe has the European Geostationary Navigation Overlay Service (EGNOS), which was designed and built by ESA then turned over for operation by the European Satellite Service Provider, ESSP, overseen by the European Global Navigation Satellite System Agency (GSA) — both of whom also participated in the meeting. ESA retains responsibility for the future evolution of EGNOS.
The U.S. has the Wide Area Augmentation System (WAAS), developed and operated by the Federal Aviation Administration, with an extension over Canada called CWAAS (Canadian WAAS). WAAS celebrated its 10th anniversary of operational life last July.
Japan has the Multi-functional Satellite Augmentation System (MSAS), developed and operated by Japan’s Civil Aviation Bureau. Japan is currently discussing plans to merge this capability with their new home-grown satnav system, QZSS.
Along with GAGAN, the meeting also covered the progress made by the other SBAS systems under definition or development — the Russian SDCM, Chinese SNAS and Korean K-SBAS.
The follow-up IWG meeting is due to take place in September in Tampa, Florida.
Planned GAGAN service coverage for the two different service levels (RNP0.1 and APV1). GAGAN has been jointly undertaken by the Airport Authority of India and the Indian Space Research Organization, ISRO, to achieve smooth transition to satellite-based navigation and seamless air traffic management across continents. GAGAN is designed to provide improved accuracy, availability and integrity necessary to enable users to rely on GPS for all phases of flight, from en route through approach for all qualified airports within the GAGAN service volume. More precisely it is aimed to provide Non Precision Approach RNP0.1 service levels to the entire Indian Flight Information Region and Precision Approach APV1 service (equivalent to the current EGNOS Service) within a specified service volume within Indian land mass.
Tackling ionospheric interference
The New Delhi IWG took place concurrently with a related meeting, the ICAO’s 4th Ionospheric Study Task Force. This group has been tasked with the objective of developing region-specific models of ionospheric models to compensate for satnav signal interference or loss.
The ionosphere, the electrically sensitive outer shell of Earth’s atmosphere, can be perturbed by solar activity. And because satnav signals pass from space by Earth they can then be disrupted in turn. Equatorial regions see the greatest disturbance, including signal delay or ‘scintillations’ making signals unstable.
The aim is to develop reliable ionospheric models to compensate for these effects, particularly for equatorial SBAS regions, such as India. ESA is contributing with data from its worldwide Monitor network, gathering data to improve future EGNOS performance and potentially support further geographical extension.
Comparing current worldwide SBAS coverage — based on WAAS, EGNOS and MSAS — to the situation envisaged for 2020–25: near-global coverage based on WAAS, EGNOS, MAAS, SDCM and GAGAN, with an expanded network of stations in the southern hemisphere, based on a common dual-frequency/dual satnav standard being finalized by the SBAS IWG.
Maiden flight trials have been successfully conducted in Moldova using GMV’s magicSBAS solution. These trials form part of a GMV-led European Commission FP7 collaboration project.
In 2011 the European GNSS Agency (GSA) awarded GMV the EEGS2 project (EGNOS Extension to Eastern Europe). The main objective of the project is to demonstrate through flight trials the benefits of the European Geostationary Navigation Overlay Service (EGNOS) in areas of Eastern Europe where it is not yet available, such as Poland, Romania, Ukraine, Moldova and Russia, and to prepare the civil aviation authorities and air navigation service providers for future use of the system.
In the context of this project, after the tests conducted in Spain, the maiden flights have been successfully carried out in Moldova, using the equipment and tools developed by GMV. The Moldova demonstrations have given pilots and service providers a clear idea of the potential benefits of EGNOS and the flying procedures of the near future, GMV said.
Four flights had previously been conducted in Spain in November, December and February. The satisfactory results of these flights then paved the way for the demonstrations in Moldova.
The magicLPVsystem, developed under this project, enables LPV approaches (localizer performance with vertical guidance) to be carried out using the signal generated by the magicSBAS application. This test environment allows any region of the world to analyze the air-navigation benefits to be obtained with deployment of a Space Based Augmentation System (SBAS). This signal is read by Internet and transmitted by radio frequency in the vicinity of the airport, allowing LPV approaches to be made in places where SBAS is either completely unavailable or available only on a very limited basis.
Eight flights in all were carried out in various Moldovan airports, including Chișinău International Airport. Test results were highly satisfactory, demonstrating the simplicity of equipment configuration and operation, and the performance of the magicSBAS signal, GMV said.
“These trials are an important milestone for GMV, for the project and, fundamentally, for the use of EGNOS in the countries of Eastern Europe in the near future,” said Miguel Romay, executive director of GNSS–Aerospace.
GMV will continue with these demonstrations in other countries of Eastern Europe. The next trip in two weeks will be to Romania, where new flights are expected to be just as successful.
The new version 2.0 of the European Commission’s EGNOS SDD (Open Service Definition Document) reflects recent improvements implemented for the EGNOS service. The document shows significant improvements in the geographic coverage of the EGNOS Open Service as can be seen from the map on this site.
The update is of particular interest to receiver manufacturers, GNSS applications developers and users.
EGNOS is the European Geostationary Navigation Overlay Service and is the European Satellite-Based Augmentation System (SBAS) that complements the GPS system by improving the accuracy and providing integrity for the signal.
Both European businesses and citizens are benefiting from EGNOS. It can support new applications in many different sectors such as agriculture (for high-precision spraying of fertilisers) or transport (enabling automatic road-tolling or pay-per-use insurance schemes). EGNOS can also support much more precise personal navigation services, both for general and specific uses.
Report from ENC: Constellation Needs 22 Satellites in Three Years
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.
OS for Improved Accuracy, EDAS for Further Enhancement, Integrity Data
EGNOS availability over Europe, as a precursor of Galileo globally, provides a guaranteed level of positioning accuracy in real time, for tracking vehicles transporting hazardous material. The EGNOS Open Service enhances position accuracy compared to GPS-only. The EGNOS Data Access Service further enhances accuracy and indicates the quality of the position data received from GPS. As a result of the SCUTUM project, EGNOS is now used in the operational transport of dangerous goods by road in Europe.
By Antonella Di Fazio, Daniele Bettinelli, and Kyle O’Keefe
The road sector is among the largest markets for GNSS applications, not only in automotive mass-market but also in professional applications such as freight transport and logistics. Carrying goods by road naturally involves the risk of traffic accidents. If the goods are dangerous, there is also the risk of incidents, such as hazardous spills, fire, explosion, chemical burn, or environmental damage. The many different kinds of authorities and operators active in the field have safety as a primary concern and make continuous efforts in this regard. To ensure that such transport continues being profitable and logistically effective, emphasis is placed on the quality and condition of infrastructure, on transport safety, and on supervision and control.
Technology’s role, particularly that of GNSS, is to provide the capability of supervision and surveillance, and thus enable better incident management and proactive prevention of accidents, while enhancing work. Use of GNSS combined with sensors and wireless devices has rapidly increased to enable continuous tracking and tracing services. GNSS-tracking devices installed on board vehicles ensure that the position, the date and time, the speed and the course, and any deviation with respect to a predefined path (coordinates and time) are transmitted automatically to a monitoring center. Combined with sensors, such devices send positioning information and the critical status parameters of the material (depending on the nature of the transported material and sensor type: identification of the goods/packaging, temperature, pressure, tampering or valve opening, and so on).
At the monitoring center, positions are displayed on digital maps, and regular data reports are processed for:
continuous tracking and tracing,
control of the shipment in a specified route (according to the plan and authorized path),
early warning/alarm when an anomaly condition is detected,
recording and logging for a regular summary of reported incidents, and
informing emergency-response forces for preparation of management arrangements and supporting emergency response plans.
These operations help reduce the possibility of human error during transport, prevent incidents, enforce regulations, and support law enforcement.
The European Geostationary Navigation Overlay Service (EGNOS), a satellite-based augmentation system (SBAS), augments the GPS signal over Europe and provides more precise positioning services. In addition, it gives users information on the reliability of the GPS signals (integrity data).
EGNOS is designed for safety-critical civil aviation operations. The characteristics of the EGNOS signal are compliant with Radio Technical Commission for Aeronautics Minimum Operational Performance Standards (RTCA MOPS) for airborne navigation equipment using the GPS augmented by SBAS. EGNOS also allows multimodal/land transport applications; however, EGNOS optimal use in these applications requires specific customizations for environments not compliant to MOPS.
The majority of receivers available on the market and integrated in operational devices are EGNOS-enabled. EGNOS provides two services suitable for multimodal/land transport applications:
EGNOS Open Service (OS) is made available to users equipped with GPS/EGNOS receivers, via the satellites’ Signal in Space (SiS).
EGNOS Data Access Service (EDAS) consists of a server that gets the data directly from EGNOS and distributes it in real time to professional users via terrestrial networks, within guaranteed delay, security, and performance.
Software solutions and technologies capable of using EDAS and able to deliver added-value services for road applications have been developed in various European projects in the past several years, have been extensively proven in real life, and are presently ready for operational use. During the last seven years, capitalizing on the efforts of national/European projects and company investments, Telespazio has developed LoCation Server (LCS) navigation software based on a patented algorithm, suitable for combined use of EGNOS OS/EDAS in road applications. LCS makes use of EDAS to augment EGNOS OS performance by:
improving the availability of EGNOS OS, since EGNOS SBAS corrections are made available to users through terrestrial networks and thus also in the cases of poor SiS visibility or complete absence;
enhancing EGNOS OS position accuracy using the patented software navigation solution to implement EGNOS SBAS corrections; and
processing EGNOS integrity information to compute the protection levels that give a qualification and a level of confidence in the position information. LCS is configured to output horizontal protection level (HPL) and vertical protection level (VPL).
Between October 2010 and November 2011, the European project SeCUring the EU GNSS adopTion in the dangeroUs Material transport (SCUTUM) conducted an extensive trial campaign in various road environments (urban and extra-urban) and real operation scenarios, to assess the performances of EGNOS OS and EDAS in comparison with GPS-only. SCUTUM trials were carried out with GPS/EGNOS receivers available on the market for automotive applications.
Analysis of the data collected during the trials shows that EGNOS OS enhances GPS position accuracy by 3 meters in road environments (see Figure 1). EDAS via LCS enables improvements over EGNOS OS by increasing the availability of SBAS corrections, further enhancing GPS position accuracy. Moreover, it affords the possibility of qualifying and guaranteeing GPS position information by exploiting EGNOS integrity and computing the protection levels.
Figure 1A. The green line indicates the reference trajectory; the position obtained by using EDAS with LCS (yellow dot) is more accurate with respect to the position obtained by using EGNOS OS (red dot) and the position obtained by using GPS only (blue dot).Figure 1B. A snapshot displaying the HPL computed by using EDAS with LCS.
SCUTUM Goods Tracking
Funded by the European Commission and managed by the European GNSS Agency (GSA), SCUTUM is the European best practice for the operational adoption of EGNOS in the transport of dangerous goods. An Italian oil company, eni, has had the opportunity to prove EGNOS added value compared to GPS alone, and to validate the relevant operational benefits in terms of higher safety and efficiency. The company adopted EGNOS to track and trace its operational fleet transporting dangerous goods throughout Europe. At the end of SCUTUM’s project timeline in November 2011, more than 300 eni tankers transporting hydrocarbon and chemical products in seven European countries were monitored with EGNOS. Today eni plans to gradually extend the use of EGNOS to the transport of chemicals and aviation products, and to further European countries.
Sensors installed on the trailer to record load status.OBU on the tanker integrating a GPS/EGNOS receiver.
The tankers (see opening photo) are equipped with GPS/EGNOS tracking devices, consisting of a set of sensors installed on the trailer to record the status of the loads. The sensors are connected to an onboard unit (OBU) installed on the truck that integrates a GPS/EGNOS receiver configured to use EGNOS OS. The OBU collects measurements from the sensors, detects information on the vehicle’s parameters, measures the GPS/EGNOS position, and sends this set of data via a GPRS link to a remote monitoring platform (the transport integrated platform, or TIP) enhanced by LCS to use EDAS. The TIP receives the data from LCS, that is, EGNOS positions (corrected by EGNOS OS if available or corrected by EDAS), the relevant HPL and VPL, and visualizes them as shown in Figure 2.
Figure 2. Operational tanker remotely monitored at the TIP by EDAS via LCS.
LCS for EDAS Services
LCS consists of several software modules, among them a module connecting to EDAS to get EGNOS data, and a module implementing the navigation solution by means of the Telespazio algorithm.
LCS makes use of EGNOS SBAS messages plus GPS ephemerides received in real time from EDAS (using Service Level 1), the positions (GPS or EGNOS OS positions when available) and time, and raw GPS measurements (code ranges) from the GPS/EGNOS receiver integrated in the OBU.
LCS calculates and returns EGNOS corrected positions (also in case of lack of SiS visibility) and the relevant protection levels obtained by processing the EGNOS integrity message. The HPL/VPL give a guarantee of the position information from the GPS/EGNOS receiver, as they qualify the reliability of position information and provide a measure of the confidence of the reliability.
If the position data from the OBU is not corrected with EGNOS OS (via the SiS), LCS uses the SBAS messages plus the GPS ephemerides, calculates and applies SBAS corrections, then calculates HPL/VPL. If the position data from the OBU is corrected with EGNOS OS (via the SiS), LCS returns only the HPL/VPL.
For remote monitoring of transported dangerous goods, the features provided by EDAS via LCS (better accuracy, higher confidence on the position, enhanced availability) are considered valuable by eni, as they enable tracking tankers more precisely and reliably along delivery routes, and also from bay to bay (Figure 3).
Figure 3. Accurate remote monitoring of a tanker in a bay area.
At the OBU, the positions are combined with other collected parameters, such as speed, engine parameters, driving parameters, loading/unloading the product on the vehicle, quantity of goods on the vehicle, product temperature and pressure, opening/closing bottom valves and manholes, opening/closing loading station. The information is sent to the TIP and visualized to the local operator, and also forwarded to the eni emergency room (shown in Figure 4) that is connected to the fire brigades and civil-protection emergency centers.
Figure 4. eni emergency room.
In an abnormal situation, such as the vehicle deviating from its planned path or being located in a dangerous/sensitive area, the local operator raises a warning and establishes a contact with the driver. If an accident occurs, an alarm is generated also at the eni emergency room responsible for emergency management and coordinating search-and-rescue operations with the proper public entities. The information is also used to keep the involved transport operator and eni’s customers informed.
Additionally, this information is stored for law enforcement and prevention purposes. Position data and parameters are analyzed to produce statistics and study cases of near-miss accidents.
Benefits generated from EGNOS lie primarily in the capability to implement more accurate risk management and to strengthen safety and prevention. The higher precision with respect to GPS alone and the location achieved by using EDAS via LCS ensure more accurate and reliable monitoring of operations in normal and critical situations, and thus are valuable for commercial purposes and safety reasons. Moreover, eni considers the position guarantee given by the protection levels useful for research on accident prevention.
Multipath-Mitigation Algorithm in LCS
SCUTUM also implemented and tested a multipath-mitigation algorithm used to enhance LCS, to further mitigate the effects of code multipath, typical of land applications. Developed in cooperation with the University of Calgary, the algorithm is based on a fault detection and exclusion (FDE) method and is designed to ensure that biased/multipath-affected observations do not contaminate the navigation solution.
As SCUTUM deals with a road transport application, the assessment targeted the HPL only. The algorithm is based on a statistical-empirical concept combining:
an FDE procedure using a statistical reliability method for the detection and removal of code-range observations corrupted by multipath; and
a field-testing procedure using the receiver under study and a geodetic-quality receiver to produce a reference trajectory.
The FDE procedure consists of sequential steps:
Computation of the navigation solution by means of a least-squares solution to obtain the calculated position, the HPL, and the residuals;
Reliability testing on the residuals, to detect the outliers (observations that contain biases and thus are considered measurements affected by multipath errors);
Exclusion of the detected outliers and re-computation of the navigation solution;
Iteration of the steps. In each iteration, the observation with the largest residual flagged as an outliner is removed.
The procedure ends once no further outliers are isolated, or the number of remaining observations is less or equal to five, or several special-case conditions occur. Outlier detection is done on the basis of a rejection threshold on the standardized residual. This rejection threshold is a parameter of the multipath-mitigation algorithm and is tuned by means of the field-test results. Additionally the multipath-mitigation algorithm behavior is a function of other parameters that depend on various factors, including satellite elevation, signal strength, and overall satellite geometry.
Field Trials
SCUTUM field trials covered several environmental conditions and LCS configurations. Tests were performed in a wide range of Italian urban and extra-urban road environments. They considered five different typical driving environments (Table 1), corresponding to different levels of GPS and EGNOS signal availability and multipath, and various vehicle speeds and dynamic characteristics, with the objective of testing the robustness of LCS’s navigation solution.
TABLE 1. SCUTUM field trials driving environments.
From a physical point of view, the presence of natural and/or artificial obstacles could lead to lack of GPS and SBAS signals, worse satellite geometry, and introduction of additional errors in the measurements due to multipath propagation effects. Urban canyons are particularly prone to such effects, although they occur also in other cases depending on the topographic characteristics of the environment. For these reasons, the trials covered all possible environments traveled by LCS users, to provide a complete technical and business analysis for each operational condition.
To accurately indentify the appropriate driving environment, trial paths were matched on clutter maps categorizing the different driving environments (as shown in Figure 5 in the example of a trial path in Rome).
Figure 5. Method for driving environment identification by means of a clutter map.
A reference trajectory, hereafter called the true path, was calculated in post-processing, through a kinematic differential GPS method, by using GPS L1 and L2 carrier-phase measurements, combined with inertial navigation system (INS) measurements.
The differential GPS L1 and L2 carrier measurements were collected with a reference receiver installed near each test location, at an inter-receiver distance not exceeding 20 kilometers. The reference receiver was geo-referenced via a dedicated GPS network solution (based on a continuous collection campaign of at least two days’ data). The combination with INS targets smooth trajectories free from jumps, even in difficult GPS environments.
The tests ran on two identical OBUs, one GPS-only and one using GPS+EGNOS. The two OBUs and the GPS/INS system were installed in a test vehicle (Figure 6) and connected to a standard GPS patch antenna for automotive applications. Two pairs of OBUs were used (Figure 7).
Figure 6. GPS/INS system installed in the vehicle.Figure 7. OBUs in test vehicle.
Test Results
The trials collected these data sets:
Raw measurements from the GPS/INS system;
Positions and raw measurements from the two OBUs, GPS and GPS+EGNOS respectively.
As mentioned, positions and raw measurements from the GPS OBU were processed by LCS’s navigation solution in three configurations:
LCS baseline, running the baseline multipath mitigation method (based on the proprietary patented algorithm);
LCS enhanced, applying the multipath-mitigation algorithm with default settings of several parameters;
LCS enhanced and tuned, applying the multipath-mitigation algorithm with tuned parameters. The tuning was obtained by applying the combined statistical-empirical concept described earlier.
Data collected during the field trials was analyzed in terms of:
average values for the horizontal navigation system error (HNSE) that is the horizontal difference of the OBU position with respect to the reference trajectory;
average values for the HPL that gives an indication of the confidence/guarantee of the position above mentioned; and
the availability of the processing of LCS’s navigation solution.
Test data was analyzed with both commercial and freely available software packages. Table 2 reports the performances of LCS in its baseline configuration for each driving environment. Table 3 reports the performances of LCS by means of the multipath-mitigation algorithm with different tunings for extra-urban and urban environments.
TABLE 2. Performances of LCS baseline for driving environments.TABLE 3. Performances of LCS enhanced by multipath mitigation algorithm with different tunings.
The results show that for the road environments tested, LCS baseline performs better than statistical FDE.
From these results, an interesting conclusion can be drawn: in the road environments tested, a traditional FDE approach is not as effective as would be expected. Specifically, the removal of observations with large residuals resulted in larger overall position errors, both before and after attempting to estimate a larger observation variance than normally used for GPS. The reason for this is that in urban environments and extra-urban road environments there is significant multipath, corrupting many observations at the same time that the number of available observations is low. The conclusion is that on average, in the environments tests, it is better to leave small, but still statistically detectable errors in the solution than to remove them and degrade the solution geometry.
The fault-detection approach will be more appropriate in a multi-constellation GNSS, and in particular in the future when Galileo satellites can be used in conjunction with GPS, resulting approximately double the satellite availability in all environments.
Table 4 summarizes average performances for GPS+EDAS using LCS baseline compared with those of the GPS-only and GPS+EGNOS.
TABLE 4. Average performances of GPS+EDAS by means of “LCS baseline” in comparison with GPS-only and GPS+EGNOS OS.
Workshop Agreement
SCUTUM also carried out a European Committee for Standardization (CEN) workshop that elaborated the CEN Workshop Agreement (CWA) 16390:2012, Interface control document for provision of EDAS-based services for tracking and tracing of the transport of goods, that is, the technical specification for development of EDAS-based products and applications.
CWA 16390 specifies:
the data (and relevant format) needed from the GPS/EGNOS receivers by the software solutions connected to EDAS, to enable the implementation of products and added value services; and
the type/format of the added value services produced by the software solutions (EDAS-based services).
The technical specification defined in CWA 16390 is architecture/technology-independent and flexible, so as to:
cope with different architectures (for example, those envisaging software solutions running in the monitoring platforms or in the OBUs); and
ensure its applicability in ITS systems and various mobility applications.
CWA 16390 was endorsed by several European stakeholders from industry, institutions, and the research sector. The Ministries of Transport in Italy and France, partners in the SCUTUM project, validated it as part of a shared vision for EGNOS adoption and exploitation. Italy’s Ministry of Transport is presently carrying out the possible evolution of CWA 16390 into an Italian standard.
Conclusions
SCUTUM represents the first step towards a larger use of EGNOS in Europe for the provision of services for road applications, and opens the market for Galileo. Its key findings are that EGNOS OS generally enhances the position measured using GPS-only in all extra-urban and urban environments. EDAS generally provides further enhancements, and also gives an indication of the quality of the position data received from the GPS.
LCS is a plug-in solution that enables easy retrofitting of existing GPS systems to use EGNOS, but optimized for road applications. By integrating it in tracking and tracing monitoring platforms and configuring the vehicle-installed OBUs, LCS enhances GPS position accuracy by approximately 4 meters and provides a level of confidence in the position information in the form of an HPL and a VPL. LCS will also improve GPS/Galileo integrated solutions when Galileo is operational. Its navigation solution will be more robust with Galileo and in general with multiple constellations, thanks to the availability of more satellites in view.
Manufacturers
A NovAtel FLEXG2-V2-L1L2 served as GPS reference with a NovAtel dual-frequency GPS-702GG antenna. An Oxford Technical Solutions RT2002 dual-frequency GPS/INS system served as rover. The two OBUs integrated a u-blox 5 GPS/EGNOS receiver. In its present configuration, LCS is connected to a dedicated GPS/EGNOS receiver, NovAtel ProPak-V3-L1 acting as EDAS back-up for robustness reasons.
Antonella Di Fazio works in the GNSS Infomobility Business Unit of Telespazio, in charge of innovative applications and services and program and technical coordinator of European R&D projects, devoted to the use of EGNOS/Galileo.
Daniele Bettinelli works in the GNSS Infomobility Business Unit of Telespazio, in charge of the specification, design and development of services based on EGNOS and EDAS, in particular for land applications.
Kyle O’Keefe is an associate professor in the Position, Location And Navigation (PLAN) group of the Department of Geomatics Engineering at the University of Calgary.
New Organization Advocates for GPS Industry; Galileo Lives to Fly Another Day, Budget Passed; Safer Skies for EGNOS; and GLONASS in Brazil
New Organization Advocates for GPS Industry
A new group, the GPS Innovation Alliance, has formed and announced itself as the voice of the U.S. GPS industry and community of users, to “support the ever-increasing importance of GPS” in the U.S. capital, Washington, D.C. The organization subsumes and replaces both the U.S. GPS Industry Council, an entity of longstanding, and the Coalition to Save Our GPS, which arose in March 2011 in response to a Federal Communications Commission (FCC) conditional waiver granted to LightSquared.
The alliance appears to reflect a desire on the part of some industry members to take a more aggressive approach inside the Washington Beltway, a sign, it would seem, of the political times. Some of those involved spoke informally of a desire to take advantage of contacts made on Capitol Hill and in the media during the highly visible LightSquared combat, fought in the glare of media attention heretofore unknown in industry circles.
GPSv Innovation Alliance logo
Members of the Alliance are drawn from a variety of fields and businesses reliant on GPS, as well as leading manufacturers of GPS equipment. The former group includes, aviation, agriculture, construction, transportation, first responders, and surveying and mapping, and consumer organizations representing users of GPS for boating and other outdoor activities, and in automobiles, smartphones, and tablets.
Joining John Deere, Garmin, and Trimble — three lead drivers of the Coalition effort at the FCC — are NovAtel Inc. and Topcon Positioning Systems. All five were previously long-time members of the USGIC, and they appear as founding members of the alliance at www.gpsalliance.org.
Affiliate members listed on the website include the Association of Equipment Manufacturers, General Aviation Manufacturers Association, National Association of Manufacturers, Association for Unmanned Aerial Vehicles International, and Boat Owners Association of the United States.
The alliance plans to build on “the proud heritage and extensive expertise of the United States GPS Industry Council (USGIC), which was formed in 1991 to promote broader commercial applications of GPS and to expand global markets while assisting in safeguarding the technology’s military advantages. The council has a long history of highly effective advocacy on behalf of the GPS industry, as well as serving as a trusted source of objective information for policy makers, the media and the public both in the U.S. and around the world.” The alliance website gives a longer statement about the history and record of the USGIC, highlighting its role in international negotiations.
Michael Swiek, executive director of the USGIC, has transitioned to become the executive director, executive branch and international, of the Innovation Alliance. In addition to working closely with leading offices of executive branch departments of the U.S. government, he will continue well-established dialogs with governmental, private sector and academic entities in areas critical to GPS and satellite navigation among key players in Europe, Japan, Russia, Korea, China, and elsewhere.
Heather Hennessey, a principal of Innovative Federal Strategies LLC, a “comprehensive government relations firm,” has taken the position of executive director, legislative, at the alliance. Hennessey has seven years of service in the House of Representatives, including two years as chief of staff for Congressman Jack Kingston of Georgia.
An active voice in alliance representations on Capitol Hill will presumably be that of Jim Kirkland, vice president and general counsel for Trimble. Kirkland was the most prominent spokesperson for the coalition during the LightSquared battle, which appears to be either over or nearly so. “The alliance is committed to ensuring constructive, robust dialog between GPS users, manufacturers and policy makers on critical policy issues affecting GPS,” Kirkland said, “a commitment Trimble is pleased to be a part of as the industry continues to innovate and modernize.”
The alliance mission statement cites the importance of GPS to global economy and infrastructure; vows to aid further GPS innovation, creativity and entrepreneurship; and to protect, promote and enhance the use of GPS.
The GPS Innovation Alliance officially launched on February 13 with a reception on Capitol Hill, a traditional lobbying tactic that previous efforts had perhaps not envisioned. The organization has also hired a public relations firm, Prism Public Affairs, and commissioned a logo.
Galileo Lives to Fly Another Day, Budget Passed
European Union leaders approved a scaled-down budget in early February, with none of the cuts to the Galileo program that had been widely feared. The project, conducted by the European Space Agency (ESA) under close supervision of the European Commission (EC), will draw on funding of 6.3 billion euros (about $8.5 billion) from 2014 to 2020. The satellite navigation program held onto its requested revised budget of 6.3 billion euros, even as telecommunications research and broadband deployment projects, including another ESA pet project, the somewhat related Copernicus Global Monitoring for Environment and Security (GMES), underwent severe cuts. Galileo has already spent more than 3 billion euros ($4 billion), three times its original budget, to launch four of an envisioned 30-satellite constellation.
The EU deliberative system requires unanimous approval of budget decisions, so what smaller countries seek for their farmers or fishermen carries practically equal weight to the desire of industrial/aerospace giants like Germany, closely followed by France and the United Kingdom. Negotiation is a delicate matter indeed, and reached an impasse in November 2012; resolution came only after a 24-hour marathon session of talks. The total budget represents the first decrease in the European Union’s history; austerity is the watchword in a region beset with an ongoing bevy of international debt crises and serious recession in many of the smaller EU countries.
Galileo supporters within the European Commission, the EU’s policy-making arm, continued to maintain that Galileo will “open a whole new world” for business to develop applications, as Antonio Tajani, EC vice president stated recently. The program drew strong support, for once, from powerful backers in the EU administrative capital, Brussels, and among industrial and political interests in key member states: France, Germany, and for an exception Britain, often a proponent of deep cuts.
Negotiators helped Galileo’s chances by placing it in a research group labeled “Competitiveness for Growth and Jobs.” This category actually rose in budget allocation by nearly 40 percent over the last seven-year allotment.
The allocation should cover operational costs for EGNOS and Galileo, the completion of the initial Galileo constellation of 14, and early procurement stages of a full, or second-generation orbiting set of 30.
The program still faces an extremely unlikely date for the establishment of early services by the end of 2014. “Then, the market, as well as the governments of the Member States, will start increasing their interest and promoting further investments,” the ever-optimistic Tajani maintained.
The budget must still secure approval by the European Parliament. Its president, Martin Schulz of Germany has stated, “The further we step away from the Commission’s proposed figures, the more likely the proposal will be rejected. More and more tasks, and less and less money — the inevitable result is budget deficits. The Parliament will not go along with this.”
Parliament’s decision is forecast for the summer months. Parliament’s budget power consists of a direct yes-or-no vote to accept or reject the budget. The body cannot make modifications, and if rejecting would simply send it back to the EU ministers to begin all over again. The picture is further complicated somewhat by the 20-nation make-up of ESA, whereas the European Union and its executive commission have 27 national members.
Safer Skies for EGNOS
Results of a September 2012 flight test in the Galileo Test and Development Environment (GATE) near Berchtesgaden, Germany, the one place on Earth where Galileo services are already routinely available, show that adding Galileo signals to the European Geostationary Navigation Overlay Service (EGNOS) should boost accuracy significantly. EGNOS augments the accuracy and reliability of GPS signals over Europe, rendering satnav usable for safety-critical applications such as aircraft guidance, as well as more general precision uses.
Operational horizontal and vertical distance “protection levels” for safety were cut by half by combining use of GPS and Galileo within EGNOS. In addition, new integrity algorithms installed within the user receiver turned out to reliably detect and exclude reflected or otherwise faulty signals.
Next-generation EGNOS, planned for 2020, is envisaged to augment both constellations and dual frequencies at the same time, making the system much more robust.
GLONASS in Brazil
The first overseas GLONASS ground monitoring station for differential correction and monitoring outside Russian territory opened in Brasilia, Brazil, in mid-February. The station represents an early step in an initiative to modernize and significantly improve the accuracy of GLONASS signals.
Plans call for similar monitoring stations “in more than 30 countries of the world. Most of the countries that received the offers for the installation of the stations responded positively.However, the process is slow because of the need to conclude appropriate intergovernmental agreements. The documents with Brazil were signed in 2012. Agreements with Spain, Indonesia and Australia will be finalized soon,” according to a Pravda story.
Europe’s two satellite navigation systems could combine in the future for heightened performance, an airborne test has confirmed. A helicopter flight took place above an alpine valley in Germany, the one place on Earth where Galileo services are already routinely available.
The test receiver. The helicopter flew a variety of maneuvers, from fast loops to mid-air hovering, to see how satnav signals were received in practice.
Results of the flight test, conducted in September 2012, show that adding Galileo signals to the European Geostationary Navigation Overlay Service (EGNOS) should boost its accuracy significantly. EGNOS, which augments the accuracy and reliability of GPS signals over Europe, renders satnav usable for safety-critical applications such as aircraft guidance, as well as more general precision uses.
Operational horizontal and vertical distance “protection levels” for safety were cut by half by combining use of GPS and Galileo within EGNOS. In addition, new integrity algorithms installed within the user receiver turned out to reliably detect and exclude reflected or otherwise faulty signals.
The first test of real Galileo navigation fixes is scheduled for later this year from the four satellites already in orbit, with more satellites set to join them by the end of the year.
The Galileo Test and Development Environment – GATE – is a giant outdoor laboratory where prototype Galileo receivers can be used freely without any modifications.
As the constellation takes shape, satnav researchers and industrial developers can already try out Galileo services with prototype receivers at the German Galileo Test and Development Environment, or GATE, a giant outdoor laboratory. GATE, in and around the town of Berchtesgaden in the Bavarian Alps, is Europe’s go-to place for Galileo testing: transmitters atop eight neighbouring mountains cover 65 square kilometers of territory with simulated Galileo signals.
ESA’s Global Navigation Satellite System Evolution program carried out helicopter-based testing here on September 24–26. The results will help to guide the development of next-generation satnav systems.
The helicopter flew a variety of maneuvers, from fast loops to mid-air hovering, to see how satnav signals were received in practice. The test relied on ESA’s SPEED platform — Support Platform for EGNOS Evolutions & Demonstrations, co-funded by French space agency CNES and operated by Thales Alenia Space France — which enabled the receiver to receive simultaneous realtime augmentation for both GPS and Galileo.
Europe’s next-generation EGNOS, planned for around 2020, is envisaged to operate in the same way, with augmentation of both constellations and dual-frequencies at the same time making the system much more robust.
A helicopter flies over the Galileo Test and Development Environment – GATE – in Berchtesgaden, Germany, gathering data on how EGNOS and Galileo will work together. The promising results from the testing are now being analyzed.
The shipping container that protected GSAT-10 during its travels from India to French Guiana is removed inside the Spaceport’s S5 payload preparation facility, revealing the spacecraft.
News courtesy of CANSPACE Listserv.
UPDATE: According to an Arianespace press release issued Thursday, the launch of the GSAT-10 and Astra 2F satellites is now scheduled for September 21. SES-5. The SES-5 geostationary communications satellite (also known as Sirius 5 and Astra 4B), which was launched on July 9, 2012, arrived at its orbital slot of 5 degrees east longitude on or about July 19. The current position is actually about 5.2 degrees.
The satellite carries L1 and L5 transponders for the European Geostationary Navigation Overlay Service (EGNOS) satellite-based augmentation system. According to a spokesperson from the Space and Missile Systems Center, the Global Positioning Systems Directorate has assigned C/A PRN code 136 and L5 PRN code 136 for use by the satellite.
GSAT-10. The Indian Space Research Organisation’s GSAT-10 geostationary communications satellite has arrived at the European spaceport in Kourou, French Guiana. The satellite carries a transponder for the GPS and GEO Augmented Navigation (GAGAN) satellite-based augmentation system.
GSAT-10 will be launched together with the Astro 2F satellite by an Ariane 5 rocket on September 21. GSAT-10 is expected to be positioned at 83 degrees east longitude and use PRN code 128. It will join the first GAGAN-equipped satellite, GSAT-8, which is at 55 degrees east longitude and is transmitting test signals on the L1 frequency using C/A PRN code 127.
Although GSAT-8 reportedly carries a dual-frequency transponder, no L5 signals from this satellite have yet been detected by International GNSS Service tracking stations.
Now GNSS smartphone application developers can benefit from a range of new features from Version 2 the European Commission’s free EGNOS Software Development Kit (SDK), reports the European GNSS Agency (GSA). The SDK helps developers to easily implement EGNOS corrections coming from the signal in space or the Internet, and make use of EGNOS advantages when using location-enabled applications.
The EGNOS SDK is a European Commission project that aims to foster the use of EGNOS in location-based services (LBS) applications for smartphones. It has been designed to allow application developers to take advantage of the benefits of EGNOS, and to use these in software they develop for mobile devices. The EGNOS SDK is the only toolkit — in an open-source library — that implements integrity and EGNOS corrections for a more accurate position than GPS alone can provide.
New EGNOS SDK features and improvements include:
Tracking feature: Allows application developers to choose different options to display their GPS and/or EGNOS and/or R&D position over the smartphone’s map.
Skyplot view: Enables to display the position of the overhead EGNOS and GPS satellites with a time span of +12h or -12h. This feature shows information about the number of EGNOS satellites available, the number of GPS satellites used for the computation of the R&D, EGNOS and GPS positions, and the number of satellites not used.
Advanced Skyplot view: Provides an augmented reality showing a live video streaming of the sky and can identify EGNOS and GPS satellites in real time.
R&D Position Type menu: Displays six features proposing innovative ways of computing a position by deviating from the EGNOS standard EGNOS DO-229D, to get even greater accuracy:
The Increased satellite constellation improving the satellite constellation used by adding GPS satellites not monitored by EGNOS.
The Best satellite constellation selecting the most suitable GPS satellites geometry for the computation of the position.
The 2D Positioning displaying the position even if only 3 GPS satellites are in view (4 satellites are normally the minimum needed to compute a position). This is important in urban situations, where surrounding buildings can obstruct a clear view of the sky, making it difficult to track four satellites or more.
The Fast correction with no RRC improving the positioning by eliminating the jumps that the Range Rate Correction (RRC) might cause in the fast corrections applied to the pseudorange (PR) measurements.
The Best Weight Matrix rating the satellites involved in the position computation on the basis of the most beneficial weight matrix.
The SBAS ranging function enabling SBAS geostationary satellites to be used in the same way GPS satellites are used to compute a position
As far as integrity is concerned, the user can define different levels of integrity to be displayed (Horizontal Protection Level (HPL)): aviation, maritime or 85 percent.
Since its initial release in November 2011, the EGNOS SDK is providing a useful tool to application developers who need the additional accuracy provided by EGNOS accessible in smartphone applications, according to customers:
“I am interested in the toolkit because I started a project that aims at developing an application based on smartphones” – GeoMatica
“I found the toolkit interesting, especially SISNet, in Finland the EGNOS signal is low…the corrections I receive with SISNet are more reliable than those I could receive with the satellite” – VTT
Roscosmos is conducting further tests on the launch vehicle for the SES-5 satellite, and have postponed the launch for two days. The new launch date is Monday, July 9, with an approximate launch time of 18:24 UTC.
The launch of SES-5 from the Baikonur Cosmodrome, originally scheduled for June 18, was first rescheduled to July 7 due to a problem with a first stage subsystem on the Proton launch vehicle.
SES-5 is also known as Sirius 5 stemming from the development of the Sirius satellite constellation by Nordic Satellite AB, now ownded by Luxembourg's SES. The satellite carries a transponder for the European Geostationary Navigation Overlay Service (EGNOS). The transponder is intended to eventually replace or supplement one of those on the currently used EGNOS satellites (Inmarsat 3-F2 at 15.5 degrees west using PRN 120, Inmarsat-4-F2 at 25 degrees east using PRN 126, and Artemis at 21.5 degrees east using PRN124, and designated for industry tests).
Unlike the present L1-only EGNOS satellites, SES-5 will have transponders on both the L1 and E5 frequencies similar to the setup on the Wide Area Augmentation System satellites, which broadcast on L1 and L5.
SES-5 is to be stationed at 5 degrees east longtiude. A second SES satellite with EGNOS transponders is under construction. The SES Astra 5B satellite is scheduled for launch in the second quarter of 2013 and will be positioned at SES Astra's 31.5 degrees east orbital position.
Two British technologists backed by the U.K. Ministry of Defense have filed patents on the future interoperable GPS and Galileo signal designs that severely disrupt modernization plans for both systems and suddenly, unexpectedly place receiver manufacturers in a highly uncertain and unfavorable situation. Some of the patents have been granted in the U.K. and in Europe, and applications are pending in U.S. patent court, with a ruling expected at any time.
Companies in the United States and outside the country are being approached and asked to pay royalties, on the basis of the patent filings, for use of the European E1 Open Service signal and the modernized GPS L1C signal. Should such initiatives prevail, costs would presumably be passed along to end users of GPS and Galileo — the same taxpayers who have already paid once for the systems.
The purveyor of the royalty solicitations is Jim Ashe, vice president for sales and intellectual property at Ploughshare Innovations Ltd., Hampshire, UK. The patents, if successfully used to collect fees from satellite manufacturers or receiver manufacturers, would have a chilling effect on the use of the new interoperable signals that all parties have labored so hard, for so long, to design. They could quite possibly lead to a return to a BOC(1,1) structure for these signals, losing the benefits of MBOC.
“There’s quite an argument going on,” said one person familiar with the controversy. “Some of the methods of arguing have not been too kind.”
The Background. A great deal of work was accomplished cooperatively between the United States and the European Union (EU) to develop the landmark 2004 signal agreement that emerged from the Galileo Signal Task Force, formalizing cooperation on satellite navigation between the United States and more than two dozen European countries, including the U.K. Part of that agreement concerned a common signal structure (spectrum) for the civilian signals for both the E1 Open Service (OS) signal — the Galileo equivalent of GPS L1 — and the new U.S. GPS L1C signal to be implemented on the GPS III satellites, coming as early as 2015.
The EU said during that process, in effect, “Even though we have agreed on this, Europe wants to be able to optimize the E1 OS signal beyond the agreement on that civilian signal being a binary offset carrier BOC(1,1) signal.” Both international entities had agreed that would be the waveform or the spectrum of the new signal.
The Europeans began to evaluate methods of optimizing their signal. They had some designs called composite binary coded symbols (CBCS), a mechanism of putting a higher frequency componenent into the signal structure, and also a version called CBCS*, meaning that they found there was a bias generated by that extra signal, and so they had to invert every other one of its repetitions.
The signal structure that they were playing with was centered on a plus and a minus 5-MHz component. (Actually five times 1.023, because of the inherent clock of GPS, you can think of it as 1.023 MHz. Everyone in doing compatible or interoperable signals agreed upon that; when reference is made to 5 or 10 MHz, or an even 5 or an even 10, it means that number multiplied by 1.023).
The Europeans were were putting an additional BOC signal on top of the BOC 1,1, and it would have plus or minus 5 MHz as the centers of those two BOC peaks, and then some kind of waveform to modulate that.
The United States pushed back against that to some degree, and proposed adoption of the so-called MBOC waveform, in which case the U.S. signal was equally optimized with a concept called time-multiplexed BOC (TMBOC). The Europeans used the CBOC approach. So, very different ways of doing this. In the European way, they transmitted a continuous but very low-power BOC(6,1) term. The U.S approach transmits four BOC(6,1) chips out of every 33 chips of code (see “Future Wave” sidebar).
A chip in this case means a part of the spreading code, so each signal has its spreading codes, just like the C/A code is a spreading code, meaning a pseudorandom code modulating the carrier. L1C and E1 OS have a pseudorandom spreading code.
The U.S. approach does not put BOC(6,1) components onto the data; that’s what is commonly called MBOC. The U.S. approach is TMBOC, on the pilot carrier only, not on the data component. The European system is like two separate signals, the BOC(1,1) signal having both pilot and data, and a BOC(6,1) signal having both pilot and data. They’ve put the (6,1) into both data and pilot components.
Cue the Antagonists. Part of the task force from Europe and the United States considering the future signals’ make-up were Tony Pratt and John Owen, who works for the U.K. Ministry of Defense and whose office sponsored Pratt’s work. The two participated heavily in all these signal discussions. They stated in early meetings they planned to file patents in some areas.
“Frankly,” states one source, “people should have paid more attention when they said that, and asked ‘What do you mean, and how’s it going to work, etcetera?’ And secondly, there probably should have been a written agreement between parties that nobody will take advantage or patent any of these ideas that we are developing.”
Pratt and Owen filed a number of patents domestically, in the U.K., and and in the European Union, in 2003 and in 2006, and in other places around the world, such as Japan, Canada, and in the United States as well. Some of the U.K. and European patents have been granted. The first of some of those U.S. patents may be issued in the near future.
The original patent filings were later amended to include new claims. The new claims were much more specifically oriented toward TMBOC and CBOC, whereas the original claims were more generally oriented toward modulated methods. The claims have been modified over the years; this is fairly standard patent practice.
As a result, the original 2003 patent doesn’t necessarily read on a particular signal, but its early filing date has precedence. The claims have been updated and modified, and if the patent office issues those, as a true patent, then the new claims apply. Plenty of big patent battles have been fought over just such issues.
Once the patent is issued, a satellite or receiver manufacturer must assume that it is valid, and has only two responses to make, other than acquiescing to royalty claims. The manufacturer can either say, if building a product, “No, my product does not infringe, and I will prove that it doesn’t.’” The other choice for manufacturers is to go back into the patent office and sue the patent filer (and grantee) in the patent courts and prove that the patent was invalid in the first place that the patentee should not have been granted it.
The United States and others were taken off-guard when the U.K. company Ploughshare, which is owned and controlled by a part of the British MoD called Defense Science and Technology Laboratory (DSTL), started making claims on manufacturers. The DSTL is similar to the U.S. Defense Advance Research Products Agency (DARPA), which is credited with inventing the Internet. If taxpayer money goes into something new and interesting, it is considered in some circles legitimate to file patents on those and attempt to recover taxpayer money through royalties on that taxpayer investment. That concept is not being challenged. Questions as to whether the patents are legitimate are very much in discussion.
Ploughshare has contacted companies, saying, “If you use these signals coming from either the European satellites or the U.S. satellites, we will go after companies using these signals.” There are different patents issued, one by the European Patent Office, applying to most of the EU countries, that applies directly to the TMBOC signal, the E1 OS signal, and possibly also to Europe’s E5 signal, which is E5a and E5b; and there is also a patent for GPS III, the L1C signal.
“If you take the patent that hits TMBOC, and you take the broadest possible interpretation of that patent against receiver companies, it says: if you bring into your antenna and process that signal, whether you use all parts of it or not, for instance if you use the BOC(1,1) and not the BOC(6,1) part — then you infringe the patent. Others argue that if you don’t use both components, you don’t infringe.
“But the claim is written broadly enough that it would apply to any receiver receiving and processing the signal. Nobody says what processing means. The patent says if you receive and process the TMBOC signal, as defined in the prior claim, you infringe the patent.
“There is confusion as to whether that will apply or not apply — some people expect that it doesn’t and some people think that it might. That’s up in the air.”
George Is Getting Upset. Various factions in the United States are upset by and trying to figure out what to do about the impasse. From a government point of view, there are three paths that the U.S. government can follow:
Put pressure on the U.K. diplomatically. That would be up to the State Department to put pressure on the EU or the U.K. in particular. The EU and the continental Europeans are equally furious at the British for doing this, as far as parties in the U.S. understand. This can’t be stated as a fact but is widely understood and thought to be the case. The diplomatic approach has its limits, obviously.
Go into Europe and fight the patents in European patent court and try to prove them invalid, to invalidate the patents. Companies could do the same thing, go into various courts, whether they be U.S. or European or Japanese, and say: “Our receivers don’t infringe,” and then have to prove that to the court; or say “The whole patent should not have been allowed, and I’ll fight the legitimacy of the patent.”
Some believe — and there is controversy and anger on this point — that, just as Galileo’s IOV satellites have the capability to transmit without the BOC(6,1) component, the United States should be able to do that with the GPS III satellites as well. Because if the signal is not there, and if the receivers are therefore not designed to process the signals that are not there, then the patent no longer has any relevance.
“If we are to turn off the BOC(6,1) term for a period of time until the legal or diplomatic or other approaches worked, then we would be able to turn the BOC(6,10) term back on again, and return to the original agreed MBOC and TMBOC signals. That requires some coordination between the United States and Europe, and it requires some work to make that possible in the GPS III satellites, putting a switch in the GPS III satellites to permit the operators to turn that (6,1)BOC on and off. This is being hotly debated.”
Some parties object, stating that L1C is too important a signal to mess with, and this proposal runs the risk of slowing down the program, and/or making it more expensive. They believe strongly that the off/on switch is not the best or most far-sighted option: why should the United States be forced to change its signal design due to an illegitimate patent, and in the end wind up with a less capable system?
It is not publicly known whether the Air Force is or is not looking into that option.
During the week of June 25 there was Working Group-A meeting in Washington D.C. followed by a plenary meeting between the EU and United States. The patent controversy was presumably discussed in some fashion, but whether formally addressed or lurking in the background is unknown at this time.
“There is some naivete around this,” said the magazine’s soure. “It’s a serious threat. People think maybe they’ll only go after the high-end receivers, and maybe the royalties won’t be so bad. Ploughshare is trying to lull people into a false sense of security. The impact of this will be great unless it is defeated.”
“The L1C waveform originally was to have been a pure BOC(1,1) (a 1.023 MHz square wave modulated by a 1.023 MHz spreading code). Negotiations between the U.S. and the European Union (EU) at that time resulted in an agreement that both GPS and Galileo would use a baseline BOC(1,1) signal. However, the EU reserved the right to further optimize their signal within certain bounds. Some of the optimization proposals were known as CBCS and CBCS*. However, in further EU/US discussions it was decided that L1C and the Galileo E1 open service signal should have identically the same spectrum. This was a significant challenge because of different baseline signal structures and existing designs.
“The breakthrough came when [U.S. representative] John Betz proposed what is called MBOC. The MBOC waveform has 10/11th of its power in BOC(1,1) and 1/11th in BOC(6,1). However, L1C and E1 OS achieve this result in very different ways. The Galileo technique is called CBOC. The GPS technique is called TMBOC. Whereas Galileo has a 50/50 power split between pilot and data and includes the BOC(6,1) component in each, GPS includes the BOC(6,1) waveform only in the pilot component by modulating four of every 33 spreading code chips with a 6 MHz square wave and 31 chips with a 1 MHz square wave. With 75 percent of the power in the pilot, the result is 3/4 x 4/33 or 1/11, as required. It is likely the BOC(6,1) signal component will be ignored by consumer-grade GNSS receivers where a narrow RF bandwidth is preferred. Fortunately that is a loss of only 12 percent (0.56 dB) of the L1C pilot power. However, for commercial and professional grade receivers, the extra waveform transitions (wider Gabor bandwidth) can be used to improve code tracking signal-to-noise ratio, and with certain advanced techniques it should be possible to improve multipath mitigation. This final point depends on careful control or calibration of the transmitted code timing and symmetry.”
EGNOS and Galileo IOV Satellites Shift Right
The next EGNOS satellite, originally scheduled for a June 18 launch, now has a rise date of July 7 from Baikonur Cosmodrome in Kazakhstan. The launch was delayed by a problem with a first-stage subsystem on the Proton rocket. SES-5 is also known as Sirius 5, stemming from the development of the Sirius satellite constellation by Nordic Satellite AB, now owned by Luxembourg’s SES.
The satellite carries a transponder for the European Geostationary Navigation Overlay Service (EGNOS). The transponder is intended to eventually replace or one of those on the currently used EGNOS satellites (Inmarsat 3-F2 at 15.5 degrees west using PRN 120, Artemis at 21.5 degrees east using PRN124, and Inmarsat-4-F2 at 25 degrees east using PRN 126 and designated for industry tests).
Unlike the present L1-only EGNOS satellites, SES-5 will have transponders on both L1 and E5 frequencies similar to the Wide Area Augmentation System satellites, which broadcast on L1 and L5.
SES-5 is to be stationed at 5 degrees east longtiude.
A second SES satellite with EGNOS transponders is under construction. The SES Astra 5B satellite is scheduled for launch in the second quarter of 2013 and will be positioned at SES Astra’s 31.5 degrees east orbital position.
Role Switch. On March 22 and 23, Inmarsat-4-F2 at 25 degrees east using PRN126 and Artemis at 21.5 degrees east using PRN124 switched roles. PRN126 became an EGNOS operational signal-in-space satellite, while PRN124 became the test satellite, transmitting message type 0. PRN120 and PRN126 returned to service around 17:00 UTC on Tuesday, June 26.
According to an EGNOS service announcement dated April 3, the switch was due to the aging state of the Artemis satellite.
Galileo October Birds. According to a usually reliable source, the launch date for the second set of Galileo IOV satellites, previously announced as September 28, has been pushed back a couple of weeks to October 12.
