The System: Galileo Countdown, PNT Advisory Board

April 1, 2014  - By 0 Comments

Galileo Countdown to 10 by Year’s End

Signs Point Toward Early Services in December, If ESA Delivers

Europe’s Galileo satnav system.

Europe’s Galileo satnav system.

A February conference on the European Union’s space policy in Brussels sought to set a course for 2020 and close official ranks behind the prospect of early Galileo services at the end of this year. Much in the business community’s perception of the new system — critical for device availability and mass- and professional-market adoption of Galileo — will depend on meeting the projected unveiling of early services in December. This is turn depends on an operational 10-satellite constellation; the fleet now stands at four.

Among trends noted at the meeting: the growing importance of the European GNSS Agency (GSA) as Galileo service provider, with perhaps more authority — and budget — than it has had in the past to get the job done. “The GSA will gradually assume responsibility for the operational management of the programmes while ESA will remain responsible for the deployment of Galileo, and the design and development of new generation of systems,” announced the European Commision (EC).

EC Vice President Antonio Tajani reiterated there will be three Galileo launches in 2014 to reach the requisite year-end total. “The first will come in June. Two satellites have passed the necessary tests. We need to keep this up, and continue to raise our game.”

Trouble on the Equator. The next two Galileo satellites may be ready to ship to Europe’s spaceport in South America by early April. But a large European commercial satellite customer is crowding the schedule, pressuring launch operator Arianespace to lift its satellites first. This could delay the Galileo birds, now set for June rise.

ESA’s year-end plan calls for two more dual-satellite launches in October and December on Russian Soyuz rockets — new partners to the Galileo dance, bringing perhaps new technical connectivity issues.

It’s Not Easy. With Galileo and EGNOS financed to the tune of €7 billion for 2014–2020, expectations are high, yet the European Commission brings a decidely conservative approach to expenditure on new ventures.

“To take a chance, to do what no one has ever done — it’s not easy in a culture that doesn’t like risk,” said ESA director Jean-Jacques Dordain.

Other conference speakers pointed to the securely established European Geostationary Navigation Overlay Service (EGNOS), the first generation of Europe’s GNSS, now fully operational.

Carlo des Dorides, executive director of the GSA, responsible for operating EGNOS through the EGNOS Service Provider (ESSP), elaborated on his big job in 2014: maintaining and improving EGNOS performance and maximizing user adoption, particularly in the aviation, maritime transport, and rail transport sectors.

“The experience we gain through our work with EGNOS will be instrumental as we move towards Galileo service delivery.”

As well as organizational experience with EGNOS, user adoption of the GNSS precursor augurs much for Galileo. With one eye on the present and another on the future, the GSA has a big serving coming to its plate by December: management of a long-awaited, heavily invested system that has been in discussion since the 1990s and in various stages of gestation since 2000.

PNT Advisory Board Hears Air Force CNAV Plan

The U.S. National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board published the minutes of its December 2013, detailing a report from  Air Force Space Command on the road ahead for implementation of the GPS Civil Navigation (CNAV) message on L2C and L5. The subject has stirred some controversy of late, particularly between the U.S. Departments of Transportation (DoT) and Defense (DoD), and DoT is currently seeking public comments on the plan.

The minutes relay the gist of General Whelan’s CNAV remarks as follows: “CNAV has been under discussion for a considerable time. Currently, L2C and L5 signals are being transmitted, but without a navigation message. AFSPC is working hard to activate these messages as soon as possible. One of the reasons for the delay is that additional time was needed to complete testing prior to activation. Testing began in late summer 2013 and, based on initial test results, a ‘way ahead’ has been plotted. . . . Current plans are to begin initial broadcasting in the spring of 2014. CNAV uploads will occur twice weekly. The signal will meet GPS Standard Positioning System (SPS) standards, but may not achieve current accuracy levels until full implementation in late 2014.

“CNAV live-sky testing occurred in June [2013] and was conducted in cooperation with civil, industry, and international partners. The two-week test series included independent assessment and verification. The tests identified four errors that required action. The first, which was addressed in real time, related to implementation of the test series. The second required improvement to the tools suite, which should be totally integrated into the ground segment by December 2014. The third and fourth errors required patches to satellite software. All four issues are now regarded as closed.”

DOT Speaks. A subsequent presentation from the Department of Transportation did not directly mention CNAV, according to the meeting minutes, but did include this update on civil signal monitoring, taken from the meeting minutes:

“DOT is responsible for performance monitoring of GPS civil signals. The International Committee on GNSS’s (ICG’s) transparency principle states that ‘Every GNSS provider should publish documentation that describes the signal and system information, the policies of provision, and the minimum levels of performance offered for its open service.’

Currently, this is only done on GPS L1 C/A signals. Performance standards for L2C and L5 have not yet been established. The crucial function of signal/service monitoring is to verify that commitments to GNSS performance are being met. Additionally, monitoring improves the situational awareness for GNSS operators, and provides assurance that any civil service failure is detected and resolved promptly.”

Opposing Activation. At the close of 2013, a departing DOT assistant secretary wrote a letter to the Air Force opposing activation of the CNAV signal in April 2014. In March, DOT opened a 30-day comment period on the proposed CNAV message on L2C and L5. The comment period closed on April 4, after press time for this magazine so no results are yet known.

Bright New IIF Aloft

A United Launch Alliance Delta IV lifts off from Space Launch Complex-37 with the Air Force's Global Positioning System (GPS) IIF-5 satellite. This launch marked the 25th Delta IV flight since the first flight in 2002.

A United Launch Alliance Delta IV lifts off from Space Launch Complex-37 with the Air Force’s Global Positioning System (GPS) IIF-5 satellite. This launch marked the 25th Delta IV flight since the first flight in 2002.

The latest GPS IIF satellite was successfully launched into orbit on February 21. GPS IIF-5 will replace the vintage 1997 spacecraft known as GPS IIA-28 in Plane A, Slot 3 of the constellation. IIA-28 will go into a reserve role in the network for the remainder of its useful life.

This is the first of three GPS launches planned through July to replace aging craft in the constellation. The IIF generation will form the backbone of the GPS space fleet for the next 15 years, providing greater navigational accuracy through improvements in atomic clock technology, a new, more robust, third civil signal, L5, for commercial aviation and safety-of-life applications, a second civil signal, L2C, for the dual-frequency GPS receivers, and improved anti-jam capabilities for military and civil users around the world.

The GPS Block IIF satellites are built by Boeing. Earlier IIF satellites were launched in 2010, 2011, 2012, and 2013. All 12 satellites in the GPS IIF series have completed production. The Air Force plans to launch the remaining IIF satellites by 2016.

Downstream Dialog, Tests in Europe

With Galileo services set to take effect in December, the two European entities charged with the program are engaging manufacturers — the European Space Agency (ESA) in consumer markets, and the European GNSS Agency (GSA) in the government security sector, respectively.

“We put out an open call to satnav manufacturers offering testing with our laboratory facilities,” said the head of ESA’s Radio Frequency Systems, Payload, and Technology Division. “We have gone on to work with five mass-market chipset makers and a comparable number of professional receiver manufacturers.”

Available ESA facilities include:

  • a hybrid localization solution rack for receiver plug-in; it generates simulated constellations of multiple satnav systems along with Wi-Fi or mobile networks. It can also simulate inputs from inertial devices.
  • the octobox, a mini anechoic chamber into which phones or mobile devices can be placed, to feed them simulated satnav and cellular network signals.
  • a telecommunications and navigation testbed vehicle for field tests, carrying its own extremely accurate receivers to assess the performance of the consumer devices under test.

“Thanks to earlier collaboration with ESA and the EU, the millions of multi-constellation satnav chips we sell annually have been equipped for Galileo signals since 2009,” stated Philip Mattos of ST Microelectronics, whose Teseo II receiver chips are used in satnavs and embedded in cars (see detailed technical article on page 36). “It will take only a software update to enable them to start using Galileo. This cooperation allows us to optimize our software based on access to actual signals and background technical information.”

Regulated Service. The GSA invited European industries and member states’ Public Regulated Service (PRS) authorities to share views and ideas on technologies at the user segment level for the adoption of the PRS. The PRS uses encrypted signals designed to resist jamming, involuntary interference, and spoofing. GSA’s objective is to ensure that PRS service is affordable and secure for all interested users while also ensuring that European industry maintains its competitive edge in the global satellite navigation marketplace.

GSA consultations will focus on:

  • steps transforming technologies into products competitive enough in terms of cost, power, dimension;
  • euro-manufacturing capability and capacity, especially nanotechnology;
  • how to build the manufacturing lines capable of serving PRS user segment needs;
  • main domains, elements, and interfaces that will benefit from standardization, allowing for a stronger market adoption of PRS.

GPS III Alternative Payloads Canvassed

GPS III prime contractor Lockheed Martin has heard from six companies concerning alternate designs for the GPS III satellite payload, according to reports. A company spokesperson said “constantly canvassing the industrial base to see what’s out there” is merely part of Lockheed’s standard business practice.

Lockheed Martin partner Exelis Geospatial Systems currently supplies the payload, as it has for all previous GPS generations. Earlier this year, Gen. William Shelton, Air Force Space Command, said the first GPS III launch date had slipped from late 2015 into 2016, and confessed to “patience wearing thin” at a press breakfast.

Part of the delay may have been due to signal crosstalk in the new, as yet unlaunched, payload. Crosstalk occurs when a signal broadcast on one circuit creates an undesired effect on another circuit.

The Story So Far. In December 2013, Lockheed Martin turned on power to the bus and network communications payload of the second GPS III satellite, SV-02, at its test facility in Denver. This demonstrated the satellite’s mechanical integration, validated its interfaces, and opened the way for electrical and integrated hardware-software testing. The first GPS III satellite (SV-01) was powered on in February 2013.

In October, the Lockheed Martin GPS III Nonflight Satellite Testbed (GNST), a full-sized, functional satellite prototype at Cape Canaveral Air Force Station, successfully communicated via cross-links to Air Force simulators of the current GPS constellation in orbit. Testing also demonstrated the ability of an Air Force receiver to track navigation signals transmitted by the GNST.

Exelis Advances. In mid-March, Exelis announced successful completion and full testing of six transmitter assemblies, which are integral payload components for the GPS III satellites. The test program includes random vibration, pyroshock, and thermal vacuum testing, replicating space-like conditions through deployment and on-orbit environments. In January, Exelis received three rubidium atomic frequency standard clocks from Excelitas Technologies specifically designed for GPS III.

Next-Gen SBAS Will Be a Multi-Constellation Affair

Plans to harness Galileo and other satnav systems for next-generation satellite augmentation systems for aviation and other high-performance uses took a step forward at the 126th Satellite-Based Augmentation Systems (SBAS) Interoperability Working Group (IWG) in New Delhi, India, in February, with plans to move to a multi-constellation design adding Galileo, BeiDou, and GLONASS systems in the post-2020 era.

International experts began converging on a standard message definition for the L5  channel 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,” explained 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.”

GAGAN to the Mix. The meeting also marked the significant progress made by India’s own SBAS system GAGAN, which underwent its final stability test in summer 2013, 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 February 14.

SBAS Services Worldwide

GAGAN is the fourth certified SBAS to enter service 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 GNSS 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 in July 2013.

Japan has the Multi-functional Satellite Augmentation System (MSAS), developed and operated by Japan’s Civil Aviation Bureau. Japan is discussing plans to merge this capability with its new home-grown satnav system, QZSS.

Along with GAGAN, the meeting covered the progress made by the other SBAS systems under definition or development — the Russian SDCM, Chinese SNAS, and Korean K-SBAS.

The next IWG meeting will take place in September in Tampa, Florida.

GPS World staff

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