U.S. aviation officials on Monday (December 30, 2013) named the winners of a high-stakes contest to operate one of six new research and test sites for unmanned aircraft. The Federal Aviation Administration (FAA) will now work to help the sites set up safe operations and create the structures needed within the agency to help it use the sites’ research results.

U.S. aviation officials on Monday (December 30, 2013) named the winners of a high-stakes contest to operate one of six new research and test sites for unmanned aircraft. The Federal Aviation Administration (FAA) will now work to help the sites set up safe operations and create the structures needed within the agency to help it use the sites’ research results.

The designated organization  — located in Alaska, Nevada, New York, North Dakota, Texas, and Virginia, which is partnering with schools in New Jersey and Maryland — are each operated by a public entity. They were chosen in part for their diversity of climate and geographic location as well as the infrastructure available on the ground, said FAA Administrator Michael Huerta in a telephone news media conference.

Testing done at the sites will be used to develop the certification and operational requirements for using an unmanned aerial system (UAS) in the United States and will help officials find solutions for key questions such as how to achieve “sense and avoid” in an unmanned craft in which GNSS positioning is expected to play a key role, handle command and control, set ground control station and airworthiness standards, and devise rules for human factors, the interface with the air traffic control system, and procedures when a communication link is lost.

The competition was fierce for what is widely seen as a critical leg up in a lucrative new business sector. The Association for Unmanned Vehicle Systems International (AUVSI) said earlier this year that activities surrounding UASs would create more than 100,000 high-paying jobs. AUVSI forecast an economic impact of more than $82 billion for the country in the first decade after the aircraft are integrated into the National Airspace System or NAS.

“Today’s announcement by the FAA is an important milestone on the path toward unlocking the potential of unmanned aircraft,” said Michael Toscano, AUVSI’s president and chief executive officer. “From advancing scientific research and responding to natural disasters to locating missing persons and helping to fight wildfires, UAS can save time, save money, and, most importantly, save lives.”

Congress in the 2012 FAA Reauthorization Act charged the agency with integrating unmanned aircraft by 2015. Alhough the overall process has been delayed — in part by concerns that unmanned craft could be used to invade personal privacy — the new test sites are expected to move the process along and help companies profoundly long frustrated by a lack of testing opportunities.

One of the sites is set to begin operations within six months, although Huerta declined to say which facility would be the first. The sites will continue their research through at least February6 2017, which is when the FAA Reauthorization Act expires.

Selections Ensure Geographic, Research Diversity
The FAA announcements elaborated on the focus of the chosen organizations:

The University of Alaska proposal was chosen, the FAA said, because it offered a diverse set of test site range locations in seven climatic zones as well as geographic diversity provided by the test site range locations in Hawaii and Oregon. The university’s research plan includes the development of a set of standards for unmanned aircraft categories, state monitoring, and navigation as well as work on safety standards for UAS operations.

The state of Nevada plans to concentrate on UAS standards and operations at its site as well as operator standards and certification requirements. It will look at how air traffic control procedures will evolve with the introduction of UAS into the civil environment and how these aircraft will be integrated with NextGen, the FAA’s next-generation air traffic control system. Huerta noted that Nevada’s selection brought a test site to the southwest part of the country.

The site at New York’s Griffiss International Airport will tackle developing test and evaluation as well as verification and validation processes under FAA safety oversight. It will focus on researching sense and avoid capabilities and help research the complexities of integrating UAS into the congested, northeast airspace.

The North Dakota Department of Commerce will use its site to develop essential UAS airworthiness data, validate high-reliability link technology, and conduct human factors research. This site, the only test range in the temperate (continental) climate zone, also includes a variety of different kinds of airspace.
 
Texas A&M University at Corpus Christi plans to develop requirements for UAS safety and unmanned operations at its site, with a goal of supporting protocols and procedures for airworthiness testing.

Virginia Polytechnic Institute and State University, also known as Virginia Tech, plans to conduct UAS failure-mode testing and identify and evaluate operational and technical risks areas. Its plan includes test ranges in New Jersey as part of a cooperative arrangement with Rutgers University. The University of Maryland has also agreed to partner with Virginia Tech and Rutgers on UAS integration.

“With our partners, we firmly believe we can introduce this new technology the right way,” said Jon Greene, interim director of the Mid-Atlantic Aviation Partnership and an associate director of Virginia Tech’s Institute for Critical Technologies and Applied Science in a prepared statement.

Virginia announced earlier this month that it was awarding more than $2.6 million over three years to Virginia Tech to operate the Virginia test site. Each site operator will need to find its own resources as the FAA will not provide funding for the sites although Congress could potentially find some money for the research and test activities down the line.

Just the Beginning
Although the sites will be helping FAA establish UAS operational guidelines, equipment standards, and certification, they will likely be a boon for American companies, which have been very vocal about the difficulty of obtaining access to the airspace and permissions needed to test UAS in the United States, especially given that the technology is widely in use in other parts of the world. Arrangements for such testing will be left to the sites and the companies to work out.

Although the six sites may now have a certain momentum, companies will likely have more than just six choices when it comes to their testing. Toscano believes that those organizations whose site proposals were not selected will continue to do research and ultimately every state may have an unmanned UAS R&D operation just like every state has a Department of Motor Vehicles.

Mississippi, which has four UAV manufacturers conducting tests at Mississippi State University, will indeed carry on, said Major General James Poss (ret.), the university’s director of Strategic Initiative High Performance Computing Collaboratory and the point person for the state’s site bid.

“We’re disappointed but we’re going to continue to test,” Poss told Inside GNSS.

Poss said Mississippi was very interested in the next step in the FAA process, where the agency will designate an academic UAS Center of Excellence or COE

“Mississippi State will be bidding on that along with 12 other schools in our coalition,” said Poss. Three of those schools, he noted, were part of test organizations that were selected.

The COE could be “kind of the brain of the test system,” he suggested.

“What we’re hoping,” said Poss, “is the Center of Academic Excellence is going to kind of be the central unit that works with the six other test sites to make sure that all of the research is happening appropriately and not everyone is researching one thing and not researching another.”

UAS Center of Excellence
Although the FAA has not made an official announcement about a COE, Poss told Inside GNSS the agency had previously said it would begin work on choosing a place for the COE soon after announcing the test sites. The FAA did not respond to a question on a future COE by press time.

However, the FAA 2012 Reauthorization Act contains a mandate for the agency to expand its existing research efforts to include unmanned systems. Section 903 instructs the FAA, “in conjunction with other Federal agencies, as appropriate, to develop technologies and methods to assess the risk of and prevent defects, failures, and malfunctions of products, parts, and processes for use in all classes of unmanned aircraft systems that could result in a catastrophic failure of the unmanned aircraft that would endanger other aircraft in the national airspace system.’’

A UAS Center for Excellence could be key in bridging any gaps that might arise between the test sites and the FAA. While the aviation agency has to approve the certification standards and regulations that UASs ultimately need to operate, no process appears to be in place yet to set a research agenda or reporting deadlines. The FAA will not have staff at the six sites, said FAA spokesman Les Dorr, but will work with the sites on establishing safe operations.

“We’re there to help them set things up and make sure it’s going to be safe,” Dorr told Inside GNSS.

Dorr said that the six sites would be part of a “structured environment” and that the sites had to periodically report to the FAA.

“These six tests sites have been specifically designated to do research that will help the FAA in integrating unmanned aircraft in the nation’s airspace,” Dorr added, noting that aviation experience was one of the criteria for selection. However, a formal structure for reporting back to the FAA — a structure that might include deadlines and feedback for the sites — is yet to be set up, he said.

The sites are an essential first step, stressed Toscano. They will help determine what is necessary for unmanned aircraft to be integrated into daily life where they can be used to monitor and fertilize fields, assess pipelines, and evaluate accident sites. There are many industry working groups that have already been established and different standards that have already started to be developed, he pointed out. Data from the sites will feed into those groups, he suggested.

“If we didn’t have the test sites, said Toscano, “how do we start to determine how safe these systems have to be in order to fly in the national airspace?”

The post FAA Taps Six Operators for Unmanned Aircraft Test Sites appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

The U.S. Department of Transportation (DoT) is asking the Air Force to cancel its plan to add navigation data to two key civil GPS signals this year, saying they are concerned that the approach and “nonstandard engineering tools” military officials plan to use could put GPS users at risk.

The U.S. Department of Transportation (DoT) is asking the Air Force to cancel its plan to add navigation data to two key civil GPS signals this year, saying they are concerned that the approach and “nonstandard engineering tools” military officials plan to use could put GPS users at risk.

The messages are to be “developed by engineers rather than certified GPS operators, and then manually uploaded to the satellite,” said then-Deputy Secretary of Transportation John Porcari in a letter sent to Acting Secretary of the Air Force Eric Fanning on December 27, 2013. This approach has “the potential to inject human error, which may result in unacceptable GPS constellation operation,” Porcari wrote.

The Department of Defense (DoD) told the PNT Advisory Board in December that it would add navigation data to both the L2C and L5 signals by the end of 2014, making the signals more accurate and the system more robust overall.

Sources tell Inside GNSS that a two-phase plan is set to launch in April. During the first phase the signals would be somewhat less accurate than other GPS signals though still fall within the standard for GPS service. During the second phase, set to kick in by the end of the year, the ephemeris data would be upgraded making L2C and L5 just as accurate, if not more precise, than current GPS signals.

Delays in transmitting the full L2C signal could also conceivably affect the DoD’s plan to discontinue support for L2 codeless/semi-codeless techniques as of December 31, 2020. That schedule was already under reconsideration according to a presentation to the Civil GPS Service Interface Committee last September.

OCX Delay Complicates Issue
The original plan was to wait for the Next Generation Operational Control Segment (OCX) to come online, but OCX has been delayed and will not be available for two to three years.

Because slight differences in the onboard memory must be allowed for in the software, the GPS L2C and L5 navigation messages would first be uploaded to and transmitted by the Block IIR satellites, then the Block IIF satellites by the end of the year. A computer would be used to develop the civil signal navigation data instead of the current control segment, confirmed experts  — which is part one of DoT’s concern.

“The official way of doing the nav message is to have it created by the operational control segment or the new system OCX,” said one source familiar with the issue. “The operational control segment generates the message for you instead of an app on a PC.”

DoT’s concern is magnified by the fact that the OCX system, which will not be on-line for a few years, is also the official mechanism for monitoring the L2C and L5.

“Without the ability to monitor these signals,” Porcari wrote, “the system will not know if the L2C and L5 signals are within specification. Given these risks, DOT is concerned that the CNAV messages could provide hazardously misleading information, impacting GPS safety-of-life, protection of property, and economic security applications.

“As the lead civilian Agency within the U.S. Government on issues relating to GPS, DOT is critically interested in ensuring that GPS remains reliable, continues to deliver quality service to civil users, and protects them from receiving hazardously misleading information that cannot be detected by the GPS control segment. Given that there is no validated requirement for early CNAV implementation and the identified risks to civil GPS users are too great to ignore, I recommend deferring the CNAV capability until OCX becomes operational, except for coordinated test periods, ” Porcari added.

Interagency Differences over Safety Issues
GPS specialists familiar with the Air Force’s plans took umbrage at the suggestion that DoD’s approach would create risk and questioned whether DoT officials understood how and why the signals were to be added.

“I just can’t imagine sending a letter to a four-star operational commander like that. It is absolutely an affront,” said one insider. Each of the sources who spoke to Inside GNSS for this article did so on condition that they not be identified because they were either not authorized to speak on the issue or were not otherwise able to speak freely on the controversial matter.

Sources pointed out that the DoD currently monitors the military L1P/Y signal but not the L1C/A signal available to civilians — but that other monitoring services filled in the gap.

“They get a feed from all the civilians that are monitoring it and, in very short order, if something is wrong with C/A they are going to hear about it,” said one expert, noting that those same services could monitor L2C and L5 as well.

Receivers are also programmed to choose the best quality signal from the variety available, which could offset any problems.

“What’s silly about this is that nobody’s going to pick up the least accurate (signal),” pointed out another authority on GPS.  “The receiver picks up the best, and integrates it with everything it has.”

Adding the navigation message data is necessary to develop both the signals and the receivers that would use them, sources told Inside GNSS.

“Developers are saying this is the necessary next step in prototyping it,” said one a source. “We turn it on [and] say it’s an at-risk signal,” the expert explained. “We do not declare it to be operational. Meanwhile the users get experience with it, the users see what they have to equip for — and we find out if there are any . . . technical things that have to be or should be modified.”

This is the same approach that was used for earlier GPS signals and signals from other systems, they said.

Taking this approach would not add risk — even on L5, said an independent third expert.

“I don’t think there’s any real safety issue with having the data on because there are no aircraft that are using L5,” this expert said, “and there won’t be until we have the standards in place.”

And, of Course, Money
Safety, however, is not the only reason DoT is requesting the project be canceled, sources suggested. Though adding the nav messages would not trigger direct expenses for DoT, experts agreed, more than one suggested that budgetary resources were still an issue.

“When the Air Force is doing this,” said one specialist, “it is taking money that the Air Force has away from other stuff that DoT has more of an interest in.”

“DoT never was in favor of doing this stuff that quickly,” the expert explained. “They certainly want the civil signals up and running as soon as they can, with the nav data, but they do understand that it won’t be very long before we have OCX operational — and also that the Air Force is tight on money. So, they would just as soon not rush things now but wait until the clean, fully developed software is ready rather than do an add-on” to the old system.”

What DoT would support is long-term testing, said a different source, confirming that there would be a "tiger team" put in place to work through the sticking points.

“The Department of Transportation works closely with the Department of Defense to ensure accurate and dependable GPS service for the benefit of the nation,” DoT said in a statement to Inside GNSS. “This matter concerns deliberations between the two agencies, and DoT looks forward to its continued collaboration with the Department of Defense on GPS issues.”

Any negotiations, however, will fall to someone besides Porcari. Four days after he sent the letter, he left DoT to join an engineering and consulting firm.

The post DoT Opposes Early Start for Navigation Messages on New Civil GPS Signals appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

At a news media conference in Beijing on the first anniversary of the BeiDou Navigation Satellite System (BDS) declaration of full operational capability (FOC) for its regional service, officials reported on the current performance of China’s GNSS system.

The BDS program also released two new technical documents, including an updated interface control document (ICD) that describes the second civil signal, B2I, and a “BDS Open Service Performance Standard (version 1.0).”

At a news media conference in Beijing on the first anniversary of the BeiDou Navigation Satellite System (BDS) declaration of full operational capability (FOC) for its regional service, officials reported on the current performance of China’s GNSS system.

The BDS program also released two new technical documents, including an updated interface control document (ICD) that describes the second civil signal, B2I, and a “BDS Open Service Performance Standard (version 1.0).”

Held December 27, 2013, in the press conference hall of the State Council Information Office, the event featured Ran Chengqi, director of the China Satellite Navigation Office; Liu Qixu, director of the China Satellite Navigation Application Management Office; and Su Jie, vice-director of the comprehensive transportation planning department in the China Ministry of Transport.
Ran described BDS performance over the past year as stable and continuous, with “performance values . . . steady and rising.”  

According to the monitoring and assessment of BeiDou services in the Asia-Pacific region during the past year, Ran said system performance meets with designed specification of 10-meter positioning accuracy, while in some areas, the performance is better than the designed specification.

“For example,” he said, “in Beijing, Zhengzhou, Xi’an, Urumqi, and other cities, the positioning accuracy can reach seven meters; in some areas with low geographic latitude, such as ASEAN countries, the positioning accuracy can reach 5 meters.”
Meanwhile, the third phase of BDS development is under way, with improved BeiDou satellites planned for launch this year. The target for global BDS coverage is still “about 2020.”

When fully deployed, the constellation of BDS will consist of 5 geostationary Earth orbit (GEO) satellites, 27 Medium Earth Orbit (MEO) satellites, and 3 inclined geosynchronous satellite orbit (IGSO) satellites. The current operational constellation is made up of are five GEO, four MEO, and five IGSO BeiDou spacecraft.

B2I Signal Specs
Like the B1I signal centered at 1561.098 MHz, the B2I signal at 1207.140MHz is modulated by quadrature phase shift keying (QPSK).

"BDS has entered an era of multi-frequency applications, and become the first system that possesses two civil navigation signal frequencies with full service capability,” Ran said. “With the publication of the ICD (version 2.0), domestic and international enterprises can develop dual-frequency, high-precision BDS receivers, to enable the users enjoy navigation services with higher accuracy.”

BeiDou satellites transmit two different navigation messages, depending on the type of spacecraft. The BeiDou MEO/IGSOs transmit the D1 NAV message and its GEO satellites, D2. The D1 message contains fundamental navigation information such as the almanac data for all satellites as well as the time offsets from other GNSS systems, the while D2 NAV message contains both the basic NAV information as well as augmentation service data (BDS integrity, differential, and ionospheric grid information).

The different messages reflect the fact that BDS has a satellite-based augmentation system (SBAS) built into its fundamental design, unlike other SBASs such as the U.S. Wide Area Augmentation System (WAAS) and the European Geostationary Navigation Overlay Service (EGNOS), which are operated as separate infrastructures by other organizations, the Federal Aviation Administration and the European Satellite Services Provider (ESSP), respectively.

The second document, the BDS Performance Standard, codifies and “enhanced and enriched” open service performance specifications published in 2012 “in accordance with international common practices” and “to meet with requirements for BDS to join international organizations, such as ICAO and IMO,” Ran said.

The document provides detailed descriptions for the overall BDS structure, signal-in-space characteristics, and performance specifications, and system performance characteristics and specifications, and represents, in Ran’s words, “an important guideline for users to understand, apply, and appraise BDS.”

Industry, Policy Developments
The press conference also described some of the official efforts to build China’s GNSS industry and promote BDS applications. In September, the State Council released the “National Program for Medium and Long-term Satellite Navigation Industry Development,” which set forth the overall long-term planning for China’s satellite navigation industry from the national level.

“A complete application industry chain has been formed, which consists of fundamental products, user terminals, system applications and operating services,” said Ran. “All-round breakthroughs have been made in some key technical areas, such as BDS core chips and modules. The performance of domestic products is comparable to that of international products in the same class.”

Chinese manufacturers are not alone in offering BDS-capable products. Today (January 8, 2014), STMicroelectronics announces its Teseo III single-chip multi-GNSS product family capable of receiving signals from  BeiDou, the GPS, Galileo, GLONASS, and Japan’s QZSS satellites. In recent months, several companies have announced products with similar capabilities: u-blox UBX-M8030 receiver IC, Broadcom’s BCM47531 (which substitutes SBAS capability for Galileo), and Qualcomm’s IZat location solution.

Currently, the Chinese officials said, the National Development and Reform Commission, Ministry of Science and Technology, Ministry of Industry and Information Technology, and other government agencies are collaborating to work out a new guidance, “Some Opinions on Promoting the Development of BeiDou Satellite Navigation Industry,” to further provide policy guarantees for development of BDS-related industries.

English language versions of the documents can be found on-line: BeiDou ICD V 2.0 here and the BeiDou Navigation Satellite System Open Service Performance Standard (Version 1.0) here.

The post New BeiDou ICD Describes Second Civil Signal; Officials Describe Progress, Plans appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

1996 soccer game in the Midwest, (Rick Dikeman image)

Nouméa ground station after the flood

A pencil and a coffee cup show the size of NASA’s teeny tiny PhoneSat

Bonus Hotspot: Naro Tartaruga AUV

Pacific lamprey spawning (photo by Jeremy Monroe, Fresh Waters Illustrated)

“Return of the Bucentaurn to the Molo on Ascension Day”, by (Giovanni Antonio Canal) Canaletto

The U.S. Naval Observatory Alternate Master Clock at 2nd Space Operations Squadron, Schriever AFB in Colorado. This photo was taken in January, 2006 during the addition of a leap second. The USNO master clocks control GPS timing. They are accurate to within one second every 20 million years (Satellites are so picky! Humans, on the other hand, just want to know if we’re too late for lunch) USAF photo by A1C Jason Ridder.

Detail of Compass/ BeiDou2 system diagram

Hotspot 6: Beluga A300 600ST

1. E-CROWDSHIPPING
Palo Alto, California USA

1. E-CROWDSHIPPING
Palo Alto, California USA
√ A California-based startup uses crowdsourced GNSS data to get your shopping bags home before you. Deliv works in 600+ malls — you call to request a pickup, leave your bags at the store, and a courier who is geolocated via Twitter picks them up and drops them off at your destination of choice within an hour for a modest fee. The company vets the drivers, social networking reviews them, and you can track the driver and the bags in real time on your phone.

2. HAPPY VALENTINES DAY!
Reston, Virginia USA
√ The 2.5 million records in the official USGS Geographic Names Information System (GNIS), locates, identifies, names and spells physical and cultural features in the USA. But we can use it for fun. For example, 192 features in 35 states carry the name “Valentine,” including a canyon, well, ridge, spring, geyser, trailhead, gulch, windmill, water hole, several mines and cemeteries plus post offices in Nebraska, Texas and Virginia. Want their postmarks on your valentines? Check out the USPS remailing service.

3. WHO YA GONNA CALL?
Linköping, Sweden
√ Rescue robots, that’s who. The 2013 IEEE Safety, Security and Rescue Robotics conference discussed advances in the caring side of UAVs — for example, a collection of bots with the abilities of hawks, wasps, and donkeys who can reach you under a mountain of snow in 15 minutes. Or fleets of little, cheap easy-to assemble “fanboats” that can transmit information and deliver supplies when you’re isolated in a flood. If you’re trapped in a collapsed building, UAVs with special cameras will be able to find access holes in piles of rubble. Better than brandy and a St. Bernard.

4. POINT COUNTERPOINT
Moscow, Russia and Pasadena, California USA
√ NASA and the FAA liked Russia’s proposal for GLONASS monitoring stations on American soil at first. Not so fast, said the CIA and Congress. Now Russia has another idea — use the International GNSS Service (IGS), a Jet Propulsion Lab–based international organization of more than 200 agencies that maintains a global network of GNSS monitoring stations and data archive. 140 stations already collect GLONASS data and will offer real-time service (RTS) for GLONASS later this year. The problem? It doesn’t have the same service and availability guarantee as a proprietary monitoring system. Stay tuned.

5. BRIDGE THE GAP
New Delhi, India
√ India certified GAGAN —GPS Augmented Navigation System — for en route navigation and non-precision approaches (RNP O.1) on December 30. The system will bridge the gap for civil aviation between Europe’s EGNOS and Japan’s MSAS. The GAGAN signal is broadcast through GEO satellites GSAT-8 and -10. A spare navigation payload will go up with GSAT-15 sometime this year.

The post GNSS Hotspots | January 2014 appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

Thousands? Millions?

Yes, back in the wreckage of the second George Bush’s second term, Barack Obama looked pretty good by comparison. Even then, though, raising the banner of “Hope” before the eyes of a desperate nation was a risky thing to do.

But now — much as I hate it — I’d have to answer Sarah Palin’s snide query, “How’s That Hopey-Changey Stuff Working Out For Ya?’’ Not so well, Mrs. Palin, really not so well.

And back in 2009, Obama’s resistance to being separated from his Blackberry by security-minded officials seemed amusing — a generational indication that smartphones might be competing for the affections of Americans toward their automobiles. Instead, it actually foreshadowed U.S. eavesdropping on the phones of world leaders.

What seemed wonkish but well-informed inclination toward new technology turned out to be mere fancy for the hipness of social media. Hence, the near-catastrophe of LightSquared driven by an impulsive search for 500 megahertz of RF spectrum to reallocate as wireless broadband.

No, once in the White House, the execution of plans fell far short of the rhetoric. Thus, the early promise to close our gulag for terrorists at Guantanamo — filled with innocent and guilty alike — appears no more likely to happen in 2014 than in 2009.

Any more than Obama’s teaching courses in constitutional law seems to have engendered a respect for the protections of the U.S. Constitution.

Or that the good intentions of universal health insurance coverage could survive its poor design and disastrous rollout. “Let it be written, let it be done,” did not work any better for the president’s health care mandate than the same mantra did for Yul Brynner as Pharaoh in “The Ten Commandments.”

What would I like to see this administration achieve in the way of space-based positioning, navigation, and timing (PNT) before last call at the polls in 2016? Well, for a starter, here’s a short list:

• Admit that the Global Positioning System — or more broadly, PNT — really is a part of the national critical infrastructure that deserves at least as much consideration and protection as the other 16 sectors identified in the National Infrastructure Protection Plan. After all, GPS has a very tangible, physical presence in its satellites and ground control segment.
• Support an international GNSS monitoring and assessment service that would benefit all system providers and users. Isn’t that a natural corollary to the administration’s 2010 amendment to National Space Policy authorizing use of foreign GNSS services to strengthen GPS?
• Acknowledge that Americans’ personal location should be considered private unless willingly made public by individuals, granting it the Fourth Amendment protections envisioned in the Supreme Court’s Katz v. United States decision. And enforce those protections against wholesale National Security Agency surveillance as well as the FBI and local police. And while we’re at it, let’s admit that Edward Snowden is closer to being a patriot in the tradition of Daniel Ellsberg with his Pentagon Papers than the traitorous spy that embarrassed officials are trying to portray him as.
• Get the unmanned aerial systems (UAS) initiative off the ground and into the air. Is it possible that we could learn from the experience of many other nations, including those in Europe, that are well ahead of the United States in this area. This may seem at odds with the previous suggestion, but with adequate legal guidelines personal privacy can remain secure while the civil benefits of UAS are revealed. The FAA’s responsibility for ensuring aviation safety are not incompatible with advancing the UAS project vigorously.
• Actually design and approve plans for — if not the completion of — a system to detect and mitigate GNSS interference as well as ensure a backup for GPS. More than nine years after a presidential directive to do so, we should either invest the resources and leadership to get it done or admit that it’s beyond our abilities.

The post Won’t Get Fooled Again appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

A common refrain in the world of GNSS is the desire for “interoperability,” the use of signals from multiple systems without a decline — and potentially even an improvement — in the quality of results.

Achieving this depends on large part in establishing comparable parameters — particularly the geodetic references and timing systems — among the GNSSs along with a dense network of ground reference stations that can provide continuous, precise monitoring of satellites’ orbital positions.

A common refrain in the world of GNSS is the desire for “interoperability,” the use of signals from multiple systems without a decline — and potentially even an improvement — in the quality of results.

Achieving this depends on large part in establishing comparable parameters — particularly the geodetic references and timing systems — among the GNSSs along with a dense network of ground reference stations that can provide continuous, precise monitoring of satellites’ orbital positions.

As recent objections to the installation of Russian GLONASS monitoring stations in the United States have shown, however, achieving this is not a trivial matter politically. And the more than 20-year effort of the International GNSS Service (IGS) — formerly International GPS Service — to establish this capability provides a measure of the practical challenges.

The IGS has established a global system of satellite tracking stations, data centers, and analysis centers that puts high-quality GNSS data and data products on line in near–real-time to support a wide range of scientific and engineering applications and studies.

To better understand the issues and possible benefits of multiple GNSS monitoring, we called on Tim Springer, a member of the IGS Governing Board’s Executive Committee. Springer is a contractor with the European Space Agency at its European Space Operations Center in Germany and a principal in PosiTim UG.

Before the establishment of the IGS, GNSS observation campaigns typically called for one or two weeks in the field followed by about six months analyzing the data back in the office. In a pilot project launched in 1992, the IGS set itself the task of processing a full day of data every day.

At that time the still-incomplete GPS system had only about 20 satellites in orbit and the IGS global tracking network consisted of a mere 30 stations. But even with this reduced set of satellites and stations, generating a solution took between 6 to 24 hours of computer processing time.

A combination of dramatically reduced processing times and increased data transfer capacities via Internet have reduced the time needed to produce IGS products from days, if not weeks, of delay to near–real-time. This development has taken place very gradually, evolving from the weekly “final” products delivered with a 14-day delay after the start of the week, to the daily “rapid” products that become available 17 hours after the end of the day.

The next step was “ultra-rapid” products that are generated four times per day at 0, 6, 12, and 18 hours UTC and contain 24 hours of estimated and 24 hours of predicted orbit and clock products. This has led to the latest development: the IGS real-time service, realized in 2013, which delivers GPS+GLONASS orbit and clock correction in near real-time.

The IGS statistics show that roughly 25,000 users per month directly access IGS products and information through its Central Bureau. In the timeframe from 2010 to 2012, download statistics from CDDIS, the main archive of IGS products, revealed that 3.6 million product files are downloaded each month, of which 64 percent took place in the United States accessed from more than 11,000 different IP addresses. The most downloaded products are the IGS ultra-rapid products.

IGM: What benefits does multi-GNSS monitoring provide in terms of positioning accuracy, robustness, and/or other metrics?

SPRINGER: The most obvious benefit of multi-GNSS is in the area of real-time applications. The gain in number of satellites clearly improves robustness, accuracy, and availability. It is also the reason why the IGS network evolved much faster than the IGS analysis capacity. Many stations in the IGS network are part of regional networks that serve surveyors and geospatial professionals for (near) real-time applications. These customers have requested multi-GNSS services because of these benefits. In general, the IGS analysis centers are more focused on scientific applications for which the addition of GLONASS did not seem to offer too much benefit.

The inclusion of GLONASS, and in the near future also Galileo and BeiDou, will improve the accuracy of the GNSS solutions. Due to the almost perfect daily repeat of GPS’s estimated parameters, the results of a GPS-only solutions are typically better than the day-to-day repeatability of the GPS+GLONASS solutions. However, when looking at annual time scales, the GPS+GLONASS solution actually does perform better than the GPS-only solution.

IGM: Differences among geodetic reference frames and GNSS system time are generally considered two of the main challenges to improving interoperability among GNSSs. What technical solutions might be theoretically possible to improve this situation and what practical issues would need to be addressed in order to implement them?

SPRINGER: As reference frames change slowly, I consider this to be much less of a technical problem then the time reference. However, firstly and primarily these are political and/or security issues more than technical issues.

The IGS does allow all users worldwide to obtain the coordinates of their stations in International Terrestrial Reference Frame (ITRF). There are different ways how this may be achieved. If political and/or security issues make it impossible to publicly disclose the data of the tracking stations, the ITRF positions of the stations can be determined by means of the well-known and established precise point positioning (PPP) technique at the 10- to 20-millimeter level. If the coordinates of the tracking stations can be made publicly available, the IGS would then be more interested in including the station’s data in its processing, thus ensuring that these stations would become an integral part of the ITRF.

In my opinion the direct inclusion of the system-specific stations within the IGS would be the ideal solution for the unification of the reference frames as it would have benefits on both sides, for the GNSS operators and the IGS. GNSS operators do not like to make changes to their stations, while the IGS lacks stations with a long, stable history. Thus, the IGS would profit by gaining a set of stations that have such a history. The GNSS operators would benefit by their stations becoming an integral part of the ITRF with their station data quality and position estimates monitored very accurately.

Timing is a much more difficult issue as it is much less stable over time then the station positions. Also my knowledge in this area is limited. The only thing I can say is that the IGS clock products may be used to monitor the timing differences between the GNSS systems with a very high precision which, on time scales of weeks if not months, could help to give feedback regarding the consistency of the time systems of the different GNSSs.

IGM: In addition to the IGS and initiatives such as its Multi-GNSS Experiment, other multi-GNSS projects are under way, such as Multi-GNSS Asia and China’s proposed international GNSS Monitoring and Assessment (iGMAS) project. What is the relationship and possible dialog between IGS, these initiatives, and organizations such as the International Committee on GNSS (ICG) for coordinating efforts?

SPRINGER: The IGS is proud of its status as an independent group of GNSS experts who have been producing very high quality products for over 20 years. The IGS is therefore a valued partner in several of these initiatives. The IGS is committed to working with different GNSS providers, as well as with organizations that have established and/or are operating regional or global tracking networks.

However, the core principles of the IGS, in particular its open data policy (both raw tracking data as well as derived products), are strongly promoted at a variety of forums, including the ICG. The IGS is an active participant at the ICG meetings, and the leadership role that it plays is highly valued. The discussions regarding an International GNSS Monitoring and Assessment Service are of great interest to the IGS as we believe that the IGS infrastructure is very well suited to contribute to the establishment of such a service.

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GNSS Event that most signifies for you that GNSS has “arrived”

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GNSS Event that most signifies for you that GNSS has “arrived”

GNSS receivers in cell phones were a shock. I always knew that electronics could be shrunk almost forever, but the physics of the antenna, and the tiny signal, seemed to necessitate at least a quarter-wave in size, and clear exposure to the sky. We had visions in the 1980s where we would speculate “by the year 2000 (which seemed forever far away) receivers (which at the time cost many 10s of thousands of dollars and weighed 10s of kilograms) would cost under $100, weigh less than one kilogram, and take up less space than a VCR tape drive.”

Engineering Mentor

If I have to pick one, it would be David Allan. He brought me into the field of time and time transfer, just as GPS was nascent. He was always very supportive and encouraging.

Patents Held:

Along with Dave Allan, Judith Levine, and Dick Davis, patent #5,274,545 issued in 1993 for “Device and method for providing accurate time and/or frequency.” Published as an article, “Smart Clock: A New Time,” in the December 1992 issue of IEEE Transactions on Instrumentation and Measurement.

What popular notions about GNSS most annoy you?:

1) Some in the industry think that clocks don’t matter, that they are of little importance compared to signals and satellites. GPS works so reliably because of atomic clocks.

2) There’s a lot of confusion about the difference between signals and data. GPS is not just another piece of the information system: it is a source of a signal. A signal differs from data in that it can only be useful if measured in the present. It can’t be stored, buffered, and re-transmitted without at least keeping careful track of all that.

3) Popular shows imply that GPS is tracking people; that somehow the satellites know what people are doing. Of course, the GPS satellites only transmit. They don’t track anything. GPS trackers do exist — because of cell phone technology.

Favorite equation:

The relativistic frequency change in clocks:

See equation, above right

Note that this uses the physics convention where Φ is negative, hence gets larger farther from the Earth. Thus, relativity says that the frequency of an oscillator runs slower as velocity increases, and runs faster as you get farther from the Earth. These combine in GPS to give a mean rate offset of 4.4647 x 10^-10 faster than on Earth’s geoid, which would produce a time offset after one day of 38,575 ns!

As a consumer, what GNSS product, application, or engineering innovation would you most like to see?

I’m going to plug here for a GNSS improvement, not directly a consumer product. I have been a long-time advocate of on-board monitoring of GPS clocks, running multiple atomic clocks on each satellite and measuring them against each other. The largest cause of signal anomalies is clock anomalies, which could easily be completely removed from the error budget. This would require a small amount of hardware change on-orbit. It’s a technique we have used in national timing labs for years. It would allow for not only detection and removal of bad signals, but automatic fast recovery.

Professional Honors/Leadership Positions

NBS 1983 Applied Research Award “For the development of a satellite receiver measurement technique that provides cost effective international time and frequency comparisons at state-of-the-art accuracy”.

NIST 2013 William P. Slitcher Award “For pioneering highly productive industry/government partnerships to advance telecommunications and data networks through precision synchronization”.

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