[Updated June 3, 2013] With the budget vise tightening, top Pentagon managers are readying some potentially dramatic changes to the GPS constellation — changes that promise to lower both the cost of the satellites and the expense of putting them into orbit.  

The first changes would be subtle and are linked to buying the next block of GPS III satellites — a decision that sources confirm will be made by the end of September.  

[Updated June 3, 2013] With the budget vise tightening, top Pentagon managers are readying some potentially dramatic changes to the GPS constellation — changes that promise to lower both the cost of the satellites and the expense of putting them into orbit.  

The first changes would be subtle and are linked to buying the next block of GPS III satellites — a decision that sources confirm will be made by the end of September.  

To bring down the cost of the GPS III, which is widely viewed as unaffordable over the long run, the next contract likely will include satellite design alterations. The Pentagon will be looking to ditch capabilities that are no longer needed, a source explained, as long as it does not cost still more money.  

“The question is whether the contract is modified to put new stuff in it or take old stuff out that is no longer useful,” said the source, who is familiar with the matter. “So, the issue is — could they come up with a modification to GPS III that would, in fact, be cheaper.”  

The Air Force has already said it will pursue dual-launch capability. The source said they are also considering easing some of the equipment standards.  

“They’re building to certain standards and those standards are probably going to be relaxed, which makes a difference in costs,” said the source. The savings come from being able to reduce the testing of the redundancy and lifetime of particular items.  

Program managers are also weighing reducing the system integrity requirement in light of information that the Federal Aviation Administration (FAA) would require decades of test data before deciding whether the system met its strict integrity standards.  

“The original requirement document had 10^-7 [risk of failure] for integrity — that was predicated on the FAA’s requirement for 10^-7 for the Wide Area Augmentation System. Today, GPS provides 10^-5.”  

When the Air Force met with the FAA, the source said, the aviation officials told them that even if the Air Force was broadcasting at 10^-7 today, the earliest they would make a decision about using it was 2050.  

The Air Force has determined that an integrity of 10^-5 was sufficient for its purposes, the source said, which leaves open the question of spending the extra money to achieve a higher integrity level that would not be fully relied upon for years, if ever. Settling for 10^-5 would permit the Air Force to drop using laser cross-links and go back to radio-based cross-links.  

The next contract will cover at least three GPS III satellites, said the source, who spoke on condition of anonymity, though it is not clear what the delivery dates will be. As reported earlier by Inside GNSS, the anticipated useful lives of the earlier GPS spacecraft were officially estimated upward earlier this year — which enables the launch schedulers to stretch things out a bit.  

Downsizing  
The real changes could come when the Air Force decides what to do after the next contract is signed.  

Momentum is building to shift to a new constellation architecture that uses two types of GPS satellites — full-capability GPS III satellites that form the core of the system and new lean spacecraft called NavSats that complete the system’s geometry.

Incorporating small satellites would not only fill gaps, they could potentially save enough money to make it possible to maintain the constellation at some 30 satellites, improving the coverage to the point that users in even the most mountainous terrain or dense urban canyons would be able to get good signals.  

One version of the concept is described in a report delivered to Congress in April. The document, entitled Lower Cost Solution for Providing Global Position System (GPS) Capability, walks through a variety of options ranging from making no changes to the GPS program to adding geosynchronous satellites and even having an all small-sat constellation.  

As envisioned, the NavSat spacecraft would have only navigation payloads and could potentially be launched two at a time. They would not carry the Nuclear Detonation Detection System payload (NDS) found on the full-up GPS III satellites. NDS is a capability that requires so much additional power and shielding that one expert estimated it adds some $200 million to the cost of a GPS satellite once the launch is taken into account.  

To further reduce the weight and power requirements, the Air Force is considering having only four signals on the small sats — two civil and two military — and possibly using digital waveform generators to be able to switch over to a different signal if needed. The number of redundant clocks and mission processors might be reduced along with the shielding.  

New technology could further reduce costs. It would be possible, for example, to shave the power requirements by using traveling wave tube amplifiers (TWTAs or TWEEtas) and solid state amplifiers.  

There are also radiation hardening improvements, more efficient solar arrays and longer lasting batteries, according to the report. Further power savings could be found by changing the specification for the power received by the user to be measured at an elevation angle of 20 degrees instead of the current 5 degrees.  

After studying the tradeoffs the Air Force found that the best choice was a constellation with a core of dual-launched GPS III satellites complemented by NavSats in at least 20 percent of the orbital slots. This combination was cited as one of the best for providing the greatest availability of accurate signals.  

NibbleSats  
NavSats are broadly similar to the Spartan sats discussed last year and to NibbleSats – a concept proposed by Brad Parkinson, former head of the first NavStar GPS Joint Program Office and Vice Chair of the National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board.  

“The idea is that if you have a problem that looks pretty insurmountable sometimes it is worthwhile to simply convert it over to a series of nibbles — and then, at the end of the day — try to figure out if you are where you would like to be,” Parkinson told the members of the PNT Advisory Board at a May meeting in Washington.  

With 33 satellites the number of minutes of outages per day that are experience by a sky-impaired user is negligible, Parkinson explained, even with two satellites not functioning and a masking angle of 45 degrees — that is when the user can only see satellites at or higher than 45 degrees above the horizon.  

With only 24 satellites in the constellation a user would typically experience outages of nearly two hours daily, even if all the spacecraft were working flawlessly. With two satellites out, the signal outage jumps to as much as five hours.  

“If you go to the mountains of Afghanistan, you will see [masking angles of] 60 degrees in many cases.” At that masking angle, Parkinson said, the outages jump to more than six hours a day with only a 24-satellite constellation. With 33 satellites, no outages occur until you lose a satellite or two — and those outages last about an hour or less.  

The question is how can the United States afford to build and maintain the 30+ satellite constellation needed for this level of service. Although the GPS constellation is about that size now, the current commitment from the Air Force is for only 24 satellites. Experts have long been concerned that budget pressures will force a shrinkage in the existing overpopulated configuration.  

“Expensive satellites are both hard to sustain politically and from the standpoint of managing a process that has intermittent ins and outs” Parkinson said.  

Parkinson suggested a constellation of 15 to 18 “full-up satellites” — GPS IIIs, for example – and an additional 15–18 NibbleSats, small satellites with all the signals but nothing else extra except the now-planned laser reflector.  

To afford such a constellation you “nibble at the satellites weight, complexity and power — and that hopefully directly drives the manufacturing cost down — and, because the size went down, it enables a triple or quadruple launch or perhaps an inexpensive single-satellite booster of the type we are now starting to see,” he said.  

“Reducing the on-orbit by cost by at least 50 percent is a goal that I think would be achievable and worthwhile,” he told the board. “Hence, getting back to the original premise of availability enabled by an affordable 33-satellite constellation and hence a greatly enhanced geometric availability — particularly for a user who is sky-impaired in any way.”  

Parkinson also proposed to use a 20-degree elevation angle when determining power requirements. This higher angle saves power and could cut antenna complexity. “Right now we have 12 element antennas — presumably that could be reduced.”  

“If you have 30 satellites, you are not giving up much” from the user’s perspective, he said. “If you also look at that 20-degree elevation angle and arbitrarily reduce that power by about 1.5 dB, you have now achieved a 40 percent reduction in power — think solar panels.”  

More savings are possible with refreshed technology, he said. “The RF power conversion efficiency is the major . . . road to reducing that solar panel size, the size of the satellite, et cetera. Right now we use gallium arsenide as our output power, and its efficiency is only about 25 percent to 30 percent. If you go to gallium nitride, it may be as high as 50 percent and if you use traveling wave tubes, it would even be greater.”  

The power reductions in turn reduce the heat with which the satellites have to cope.  

With the current design, said Parkinson, “somewhere on the satellite it has to radiate about a kilowatt out into space. It means surface area. It means heat pipes. It means a number of other things. We know how to do it; it’s just adding weight and complexity.” The NibbleSat, he estimated, would have well under a third of the heat rejection requirement.  

These technologies plus other developments, such as lithium batteries and more efficient state-of-the-art solar panels, would make it possible, Parkinson argued, to slash the cost of a navigation satellite from its current $450 million on-orbit price tag to as little as $110 million, if four at a time were launched.  

That could cut costs to the point that a larger 30-satellite constellation incorporating 12 NibbleSats would cost $1 billion less than a constellation made up entirely of 24 GPS IIIA spacecraft.  

Progress  
The idea of using a bevy of austere small satellites to augment fully equipped spacecraft has been around for a least a decade, one expert pointed out.  

This time, however, it might get off the ground.  

The Air Force has already gotten industry involved via a Broad Area Announcement, the report said, firms that could help support the development of the concept. Space and Missile Command is also already teaming with the Air Force Research Laboratory to investigate “a prototype demonstration program” to be launched in the 2018 timeframe.  

“The program could implement an aggressive goal to productize the payloads and develop NavSats that save 30 to 60 percent when compared to the cost of a GPS III satellite,” the report said.  

“What they are looking to get authorization for,” said one source, “is to put money on a demo of NavSat prior to any (other) changes in the GPS III program.” If they succeed, the source suggested, it might be enough to trigger a real shift. “The pressure on the budget will be so great that people will say ‘Well, forget about the demo. Let’s just make this the real article for GPS III sustainment.’ ”  

But the results of any research will not be available for some time and a determination needs to be made soon on how to proceed with GPS III.  

Gen. William L. Shelton, commander of Air Force Space Command, is facing a tough decision, noted another source, because the satellites they decide to buy, or not buy, in September will be in place for years.  

But, the source said, “they have been looking for sometime at the smaller configurations. So if there is a time to decide to begin to cut that into the pipeline now is as good a time as any.”

The post Air Force Proposes Dramatic Redesign for GPS Constellation 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. PESTS

State of California, USA
√ The California Agriculture department is using collective intelligence and GPS to “report a pest.” State residents can download the new CDFA smartphone app and use it to photograph and report bad bugs when they see ‘em. Those with iPhones can choose to send GPS coordinates for quick response to invasive pest emergencies.

1. PESTS

State of California, USA
√ The California Agriculture department is using collective intelligence and GPS to “report a pest.” State residents can download the new CDFA smartphone app and use it to photograph and report bad bugs when they see ‘em. Those with iPhones can choose to send GPS coordinates for quick response to invasive pest emergencies.

• California Department of Food and Agriculture Report A Pest mobile app

2. TAKE FOUR
Cape Canaveral, Florida
√ The fourth GPS IIF took off from Cape Canaveral on May 15. It was the first time a ULA Atlas V rocket carried a GPS satellite. Once in orbit, SV66 will relieve from duty SVN33, a 19-year old Block IIA veteran, which will take emeritus status as a spare.

• U.S. Air Force [May 16]: GPS IIF-4 successfully launched from Cape Canaveral
  

3. PHONE HOME
Wallops Island, Virginia
√ On April 22, NASA launched 3 off-the-shelf smartphones to find out if they could manage flight avionics, communications, and photography for a cheap mini-satellite. The consumer-grade “PhoneSats” have many of the needed capabilities already built in — including GPS. During the short experiment, they sent back beautiful earth images retrieved by ham radio operators. More PhoneSats will go up next year.

• Inside GNSS [April 30]: NASA successfully launches three smartphone satellites
  

4. 24 AGAIN for GLONASS
Plesetsk, Russia and Honolulu, Hawaii
√ A Soyuz rocket successfully launched a 3,000-pound GLONASS-M satellite on April 28 from Plesetsk Cosmodrome. Sergey Revnivykh, director of the PNT Center, Roscosmos, said it will replace a failing satellite thus restoring Russia’s full 24-satellite constellation. He told a group at the ION Pacific PNT conference in Honolulu that the second K-type satellite will go up before the end of the year.

• Inside GNSS [April 28]: Russia launches another GLONASS-M satellite  

5. PRECISION
Canberra, Australia
√ On May 20, two super-customized outdoor calibration robots introduced themselves to Australia’s 200 GNSS antennae with the goal of improving accuracy to less than one millimeter. “We know the robot’s tool point, to within 0.1 mm per year. Now, the intent is to characterize the behavior of the antenna as [multi-GNSS] signals enter it” said John Dawson, head of the national geographical survey geodesy program. The plan? Faster crustal deformation studies, better mobile devices and more.

• Australian Government/Geoscience Australia press release [May 20]: Sub-millimetre Accuracy for Global Positioning

The post GNSS Hotspots | May 2013 appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

A key take-away from the event: China is rapidly preparing to bring BeiDou products and technology into the international marketplace is encouraging its industry to build an internationally applicable knowledge base in standards, patent law, and intellectual property rights (IPR).  

The fourth China Satellite Navigation Conference (CSNC 2013) wound up its three-day run on May 17 in Wuhan — by all measures a clear success for an event that has become the nation’s leading international GNSS forum.  

A key take-away from the event: China is rapidly preparing to bring BeiDou products and technology into the international marketplace is encouraging its industry to build an internationally applicable knowledge base in standards, patent law, and intellectual property rights (IPR).  

Well more than 2,000 attendees had their choice of 627 technical papers spread across a broad array of topics in 12 session tracks under the conference theme: BeiDou Application — Opportunities and Challenges.”  

“This conference shows the results of academic research and an inspiration for commercial development,” conference chairman Jiadong Sun told the opening plenary session audience. Sun, a well-known figure in China’s space program, is chief designer of the BeiDou system.  

Satellite navigation is reshaping traditional industries, Sun said, which is triggering a huge market potential.  

Indeed, the conference underlined China’s intention to rapidly commercialize its GNSS system, which reached regional operational status last December and is scheduled to have full global reach by 2020. Some 109 exhibitors — including large, medium, and small companies as well as numerous institutes and associations — filled the large commercial exposition area.  

“Industries related to the BeiDou system are entering a booming development stage,” said Qiangwen Yang, a senior engineer at the China Satellite Navigation Office (CSNO).  

By 2015 China is expected to invest 7 billion yuan (US$1.13 billion) to support the development of related industries, according to the CSNO, on top of 3.5 billion yuan already invested to date.  

CSNO Director Chengqi Ran pointed out that BeiDou enjoys support from the highest levels of the Chinese government, including the National Development and Reform Commission and the Ministry of Science and Technology (MOST), which prominently included satellite navigation in the department’s 12th Five Year Plan.  

As the support from the central government continues, Yang said that the BeiDou system will bring new economic growth to the country.  

Jingnan Liu, executive chairman of the conference and a member of the Chinese Academy of Engineering, predicted that commercial use of GNSS could be worth hundreds of billions of U.S. dollars. Liu heads the China National Engineering Research Center for Satellite Positioning Systems located along with the GNSS Research Center at Wuhan University, where he is a former president.  

IPR-Driven Market Strategy  
Perhaps one of the indicators that China and Chinese companies are planning to take BeiDou into the global market was a full-day track of papers in a “Policy & Regulations, Standards, and Intellectual Property Seminar.”  

During the presentations, speakers identified the most important international organizations involved in standards- setting, discussed the treatment of intellectual property (IP) under patent protection, and laid out strategies for securing Chinese IP while gaining access to foreign GNSS-related IP through licensing and other means.  

China clearly intends to learn from the experience of GNSS industries in other nations. During his presentation, Fang Bu, of the China Patent Office, State Intellectual Property Office, revealed a thorough analysis of Trimble, NovAtel, and Google patents and strategies in the GNSS marketplace.  

Bu pointed out that Trimble had acquired 73 companies between 1989 and 2012, divided between core technology IP and application markets. Later, after recounting the patents that underlie any new Google service, Bu urged Chinese manufacturers to avoid reinventing technical solutions already available.  

“We can acquire all the IP that we need through mergers and acquisitions,” he said, adding, “In China we are usually talking about our IP, but we need to respect others’ IP.”  

That point was reinforced by Shunde Li, from the Chinese Academy of Social Sciences’ Institute of Law, who provided a lengthy tutorial on the key differences between national and international patent protection and IPR. He described the important conventions, IP protections, and international players, such as the World Trade Organization (WTO), that Chinese companies encounter as they take their products into a global market.  

Li acknowledged that companies will want to rely first on their own innovations but need to be willing to acquire or license existing IP. “We need to do independent research,” he said, “but also to use and respect other people’s IPR.”  

Another interesting presentation came from Lei Shi, legal counsel for antenna manufacturer Harxon Corporation. She traced the history and implications of the controversial UK Ministry of Defense effort to patent key elements of the modernized GPS civil signal design (L1C) and its European multiplex binary offset carrier (MBOC) counterpart.  

Shi pointed out that the MoD’s commercialization arm, Ploughshares Innovations Ltd., had secured related patents in 11 countries, including China. Noting the agreement reached by the United States and the UK in January only covered GPS but not Galileo, she warned the Britain might still attempt to assert intellectual property rights (IPR) for related GNSS signals in China.  

Another indicator of the global aspirations for BeiDou was the preparation and presentation of the conference itself. The CSNC has broad and high-level backing from Chinese national government agencies, which sponsored the event and populated the program with prominent representatives.  

Foreign participants numbered around 100 and many of them presented during a half-day session organized in cooperation with the U.S. Institute of Navigation (ION). Nonetheless, excellent simultaneous English translation was available in all of the technical sessions this year, making the event more accessible to non-Chinese attendees.  

This is expected to continue at next year’s event in May 2014 in Nanjing, according to the conference secretary-general, Haitao Wu, chief engineer at the Chinese Academy of Science Navigation Headquarter Office.  

China currently has 14 operational satellites in a regional system whose footprint stretches from 55˚ East to 180˚ East and delivers 10-meter real-time positioning accuracy and one-way 55-nanosecond timing accuracy, according to Ran.  

One source at the conference told Inside GNSS that five test satellites will be launched beginning in 2014 to help BeiDou system engineers evaluate the third-phase technologies, including new Chinese-built atomic clocks and new signal designs and frequency.

The post BeiDou Gets Ready for the Global Marketplace appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

Since announcing plans in late 2006 to build its own GNSS system — BeiDou-2 (BDS), China proceeded quickly to establish a fully operational regional system late last year with a clear plan to complete a global system by 2020.

Beginning with its first launch in April 2007, BDS has put 16 satellites in orbit, some in dual launches, with 14 BeiDou space vehicles currently transmitting healthy signals: 5 in geostationary orbits (GEO), 5 in inclined geosynchronous orbits (IGSO), and 4 middle Earth orbit (MEO) spacecraft.

Since announcing plans in late 2006 to build its own GNSS system — BeiDou-2 (BDS), China proceeded quickly to establish a fully operational regional system late last year with a clear plan to complete a global system by 2020.

Beginning with its first launch in April 2007, BDS has put 16 satellites in orbit, some in dual launches, with 14 BeiDou space vehicles currently transmitting healthy signals: 5 in geostationary orbits (GEO), 5 in inclined geosynchronous orbits (IGSO), and 4 middle Earth orbit (MEO) spacecraft.

This innovative mixed-satellite design has enabled China to do two key things: first, build a highly accurate and available GNSS capability over the national territory and adjacent regions and, second, encourage early adoption of BeiDou-supported applications.

According to Chinese researchers, most areas in the Asia/Pacific region can receive signals from 8 to 9 BDS satellites on average and achieve a standard positioning service (SPS) level with the following real-time accuracies: horizontal positioning, 10 meters; vertical positioning, 10 meters; velocity, 0.2 meters per second; and one-way timing, 20 nanoseconds.

China is now exploiting the BDS for numerous applications, while evaluating the system’s current performance and planning the final design and implementation of the next stage of the system.

To help us gain further insight into the current status of BDS operations, we turned to Professor Jingnan Liu, former president of Wuhan University where he currently heads the National Engineering Research Center for Satellite Positioning System. Liu is an academician of the Chinese Academy of Engineering with deep expertise in GNSS system technology in general and BeiDou in particular.

IGM: What sectors of the Chinese civilian economy have shown the most interest in applications of BeiDou?  

LIU: The most interested application should be the transport sector in the Chinese civilian economy. As a large developing country, automobile consumption is growing fast in China.

Consequently, traffic congestion, road safety, and environmental pollution have become a serious social issue. People waste a lot of time on the road. This requires Intelligent Transportation. Most land vehicles now use GPS for navigation in China, but its availability decreases in some urban areas. Using GPS+BDS increases the availability and accuracy for users.

The BDS Wide Area Augmentation Differential Positioning and Wide Area Precise Positioning System can offer meter to sub-meter level service, which contributes to land vehicle lane-level navigation, intelligent transportation, and management. Therefore, the most interested application may be in the transport sector.

For commercial applications, since the quick development of E-commerce or online shopping, commodities need improved logistics and transportation to reach clients. Whether the clients are mobile or not, this can be done using the instantaneous service of GNSS positioning.

China is flourishing, with rapid economic development and urbanization. Precise positioning techniques play a significant role and can guarantee the planning, construction, and management of cities.

IGM: What are some of the leading initiatives in China to encourage use of BeiDou in various types of applications?  

LIU: The central government, local governments, and some industries have all established policies to encourage the use of BDS. The National Development and Reform Commission (NDRC), Ministry of Industry and Information Technology of the PRC (MIIT), and Ministry of Science and Technology (MOST) of the PRC develop policies to encourage the development of BeiDou applications.

Governments at all levels in China are also establishing some development funds to implement new ideas for BeiDou applications after proposals are evaluated and demonstrated. The funding from the government is just start-up support. Through market-based mechanisms, promotion of BeiDou’s application can be achieved.

The NDRC mainly focuses on BDS applications development; MIIT focuses primarily on the development of industry related to BDS chips, user equipment, and software; and the MOST mainly focuses on fundamental aspects of frontier technologies and innovation of BDS.

Scientific and professional applications have their own resources and motivation to promote BDS based on their requirements. Scientific issues have gotten the attention from government and have gained attention from scientists and the professional sector.

The Chinese government will give priority to public service applications of BDS. For example, the short message service (SMS) function of BDS has already played a significant role in earthquake relief in China in recent years.

IGM: The BeiDou constellation has a unique composition among the world’s GNSSs with its use of IGSO, GEO, and MEO spacecraft. What are some of the differences among the various types of satellites in terms of their positioning accuracies and characteristics?  

LIU: For the current regional navigation service of BDS, the main contribution to positioning comes from the GEO and IGSO satellites. Due to the characteristics of the BDS constellation, the positioning service will be affected by the geometry of the satellites. The GEO satellites are static relative to the earth; only two-dimensional positioning can be achieved using only GEO satellites. Moreover, in the northern and southern hemispheres, the elevation of GEOs is generally low. This leads to some signal blockage and decrease in the availability of the GEO satellite signals.

Due to the current uneven distribution of the BDS monitoring stations in the Asia/Pacific region and the weak satellite geometry of the constellation, the accuracy of orbit determination of the GEO satellites is affected in some directions, especially in the along-track direction, which has approximately a two- to three-meter level of accuracy. This leads to worse accuracy of positioning in some directions. The orbital movement area is also small for IGSO relative to MEO satellites.

Geometry and the number of satellites affect positioning performance. With the increase of MEO satellites and more even distribution of monitoring stations in the future, these situations will get better. In general, elevations of GEO satellites may be low for many BDS users, which lead to significant multipath effect currently. Some relevant research and measures to overcome these issues are under way.

IGM: Presumably, with more satellite signals available from the IGSOs and GEOs, this will produce higher accuracies over the Asia/Pacific region than in the rest of world, which will rely primarily on positioning signals from BeiDou MEOs once full global service is available. Has the difference of regional versus global accuracy been estimated? Do the BeiDou GEOs also support China’s satellite-based augmentation system (SBAS)?  

LIU: As for the difference between the global and regional services, some simulations have been undertaken to evaluate these. Results shows that standard positioning service (SPS) can be offered for both global and regional coverage.

Due to the larger number of satellites in the Asia/Pacific area, BeiDou signal availability will improve and accuracy should also be better when compared with global performance. We expect a 5 to 10 percent improvement in BDS positioning accuracy in Asia/Pacific area compared with the rest of the world.

Another major advantage for the Asia/Pacific area is that SBAS service can be acquired from the current BDS GEO satellites, which means sub-meter and meter level positioning accuracy for dual-frequency and single-frequency receivers, respectively. Once full global service is available, the GEO satellites will undoubtedly be maintained as the components of BDS’s SBAS.

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SIDEBAR: Di Qiu’s Compass Points

Landing all-weather aircraft safely in storms. Protecting sensitive data not only through encryption but based on the location at which it is being accessed. Ensuring that accurate and timely information reaches first responders responding to emergencies. 

Although still in the early part of her career, Di Qiu has already made significant contributions to these crucial applications of navigation technology. 

SIDEBAR: Di Qiu’s Compass Points

Landing all-weather aircraft safely in storms. Protecting sensitive data not only through encryption but based on the location at which it is being accessed. Ensuring that accurate and timely information reaches first responders responding to emergencies. 

Although still in the early part of her career, Di Qiu has already made significant contributions to these crucial applications of navigation technology. 

Currently a senior research engineer at location-based services (LBS) solutions provider Polaris Wireless, Qiu’s work brings together the fields of navigation and security through innovative engineering, adding value to existing technologies and creating exciting new synergies. 

Qiu developed her expertise through research and experimentation in the aerospace engineering and aeronautics and astronautics departments, respectively, at the University of California, Los Angeles, and Stanford. Since completing her Ph.D. at Stanford in 2009, she has applied the lessons of those academic exercises to her professional endeavors. 

From Physics to GNSS 
“My mom is a doctor,” says Qiu. “So, I always wanted to become a physician when I was a kid to follow in her footsteps. My first physics class in junior high made me change my mind. I had a great hands-on experience in the class and enjoyed all the experiments as well as solving the challenging problems.” 

Di Qiu’s first glimpse of the possibilities of GNSS technology came as an undergraduate at UCLA. She obtained a student position as a lab assistant in the Institute of Geophysics and Planetary Physics (IGPP), a research arm of the university that was working on projects exploiting GPS data to address problems in the earth sciences. 

She recounts seeing how real-time differential GPS with good resolution and accuracy within a meter was able to provide significant benefits to earth scientists. 

“I was impressed with the technology,” she says, and this proved to be a first step toward appreciating and “learning the widespread use of GNSS in many other applications and its impact on our daily lives.” 

In the course of her work toward a B.S. degree in aerospace engineering, Qiu found an important mentor in William Greer, the principal electronics technician at the IGGP. This work at UCLA required an attention to detail and control of intricate systems that Qiu would develop further in her subsequent research and professional roles. 

Qiu graduated from UCLA in 2003, and entered Stanford University’s aeronautics and astronautics engineering program. In her first year at Stanford, she worked on carrier phase smoothing in a GPS course taught by Professor Per Enge and later joined the GPS lab that he directs. 

Enge became another important mentor for Qiu, and she recalls how exciting it was “to play around with the [lab’s] Garmin receiver, plan our own experiments, design the smoothing algorithm, and to validate our performance using real data.” 

She completed an independent study with Enge focusing on ionosphere threat modeling for local area augmentation systems (LAASs), also known as ground-based augmentation systems or GBASs. 

LAASs are designed for all-weather aircraft landing using real-time differential correction of the GPS signal. Under extreme space weather conditions, fluctuating ionospheric spatial gradients are likely to affect the LAAS architecture, particularly for precision approach and landing capability. 

In her independent study, she developed a moving wave front model and extrapolated a “threat space” based on previous ionosphere storms. This work outlined a comprehensive methodology to analyze ionospheric anomalies and estimate the moving speed of a modeled ionosphere front based on historic storm data. 

The method Qiu developed has subsequently been used to analyze the potential effects of ionosphere anomalies on LAAS users. 

Security from Location. Security for Location 
The work on LAAS was instrumental in leading Qiu to achieve the objectives of her Ph.D. thesis: the design, development, and implementation of a robust geo-security system. 

Geo-security, or location-based security, employs algorithms that limit access to information content or electronic devices based on verifying a specified location or time. Rather than replacing any of the conventional cryptographic means of protection, geo-security instead increases security by augmenting it with added contextual data. 

As Qiu explains, “It is not appropriate for a bank official to be viewing a client’s personal financial information at a local coffee shop, where strangers can walk by and pick off sensitive information, such as social security or account numbers. These users should only be able to access this data at trustworthy and secure locations.” 

Geo-security uses a location verification tag, called a geotag, to extend the security parameters for sensitive data to include the precise physical environment in which it is being viewed. 

Qiu believes this approach can play a role in “bridging the very different languages used by the navigation and security fields.” Her efforts directly led to two U.S. patents being issued. 

She sums up this work as “security from location,” protecting sensitive information based on where it accessed. 

At Stanford, Qiu’s doctoral work explored a related angle, which she describes as “security for location.” Signals for geosecurity should have anti-spoofing capabilities, that is, the capability of detecting and avoiding false signals, a system is vulnerable to spoofing, an attacker can easily bypass location verification. 

She developed and implemented a test of Timed Efficient Stream Loss-tolerant Authentication (TESLA), an authentication method for broadcast network communications, and validated its performance with her research partners. The combined effect of “security from location” and “security for location” presents a robust location-based security solution, she feels.

Signals of Opportunity and Coordinate-Free Navigation 
After completing her Ph.D., Qiu accepted a position as senior research scientist at Sigtem Technology, Inc., a GNSS engineering firm in San Mateo, California. There, she worked on positioning in environments resistant to GNSS signals. 

Qiu led a project focused on signals of opportunity (SoOP) to achieve indoor positioning by integrating cellular signals, Wi-Fi, and AM/FM, and other radio transmissions. 

The team built mobile test-beds consisting of a multichannel software-defined radio and associated software receivers. The cooperative mechanism solves the problem of a user’s position when challenged by the absence of time synchronization between signal transmitters and the lack of encoded timing information in the received signals. 

Qiu also expanded on her work with geo-tagging at Sigtem, developing “coordinate-free navigation” by applying geo-tags derived from various location-dependent features of non-navigational signals to facilitate navigation without defining a position in spatial coordinates. This technique works well in scenarios where GNSS signals are partially or completely denied. 

Qiu explains another advantage of the method: It requires lower power consumption by user equipment and integrates various systems without time synchronization of all of the transmitters, which has always been a problem in the conventional navigation techniques. Her innovative design led to a U.S. patent application in 2010.

E911 and Radio Frequency Pattern Matching 
Qiu joined Polaris Wireless in 2012 and has been working on the integration of GNSS, cellular signals, and low earth orbit (LEO) communication satellite signals for indoor positioning. 

Polaris Wireless is a Mountain View, California—based company that develops software-based location solutions, concentrating in the areas of public safety and location surveillance. One of her ongoing projects at Polaris involves the integration of sensors in smart phones to provide wireless operators a solution for compliance with the Federal Communication Commission’s (FCC) Enhanced 911 (E911) phase 2 mandate. 

The second phase of the FCC mandate requires wireless operators to provide first responders at Public Safety Answering Points (PSAPs) with the latitude and longitude of emergency callers within six minutes after receiving a call. Location information is used to send emergency services to the scene of an incident and is also used by the wireless carrier to determine which Public Safety Answering Point (PSAP) to route the call to. 

Accuracies for network-based E911 techniques must be at least 100 meters for 67 percent of calls and 300 meters for 95 percent. Handset-based technologies, typically using GNSS, must be within 50 meters for 67 percent of calls and 150 meters for 95 percent of them. 

Indoor and dense urban environments present serious challenges to achieving these accuracies using GNSS. Integrating signals and positioning techniques can generate more reliable positioning data to achieve compliance with the E911 mandate. 

Polaris Wireless employs radio frequency pattern matching (RFPM) to enhance location-based services such as E911. 

As with satellite-based navigation systems, RFPM is based on correlation techniques. It matches the signal strength of cellular signals measured by mobile phones to a geo-referenced database that maps cellular operators’ signal strengths in a given coverage area. RFPM accuracy depends heavily on the quality of the values in the signal-strength database. 

At Polaris, Qiu is developing a sophisticated signal-propagation model to help construct the signal-strength database, aggregating data on cell transmitter antenna locations and cell type. 

Geo-referenced data incorporated into this signal-propagation model include tree canopy, buildings, and terrain elevations, as well as other topographical and traffic details. Qiu’s work enhances the accuracy of the signal-strength database and estimates of signal availability at a given location — the linchpin in achieving E911 phase 2 compliance. 

A Collaborative Partner 
Throughout Qiu’s student and professional life, teamwork and collaboration have proved essential to delivering the impressive results her projects have generated. She has benefited from the guidance and inspiration of mentors at UCLA and Stanford, and has consistently worked on very team-oriented projects. 

Qiu’s efforts at Sigtem won praise from GPS pioneer Jim Litton, who says that her work “demonstrated keen insight into customer applications and the essential aspect of technical problems,” while also displaying “a generous spirit and excellent social skills.” 

This affinity for contributing to a group effort manifests itself outside of engineering as well. She likes to balance efficiency and enjoyment in her personal and working lives by making the most of her days. 

“It is a trade-off curve,” she says. “Recently I’m very much interested in playing badminton with my Polaris colleagues! It’s a fun sport and a great aerobic exercise to help build and maintain overall fitness.” 

The post Di Qiu: Opportunities of Signals appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

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Engineering Specialties 

• Signal processing  
• Control and estimation  
• Signals of opportunity  
• Location-based security and signal authentication 

Engineering Mentors 

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Engineering Specialties 

• Signal processing  
• Control and estimation  
• Signals of opportunity  
• Location-based security and signal authentication 

Engineering Mentors 

William Greer — Principal Electronics Technician at Institute of Institute of Geophysics and Planetary Physics (IGPP), UCLA. “I was very much inspired by William to develop my interest of building things to solve small engineering problems when I was working as a lab assistant at IGPP in my undergraduate years.” 

Per Enge — Professor of Aeronautics and Astronautics at Stanford University and Qiu’s Ph.D. advisor, helped Qiu grow as an engineer. “He has taught me to be proactive, encouraged me to express my ideas and opinions, and motivated me to work on whatever I was feeling in a proactive way.” 

Dan Boneh — Professor of Computer Science and Electrical Engineering at Stanford University, specialized in applied cryptography and computer security. “I’ve learned something new from Dan every time I had discussions with him, and the result of discussions has always been encouraging and inspirational.” 

Patents 

1) Method and apparatus for using navigation signal information for geoencryption to enhance security 

2) Geosecurity methods and devices using geotags derived from noisy location data from multiple sources 

3) Coordinate-free radio navigation and guidance using location-specific received signal and propagation channel parameters vector (pending) 

GNSS Event that most signifies that GNSS has “arrived” 

When my friends say to me, “I know how to get there. . . . I have a GPS”. 

Popular notion about GNSS that most annoys 

That GPS is available everywhere! Also some people think navigation engineers should have the intelligence for choosing driving directions in the physical world. 

Favorite equation 

Taylor’s series (see inset photo, above right) 

Taylor’s series equation provides an estimate of the error made in a polynomial approximation to a function. “It makes our life much easier to construct linear models from nonlinear systems.” 

As a consumer, the GNSS products, applications, and engineering innovations she would most like to see 

1) Air traffic control 

2) Automobile traffic control — an integrated system that provides drivers current traffic conditions, optimum route finding, and other information for safe and efficient driving 

3) Reliable indoor positioning solution in personal electronic devices for location-based services.

The post Di Qiu’s Compass Points appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

Back in the 1990s, when I first came across the U.S. Federal Radionavigation Plan (FRP), I learned that the rise of the Global Positioning System drove the biannual FRP process because of the expectation that GPS would enable the government to shut down many pieces in the hodgepodge of positioning, navigation, and timing (PNT) systems.  

It’s all about the backups now. The alternatives. The gap-fillers.  

Back in the 1990s, when I first came across the U.S. Federal Radionavigation Plan (FRP), I learned that the rise of the Global Positioning System drove the biannual FRP process because of the expectation that GPS would enable the government to shut down many pieces in the hodgepodge of positioning, navigation, and timing (PNT) systems.  

To a certain extent, this has proved true. The OMEGA radio system, for instance, was totally eclipsed by GPS service. More recently — shortsightedly — LORAN was taken off the air.  

But as the expectations of affordable, omnipresent PNT keep rising, and the attendant security concerns become more visible and worrisome, GNSS no longer has the can-do-it-all aura of those early, heady years. Even the FRP, the 2012 edition of which was recently released by the U.S. departments of defense and transportation, now frames its contents in terms of PNT — not just GPS and the “others.”  

So, it’s no longer just a question of simply eliminating systems from the mix and closing redundant operations. It’s more a matter of plugging gaps, ensuring coverage. It’s about providing ubiquitous PNT with alternatives (APNT) — reliable, uninterrupted service wherever and whenever we need it.  

Now GNSS will be the foundation of global PNT for at least the next 30 years or so, probably far longer. That means we have to secure that base at the same time we are broadening it. Diversifying it. Augmenting it.  

It also means protecting GNSS — locally against interference, jamming, and spoofing, internationally to ensure compatibility and interoperability.  

The latter task seems well in hand. Except for the occasional hiccup — untoward signal patent maneuvers, overlays mixing civil and restricted signals — bilateral and multilateral progress on harmonizing systems reflect the consensus that the issues uniting GNSS providers are stronger than those dividing them.  

We also need financial protection against the budgetary starts and stops that afflict most GNSSs, the ambiguities that unsettle industry and delay new products and services. GNSS needs to be established and financially protected as a critical infrastructure per se, not just as a multiplier or enhancer of other infrastructures.  

So, let’s assume that, conservatively, a single GNSS frequency at L1 (~1575.42 MHz) can provide 80 percent of users’ needs 80 percent of the time. This still leaves a lot of life-critical, challenging, and often more expensive PNT solutions needing to be found.  

It doesn’t mean, however, that national governments or public agencies need to do it all.  

One of the most intriguing ideas that I’ve heard lately is the suggestion that a private organization could take over some or all of the shuttered but intact North American Loran facilities in order to restart and expand enhanced Loran (eLoran).

More generally, for those demanding, specialized, and customized applications, the responsibility will still lie largely with product designers and system integrators to bring the mix of PNT sensors and technologies that provide a robust solution.

The good news is that more PNT resources than ever appear available and practically useful: inexpensive inertial sensors, of course, but also new methods such as image-aided navigation, signals of opportunity, magnetic or gravity field navigation, WiFi fingerprinting, and so on.  

As always, the application will determine the needed PNT technologies. 

If we need to meet someone at a restaurant, we may only need 20 or 30 meters accuracy and only need our location updated every few minutes.  

If we are surveying the site of a new building, we may want sub-centimeter accuracy but only need to determine that position once and can take as long as necessary to obtain it.  

If we are driving a car at 100 kilometers an hour and want to be warned if we are going out of the lane, we may need decimeter accuracy updated several times each second.  

Each of these applications will suggest a different PNT technology or combination of technologies to provide the required positioning accuracy and timing.

The post Living in an APNT World appeared first on Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design.

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