Roads and Highways

January 3, 2008

China GNSS 101

Late last year, I attended China’s only government-sanctioned international conference on GNSS and visited a number of local companies. I came to one conclusion: The world of GNSS is about to change, and China will have a lot to do with that.

Consider this: China has launched its own GNSS system, Compass/Beidou. It has liberalized policies on GNSS receivers and navigable digital maps. It is already one of the world’s largest economies with enormous capital reserves and steadily-growing disposable income in the hands of millions of citizens.

Late last year, I attended China’s only government-sanctioned international conference on GNSS and visited a number of local companies. I came to one conclusion: The world of GNSS is about to change, and China will have a lot to do with that.

Consider this: China has launched its own GNSS system, Compass/Beidou. It has liberalized policies on GNSS receivers and navigable digital maps. It is already one of the world’s largest economies with enormous capital reserves and steadily-growing disposable income in the hands of millions of citizens.

As a GNSS player, the People’s Republic of China (PRC) arouses interest and concern on at least four levels: as a service provider (compatible or incompatible?), as an equipment manufacturer (competitor or partner?), as a product designer and technology distributor (re-engineering or innovation?), and as an enormous market of largely untapped potential (closed or open?).

In their own fashion, of course, every other GNSS provider brings the same set of questions and, like China, a distinct way of answering them. The real questions are what lessons has China learned from the world’s 30-year experience with GNSS and how will it apply those lessons to the nation’s emerging role of GNSS provider, designer, manufacturer, and marketplace.

One measure of that can be taken from increasingly public, though still carefully scripted statements on the subject from Chinese public officials and industry leaders.

NaviForum: Beidou’s Debut
The Shanghai Navigation Forum (NaviForum) bills itself as the only international GNSS exhibition and conference officially approved by the Chinese government, which is also deeply involved with the organization of the event.

(Sponsors included the Department of High & New Technology Development and Industrialization, Ministry of Science & Technology (MOST); Department of Map Management, State Bureau of Surveying & Mapping (SBSM); and the Science & Technology Commission of the, Shanghai Municipal People’s Government.)

Its fourth annual staging in December 2007 drew more than 700 attendees, with 29 percent coming from outside China, according to conference organizers. And it was, in many respects, a coming out party for Compass, which is also widely known by its Chinese pinyin (alphabetized) name, Beidou.

As with GPS and Russia’s GLONASS systems, Compass began as a military program operated by China’s defense mapping agency and, as with those other two GNSSes, will continue to have a military component. Several geostationary satellites were launched beginning in 2000, broadcasting on a center frequency of 2491.75 MHz in a small slice of spectrum allocated for radiodetermination/mobile satellite.

Until late in 2006, it appeared that Compass/Beidou would remain a regional system, augmenting full-fledged GNSSes. A 2003 agreement committed China to investing €200 million ($290 million) in cooperative development of the European Union’s Galileo system.

In October 2006, however, China announced that it would build a full-fledged GNSS system that would transmit signals in the L1 band where GPS and Galileo military and public safety services are located. Then, last April 14 China launched a middle-earth orbiting (MEO) satellite and quickly began broadcasting signals.

The Compass signals were soon analyzed by researchers at Stanford University and Belgian GNSS receiver manufacturer Septentrio, who published articles in the July/August 2007 issue of Inside GNSS describing their findings.

Subsequently, in a break with a previously restrained public posture on the subject, several representatives from the China Satellite Navigation Engineering Center described the program in some detail at NaviForum 2007. In another session, “New Positioning System,” European and Chinese public and industry panelists focused on Compass. And throughout the conference, Chinese speakers referred repeatedly and favorably to the domestic GNSS system.

Something Old, Something New
Much of the information revealed in the Shanghai meeting merely confirmed what had already been published by outside researchers: L-band signals centered at 1561.098 MHz ± 2.046 MHz (Beidou 1 or B1, overlaying the Galileo E2 band and part of the GPS L1) and 1589.742 MHz (B1-2 on Galileo E1 and the upper portion of GPS L1); 1207.14 MHz ±12 MHz (B2, E5b), and 1268.52 ±12 MHz (B3, on the lower portion of E6).

B1/B1-2 signals would use quadrature phase shift keying (QPSK) and binary offset carrier (BOC) modulations similar to those employed by GPS and Galileo on those frequencies, according to Yang Qiangwen, senior engineer, China Satellite Navigation Project Center (CSNPC, also sometimes referred to as the engineering center) in the Beijing region. The signals will have a pseudorandom noise (PRN) code chipping rate of 2.046 Mcps and a minimum received power level of -163 dBW.

Several of the speakers, however, also provided further insight into Compass and China’s ambitious plans for the system. Ran Chengqi, the CSNPC deputy director speaking in place of the center’s director, Yang Changfeng, told the NaviForum audience that open services would be operated at L1 and L5.

He also emphasized the need for compatibility and interoperability with other GNSS systems, saying, “China will work with the other GNSS providers under UN International Committee on GNSS (ICG) rules.”

“Beidou is a huge investment,” Ran said. “We need to be very careful in its implementation and look at the risks in the market. Our goal is a long-term commitment to users.

He underlined the system’s “strategic role,” adding, “although Beidou has made a fast start, we still need to commit our resources to make sure. We need more open industrial policies,” alluding to the promised publication of a public Interface Control Document (ICD) that would specify Compass’s technical parameters so that receiver manufacturers could build user equipment confidently.

“We have to build up [Compass/Beidou] awareness and our own brand in the world,” Ran concluded. “An open, prosperous, and strong China will develop based on an open, strong, and healthy navigation system.”

In a plenary session speech, Liao Xiao-han, deputy director of High & New Technology Development and Industry, Ministry of Science and Technology (MOST), said, “After completion of Compass, we believe it will be the major supplier of positioning, navigation, and timing [PNT] in China and also a significant supplier of PNT in the world.”

Liao emphasized the need to make Compass “compatible and interoperable with GPS and Galileo” by working to share common frequencies and avoid interference on limited GNSS bandwidth.

Meanwhile, he added, “We are working with Galileo to create synergy,” he said, “We want to expand the PNT footprint.”

According to several speakers, Beidou will be providing a regional service over the east Asia region by 2009 and a global service later at an indeterminate date. Beidou’s open services will be offered without “entrance or authorization fees.”

In the New Positioning System session, Yang reported that the CSNPC would provide an open and free ICD on its website “in the very near future,” admitting, however, that the website was still under development. Compass operators have a “very detailed plan for future beyond 2009,” which would be released along with a launch schedule – also “in the very near future,” he said.

In tests of Beidou’s signals conducted August 21–30, 2007, the CSNPC found an average 0.5 meter residual ranging error and a one-meter sequential error in the MEO satellite’s orbital positions based on comparisons with satellite laser ranging to the satellite. (to see Table 1 and Figure 1, which illustrate this point, download the article pdf above.) The on-board clock error was 5 nanoseconds over 3 hours, and 11 nanoseconds in the course of 24 hours.

Industry on Parade
A well-attended exhibition accompanying the conference drew a couple of dozen Chinese and foreign companies and public agencies. These included the country’s first GNSS company to issue public shares of stock (and the provider of services for the first phase of Beidou), Beijing BDStar Navigation Co., Ltd. Although organizations representing the automotive, portable navigation, and telecom sectors dominated the exhibit, Beijing UniStrong, which plans on entering the U.S. survey market, also was represented.

Underlining the Shanghai region’s generally accepted status as the economic center of China, Chen Kehong, vice-chairman of the Shanghai Municipality’s Science and Technology Commission, described the region’s 14-station differential GPS network.

“In the future, would like to see incorporate multiple [GNSS] systems [into the DGPS network], including Beidou.” Chen said that the regional government would like to see such services based on market rather than planned economy.

“The Shanghai municipal government will move Beidou into the application industry chain,” he added. “We will spare no effort to implement Beidou services and technology development.”

In a corresponding show of bureaucratic support for commercial development, Li Yongxiong, director general of the Department of Map Management, State Bureau of Surveying and Mapping (SBSM), described efforts to liberalize China’s regulatory policies on access to data with which create navigable map databases.

Eleven companies approved by central government to product digital maps with maps currently available from six Chinese companies. These cover every city in China except two, and 95 percent of all of highways, according to Li.

Available mapbases incorporate 5 million points of interest and 1.8 million miles of highways and expressways at 1:10,000 scale. The SBSM is “working very hard on 1:2,000 scale databases in urban areas,” for which the agency would like to create a system to provide real-time updates.

(Articles in future issues of Inside GNSS will return to the subject of China’s domestic GNSS design and manufacturing sector as well as the effect of Compass/Beidou’s development on the world’s other GNSS systems.)

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December 3, 2007

Measuring Up: Certification Processes and Testing of A-GPS Equipped Cellular Phones

More and more GPS-enabled devices are entering the consumer marketplace, many incorporating assisted-GPS (A-GPS) technology. These include not only cellular phones, but laptop datacards, PDAs, and other mobile equipment.

Increasingly, GPS devices that were previously standalone now incorporate a cellular modem for such applications as mapping download or live traffic alerts. The proliferation of GPS in the consumer space can also be seen in the availability of GPS automotive navigation systems in local supermarkets or large grocery stores.

More and more GPS-enabled devices are entering the consumer marketplace, many incorporating assisted-GPS (A-GPS) technology. These include not only cellular phones, but laptop datacards, PDAs, and other mobile equipment.

Increasingly, GPS devices that were previously standalone now incorporate a cellular modem for such applications as mapping download or live traffic alerts. The proliferation of GPS in the consumer space can also be seen in the availability of GPS automotive navigation systems in local supermarkets or large grocery stores.

Those who purchase these products expect the technology to function everywhere, continuously, be simple to use and to always have the most obscure address in its database.

To help ensure the successful deployment of this concept in cellular devices, the telecommunications industry’s standards and certification bodies have been working diligently on a standardized approach to A-GPS certification.

In recent years, the subject of A-GPS, its purpose, and operation, has gotten a lot of attention in the technical and trade media. The authors of these various sources have focused on either the technical details or on the performance of the technology in the areas for which it was or was not primarily designed.

For example, performance in urban canyons and indoor environments or development and testing by manufacturers, cellular network operators or research organizations of products using this technology.

In contrast, this paper focuses on how a mobile device that incorporates A-GPS technology gains certification for use on a 2G or 3G (GSM or UMTS) cellular network.

(For the rest of this story, please download the complete article using the link above.)

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October 20, 2007

Bring Out the Galileo ICD

Here’s an idea whose time may have finally arrived: release of an Interface Control Document (ICD) for the Galileo open service (OS) — in essence, a set of specifications to which engineers can design and manufacturers can build receivers.

Here’s an idea whose time may have finally arrived: release of an Interface Control Document (ICD) for the Galileo open service (OS) — in essence, a set of specifications to which engineers can design and manufacturers can build receivers.

European sources suggest that publication of the ICD could take place around April 20 and would fill in some key missing details. This development follows on the heels of a late-March decision by a bilateral U.S./European technical working group that the future GPS civil signal (L1C) and the Galileo OS will use an optimized version of the BOC (1,1) format tentatively accepted under the 2004 agreement on GPS/Galileo cooperation.

If realized in action, this would be doubly welcome news for manufacturers, design engineers, and system developers eager to exploit the promise of expanded, modernized GNSS signals. It would also help sustain the surge of interest in Galileo that has taken place since launch of the program’s first experimental spacecraft last December.

Over the last couple of years, a series of papers coauthored by members of the European Commission (EC) Galileo Signal Task Force have laid out elements of the frequency plan and signal structure: RF bands, lengths and types of codes, data rates, and so forth. What had remained missing were the Galileo codes and the navigation message structure.

Some manufacturers have tried to overcome this problem by designing GNSS receivers with reconfigurable chips, using field programmable gate arrays (FPGAs) that could be updated when the final spec became available. But such work-arounds are inherently messy, complicating sales and marketing efforts and building in a need for early upgrades and extra customer support.

Moreover, the absence of technical guidelines and standards inhibits engineering managers and companies in adapting new technologies, particularly those in sectors such as aviation and automotive engineering with lengthy design and certification cycles.

Galileo, of course, is a work in progress, and most people in the GNSS community understand that technical details will change as the project evolves. That was the situation with the Global Positioning System, in which smudged and much-photocopied documents circulated in the engineering community and helped with the design of GPS products that appeared long before the final official ICD in the early 1990s. What made the ad hoc process work and kept this GPS “living document” alive was the willingness of the GPS Joint Program Office and its contractors to communicate openly with the manufacturing community.

However, it was becoming unclear as to who was really in charge of the Galileo ICD process: the European Space Agency (ESA), the EC through its signal task force, the Galileo Joint Undertaking (GJU) negotiating the concession contract, the Galileo Supervisory Authority that will oversee the program, or even the concessionaire who would understandably want to claim every possible piece of Galileo-related intellectual property. And, finally, GARMIS, a consortium of 30 companies led by France Developpement Conseil holds a €4 million GJU contract to provide “engineering support for optimizing the Galileo documentation,” including the Galileo ICD.

In addition to this divided responsibility for the ICD, a divergence was occurring, not only between European and non-European companies, but even among European companies. That created the peculiar situation of one manufacturer announcing a GPS/Galileo-capable receiver with the caveat that the Galileo functionality was available only to customers authorized by ESA. Or a well-positioned European company offering a GNSS signal generator with Galileo functionality that the vendor claimed would always be a step ahead due to the company’s involvement in writing the Galileo ICD.

So, the prospect of an initial Galileo ICD appearing in the near future will dispel doubts, sustain enthusiasm for the project, and provide a crucial resource for the real work of engineering a better GNSS future.

glen@insidegnss.com

 

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March 1, 2007

The Promise of MEMS to the Navigation Community

GPS clearly dominates the current market in positioning and navigation (POS/NAV). Besides being globally available, it provides the whole range of navigation accuracies at very low cost. GPS is also highly portable, has low power consumption, and is well suited for integration with other sensors, communication links, and databases.

GPS clearly dominates the current market in positioning and navigation (POS/NAV). Besides being globally available, it provides the whole range of navigation accuracies at very low cost. GPS is also highly portable, has low power consumption, and is well suited for integration with other sensors, communication links, and databases.

At this point in the development of navigation technology, the need for alternative positioning systems only arises because GPS does not work in all environments. Current GPS receiver chips are reaching a unit price of about $5, and the predictions are that this figure will drop to about $1 when, most likely, it will level off.

Module cost is not equivalent to system cost, but the recent development of receivers at a price of $100 shows clearly that module costs are an important factor, not only in consumer mass markets, but also for high-volume commercial products, such as asset and container tracking.

Even more important is the fact that with unit cost that low, GPS is becoming a commodity, comparable to a Sony Walkman, pocket calculators, or a digital wristwatch. Thus, personal GPS devices will drive the module market and provide navigation receivers of high versatility at even lower cost.

Considering these price trends, can any POS/NAV technology be competitive with GPS?

At this point the answer is clearly in the negative. Therefore, other navigation technologies would typically be developed for “non-GPS” environments, that is, for environments in which GPS does not function at all (underground, underwater, in buildings) or where it performs poorly (forested areas, urban environments). Although a substantial navigation market for operating in “non-GPS” environments exists, it is much smaller than the one predicted for GPS.

In the portion of the market where GPS is only available for part of the time, the question will be, “How much is the user willing to pay for a continuous navigation solution?” This obviously will depend on the specific application, and it might be possible that niche markets will develop around such applications.

In such applications, integrated solutions will be of high interest and may involve sensor integration as well as data base integration for techniques such as map matching. In those applications where GPS does not work at all, the search for cost-effective alternatives will continue.

One promising development is the emergence of micro-electromechanical systems (MEMS) technology (also known as micromachined technology). MEMS is an enabling technology with a massive global market volume worth $12 billion in 2004 and is expected to reach $25 billion in 2009 (Source: “NEXUS Market Analysis for MEMS and Microsystems III, 2005-2009”). This means that, overall, MEMS technology will be much larger than the market size of GPS at that time.

A small portion of this MEMS market will support inertial sensor technology. Yole development estimated that the world markets for MEMS-based inertial sensors have reached almost $0.7 billion in 2004 and will exceed $1 billion in 2008. The major growth opportunities will come from automotive and consumer application markets, with a steady growth of the industrial and defense business, too. (Source: World MEMS Inertial Sensor Markets, Research Report # YD4264, Yole Development, April 2005).

Since INS technology is capable of working in all environments where GPS has difficulties, MEMS inertial technology is seen as both a possible complement of GPS technology and a potential alternative to GPS is market volumes develop in the way anticipated. The idea of an “inertial measurement unit (IMU) on a chip” and unit cost as low as GPS modules are anticipated in the very near future.

(For the rest of story, tables, graphs and formulas, please download the complete article using the PDF link above.)

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