Tag: ION GNSS

Locata, A New Constellation: ICD and Live Demos at ION-GNSS 2011
“GPS can no longer evolve fast enough. Satellite-based systems cannot maintain the speed of development now required for the hyper-fast evolutionary pace of modern applications and devices. For positioning for the future, it has become exceedingly clear that GPS now needs a terrestrial component.” — from a Locata Corporation prospectus

A large number of companies and engineers have thrown billions of dollars at trying to improve GPS in urban and indoor applications,” states Locata Corporation co-founder Nunzio Gambale. “From a technological perspective, Locata has created something completely new: the capability to autonomously create a GPS-style system on the ground.”

Members of the GNSS community can see for themselves at Locata’s coming-out party at ION-GNSS 2011, including release of a Locata signal interface control document (ICD). GPS World took an advance look at the technology in a June trial of the demo that all ION attendees can see. This article presents these reports, after an outline of the technology.

The key to Locata’s positioning system is the signal generated by the Locata transceiver, or LocataLite, to synchronize its time to other LocataLites in a network. Locata creates a network that, according to the company, “is in almost perfect synchronization” without using atomic clocks. Each transmitter dynamically synchronizes with other Locata transmitters using a patented method called Time-Loc. Gambale says that a Locata network currently locks to about 2 nanoseconds.

Each LocataLite base station has an uninterrupted range of approximately 10 kilometers, with indoor signal penetration similar to that of a mobile phone tower.

The company emphasizes that its transceivers are not pseudolites, but devices that create TimeLoc synchronization, and thereby enable an autonomous synchronized network that, locally, looks like GPS. The local constellation is under local control, and can therefore be designed for deployment at any power, any frequency, or any density required by an application.

The networks can scale easily. The term “local” can mean a room or warehouse (100s of m2), a campus or open-cut mine (10s of km2), an airport terminal area with approach and landing routes (100s of km2), or a wide area, range, or city (1,000s of km2)

Gambale sees markets for Locata’s technology in defense, mining, emergency services, construction, and security. Locata is designed to integrate with existing GPS technology, as simply another constellation. This means an approprieate GPS-Locata receiver can use the satellite signal when outside the range of a Locata network. To a combined GPS-Locata chip, the LocataLite will appear as another satellite.

The company sold its first Locata network in July 2005. Locata has signed partnership agreements of various kinds with Leica Geosystems and Newmont Corporation (mining), the U.S. Air Force, the Advanced Navigation Technology Center of the Air Force Institute of Technology, and several other firms under non-disclosure terms. There was an initial test deployment at Holloman Air Force Base in May 2008, as a truth reference system spanning a test area of about 52 by 15 kilometers.

For high-multipath environments such as indoors and warehousing, the company’s latest development is a new antenna called a TimeTenna, which it will demonstrate at ION-GNSS.

Future research and development will focus on the miniaturization of the Locata receiver. Work has begun on a combined GPS-GLONASS-Locata chip that can be integrated initially into professional and industrial devices, and eventually into consumer devices such as mobile phones.

Locata plans to work with integrators only, not with end users, making the technology available to qualified partners developing receivers and applications. The ICD is the first step in Locata’s technology rollout.

LocataLites awaiting boards. Each LocataLite transmits four PRN signals.

A Long Time Coming

Eric Gakstatter, Survey editor

You may have heard the Locata name pop up over the past several years. It would be in the news, then back underground into stealth mode. About five years ago, I heard some interesting rumors about its technology but I decided not to take them seriously until I saw some real products.

Two years ago, I sat down with Nunzio Gambale, Locata CEO, at the ION-GNSS conference. At last year’s ION, I talked with him again. At that point, I understood the potential impact of Locata’s technology — if it worked as advertised. I again told myself that before I spent more time on it, I wanted to see a product introduced to the market based on Locata technology. In January of this year, it happened.

Leica Geosystems introduced its terrestrial GPS Augmentation Network for the mining industry, based on Locata technology. To me, that was a pivotal point. Leica is a reputable company and wouldn’t introduce a product without a thorough vetting.

I contacted Nunzio and we had further discussions. I wanted to see the technology in action — hard to do since Locata is based in Australia, I’m in Portland, Oregon, and an early installation occurred in South Africa. Fortunately, the company’s need to do a real run-through of its demo on site, prior to ION, meant that I got what I wanted to see, right on my doorstep: a Locata preview at the Oregon Convention Center in June.

The Technology

Essentially, Locata has developed a system that is very much GPS-like in that one has a network of reference stations (LocataLites) that interface to an unlimited number of rovers. One major difference is that there is no space segment. It doesn’t need or use satellites. Essentially, each reference station behaves like a satellite on the ground, with the rover moving around inside the polygon formed by the reference stations. The rover position is accurate to the centimeter level.

The value of the Locata receivers is that they don’t need a clear view of the sky to operate like a GPS receiver does. Yes, that means centimeter-level positioning indoors, where RTK GPS doesn’t work due to satellite visibility constraints, as well as outdoors.

Sound cool? It is. I saw it working indoors at the Oregon Convention Center. Locata staff set up a large room with Locata reference stations around the perimeter. They had two different rovers: one mounted on a small push cart and the other on a golf cart. We were able to move the rovers around the room freely and view the updated coordinates at 1 Hz intervals (although it’s capable of much faster update rates).

The Challenges

The new TimeTenna (see facing page) is large. Today that form factor is required to handle the high-multipath indoor environment. Locata is working on a scaled-down version, although it’s not unreasonable to envision the current model being mounted on a forklift or other vehicle if it was mechanically hardened. The antenna for Locata’s outdoor systems (for mining and other less hostile environments) is much lower profile and similar to a standard GPS antenna.

The Locata system requires that you manage a network of Locata reference stations. Similar to an RTK network, the Locata system is based on a network of reference stations around the project area. The baseline distances can be quite long (tens of miles), but nevertheless, one must install and manage the network much as one would a GPS RTK network, albeit with much less IT department involvement than a GPS RTK network.

Lastly, Nunzio Gambale wholeheartedly agrees that Locata’s technology is still developing. He likens it
to where GPS was in 1990. I tend to agree. The antenna technology needs to reduce in size and the system architecture needs to be vetted for reliability in production environments. But keep in mind that Leica and the U.S. Air Force’s 746 Test Squadron have already bought into Locata’s technology in a big way.

Although I don’t pretend to have the technical understanding that some of the others in the room possessed during the June demo, I did hear one of the sharper engineers exclaim “genius” at one point, referring to the design.

It’s certainly worth a close look as Locata’s technology continues to develop and be deployed. I think the day isn’t far away when we will see a system from Locata that will allow a user to transition seamlessly from centimeter-level positioning outdoors using RTK GPS to centimeter-level positioning indoors without breaking a step.

Now I’m a Believer

Tony Murfin, Professional OEM editor

I was invited to Portland in late June to preview an operational system which promises to help GPS in tough signal situations and work well indoors. While Europe, China, India, Japan, and of course Russia are all working to get more operational satellites in space, Locata in Australia has quietly been perfecting its terrestrial navigation system. I say perfecting because skeptics and naysayers have criticized Locata and what was seen as a pseudolite system with a rather lengthy development cycle. But nothing speaks as loudly as an operational system adopted and fielded by Leica Geosystems or a contract with the U.S. Air Force to get people’s attention back in the right place, even though Locata would claim it is only just getting started.

As I walked into the Portland Convention Center I was certainly apprehensive as to how any GPS-like system could function well within the massive concrete and steel building. When I found the smiling Locata group tucked away in one of the side ballrooms, it didn’t take long before I became a believer. Those wall dividers that allow the Convention Center to reconfigure rooms are apparently referred to as Acousti-Seal 931 Steel Operable Wall panels — yep, perfect multipath reflectors. So to see totally repeatable few centimeter positions in this cavern was not what I was anticipating.

The ballroom’s carpeted floor had been carefully laser-surveyed with a matrix of 5-meter squares, with a high-precision dot marking each grid intersection. LocataLite stations were set up at each corner and one in the middle at the far end, each with three antennas. A master station at the left corner of the entry wall originated the TimeLoc signal, and on each station one antenna pointed to an adjacent station, over which TimeLoc synchronization was cascaded around the network. This is a key feature of the ground network, allowing it to become fully synchronized and also to be extended or reconfigured at will.

Of course, when you run your own ground network it helps to be able to run at power levels significantly higher than GPS, so it’s easy for each station to communicate with another, provided they roughly have line-of-sight of each other — kind of like having to actually see a GPS satellite to get it into your GPS position solution. If you have some buildings or bushes or trees to contend with, having higher power available makes things easier, especially if you want an RTK carrier solution.

The secret to working indoors appears to be the TimeTenna phased-array antenna that Locata demonstrated in the steel-clad ballroom. With this top-hat-like antenna mounted on a wheeled cart along with a receiver and laptop, and positioned over one of those surveyed locations on the carpet, we could easily see that positions within less than 5 centimeters were consistent and solid. As a truth system, the company also had a motorized laser scanner pumping out centimeter-level positions on a parallel measurement system, and it was clear that there was excellent centimeter-level correlation.

But don’t take my word for it. Come to Portland for the ION-GNSS conference, September 20–23, and see the Locata demo for yourself — you’ll be impressed too!

Then there is the sole-source U.S. Air Force contract that has Locata updating an existing network to provide independent reference positions over 2,500 square miles of the White Sands Missile Range in New Mexico. The Air Force apparently needs to know how its navigation systems work when it turns on localized GPS jamming. The Locata system is designed to give the Air Force better than the specified <18-centimeter position accuracy in GPS-denied environments.

In August, Locata cleared the final USAF critical design review milestone for the wide-area White Sands Missile Range deployment. This is clearly a good sign that Air Force wants to continue with the next-generation Locata system. With GPS denied on this range, test vehicles will likely be constrained to inertial-only navigation, but with a LocataLite receiver onboard pumping out high-accuracy position measurements, the Air Force will no doubt have plenty of location data to track dynamic performance under GPS jamming conditions.

Another application that Locata has been investigating involves airborne trials in Australia, where initial results indicate position accuracy of less than 3 meters at up to 50 kilometers. The trials have involved a ground network with six base stations spread over a roughly square area of 1,500 square kilometers.

A University of New South Wales test aircraft equipped with precision GPS, inertial reference system, and laser scanner for truth reference use flew to within 3 to 49 kilometers of the reference stations at around 7,000 feet, producing the reported <3-meter code solution. Trials data is still being analyzed to produce a higher accuracy carrier solution, and Locata expects to issue these results at ION.

Airborne Reference Equipment

Leica has apparently been working with Locata for some time. The proof-of-concept installation at a 300-foot deep diamond mine in South Africa and a production set-up at a gold mine in Western Australia are going strong.

The gold-mine installation has now been extended to two pit sites using 15 LocataLite transmitters in total. LocataLite receivers are mounted on vehicles, atop drills and shovels, and all run off the multi-pit Locata network. The mobile units not only carry LocataLite receivers, but also precision Leica GNSS receivers running off side-by-side antennas. As time progresses, the ultimate solution will use integrated multi-constellation/LocataLite receivers: the Locata signals integrated into a combined satellite+terrestrial receiver position solution, using a single integrated antenna.

It’s easy to envisage such an integrated receiver and antenna where the Locata ground-network signals are used as just another local constellation. The investment to get to such a receiver would of course have to be justified by a whole proliferation of Locata networks. This would seem to be on the way, given the significant progress that Locata has now unveiled.

Will It Fly — Literally?

William Shears, aviation engineer

If you are an aviation satellite navigation enthusiast, you probably noticed this hasn’t been an auspicious year for aviation GNSS or for GNSS applied to any other user segment that needs highly reliable GNSS service. Between personal privacy jammers, instances of accidental interference, and the big chill sent through the community by the LightSquared debacle, many are asking if GNSS is now or ever will be reliable enough to be a sole means of position and time for safety-of-life applications.

A few years ago, the very idea that ordinary people would want to own GPS jamming devices and that they would be easily obtainable on the Internet would have been considered absurd. Similarly, the idea that the U.S. government would not vigorously protect GPS from interference was just not credible. But here we are in mid-2011 and the vulnerability of GNSS to interference has come home to roost, in several very big ways. This new awareness of the weaknesses of GNSS has led the U.S. Federal Aviation Administration (FAA) and civil aviation authorities of other countries to start rethinking their long-term strategies with respect to satellite navigation.

Even well before LightSquared crept into the consciousness of the GPS community and then burst forth as the apocalyptic specter that threatens to virtually end the utility of GPS in North America, the FAA had begun a study to consider the need for an alternate positioning, navigation, and timing (APNT) system to support critical aviation needs. The idea being that as the U.S. air traffic management system transitions to become increasingly dependent on management of traffic via four-dimensional trajectories, reversion to a non-trajectory based mode (for example, controllers vectoring aircraft as they do today) would become unfeasible. Hence, airplanes will need a very reliable source of 4D positioning and outages for any extended period of time due to interference, or anything else will be unacceptable. The FAA set about studying what level of performance would be required for a system intended to back up GNSS in the future. Other countries began to follow suit, and whereas the concept of an APNT was obscure a year and a half ago, it has become a significant point of discussion at the International Civil Aviation Administration (ICAO) as well as within various countries, including the United States, Australia, and several in Europe.

At first blush, the Locata system would seem to be a ready-made solution poised to fulfill aviation’s need for a GNSS backup system. In fact, acting as an independent backup (and/or an augmentation to) GNSS is one of the main motivations in Locata’s development. The technology seems to have promise in meeting the aviation community’s needs for an APNT. Locata is relatively mature technology that has demonstrated accuracies well in excess of what is required of an APNT meant to back up GNSS for enroute, terminal, and non-precision approach operations. Perhaps even precision approach and landing could be supported. Also, the system is very flexible, which suggests that service coverage could be tailored as needed around important airports. The system has significant redundancies built in, including multiple frequencies, multiple antennas for path diversity, and the ability for the network to reconfigure which LocataLite uses which other LocataLite for time synchronization.

Given this flexibility and redundancy, it should be possible to configure a system that provides highly reliable service where it is needed. Another major advantage of the Locata technology for aviation is the higher signal power level that comes from using terrestrial signals rather than signals from space. In theory, a Locata system would be more robust to interference than space-based GNSS signals.

Some people are indeed thinking about Locata for aviation use. Locata has conducted flight trials in Australia using a prototype demonstration network of six LocataLites covering an area of more than 1,500 square kilometers around Cooma airport in Australia. Locata has reported code positioning solutions of better than 3 meters at ranges up to 50 kilometers, and will present higher accuracy carrier-phase solutions at ION. The U.S. Air Force is also preparing to use Locata in an aviation environment as an independent truth reference.

At the ICAO Navigation Systems Panel (NSP) meeting in May 2011, the Australian panel member presented a paper outlining the general need for an APNT. The paper included a description of Locata as an example of what an APNT solution might look like. However, it is interesting that the paper fell short of proposing that the panel pursue Locata as the solution or to suggest that any standardization of a solution for APNT begin immediately. In spite of all the potential advantages discussed above, the Locata system faces a major obstacle before it can practically be used in aviation applications: standardization.

The first aspect of standardization that is likely to be a huge impediment for Locata (or any other APNT proposal, for that matter) is spectrum. The Locata systems implemented to date have been designed to operate in the 2.4 GHz unlicensed industrial applications band. For Locata to support safety-of-life applications, national aviation authorities will require that an APNT system use spectrum that is properly allocated for use in a safety-critical aeronautical navigation system, that is, spectrum allocated for Aeronautical Route Navigation Services (ARNS). Spectrum allocated as ARNS is afforded special protection from interference. Coordination of services in or near ARNS spectrum is often difficult, time-consuming, and expensive. For example, coordination between civil aviation use of the 108–118 MHz band (used for instrument landing systems, or ILS, and VHF omnidirectional range, or VOR) and FM broadcasting in the 88.1–107.9 MHz band produces real costs and restrictions to be borne by the FM broadcasters. Consequently, any proposal to convert non-ARNS allocated spectrum to ARNS is likely to be met with significant opposition.

Spectrum is a finite resource, and virtually all spectrum is already in use by someone. So, the reality is that a future APNT will likely have to be implemented in some existing ARNS spectrum, since a new global allocation of spectrum for ARNS is an unlikely proposition.

The current allocations for ARNS include:
- 108–118 MHz (ILS/VOR),
- 960–1215 MHz (DME/Mode-S/ADS-B/SSR/JTIDS/MIDS),
- 1556–1626 MHz, and
- 5.1–5.25 GHz.
All indications are that a Locata system could be could be operated at these frequencies. However, services that already exist in those bands will continue for the foreseeable future. So, to be viable, a Locata system would have to coexist in one of these bands with other existing systems, that is, not interfere with the operation of those other systems. Such coexistence has yet to be demonstrated either by analysis or test.

After suitable spectrum has been identified, the next major hurdle for Locata is standardization of the signal-in-space to the degree that supports interoperability of equipment produced by different manufacturers in different countries. The Locata ICD released at ION-GNSS 2011 is a good step in the right direction. But for an aviation application, a great deal more would need to be specified, including details about the waveform (spectral mask, out-of-band emissions, and so on), the protocols for producing the signals, and the standard protocols for the application of data to derive a position solution. A clear allocation of responsibility between the ground processing and airborne processing will need to be defined so that system integrity can be analyzed and assured.

At the international level, such standardization activities can take a decade or more. The length of time required depends on the maturity of the system that is proposed for standardization. The existence of a similar standard, with perhaps a significant user base and operational experience also helps (for example, an IEEE standard or RTCM standards). So, again, the ICD is a good start.

Beyond the technical aspects of standardization, there are political and institutional aspects that can often be more formidable barriers. Issues with spectrum have already been mentioned. Beyond that, there are issues with intellectual property. Creating aviation standards based on proprietary technology is unpopular although not unprecedented. Proposals for standardization are more likely to be successful the fewer strings, such as licensing agreements or fees, that are attached. This is a challenge since companies that have worked hard to develop cool new technology are often reticent to give away their intellectual property in the name of standardization.

Given all the barriers, how does new technology ever get implemented in civil aviation? Typically, applications begin in one of two ways:
- in support of war.
- in support non-safety related industrial applications.
The military has historically pioneered many technologies (radar, DME/TACAN, GPS) that would probably not have been developed otherwise. Even after the initial military experience, there is typically a period of time when the new technology is used in a non-safety-critical capacity to support some commercial objective. In the case of Locata, some potential applications would be flight-test position-reference systems, high-precision photogrammetry, high-precision positioning for crop dusting, and any other applications that require a highly robust, high-accuracy position solution in a well-defined region where interoperability and certification are not issues. Those are relatively small niche applications, which may provide some valuable operational experience.

However, serious movement towards adopting Locata as a standard for APNT is unlikely to happen without the support of at least a couple of large countries. Even a large user base with equipage does not guarantee that countries will adopt the technology or that air navigation service providers will authorize the use of the technology for safety-critical applications. For example, many carriers are equipping with broadband Internet equipment to provide service to the passenger cabin. Yet, there is no serious discussion of using that datalink capability for safety-related communications. Similarly, a very large number of aircraft are equipped with Aircraft Condition and Reporting System (ACARS) datalink, yet use of that system is largely limited to non-essential Airline Operational Communication (AOC) applications.

So will Locata fly? I believe that is entirely up to Locata and other companies that work with Locata to address the initial military and niche airborne positing markets. Operational experience gained by such early adopters will be critical in laying the groundwork for the support that will be needed from large states like the United States, Australia, China, and those in Europe, if Locata is to be a player in the longer-term international standardization of APNT.

In the near term, Locata is already serving the aviation community by demonstrating the art of the possible relative to what a ground-based navigation system based on modern technology could be.
September 1, 2011
ION Exhibit Hall Is My Beat

The exhibit hall is nearly full for the ION GNSS conference in September, and this year’s crop of new products and technology promises to showcase the very latest and greatest. In recent years some companies may have cooled a bit on exhibiting, but this fall has all the earmarks of a resurgence. As a business development guy, the exhibit hall is where I tend to spend most of my time at ION. I like to catch up with each of the companies I’ve done business with and carefully assess how the competition is heating up between the main rivals. This year I sense a slight increase in the number of European exhibitors, so I’m eager to see how far Galileo/EGNOS/GLONASS enthusiasm has been converted into commercial products and services.

Another year has somehow flown by and we’re already preparing for the coming ION conference that will run September 20-23, and it’s once again in Portland, Oregon. I was just in Portland in June and it’s a wonderful city to explore — never seen so many bridges — with a bustling downtown weekend market, great hikes, and that fantastic surface train/bus/tram transportation network to get around. We dropped in on the weekend market under the Burnside Bridge, bought ice-cream, and walked along the pedestrian sidewalks on both sides of the river. The next day we did the T4 trail hike from the Zoo up to a great view of the city from Council Crest, then after lunch at great little Vietnamese restaurant near the huge OHSU campus, down the hill to the waterfront on the cable car and back to the city on surface tram and MAX light rail. Just a wonderful setting for what promises to be yet another successful ION conference at the Portland Convention Center.

I counted 82 of the 88 booths (as of a June 22 ION web update) in the exhibit hall are already taken, with the well-known larger companies all exhibiting as well as several new names who have not exhibited before. In recent years some companies may have been a little cooler on exhibiting at ION, but this year’s crop of product and technology exhibits promise to once more showcase the very latest and greatest in GNSS.

As a business development guy, the exhibit hall is where I tend to spend most of my time at ION. I like to catch up with each of the companies I’ve done business with and carefully assess how the competition is heating up between the main rivals. This year the impression is that there seems to be a slight increase in the number of European exhibitors, so I’m always interested to see how far Galileo/EGNOS/GLONASS enthusiasm has been converted into commercial products and services. I looked hard, but couldn’t readily find any Asian exhibitors, so we may have to wait a while for Compass or QZSS capability to hit this market forum. Of course some of the major Western GNSS companies are already claiming that their receivers are compatible with these Chinese and Japanese systems.

There does seem to be a slew of good-looking papers, and the whole presentation program appears to have a broad spectrum of interesting topics and the potential for new innovations which people want to talk about. It’s always interesting to see how the main players skate through or around the papers — most now seem to hold back and maintain a firmer proprietary outlook, preferring to protect their ideas and innovations — this is perhaps an indication that our industry is becoming much more mature. In the early years, engineers and researchers from the main players seemed to bubble over publicly with reports of leading innovations. Now the industry leaders prefer to patent first and hold things closer to the chest. Nevertheless, the academics, government, and new start-ups promise to provide an entertaining insight into the active investment in research and development that fortunately still seems to be characteristic of our industry.

As for the papers, if you can’t make it to the Civil GPS Service Interface Committee (CGSIC) meetings on the Monday and Tuesday, there will likely be a condensed re-run of the CGSIC constellation updates at John Betz’ panel, which runs through Wednesday morning. I always find these ‘global’ constellation updates to be very broad and somewhat fuzzy, but they do keep you up to date with the latest complexities of fielding and maintaining the systems we rely on. If you want more specifics, there are concurrent sessions on almost every topic throughout the whole week.

The LIghtSquared controversy continues to swirl, even though almost every user, manufacturer, and government agency has decried the threat to GPS, and Congress has forsworn FCC from funding any further activity. Tom Stansell will guide a panel discussion on the topic on Wednesday afternoon. With these two sessions and the manufacturer’s reception in the evening, my Wednesday will be pretty full.

Thursday, I’ll have to find time to browse the exhibits and catch up more with people, but I would like to hear some of the session in the morning on Global and Regional Satellite System Providers & the United Nations ICG, which seems to promise updates on the WAAS-type systems around the world. On the exhibit floor, Locata is making a return to the public scene and there are promises of an open ICD offering compatible operation with GPS, so that’s a must to catch up with.

Then the Thursday evening social evening still remains unclear, but with NovAtel’s bash apparently absent from this year’s ION, I’m sure there will be other interesting events to fit round Navtech’s anticipated open-mike event.

Yes, another ION with the prospect of re-connecting with a whole bunch of people, a great looking technical agenda, a full slate of manufacturers exhibiting, and Portland to explore once again — a conference not to be missed. I must get my membership renewed and register!

Another must-see show for me includes Intergeo, which runs September 27-29 in Nuremberg — but the overlap with ION is hard for me to overcome. But if you can’t make ION, and you want to visit Germany in the late summer, Intergeo is billed as a conference and trade show for geodesy, geoinformation, and land management, with an emphasis on almost every foreseeable way that GNSS is being used around the world. The show is big, with a huge number of exhibitors, and promises 1,500 participants. A “Navigation Conference — Finding your way in the intelligent world” is slated to run concurrently.

ENC-2011, November 29-December 1, is another interesting place to catch up with how Europe views the current status of satellite and other navigation. However, the scope of this meeting, which has in the past been billed as Europe’s answer to ION, has certainly contracted. This year the Royal Institute of Navigation (RIN) is running the conference from the heart of downtown London, and promises 350 delegates, but exhibit space is somewhat limited.

Tony Murfin
GNNS Aerospace

July 18, 2011
Photos from ION GNSS 2009

Chefs from U.S. Air Force 746th Test Squadron GPS Test Center of Expertise cook up a winning formula for a booth display, a RECIPE of Resources, Experience, Capability, Innovation, Process, and Efficiency. Visitors were asked to solve an intriguing word puzzle to receive a delicious prize.

GPS World’s booth offered a Wii bowling challenge for fun and exciting prizes.

A young bowler from Bavaria (above) and ION President Mikel Miller’s family (below) enjoy an evening at the GPS World bowling alley.

A visitor to NovAtel’s booth tries his piloting hand in a 3-D attitude solution with NovAtel’s GPS/INS SPAN-CPT product. Used as a controller in the flight simulator, it mimics an actual SPAN application as profiled in the September GPS World.

Miniature autonomous vehicles navigating the mean streets of a LEGO town take center stage on the show floor to highlight the Institute of Navigation’s first Mini-Urban Challenge and upcoming second challenge, now seeking sponsors.

Northrop Grumman personnel Jill Rigler, Ed Chou, George Vannick, and Velvet Hoover explain the company’s programs to booth visitors on the show floor. Northrop Grumman was a Gold Sponsor of GPS World’s Leadership Dinner.

Larry Skorski of the U.S. Coast Guard took first place in GPS World’s Wii Bowling Challenge (score, 225). Editor Alan Cameron presents him with a copy of Brad Parkinson and James Spilker’s book, The Global Positioning System, signed by the first author.

September 25, 2009
ION GNSS/CGSIC annual conference

I realize the GIS world doesn’t revolve around GPS but I’m going to spend some space on it this month. Currently, I’m in Savannah, Georgia at the annual ION GNSS/CGSIC conference.

This is where one can peer into the future of where GPS technology (and positioning technology in general) is heading. This is where all of the GPS and GNSS brainpower get together every year. There are a lot of military folks here. The GPS Chief Engineer (Col. David Goldstein), GPS Wing Commander (Col. David Madden), Boeing scientists (GPS satellite builders), Lockheed Martin scientists (GPS satellite builders) and all companies and organizations involved in designing and building GPS infrastructure are here. These are the true rocket scientists. I bet the average IQ would be a pretty good bowling score.

The way this conference works is that the CGSIC meetings take place on Monday and Tuesday. The ION GNSS meetings take place on Wednesday through Friday.

CGSIC is an acronym for the Civil GPS Service Interface Committee. CGSIC is coordinated by the US Coast Guard. According to its website, it’s the “recognized worldwide forum for effective interaction between all civil GPS users and the U.S. GPS authorities. It was established and chartered to identify civil GPS user needs (e.g. navigation, timing, and positioning) in support of the Department of Transportation’s (DOT) program to exchange information concerning GPS with the civil user community as part of the GPS “outreach” program. In fulfilling this responsibility, the CGSIC reports its activities to the National Space-Based Positioning, Navigation, and Timing (PNT) Executive Committee and the Office of the Assistant Secretary for Transportation”.

The CGSIC meetings on Monday and Tuesday consist of briefings from government officials on the status of GPS and various related programs like NDGPS, WAAS, OPUS/CORS and many more. You can view the CGSIC meeting agenda here. There are also many user presentations from various government and commercial entities discussing how they are using GPS/GNSS in their work.

I’ve been blogging about the meetings while I’ve been in Savannah. You can read my blog here. Of particular interest was the focus on RTK Networks in the Surveying, Mapping and Geosciences Session. RTK is an acronym for Real-Time Kinematic. Essentially, it’s real-time positioning at the centimeter level.

With respect to GIS and infrastructure mapping, RTK Networks are one of the most significant advancements in GPS you will encounter over the next few years in the Geospatial business. They have the potential to significantly transform the accuracy of infrastructure data that is collected. If you want to learn more about them, you can read some of what I’ve written before about RTK Networks as well as the webinar I conducted on the subject.

RTK Networks: The Wild, Wild West

What RTK Users Want; Prospects for Network RTK (Rob Lorimer)

Webinar – RTK Networks: What, Where, Why

Here were the subjects discussed regarding RTK Networks at CGSIC:

PANEL SESSION: Guidelines for Real Time GNSS Networks (RTN)
A. Site Considerations – Dan Martin, NOAA’s National Geodetic Survey
B. Planning & Design – Gavin Schrock, Washington State Reference Network
C. Administration – Gary Thompson, North Carolina Geodetic Survey
D. Best Methods for Users – Bill Henning, NOAA’s National Geodetic Survey
Question & Answer Session with Speakers

Interactive Sessions within Small Discussion Groups
Group 1. CORS/OPUS
Group 2. RTN Site Considerations and RTN Planning & Design
Group 3. RTN Administration and RTN Best Practices for Users
As I wrote in my blog, this was the place to be if one is interested in Real-Time Networks, from the user perspective to the administrator perspective. There’s a tremendous amount of interest and activity on the RTN space right now.

While the CGSIC meetings are all about what’s happening now, the ION GNSS meetings are all about what’s going to happen in the future. At ION GNSS, researchers present the results of their hard work. The result of some of this research will be the technology we are using tomorrow.

Be sure to check my ION GNSS blog. There will be some lag time, but it should all be up by early next week.

Thanks and see you next week.

September 25, 2009
ION GNSS Conference Peers into the Future of Surveying
The Institute of Navigation’s Global Navigation Satellite Systems (ION GNSS) conference is one of my two favorite industry events of the year; the other being the ESRI conference. At ESRI, I mix it up with GPS technology users, listen to what they are doing and what they want to do with the technology. At ION, I listen to GNSS designers and researchers.

ION GNSS is where these heady folks come together to share ideas and show the fruits of their labor. It’s also a place where GNSS policy-makers and administrators meet and share ideas. As with GNSS engineers, the administrators and policy-makers are an important part of the future of GPS technology. If a budget gets whacked on a certain GNSS program (say, for example, NDGPS), do you think companies will continue to spend R&D dollars on that technology? If you want to know the future of GNSS and how it will affect surveying, look at R&D today.

What’s so fun for me about ION GNSS is seeing where engineers spend their money and time. The research they present today will be in products you can use tomorrow.

But first, be sure to sign up for my free webinar to be held on September 15. I’ll be talking about modernized GPS signals (L2C, L5) and GLONASS. Do they (or in the case of L5, will it) really make a difference? Let’s talk. I’ll take your questions online after making a presentation.

I hope I’ve made this clear in the past and if not, here goes. I’m not a GNSS scientist. Not even close. Yes, I’ve managed product development where we integrated GPS technology and software to create surveying and mapping products. Yes, I managed the software and hardware engineers who made those products come to life. But if you asked me to write a line of C code or design a circuit, my 17 year old could finish it before I could start. I’m a block diagram sort of person that sees the big picture and communicates my vision reasonably well. And I listen to people, a lot.

Look at some of the ION GNSS presentation tracks below. Keep in mind that each one of these tracks has six to a dozen research papers within it — and these are only 11 of the more than 40 tracks at the conference. A full list of panel descriptions and speakers is available.
- Multi-sensor Navigation
- Urban & Indoor Navigation Technology I
- Surveying & Geodesy
- GNSS Space-Based Augmentation Systems (SBAS)
- Multipath Effects and Mitigation
- Next-Generation GNSS Integrity
- PPP and Network-based RTK
- Software Receivers
- Atmospheric Effects and Modeling
- GNSS Inertial Navigation Systems
- GLONASS Modernization, QZSS & other GNSS
Just as a sampling, here are a few abbreviated abstracts from the above sessions:

Development and Field Testing of a DSP-Based Dual-Frequency Software GPS Receiver
B.W. O´Hanlon, Cornell University; T.E. Humphreys, University of Texas at Austin; M.L. Psiaki, P.M. Kintner, Jr., Cornell University
A real-time software GPS receiver for the L1 C/A and L2 C codes has been implemented on a Digital Signal Processor (DSP) and tested in a scintillation environment. This receiver is being developed as a low-cost space weather instrument with improved tracking robustness in comparison to a traditional semi-codeless dual-frequency receiver and with flexibility in its choices of signal tracking algorithms and data outputs. The receiver is capable of tracking 12 L1 C/A and 12 L2 C channels while also calculating receiver position and velocity and total electron content (TEC). The current work is a direct continuation of the work presented in Ref. 1. This work discusses several modifications to the software developed earlier, challenges addressed in updating the receiver to be easily adapted to new GNSS signals (e.g., L2C), and lessons learned from operation during ionospheric scintillation.

Improving Real-Time Kinematic PPP with Instantaneous Cycle-Slip Correction
S. Banville, R.B. Langley, University of New Brunswick, Canada
Over the last decade, precise point positioning (PPP) proved to be a powerful processing strategy. It vastly spread in several fields of applications such as atmospheric sciences, geodynamics, surveying in remote regions, processing of large networks, etc. On the other hand, the success of this technique in kinematic mode (with a moving receiver) is still muted due to a rather long convergence period required to obtain a centimetre level of precision. Several efforts were mounted to overcome this limitation, which led to the possibility of fixing carrier phase ambiguities to integers, which is the key to reducing the convergence period. In our approach, both carrier-phase and pseudorange measurements are included in the processing which allows estimating, not only receiver position change and receiver clock offset variation, but also cycle-slip parameters. Since time-differencing over short time spans is used, the assumption that instrumental biases cancel out seems reasonable. Hence, the cycle-slip parameters estimated are integers and conventional ambiguity search methods can be used to statistically determine the optimal cycle-slip (ambiguity) combination. Once the correct combination of integer cycle slips has been determined, their effects can be removed from the carrier-phase measurements, and the PPP processing can be executed without having to introduce new ambiguity parameters in the estimation filter. The benefit of this additional step is that a continuous time series can be obtained for the receiver coordinates, without the need for a new undesirable convergence period.

Augmenting Low-cost GPS/INS with Ultra-wideband Transceivers for Multi-platform Relative Navigation
A. Vydhyanathan, H. Luinge, M. Tanigawa, F. Dijkstra, Xsens Technologies B.V., The Netherlands; M.S. Braasch, M. Uijt de Haag, Ohio University, USA
This paper explores the use of impulse radio based Ultra-wideband transceivers to augment the low-cost GPS/INS navigation estimates in GPS-challenged/denied environments for multi-platform relative navigation. Such low-cost GPS/INS systems are increasingly being used in automobile, aerospace and marine applications for vehicle dynamics analysis, performance testing, Unmanned Aerial Vehicles (UAV) and Unmanned Ground Vehicles (UGV), autonomous attitude and navigation control and camera/LADAR stabilization and correction. The architecture and algorithm developed in this paper has independent ´loosely-coupled´ GPS/INS EKF´s running on each platform. A separate filter then takes the independent filter outputs and combines them with the ranges derived from the Ultra-wideband broadcasts to output relative navigation estimates.

The Benefits of Multi-constellation GNSS: Reaching up Even to Single Constellation GNSS users
B. Bonet, I. Alcantarilla, GMV, Spain; D. Flament, C. Rodriguez, EGNOS Project Office, ESA, France; N. Zarraoa, GMV, Spain
Europe has launched, under the European Space Agency’s (ESA’s) European GNSS Evolution Programme, the MRS initiative. MRS standing for Multi-constellation/multi-frequency Regional System, the initiative is putting different teams of experts into the exciting goal of defining the paths for the most successful GNSS usage on a future of multiple choices. ESA has prepared a detailed experimentation plan aimed to proof the benefits that the multi-constellation approach can provide to today´s GNSS users. This plan covers a wide range of objectives covering different user domains (aeronautical, land mobile, maritime) eq
uipped with different types of receivers. This set of experimentations will rely on the deployment of several Test Beds combining multi constellation multi-frequency processing and several broadcast channels (GEO, MEO, terrestrial). Among the first experimentations planned, there are some devoted to experiment and validate the performance benefits for SBAS users (GPS L1 only first then GPS/GLONASS or GPS/Galileo — dual-frequency SBAS users). This paper presents the outcome of the first step of this experimentation campaign, which has been performed based on the magicSBAS tool, a flexible SBAS processing platform, able to acquire single and dual frequency GLONASS data, in addition to GPS, to compute and provide both standards SBAS corrections and integrity, as well as augmentation to GLONASS.

From studying the track titles and abstracts, one can read between the lines and take a peek into the future of GNSS products. It’s clear to see that software receivers, SBAS, other GNSS, other sensor technology, PPP, atmospheric modeling and mitigation, and more reliable positioning all are active R&D topics that will mold the products in our future…some now and some a few years out.

I really enjoy this “look into the future” and will do my best to communicate the highlights to you. Our GPS World team will be at the ION GNSS conference in full force. Daily blogs will be written by several editors including myself. The GPS World website will be updated daily so be sure to check in throughout the week (September 21-25.)

The ION GNSS conference doesn’t actually start until Wednesday (kick-off is the plenary Tuesday evening) of that week. The Civil GPS Service Interface Committee (CGSIC) schedules their annual meeting on the two days prior to the ION GNSS conference. If you aren’t familiar with the CGSIC, I wrote an article about it a couple of years ago. Briefly, CGSIC is the body through which the civil GPS community can communicate with GPS authorities.

The two days of CGSIC meetings are chocked full of fantastic presentations from the status of GPS/GLONASS/Galileo/SBAS/NDGPS programs to presentation by users of GNSS. Normally I see the agenda posted on the CGSIC website, but I haven’t seen it there ye but check back in a day or two and I bet it will. Typically, the first day are program status briefings (GPS, GLONASS, QZSS, Galileo, SBAS, NDGPS, etc.). The second day contains breakouts sessions from the different subcommittees (US States and Localities, Survey Mapping & Geosciences, International and Timing). I’ll be giving a briefing on RTK Networks Tuesday at the US States and Localities subcommittee breakout session.

The guy who kicks my butt all over the landscape when I don’t file this column on time, GPS World editor Alan Cameron, also presents at CGSIC on Monday afternoon, with the topic “User Concerns.” For a preview of his presentation, see the latest installment in his Wide Awake blog, Wide Awake on the Midnight Train to Georgia [[http://stage.globalpositioningnews.com/gnss-system/wide-awake/wide-awake-midnight-train-georgia-8807]], in which he plays back results from a magazine survey of readers who answered the question, “Where is society going with GPS/GNSS use, and how will that change the GPS/GNSS industry?”

We’ll be blogging on the CGSIC meetings as well. Cameron and I will both have digital video recorders in our traveling bags, and we’ll post footage of highlights during the week. That’s another great way for you to get a bit closer to this goldmine of a conference.

In other notes, only 10 days after it was launched, the latest and last Block IIR-M GPS satellite was declared healthy and ready for service on August 28. Your receiver should be already tracking it and using it. It is identified as PRN05.

Meanwhile, the status of PRN01 (SVN49) that was launched back in March is still unhealthy and not usable. There’s been no significant news since the flurry of reports detailing its flaw a month ago. I suspect the Air Force will make some sort of announcement at the ION GNSS conference later this month with an update and/or plan to deal with the sick bird.

And again lastly, be sure to sign up for my free webinar to be held on September 15. I’ll be talking about modernized GPS signals (L2C, L5) and GLONASS. Do they (or in the case of L5, will it) really make a difference? Let’s talk about it. Sign up here.
September 1, 2009