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  • Survey & Construction Newsletter, Late September 2008

    ION GNSS Conference – Not This Year

    Well, it wasn’t meant to be. Hurricane Ike made sure of that.

    I travel quite a bit and I never fly Continental Airlines, but there aren’t a lot of choices when flying to Savannah, Georgia from Portland, Oregon. So a couple of months ago, I booked my flight to Savannah on Continental with a connection in Houston, Texas.

    Hurricanes and Houston don’t mix well this time of year. Anyway, Hurricane Ike wreaked havoc on southeast Texas. Houston’s airports were closed for the weekend (my flight was supposed to depart last Sunday). Continental, being a small airline with limited routes, couldn’t get me to Savannah until Wednesday night at the earliest. Other airlines were jammed up trying to reroute people around the Hurricane-affected airports.

    So be it … no ION conference for me this year. Too bad, it’s my favorite conference of the year because I get to see where companies and organizations are putting their research effort which, in turn, gives me a good idea where GNSS technology for surveying/construction is heading.

    At ION, one of the things I was scheduled to do was give a presentation at the Civil GPS Service Interface Committee (CGSIC) meeting on Monday. This year is the first time the CGSIC is allocating GPS World a slot on the agenda. The topic of my presentation was entitled “WAAS for Mapping: It Works Where You Work.” So, instead of presenting it at ION this year, here you go.

    First of all, let me tell you that even though the applications featured are focused on WAAS, this is really about SBAS (satellite-based augmentation systems) in general. That includes MSAS (Japan), EGNOS (Europe) and soon, GAGAN (India).

    Trends in GPS mapping

    The user community expects GNSS technology products to become smaller, cheaper, simpler, and higher performance.

    For the most part, we have seen that trend develop in the past decade. GPS mapping products have migrated from heavy, backpack-based systems with a medium-sized dome antenna, DOS-based data collector, VHS recorder batteries, antenna cable, data collector cable, and power cable to the small handheld devices and small receiver boxes of today. Likewise, prices have fallen considerably. The market prices for a sub-meter mapping system are 50 percent to 60 percent 60 less than a decade ago.

    The GPS mapping user community is moving away from post-process differential correction and towards real-time correction.

    The reason is quite simple: simplicity and cost. Post-processing is a pain and it’s expensive. It’s not just the cost of the software and software maintenance contracts, it’s the personnel training to stay current on the software, it’s the cost of time to post-process and it’s the cost of not having real-time data in the field. Yes, there is a cost of not having timely data.

    One of the arguments for post-processing is that it’s more accurate. From a pure scientific standpoint, that’s a correct statement, but it’s crazy to make that sort of general statement. I could show you data that shows that statement is correct and also incorrect. Like most answers to GPS accuracy questions, the answer is, it depends: it depends on the receiver, it depends on the application, it depends on your personnel qualifications, etc.

    SBAS makes real-time GPS correction simple and cheap, as in free. WAAS has matured over the last five years since it was declared operational from providing 1 meter to 3 meter accuracy to where it is today, providing accuracies of well under a meter in the continental United States, Alaska, Mexico, and most parts of Canada. The simplicity and low-cost of SBAS makes sub-meter mapping attainable by a larger percentage of the user community.

    All WAAS (SBAS)-Enabled Receivers Aren’t Created Equal

    One of the common experiences with WAAS (SBAS) in mapping applications is that the user will attempt to use a consumer-grade GPS unit (eg. Garmin) and, predictably, the performance will be poor. Consumer-grade GPS units aren’t designed for accuracy. They are designed for fast satellite acquisition, low-power consumption, low-cost, and easy user interface.

    I don’t know if you’ve been paying attention, but the newer consumer-grade GPS units don’t mention SBAS like they used to. It’s because the difference between autonomous positioning and WAAS-corrected positioning isn’t a significant issue with respect to the average GPS consumer who is navigating from point A to point B. Go look at the mapping Handhelds section on the Garmin website. There is no mention of WAAS in the specs. The reason? Garmin doesn’t care about WAAS for the ground user.

    If the GPS manufacturer does care about WAAS for ground users, there is a lot they can do to optimize the use of WAAS (SBAS) so it can perform in environments where a standard WAAS-enabled receiver couldn’t dream of working. One technical paper on this subject was published by Stanford University and presented at the ION conference in 2006. Euiho Kim, Todd Walter, and David Powell from Stanford presented a paper entitled Optimizing WAAS Accuracy/Stability for a Single Frequency Receiver.

    Some manufacturers have done this and more to exploit WAAS so it can be used in environments where a receiver implementing the traditional use of WAAS couldn’t. I can write about this until I’m blue in the face, but the proof is how the user community is using WAAS with high-performance receivers in applications where many people say WAAS can’t be used. I know of a few of them around North America and have provided a short synopsis of each to give you an idea.

    Applications of WAAS in North America

    Company: J.D. Irving Ltd.
    Employees: 15,000
    Industry: Forest products
    Location: Eastern Canada
    Application: harvesting timber
    User Statement: “The general misconception is that WAAS doesn’t work under forest canopy. (For us) It’s proven to be a false assumption if the right receiver is used.”

    Company: American Forest Management, Inc.
    Employees: 250
    Industry: Forest management
    Location: Virginia to Texas, Maine to Michigan
    Application: Area calculations, forest road work, land owner mapping
    User Statement: “Our field efficiency has drastically increased due to reliable reception and ease of use … office productivity also increased because of real-time correction.”

     

    Company: Portland General Electric
    Employees: 2,600
    Industry: utility
    Location: Oregon
    Application: utility pole mapping
    User Statement: “Four years ago, we started out using low-end WAAS receivers, but switched to mapping-grade WAAS receivers after 60 days due to accuracy problems. 225,000 poles and four years later, we are still using the same WAAS receivers.”

    Company: State of Minnesota
    Employees: a bunch
    Industry: state government
    Location: Minnesota
    Application: mapping abandoned chemical facilities
    User Statement: “Approximately 500 facilities were mapped using a Bluetooth, sub-meter WAAS GPS and a Windows Mobile data collector. Wireless technology eliminated connectivity problems and the receivers had COAST technology, consistently giving us submeter, real-time results, even in areas that had poor visibility.”

    Company: U.S. National Park Service
    Industry: federal government
    Location: sub-arctic Alaska
    Application: map archaeological sites
    User statement: “Many mapping grade GPS users still do not feel good about relying on WAAS. You can always post-process, but after reading these numbers, some may ask why bother?”

    Other Related Trends in Real-Time GPS Mapping

    Not only is WAAS (SBAS) being exploited by some manufacturers of sub-meter GPS mapping equipment, some manufacturers have introduced survey receivers that also exploit WAAS, but use another satellite observable for centimeter-level positioning rather than using the WAAS correction itself.

    In optimal scenarios, this potentially adds another two observables when resolving ambiguities for RTK positioning.When manufacturers start designing products around a technology, it speaks highly of the future of that technology.

    RTK networks (RTN) are experiencing explosive growth around the world.

    It’s a relatively new technology that will add to the proliferation of real-time users for both RTK and sub-meter mapping systems. RTN’s primarily cover metro areas at this time, but some countries have recently announced the implementation of country-wide RTNs. Look for more editorial coverage on this in the future.

    Commercial DGPS services have shifted from offering L1 sub-meter DGPS products to decimeter L1/L2 products in certain regions in the world.

    DGPS signal providers have recognized that WAAS/SBAS fills the requirement for sub-meter corrections where it’s available. They haven’t stopped offering L1 sub-meter DGPS corrections, but certainly have shifted their focus to the GPS L1/L2 market.

    On The Not-So-Positive Side of Things

    We’ve enjoyed many years of relatively quiet ionospheric activity. In a sense, we’ve taken for granted the awesome increase of GPS accuracy (both autonomous and DGPS). This is going to change as the next solar cycle cranks up. It’s an 11 year cycle that began early this year and will reach its high point in 2011 or 2012.

    What’s so bad about solar activity?

    For GPS users, errors induced by significant ionospheric activity can be measured in meters or even tens of meters even if you are using a DGPS correction source such as WAAS, beacon or RTN. Some experts say the next solar cycle will be worse than average. Some say not. All of them say “we won’t know until it’s here.”

    Read more about Solar Cycle 24 here. The subject is worthy of an entire article; which I will write in the coming months.

    Be sure to watch the live coverage that my fellow editors will be providing from the ION GNSS conference in Savannah this week.

  • Seeking Synergy

    By Art Kalinksi, GISP

    Three weeks ago, I attended the Second Annual Synergy Conference and Expo in southern Florida. The operations and intelligence conference was organized by Nancy Wheeler and Brigadier General Billy Bingham, USAF (Ret). Although both are retired from intel, they continue to work in the community through their support of the Government Emerging Technology Alliance and the conference co-sponsor, the United States Strategic Command (USSTRATCOM).

    The conference was very well organized and was a superb opportunity for civilians, contractors, and all ranks of military personnel to interact freely. Junior enlisted personnel, such as Air Force Sergeant Barrett and Senior Airman Roach, who had hands-on Predator image analysis experience, were given as much attention as their senior counterparts.

    I’m writing this column not as a knowledgeable intel guy, but rather as an intel outsider with a GIS focus. Although I served 20 years in the Navy, my experience with the Navy intel community was very limited. The “spooks,” as we called them, were usually cloistered behind cipher-lock security doors in rooms that were impervious to electronic spying, where disruptive background music thwarted any eavesdropping. Occasionally, someone reminiscent of the Wizard of Oz door guard would open a security window and pass us a scrap of classified paper telling us to do something or sharing some very limited information. We “ops pukes” would then act on the intelligence, sometimes blindly depending on the source. At the time, that was the model common to all branches of the military, with its origins going back to Napoleon’s army.

    At Synergy, I learned that the old Napoleonic model is changing dramatically; the conference title confirmed the evolution in thinking and action. Synergy refers to the merging of Operations and Intelligence divisions, and is spurred by changing operational needs — specifically, the increasing need for speed. According to General Bingham, gone is the time when operational forces reacted to intelligence within days. Now, even a reaction time of hours is not good enough; instead, it must be measured in minutes. Additionally, many of the operational forces are also major intelligence collectors.

    In the old days, the need for security trumped the need for fast response. Information was secured through multiple layers of security and compartmentalization. Even if there was a bad apple who leaked information, very few individuals possessed enough information to cause serious damage.

    Today, that model is changing because of the rapid changes to the operational situation. However, much of our satellite imagery, sources, and methods are still carefully protected, with limited access by our operational forces. That’s the key reason I joined my current employer: to get very high-resolution, but unclassified, oblique imagery into the hands of our operational ground troops quickly. (In fact, I attended the conference because Pictometry will be an exhibitor next year, partnering with Lockheed Martin to install oblique imagery cameras on the Predator and perhaps the Osprey.)

    The keynote speaker, Lt. General Mark Owen of USSTRATCOM, discussed the evolution of the command’s mission. Historically, USSTRATCOM was primarily involved in strategic nuclear deterrence, but its mission has been extended to cover all WMDs, space warfare, and cyberspace.

    Colonel Stuart Maberry, USAF, addressed the problems associated with irregular warfare. His presentation reminded me of a visionary Naval War College Review article written back in 1989 by CDR Steven Rose that described the array of threats we would face, including chemical weapons, biological attacks, and even nano-technology. Rose mused that one day we might long for the “good old days” when all we had to worry about were nuclear weapons. I can relate to that, having served in sensitive weapons assignments. Nuclear weapons require significant technical skill and ongoing maintenance if one hopes to achieve nuclear yields, as opposed to just a dirty bomb. The other dubious upside of a nuclear attack is that you know that you’ve been attacked, as well as when and where. This information may then point to the attacker.

    That may not be the case with cyber, chemical, and biological attacks that could seem like accidents or natural outbreaks. Add to that the relative simplicity of creation and delivery, and the fact that some of our enemies have no concern for collateral damage — or even their own lives — and the problem gets very serious. The only effective defense seems to be very good intelligence and constant vigilance.

    Major General Michael Ennis USMC of the CIA discussed current intelligence efforts, with a focus on human intelligence collection. It was interesting to note how valuable he considered open-source information as a way of confirming intel collected from other sources. He indicated that Internet blogs and Web sites, because of their numbers, are sometimes a superior source of information. He also expressed concern over the chasm between the ops and intel groups, and the walls that still exist between domestic and overseas collection, as well as the cultural differences between military and homeland agencies (such as the ATF and FBI).

    The vendor expo section had a strong focus on data management and data mining; countless products addressed the complexity of managing a flood of data. I observed numerous products and services that were not easily understandable. In many cases I couldn’t tell if I was looking at vaporware or I just wasn’t smart enough to understand that I was looking at a marvelous new development. After talking to some attendees, I suspect that it was a little of both.

    Of course homeland security agencies, all the military branches, and the intelligence community are big users of GIS technology, so one would expect ESRI to be an exhibitor. Indeed, ESRI had a booth demonstrating ArcGIS and ArcGIS-related products, including custom applications, but I didn’t see anything new other than some statistical analysis packages and discussions about Image Server. Spatial Analyst seems to be more important to the intel community than to most other GIS users I’ve seen, who are more involved in cataloging than analysis.

    ERDAS demonstrated its wide array of GIS data and image processing software, including the universal data translator TITAN. Adobe demonstrated its geo-referenced PDF maps, as well as publishing and collaboration tools. In the coming weeks I’m going to learn about (and report on) the differences between PDFs and the capabilities of TerraGo Technologies’ GeoPDFs.

    Zebra Imaging showed examples of its 3D holograms of buildings and neighborhoods. Although they looked very impressive, it was difficult to assess the benefit holograms offer over other visualization tools. I believe that we are still early in the life cycle of this promising technology, and I look forward to seeing how it will evolve.

    In one of the closing plenary sessions, LTC Casey Carey discussed the Sons of Iraq program, which (along with the surge) changed the entire dynamic in that country. By enhancing community relations and bringing Iraqis into the fold, intelligence gathering and the effectiveness of all coalition forces was greatly improved. This was a complex effort that required imaginative thinking. Life was simple when all we asked the military to do was kill people and break stuff. Now they also have to be military tacticians, spies, intelligence analysts, public works engineers, economic developers, diplomats, and even social workers. As if that isn’t enough, most of them are very young, without the benefit of college degrees or years of experience.

    As part of a panel discussion on mega-trends, Bob Gourley of Crucial Point, LLC, talked about the convergence of PCs and cell phones; there will be more than 6 billion G3-type phones in use worldwide by 2014. Add to that the changing rules governing domestic origins of calls, and we have a very daunting surveillance task. The panel also discussed In-Q-Tel, the nonprofit incubator for CIA support companies. One of In-Q-Tel’s success stories was the creation of Keyhole, which was later acquired by Google as Google Earth.

    There are three themes of the conference that I can’t overemphasize. First of all, GIS and related image processing software, along with data mining software, are growing in importance as the environment of the intelligence community grows increasingly sophisticated and complex. Second, there are many more people, military and civilian, involved in this work than the average person would imagine. Third, if you know any new graduates with GIS or computer science backgrounds, let them know that there are some very interesting career opportunities in the intel communities — the work is serious and significantly more interesting than printing road maps or maintaining a parcel tax map.

    My hat is off to the legions of military and civilian workers that are currently operating to keep us safe. They need all the support we can provide, and I hope our leaders keep politics out of these profoundly important issues. My overarching impression is that we have a lot of very smart military and civilian people spending countless hours to protect our interests. It’s very hard work in a constantly changing environment of one-upmanship. The classic Mad Magazine Spy vs. Spy cartoon serves as a good analogy, and I saw the cartoon included in several presentations. The difference is that the stakes are very high, and the results of failure not funny.

  • Survey & Construction Newsletter, Early September 2008

    Civil P(Y) follow-up and ION GNSS

    I figure it’s about time for a follow-up newsletter on the Civil P(Y) sunset proposal by the GPS Wing.

    In June, I wrote a very important column about the GPS Wing proposing to discontinue supporting P(Y) on L1/L2 for civilian users after December 31, 2020. Essentially it would mean that many dual frequency receivers of today will be rendered obsolete after that date.

    The U.S. Department of Commerce attempted to solicit comments from the public regarding the proposal. You can view the responses here. I was somewhat surprised at how few responses were submitted.

    It is predictable that equipment manufacturers are in favor of the proposal. There is significant upside for them in terms of new equipment sales and little downside, if any at all. The objections again, predictably, are from the users in the trenches who have invested a significant amount of their own capital into high precision GPS equipment.

    I can see a several reasons for the lack of responses:

    • Users aren’t aware of that impact this may have on their operations.
    • It’s too far in the future for users to be concerned.
    • It’s far enough in the future that users feel technology will change and render this a non-issue.

    Of course, I think it’s a little bit of all three. The first is the one that concerns me the most. That’s why I supported an extension to the comment period (30 days). I strongly believe there is a general lack of awareness of the subject at all, not to mention the impact it will have. If surveyors/technicians around the world haven’t been keeping up with the trade publications these past three months, they have no clue what’s in store for them.

    The second and third assume the user is educated on the issue and has made conscious decision not to be concerned.

    A few of you asked for a list of specific model numbers which will be affected. I’m working on one, but I don’t think it will ever be comprehensive enough to be 100 percent complete. What I tell people is that if the receiver isn’t able to utilize at least L2C (preferably L5 also), then it’s considered a legacy receiver and will be affected by the GPS Wing’s proposal. If you have any question as to whether your receiver can utilize L2C, you should contact the manufacturer of the equipment. Keep in mind that most companies begin to phase out support for older products (so called EOL or end of life models) after a few years, and some manufacturers may no longer exist at all.

    If you confirm your receiver uses legacy technology, I wouldn’t be in a panic to take action now. I have a feeling that manufacturers will offer some sort of trade-in program at some point. It may not be for another 7 to 10 years from now, but I think they will. The exception would be that if prices for high precision GNSS receivers drop dramatically (looking out 7 to 10 years from now) because of fierce competition, they will be so low that manufacturers won’t be able to afford it. But then you probably won’t care as much anyway.

    As I mentioned in the last newsletter (about the ESRI conference), I spoke briefly with Col. Madden, Commander of the GPS Wing, about the Civil P(Y) sunset proposal. Quite a straight-forward guy if I can say so. He says that maintaining backward compatibility in GPS is becoming increasingly expensive and that they have to draw the line somewhere.

    “Whether it’s 10 or 20 years, we don’t care,” said Madden. “But we need to put a marker down.” He said it currently costs $2.5 million per day to maintain GPS. In 2009, he said that cost will rise to $3.5 million to $4 million per day.

    The December 31, 2020 date is not final yet, but all indications are that it will indeed be the date. I should learn more at the Institute of Navigation (ION) GNSS conference held in Savannah, Georgia in a couple of weeks.

    I’m at ION

    Speaking of the ION GNSS conference, I’m on the agenda for the CGSIC meeting prior to the conference. The DOT has been pushing their NDGPS agenda pretty hard this past year to try to save the program. That’s fine, but I get a little ticked off every time I hear them tell people that WAAS isn’t a valid technology for mapping. Hey, if you think NDGPS is the way to go for you, then talk about NDGPS and stop trying to bring down other programs to further your cause.

    So anyway, I think a little equal time is in order. I’ll be presenting on how WAAS is being used for mapping. I picked out a half a dozen or so organizations around North America that are using WAAS with high performance GPS receivers. There are some neat examples of where WAAS is being used in places you might not think possible, and also how WAAS is being used by centimeter-level GPS equipment to speed up initialization times.

    I’m sorry I can’t include examples of EGNOS (Europe) and MSAS (Japan) users in the presentation, but I’ve only got 15 to 20 minutes. But I’ll be sure to mention EGNOS, MSAS, and GAGAN as well. I know you are all alive and well.

    Be sure to follow the live coverage that I and my fellow editors will be providing from Savannah the week of Sept. 15-19.

  • Leica Geo, TeeJet Pair Up for Ag Market Efforts

    Leica Geosystems and TeeJet Technologies have embarked on a partnership in which TeeJet will distribute Leica’s No-Drift mojoRTK auto-steer system under its own label, adding RTK-accuracy guidance to TeeJet’s suite of precision agriculture products.

    Under the same agreement Leica will capitalize on TeeJet Technologies’ range of vehicle-specific assisted steering kits to increase the number of tractors the mojoRTK can steer, the companies said. The list of kits offered by TeeJet currently tops more than 50 individual kits, designed to fit approximately 150 individual vehicle models. Initially, Leica will offer TeeJet vehicle kits through its network of resellers, according to the company.

    The companies also plan to work together to develop additional products for the agriculture market.

    Leica’s Virtual Wrench technology, which provides remote service and support, will also be expanded to support products for both companies, allowing technicians from both companies to provide customers with on-demand service and support, according to the companies.

  • Survey & Construction Newsletter, Late August 2008

    Attending the Annual ESRI Networking Conference

    As much as surveyors, engineers and constructors may not appreciate geographic information systems (GIS) technology, at some point everyone should attend at least the ESRI Survey/Engineering Summit and the first couple of days of the ESRI User Conference held every summer in San Diego, California. This is not a GIS sales pitch. It’s a networking sales pitch. When other conferences are struggling to maintain attendance levels, the ESRI conferences seemingly never fail to grow in attendance. This year, it attracted some 15,000 people from 120 countries. That means gobs of GIS people, and also gobs of surveyors and engineers.

    The Survey/Engineering Summit is a much smaller subset with some 500 attendees, and takes place the weekend before the User Conference. This year, it was the first weekend in August. Although relatively small in size, the conference is significant enough to attract someone the caliber of Col. Dave Madden as a keynote speaker. Col. Madden is the U.S. Air Force GPS Wing Commander, and as such he’s in charge of GPS. With a fiscal 2009 budget of $1.5B, it is the fourth largest budget in the U.S. Air Force. That means he has some clout, and that’s the quality of speaker that the ESRI conferences have the ability to attract.

    It’s All About Networking

    Most times, I’m like you: worried about the day-to-day stuff of running a business or department, or just getting stuff done on time and on budget. CEUs are hard enough to keep up with, not to mention taking a few days off during prime outdoor season (and spending a chunk of change) to attend a GIS conference.

    But I tell you what; this is the place to mix it up with all kinds of people beyond your local association chapter. Not that there’s anything wrong with that, but I guarantee that networking with 15,000 people will open your eyes a lot wider than networking with 25 people. If you’re looking to expand your business, whether it’s GIS-related or not, you will probably meet someone in San Diego who is doing it already.

    Take, for example, Michael Dennis of Geodetic Analysis LLC. Have a question about geodesy? Here’s a guy who gave a presentation entitled “GPS, Geodesy and the Ghost in the Machine.” Part of his presentation included dissecting National Geodetic Survey (NGS) Datasheets. Mind you, there’s a half dozen NGS people in the crowd! Sort of like giving a presentation on Windows to Bill Gates, isn’t it? That’s the kind of expertise walking around at this conference.

    While I’m on the subject of NGS, they had a whole pack of people there. Soon-to-retire director Dave Zilkowski gave a lunch-time presentation to approximately 200 attendees. Want to talk to the manager for CORS at NGS? He was there. Want to talk to someone at NGS about network RTK? Bill Henning was there. Want to talk to someone at NGS about OPUS? Yep, there too.

    What other opportunity do you have to sit down and have some face time with this caliber of people?

    Back to Col. Madden

    The theme of his presentation was about how the GPS Wing needs to improve on executing their strategy. A big part of what he was alluding to was keeping the schedule on target for the different programs. For example, there’s no navigation message on L2C and he said there won’t be until 2011, when the control segment (OCS) systems are upgraded. There won’t be a navigation message for L5 either until 2011, even though the first Block IIF (L5) satellite will be launched next year. It’s a good example of the space segment (satellites) and control segment (ground infrastructure) not being in sync. The L2C pilot carrier is available now, so carrier phase users (centimeter-level) are still able to use L2C carrier while utilizing the navigation message from L1.

    When he was on the subject of keeping schedules, I asked Col. Madden about launch schedules — more specifically, keeping the schedule that they set. He said two things.

    First of all, they need to do a better job of giving realistic launch dates. They move a lot. The seventh Block IIR-M satellite was due to launch last June and has been pushed out until October. The eighth, and last, Block IIR-M satellite was pushed out until December. Also, the first Block IIF satellite, in which an early 2009 date has been floated for quite some time, doesn’t look like it will be put into orbit until August 2009 or later.

    Secondly, and most importantly, he said it’s all about the $$. Launching satellites is an expensive business. He said “it takes $60 to 70 million to build a GPS satellite and its $200 million for the launch vehicle.”

    As successful as GPS is, Col. Madden is fighting for budget dollars like other program managers. As I mentioned above, he’s got the fourth largest budget in the US Air Force. When Congress looks at areas to save money, it’s easy for someone to say “Just cut 10 percent from GPS and we’ll save $150 million!” Also, it doesn’t help that there are now 31 operational satellites, way more than the guaranteed minimum constellation of 24. The problem is that, as high precision users, we need every one of those 31 operational satellites. We need to continue to raise our hand from the back of the room and be counted.

    I know it’s hard, but plan for the ESRI conference next July. I know, I know, it’s prime field season. But, give it a chance and you can take a lot from it. Like I wrote above, don’t look at it as a GIS conference, but rather a networking conference. It may change your business model or even your career path. You’ll have the opportunity to talk to more people than you have in years.

  • ITC Upholds Ruling in SiRF/Broadcom Patent Dispute

    The U.S. International Trade Commission (ITC) has denied the request of SiRF Technology to review its initial determination that found that Broadcom subsidiary Global Locate Inc. didn’t infringe two SiRF GPS patents.

    ITC Administrative Law Judge Paul Luckern had previously ruled that two of SiRF’s GPS patents were not infringed by Global Locate and that the asserted claims of one of the patents were invalid, following a six-day trial last March, according to Broadcom. SiRF had already dismissed two additional patents from the case before trial.

    This ITC case is separate from a case in which an ITC judge ruled earlier this month that certain SiRF Technology products, including SiRFstarIII chipsets, infringe six patents related to improving GPS processing and sensitivity held by Global Locate.

    Broadcom and SiRF have been battling on multiple fronts over patent infringement claims in federal court, the ITC, and before the U.S. Patent and Trademark Office. The August 8 ITC ruling against SiRF caused the company’s stock to take a pounding on Wall Street.

  • BIM, Son of CAD and GIS

    By Art Kalinski, GISP

    For those of you who haven’t been looking over the cubicle wall, there is a quiet revolution occurring in the CAD world that is affecting the GIS community. That revolution is BIM (building information modeling). BIM was developed in the mid-90s by the American Institute of Architects (AIA) to bring building design into the 21st century, but BIM is much more than just a building design model. Very simply put, it combines the best capabilities of CAD software with the best capabilities of GIS in a 3D environment.

    For years, many designers understood that the primary limitation of CAD software is that CAD drawings consist of points, lines, and polygons, with no topology and no link to a database — just object ID numbers. CAD traditionally focused on the quality and detail of the drawing, with a strong focus on 3D visualizations.

    Conversely, GIS is a topological model of points, lines, and polygons that’s linked to a database. Because of topology, a GIS understands relationships and can perform analyses such as what object is next to another, what object is within another, and what object intersects another, and display the results graphically or within the linked database.

    CAD drawings can look very good, because the software was designed to that end. GIS also draws points, lines, and polygons, but the tools were not designed to do sophisticated renderings. The best analogy I can think of is Microsoft Office. You could draft a letter in Excel, but it would be awkward and probably not look as good as one prepared in Word. Likewise, you could create a spreadsheet-style document in Word, but it wouldn’t have all the mathematical functionality of an Excel spreadsheet.

    Family Factions

    The CAD and GIS communities have, for the most part, lived separate lives, even in my own family. For years, while I was the GIS manager of the Atlanta Regional Commission (ARC), I taught ArcView classes. I offered to teach my son and daughter this entry-level GIS so they would have one more tool to put on their resume, but neither was interested in “that GIS stuff.” My son Alex was an electrical engineering major, and he learned CAD software as part of his program. Two years ago he received an internship with CH2MHILL doing CAD work. After he graduated, CH2MHILL grabbed him full-time, and he continued working on electrical design projects.

    Six months ago I was chatting with Alex about his new job and budding career. He was excited, explaining that he was now doing much more sophisticated work. He described a new software program that permitted him to link the elements of CAD drawings with a database that could then be searched spatially or through the database. With a tilt of my head I asked, “Do you realize that you’ve just perfectly described a GIS?” He said, with a look of revelation, “Is that what you’ve been doing all these years!” We both laughed, realizing that — unknowingly — the apple didn’t fall too far from the tree.

    My son “gets it” and understands the broad capability of BIM, but he’s in the minority. If you read some of the CAD blogs regarding BIM, most CAD people don’t get it yet. Many still view BIM as just a new kind of 3D model and miss the entire concept of topology and linked databases. This presents a huge opportunity for GIS professionals, since you already understand and have been performing spatial analysis in this topological environment.

    BIM of a Pantex Plant during initial design phase. Note building components, conduit, piping. Images courtesy of CH2MHILL.
    BIM of a Pantex Plant during initial design phase. Note building components, conduit, piping. Image courtesy of CH2MHILL.
    Images courtesy of CH2MHILL.
    Images courtesy of CH2MHILL.
    BIM showing complex system of piping, ventilation, electrical and other building and equipment components. Courtesy of CH2MHILL, Atlanta, GA.
    BIM showing complex system of piping, ventilation, electrical and other building and equipment components. Courtesy of CH2MHILL, Atlanta, GA.

    John Przybyla of Woolpert, who has worked in both disciplines for years, cautions us GIS people not to underestimate or downplay CAD projects. He used a simple wall as an example. In a GIS a wall may be represented as one or two lines, but the detailed CAD drawing could contain more than six layers of data: paint, drywall, framing, blocking, fire stops, insulation, etc. So there will be a learning process on both sides as we evolve. On the other hand, Przybyla wishes that GIS had more robust 3D modeling.

    Putting BIM to Work

    The 500-pound gorilla in BIM software is Autodesk’s Revit. Bentley BIM and Oracle are big players, and ESRI is working hard to be a contender in the BIM environment too. At the ESRI International User Conference, the plenary session included a demo of work being done at M.I.T. Michael Parkin demonstrated a 3D GIS model of the Cambridge campus that he created. Using the model, he was able to spatially identify by horizontal and vertical location each laboratory that was sensitive to noise and vibration. Parkin then created an intersecting 3D sphere of influence that would result from a planned construction project. This would help campus officials minimize the interference by changing schedules, or even moving some labs.

    Parkin also mapped, in 3D space, the location of campus parking spots and of the offices of assigned users. This helped the school assign spots closer to the users’ workplaces — something of a 3D trade area analysis for parking garage customers. Also at the conference were numerous presentations on building models and facility management (FM), even though most were not using the term BIM. ESRI has a team of people dedicated to all aspects of BIM, headed by Matt Davis of the Boston regional office and John Young of the Charlotte office. Both are good points of contact regarding BIM and GIS.

    We must all understand that BIM is much bigger than just building models. The AIA designed BIM as a full life cycle management tool that captures and uses the continuous stream of data, from construction to day-to-day operations to ultimate demolition. It’s the in-between area that will affect so many more users than just architects and builders. That wealth of data will be a boon to new users who will also add to the database.

    David Fouche of CH2MHILL worked on the development of early BIM software such as Bentley MicroStation and TriForma, as well as the more current Bentley BIM. He indicated that there is still much confusion and jockeying for position. He stated that use of BIM in design work is a given, but there is still much discussion as to where BIM will fit into the big picture of building life cycle management. Fouche indicated that when one considers the total cost of a facility, roughly 0.5 percent goes into design, 10 percent goes into construction, and the remaining cost is in life cycle management. Obviously there is a huge potential for efficiency and savings with the proper application of BIM tools.

    Fouche also mentioned that complex facilities such as oil refineries and other processing plants have been using BIM-like models for years, combining CAD and GIS tools to manage the facilities in a 3D model. GIS software such as Network Analyst is a natural for this kind of work. I remember seeing a poster at an ESRI User Conference years ago that showed the human circulatory system built with ArcView and Network Analyst. This was an eye opener, and I thought to myself, “Of course — a network is a network whether it’s a highway, oil pipes, or the blood supply system.”

    I remember that when ARC moved into a new facility in 2000, we took the building CAD drawings and brought them into ArcView 3.3. We then attached attributes to each room, including the occupant, furniture, computers, phone/data ports, etc. We then used ArcView to manage our facility, including the allocation of square footage to each department.

    One Step Forward, Two Steps Back

    Large FM companies like ARCHIBUS, Woolpert, and Penobscot Bay Media “get it,” and have a foot in both the CAD and GIS communities. All were exhibitors and heavy participants at the ESRI User Conference this year. They see where the world is evolving and plan on being there.

    But all is not rosy. On the federal side, the Army Corps of Engineers (ACE) is involved with BIM in a big way, but has changed the name of its CADD/GIS Technology Center to the CAD/BIM Technology Center. (Some of us GIS people look at that as one step forward and two steps back.) Looking at the ACE CAD/BIM Web site, I was surprised by how little attention is devoted to GIS and spatial analysis tools. The majority of material seems focused on BIM and CAD drawings, with little or no mention of GIS and spatial analysis. (We GISPs have a lot of educating to do.)

    ACE is working with all DOD agencies to establish standards and common data formats for BIM. A recent posting by ACE staff indicates that many military construction projects will require BIM models as a project deliverable. Most believe that BIM will become a nationwide federal requirement soon.

    Keep in mind that BIM models are spatially searchable or database-searchable 3D models, not just pretty 3D renderings. Again, think of CAD drawings combined with GIS spatial capability in a 3D model. As one considers the potential uses, including links to traditional GIS tasks and even temporal models, the list grows significantly. Some are already using BIM models with traditional GIS for energy management based on interior usage and building loading, measurement of water runoff and impermeable surfaces, and even links to transportation demand models and visualizations.

    An example of lifecycle management using GIS and BIMs. This shows Carbon Monoxide concentrations in one floor of a building. Courtesy of Penobscot Bay Media, New York.
    An example of lifecycle management using GIS and BIMs. This shows Carbon Monoxide concentrations in one floor of a building. Courtesy of Penobscot Bay Media, New York.

    The application of BIM models that could be especially critical is their potential use by first responders. Currently most fire departments maintain pre-plan data in the form of building blueprints and large paper ledgers that list hazardous materials, fire hose connections, etc. Imagine firefighters accessing BIM models that were created when a building was designed and updated throughout the life of a building. Additionally, picture how quickly they could view the complex systems as interactive 3D models, especially if they were presented as oblique views.

    A map of hazardous materials inside a building, including both location and description for emergency responders. Image courtesy of George MacBeth and Brad Peterson of ARCHIBUS, Inc.
    A map of hazardous materials inside a building, including both location and description for emergency responders. Image courtesy of George MacBeth and Brad Peterson of ARCHIBUS, Inc.

    It was interesting to note that CH2MHILL also used 3D PDFs as a quick way of sharing the models with many staff members. This proved to be a valuable collaboration tool and way to get input from many designers involved in the project. Some users are even enhancing the BIM models with photo-accurate surfaces or photo-accurate 3D models.

    A photo-accurate Precision Light Works 3D model using Pictometry oblique imagery. Image courtesy of Precision Light Works and Pictometry International.
    A photo-accurate Precision Light Works 3D model using Pictometry oblique imagery. Image courtesy of Precision Light Works and Pictometry International.

    The playing field is still very unsettled, with many groups pushing their own data standards, approaches, and naming conventions. The names BIM, CAD, and GIS could evolve, but the basic functionality will still be there and smell just as sweet. BIM is here to stay, along with its parents CAD and GIS. Look for BIM to become a requirement — and a huge opportunity — in your future work.

  • ITC Says SiRF Infringes Six Broadcom Patents

    A U.S. International Trade Commission (ITC) judge has ruled that certain SiRF Technology products infringe six patents related to improving GPS processing and sensitivity that are held by Global Locate Inc., a wholly owned subsidiary of Broadcom.

    The infringement findings cover a range of SiRF products, including those incorporating the SiRFstarIII and SiRFInstant GPS architectures, according to Broadcom.

    The ruling came Friday, August 8, just a day after SiRF said it had asked the U.S. Patent and Trademark Office reexamine four patents that are the subject of an infringement suit Broadcom has brought against SiRF in federal court. Furthermore, In June the ITC rejected claims by SiRF Technology that Global Locate infringed upon two of its patents, and also found that SiRF’s asserted claims on one of the patents at issue were invalid.

    The ruling Friday followed a trial earlier this year. Broadcom said it expects a final determination by the full six-person commission by early December.

    The six patents that SiRF was found to infringe are U.S. patents 6,417,801; 6,937,187; 6,606,346; 7,158,080; 6,704,651; 6,651,000 — relating to extended ephemeris assistance, calculating time in GPS receivers, enhancing sensitivity in assisted GPS systems, and implementing hardware structures for parallel correlation, according to Broadcom.

  • SiRF Requests Reexamination of Broadcom Patent Ruling

    SiRF Technology Holdings, Inc. of San Jose, California, has completed filing with the U.S. Patent and Trademark Office official requests for reexamination of each of the four patents that Broadcom recently asserted against SiRF in the Santa Ana, California, federal district court.

    SiRF seeks review and invalidation of all four of the Broadcom patents named in the lawsuit, through its requests for ex-parte reexamination and in view of what it terms “substantial new questions of patentability raised by prior art not previously considered by the Patent Office,” according to the company.

    SiRF also intends to seek a stay of the federal district court case.

    SiRF and Broadcom have been engaged in an ongoing legal battle over patents held by their respective companies, both claiming patent infringement. In late June, SiRF Technology petitioned the International Trade Commission (ITC) to review part of a ruling that found that Broadcom didn’t infringe upon two of its patents as the company alleged.

    A ruling in Broadcom’s six claims of patent infringement against SiRF before the ITC is expected any day. The trial took place in April.

  • Boeing Awarded Contract for GPS Enhancement Demonstration

    The Boeing Company has been awarded a $153.5 million U.S. Naval Research Laboratory contract to demonstrate High Integrity Global Positioning System (GPS) technology concepts. The contract is expected to run through 2010.

    The High Integrity GPS effort combines satellite signals from the Iridium Low Earth Orbit telecommunications system and GPS Mid Earth Orbit navigational satellites to enhance navigation availability, integrity, accuracy, and jam-resistant capabilities for warfighters.

    “High Integrity GPS is an effective near-term tool that will augment GPS satellites to provide critical new capabilities, including aggressive levels of additional anti-jam protection,” said David Whelan, Boeing Integrated Defense Systems chief scientist and vice president/deputy general manager, Advanced Systems. “Our research concluded that significant low-cost improvements to GPS can be achieved by using existing signal platforms and systems such as the Iridium constellation.”

    The need to provide a more capable GPS for warfighters stems from the increasing sophistication of hostile jamming capabilities, according to Boeing. GPS supports numerous military and civil applications, so the ability to jam the system presents a grave threat, the company said.

    “Boeing has been working over the years to find new ways to maximize the effectiveness of the GPS constellation,” said Alex Lopez, vice president, Advanced Network and Space Systems. “With this integrated approach, we can increase the value of the current system by improving its operational mission-assurance capabilities.”

    Based on its years of experience supporting the operation of the Iridium system, Boeing is able to integrate the system with GPS in a manner to create the first such combined navigation and communication “system-of-systems,” the company claimed.

    The High Integrity GPS team includes Boeing Advanced Systems and Phantom Works, Iridium LLC, Rockwell Collins, Coherent Navigation, and experts from academia.

    Iridium Satellite LLC, headquartered in Bethesda, Md., operates the Iridium constellation to provide worldwide voice and data satellite communications services for the private sector and the U.S. government. Boeing has provided Iridium with systems engineering and constellation management functions since the system became operational in 2000.

    Phantom Works is the advanced research and development unit of Boeing. Its charter is to provide innovative technology solutions that reduce cycle time and cost of aerospace products and services while improving their quality and performance.

  • Survey & Construction Newsletter, Early August 2008

    The Latest from Moscow and JAVAD GNSS

    It seems every industry has at least one person’s first name that, when spoken, sparks recognition from anyone who has a reasonable amount of experience in that field. In the computer database industry, everyone knows that “Larry” is Larry Ellison of Oracle fame. In GNSS, Charlie Trimble has a street named after him, not to mention a company bearing his name. But no person’s first name carries as much recognition in the industry as Javad.

    I attended the First Annual JAVAD GNSS User Conference in Moscow a couple of weeks ago. The company is putting together a serious effort in order to compete in the survey/construction/engineering industries.

    Javad is a name synonymous with high-quality, high-precision GNSS receivers — and with some amount of controversy. No matter what you think of the history and circumstances, you have to appreciate the fine GNSS technology produced under the guidance of Dr. Javad Ashjaee.

    JAVAD GNSS is, perhaps, his most ambitious endeavor since he started Ashtech some 21 years ago.

    The reason I believe it’s his most ambitious effort since Ashtech is because although Javad’s companies have a proven history of providing high quality, state-of-the-art GNSS receivers to the world, everyone in the survey/construction industry knows that while a solid GNSS receiver is important, the software makes the solution. Solid data-collection software and PC processing software is a “must-have” in order to compete with the Trimbles, Leicas, Topcons, and Magellans of today.  A big reason Ashtech always played second fiddle to Trimble wasn’t due to the quality of the receivers themselves. In fact, many viewed Ashtech receivers as superior to Trimble’s in that era. But Trimble’s heavy emphasis and investment in developing a complete software solution and a powerful distribution channel are key reasons that Trimble is valued at ~$4 billion today.

    While you can debate whether Javad GNSS will ever achieve the same success as Trimble, you can’t argue about the effort that Dr. Ashjaee is putting forth. He doesn’t need to work and probably has enough money to last a couple of lifetimes, but I think he’s a competitor and he wants to win.

    First Annual JAVAD GNSS Conference

    The new Javad receiver design appears very nice from an ergonomic standpoint. The RTK communications antenna appears to be missing, but it’s actually integrated inside the rangepole. Last year, Javad bought ArWest Communications Corp., a maker of narrow-band and spread-spectrum radios, so JAVAD GNSS has the flexibility to integrate RTK communications in creative ways. Also, with a Bluetooth interface to the data collector, no external cables are required.

    In true Javad style, the Triumph series has 216 channels capable of tracking all existing signals and is prepared to track new signals as they come online, such as GPS L5 and Galileo E1/E5.

    From listening and talking with other attendees, there appear to be four areas they see where Javad is trying to set himself apart from the rest of the manufacturers:

    1. Pricing. Javad’s innovative pricing scheme. You can look for yourself at http://www.javad.com, although you might be somewhat confused with all of the options. The bottom line is that the system will be pretty competitive. Something unique, though, is that pricing is the same for every country in the world.
    1. “Instantaneous” RTK initialization. It’s hard to buy into this one at face value until I (or you) have tried it in true field conditions. Many other systems have pretty quick RTK initializations. “Instantaneous” re-initializations after loss in tree canopy or next to buildings would be very nice, and if it performs true to specs, would be an advantage.
    1. In Band Interference Rejection (IBIR). The claim is that RTK users experience times during the day when RTK doesn’t work, due to local RF (radio frequency) interference. In my experience, the most common RTK problem, by far, is the communications link between the base and rover, whether that link be UHF, VHF, spread spectrum, or GSM/CDMA. What Javad is referring to is jamming or harmonic interference at the GNSS frequencies that prevent your GNSS receiver from processing the signals from the satellites. Personally, I’ve never experienced this type of interference, that I’ve been aware of. Any time I’ve had a problem with RTK, I’ve always been able to trace it back to the RTK communications link. So, I’m not sure there is measurable upside to this claim.
    1. Superior use of GLONASS. You can read the explanation that JAVAD GNSS lays out in the company’s advertisement in GPS World. I can see that they are in a great position to capitalize on GLONASS given the long history that Javad has in Moscow. But the proof lies in how it performs in the field, so the jury is out on this one. I’ve used several GPS/GLONASS system in the field, and all performed superior to my GPS-only system. Whether Javad’s GPS/GLONASS technology is superior to other GPS/GLONASS receivers on the market is something we need more data on before that conclusion can be drawn. However, it is clear there is some wiggle room here, especially when it comes to resolving biases when the rover GNSS unit is of a different manufacturer than the manufacturer of the RTK network infrastructure receiver. Each manufacturer handles this differently and perhaps JAVAD GNSS has found a novel method.

    I haven’t mentioned the “antenna umbrella” that many of you have seen in advertisements or read about. First of all, this isn’t required in order to use JAVAD GNSS equipment. The Triumph-1 pictured earlier is the standard configuration. The “antenna umbrella” you’ve seen is used with the Triumph-4 (not released yet) so the user can benefit from multi-baseline redundancy and integrity with one GNSS receiver.

    The Triumph-4 includes four GNSS receivers, three accelerometers, and three gyros to allow positioning in adverse conditions. I really like the idea of the accelerometers and gyros to augment the GNSS measurements. I think this is the wave of the future. But I don’t think the antenna umbrella concept is going to fly, at least for mobile production work like topo surveys, construction staking, and high-precision GIS. I could maybe envision it for geodetic control, deformation monitoring, and machine control, given the right type of packaging.

    A Word about GLONASS

    Sergey Revnivykh from the Russian Federal Space Agency gave the audience an update on GLONASS. He reasserted the Russian government’s commitment to GLONASS and its intent to support CDMA to ensure “compatibility and interoperability with other GNSS and augmentations.”

    GLONASS currently has 12 operational satellites. Only one of those twelve is a legacy satellite that will probably fail in the next year. The other eleven are GLONASS-M satellites with a “guaranteed” life of seven years. Revnivykh says Russia expects to launch six more GLONASS satellites this year. Finally, it looks like we are moving beyond the GLONASS constellation vacillating between nine and fourteen satellites. We should have seventeen solid GLONASS satellites to with work in 2009. Another six GLONASS satellites are planned for launch in 2009, so by December 2009, the number of operational GLONASS could reach twenty-three.

    Post-conference Social Event

    A Saturday party took place at a lakehouse (the traditional Russian dacha, with modern accoutrements) about 90 minutes from Moscow. A tour bus ferried conference attendees and JAVAD employees to the catered event with activities ranging from miniature golfing to boat rides on the lake. Entertainment was provided by a Brazilian dance troupe and capped off by a trio of opera performers. It was a very well put-together family-oriented event.


    Javad Ashjaee in middle,
    wearing cap

     

     

  • Survey Perspectives – Late July 2008

    Software Receivers May Hold the Key to Multi GNSS

    It’s not often that I read a technical paper that really catches my attention to the point that I read and reread it, then write the authors to probe further. That happened to me last week.

    I’m on the IGS (International GNSS Service, formerly International GPS Service) email distribution list. IGS is a consortium of 200 world-wide agencies that combine resources and share GPS/GLONASS data in order to generate precise GPS and GLONASS products. According to the IGS website, you can think of the organization as the highest precision international civilian GPS community.


    The IGS GNSS Tracking Network

    If you’re signed up, IGS will occasionally send out informative emails about current GNSS events. To subscribe to IGSMAIL send an email to [email protected] with a line in the body following this format (substituting your own email address):
    subscribe igsmail [email protected].

    Last week, I received IGSMAIL-5791. It was a notice that a paper was posted from the IGS 2008 Workshop held in Miami, Florida last month. The paper was entitled Considerations for Future IGS Receivers. It was authored by Todd Humphreys of Cornell University, Larry Young at NASA’s Jet Propulsion Lab (JPL), and Thomas Pany with University FAF Munich, Germany.

    It’s a great paper to read if you are interested in the future of high-precision GNSS receivers. It touches on a lot of the subjects (GPS modernization, Galileo, GLONASS, etc.) that I’ve been writing about for awhile and also an interesting subject that I haven’t written about: GNSS software receivers.

    IGS is interested in being the gold standard of GNSS data: orbits, clocks, reference frame positions, and ionosphere/troposphere maps. A noble goal for sure, but most of the commercial GNSS applications don’t require the sort of accuracy the IGS is chasing after. Nonetheless, the paper discusses many of the issues that face the commercial GNSS industry, and even takes into account the very recent proposal by the Department of Defense to cease support of L1/L2 P(Y) semicodeless. Also, IGS isn’t heavily involved in real-time kinematic (RTK) applications, which have become very prevalent in the commercial GNSS industry.

    After reading the paper, I formulated a few questions and sent them to the authors. They promptly answered and I thought it would be insightful to include them in this column.

    Eric Gakstatter (EG): You touch on GLONASS and Galileo a bit, but don’t delve into current constellations, launch schedules, etc. This leads the reader to believe that you value GPS modernization over an increased number of observables from other GNSS (GLONASS, Galileo). Is that a correct assumption? The “more signals from the same number of space vehicles (SVs) vs. today’s signals on more SVs” debate is a hot one right now. Which do you value more?

    Larry Young: (LY) More satellites with at least two-frequency signals definitely trumps more signals per satellite. For ground uses I believe the limited number of satellites currently reduces our ability to estimate, for example, a spacially and temporally varying tropospheric delay.

    We concentrated on GPS because:

    1. We have excluded the current FDMA GLONASS signals as less accurate for high-accuracy science applications, but look forward to including possible future CDMA signals from GLONASS.
    2. We expect the Galileo signals will be very useful, but there are as of yet only two prototype Galileo satellites in orbit. Actually, we went to some length to describe benefits from the Galileo signal structure. I think any launch schedule for Galileo is even less certain than the schedule for GPS replenishment.

     

    (Editor’s Note: Larry’s reference to FDMA GLONASS accuracy (the current GLONASS architecture) doesn’t mean that GPS/GLONASS receivers sold today are less accurate than GPS-only receivers sold today for real-time kindematic RTK/machine control applications. Companies that design GPS/GLONASS receivers have developed methods to mitigate the internal biases that exist in the GLONASS broadcast signals.)

    EG: How did you determine 16 as the minimum requirement for the number of L2C SVs in orbit?

    Todd Humphreys (TH): We tried to temper the pressure to modernize the IGS network with an understanding that the IGS is a volunteer federation with enormous inertia, and so can’t be expected to respond to drastic requirements upheavals. The presence of 16 L2C-capable SVs (which implies 8 L5-capable SVs) on orbit is what triggers Event 2 in the minimum requirements schedule. The primary changes brought on by Event 2 are:

    1. newly incorporated IGS receivers must be L5-capable
    2. newly incorporated receivers are no longer required to track L2 P(Y).

    Change 1. keeps the IGS current by beginning to measure and characterize the L5 signal. Change 2. is meant to begin the inevitable conversion to a network that does not use P(Y)-code tracking. Change 2. also reduces the barrier to entry into the IGS network. By not requiring L2 P(Y) tracking, we open the IGS network to receivers without semicodeless tracking capability, such as some software receivers. It’s also a recognition that commercial receivers capable of P(Y) tracking will likely be more rare and more expensive after Event 2, given that semicodeless P(Y) tracking is slated for obsolescence.

    EG: Given the intention of the U.S. Department of Defense (DoD) regarding semicodeless access, do you think it will halt all development of GNSS software receivers in that area, and that they will focus purely on L1 C/A, L2C and L5 (and L1C)?

    TH: The paper mentions that software receiver developers are not as keen on codeless/semicodeless techniques as they are on standard coded tracking for two reasons:

    1. Software receiver designers want to get the most performance they can from their limited computational resources and so it makes sense to concentrate on coded tracking.
    2. The restrictions on use of proprietary codeless/semicodeless tracking techniques makes these techniques less attractive than standard coded tracking.

    Add to this that the DoD plans to discontinue semicodeless access by around 2020, and you can see why semicodeless tracking hasn’t been on the forefront of most software receiver developers’ minds.

    On the other hand, the IGS minimum receiver requirements schedule proposed in the paper would require semicodeless-capable receivers until 8 IIF SVs are in orbit (making a total of 16 L2C-capable SVs on orbit). Hence, if software receiver developers want to see their products used as stand-alone receivers in the IGS before then, they’ll have to provide semicodeless tracking.

    Thomas Pany (TP): Semicodeless access is an interesting topic on its own and software receiver research will continue on it (at UniFAF we got funding for it).

    LY: JPL needs to track P-codes in its software receiver in order to get the best accuracy for surface-reflection experiments. When this is done with post-processing, we are able – and others should be able – to obtain the actual Y-code chip sequences that had been used. We also implement semi-codeless processing into software receivers. Sometimes it’s just handy to have both the L2C and P2 signals, for example, to investigate effects of long-delay multipath.

    What is a GNSS software receiver?

    I think a real interesting part of this paper, and one I haven’t touched on yet, is the discussion of software GNSS receivers. A friend of mine has been putting the software receiver bug in my ear for some time. I’ve been dismissing it for the most part because he and I have been speaking in terms of the consumer GPS market. I hadn’t really thought of it with respect to the market for high precision commercial GNSS receivers, especially those that are in fixed installations like CORS.

    First of all, one of the reasons today’s complex GNSS receivers are so small is because there is a high level of electronics integration. What that means is that engineers design many different processing functions into one or two custom integrated chips. These chips are called application specific integrated circuits (ASICs). Using ASICs help reduce the size, cost and power consumption of complex electronic products such as GNSS receivers.


    The Cornell University GRID GNSS software receiver based on DSP technology.

    But an ASIC is not required to build a GNSS receiver. Granted, without an ASIC or two it might be larger and more power hungry, but you can build one nonetheless. A GNSS software receiver doesn’t mean you get a GNSS receiver delivered on a $2 DVD either. No sir, there are still plenty of electronic components involved. The core difference is that instead of one or two ASICs, there would be a series of off-the-shelf discrete components. There are essentially two different approaches in designing a GNSS software receiver; one uses a digital signal processor (DSP) and the other uses a field programmable gate array (FPGA). Sometimes both a DSP and FPGA are used in a design. The GNSS software is loaded in the DSP and/or FPGA and this is how the GNSS software receiver gets its name.

    Essentially, a GNSS software receiver is a design where all signal processing that comes after the analog radio frequency front-end is completely software re-configurable.

    Why use a GNSS software receiver?

    Higher power consumption, larger size and higher chip count doesn’t seem like a good argument in favor of GNSS software receivers. So what is? I posed that question to the paper’s authors.

    EG: What is the major attraction of GNSS software receivers? Cost? Flexibility?

    TH: From the point of view of the IGS, the major attractions are flexibility and transparency. The IGS’s goal is to deliver gold standard GNSS orbits, clocks, reference frame positions (and thereby contribute to gold standard Earth orientation parameters), and iono/tropo maps. For this, we need transparency into receiver operation so that we can better model the statistics of the receiver products that we use. Better yet, we’d like to implement our own specialized tracking loops and other specialized receiver features. Software receivers offer us this transparency and flexibility.

    Although it probably takes a back seat to transparency and flexibility, price is certainly an attraction. For example, the ASTRA software receiver mentioned in the paper is planned to be offered for around $1,200 (hardware) plus $200 or so per receiver for a software maintenance contract. This is about 10 times less expensive than the traditional receivers that the IGS buys. If ASTRA and others can really deliver at such reduced prices, you may see an exciting densification of IGS sub-networks for tropospheric and ionospheric study.

    EG: Do you think there is a strong possibility that GNSS software receivers are technically able to replace traditional GNSS receivers in fixed GNSS infrastructure environments (eg. CORS, IGS, JPL, SoPAC, etc.)?

    TH: Absolutely. The JPL BlackJack receiver is arguably the best-performing GPS receiver on the planet today, and it’s essentially a software receiver with an FPGA-based correlation engine (see the Montenbruck reference in the paper for a comparison of the BlackJack against other receivers). I suspect that the reference-frame receivers sold by some traditional vendors are, in fact, software receivers in the mold of the BlackJack. I predict a market-wide convergence toward FPGA/DSP-based software GNSS receivers over the next decade as the FPGS/DSP price per transistor count continues to fall.

    The real question is what kind of access the IGS will have to the software of these receivers. The traditional model is that the IGS has no control over their receiver’s software aside from setting a few parameters and downloading the occasional vendor-provided firmware update. Suppose vendors instead license their source code to the IGS, or provide “plug-ins” for IGS-specific routines. Such transparency and flexibility is just what the IGS needs to carry out its demanding mission.

    EG (following-up on Humphreys’ comment on a market-wide convergence toward GNSS software receivers over the next decade): If a vendor can sustain its business by licensing their source code, then it will happen. The alternative is a Linux-type approach where the development is a shared effort. The commercial demand will be great enough that I think one of these models will materialize.

    TP: If an open-source software receiver emerges in the near future, it has to overcome the following difficulties, which are not easy to solve (at least this is our experience at the University FAF Munich).

    1. The front-end development has to be done and drivers have to be developed.
    2. The software requires assembler programming skills including multi-threading.
    3. The software needs to have a high stability to run 24 hours per day with basically no failure. This all applies for FPGA, DSP or general-purpose based receivers, and are eventually most easily solved on the general-purpose processor.
    4. Last but not least, you have to implement competitive signal processing algorithms to achieve results similar to commercial receivers. So if one succeeds with all this stuff, it’s questionable, if the software will be free of charge.

    EG: I guess network RTK users would see some upside (to a densified reference station infrastructure)? How about static post-processing users? Maybe longer baselines?

    TH: Accurate estimates of SV clocks and orbits don’t depend strongly on dense networks. By extension, network RTK users or static post-processing users won’t see marked improvement just because the surrounding network is denser. What improvements come from denser networks will be due to a better characterization of the troposphere and its gradients. Such improvements will indeed allow longer baseline carrier-phase-differential techniques. One could imagine a dense regional network making possible carrier-phase-differential techniques with millimeter-level accuracy on baselines of up to 100 km. Whether this will be of great commercial interest, I can’t say. As a researcher, I’m interested!

    If the user has a single-frequency receiver, then dense networks help to mitigate both ionospheric and tropospheric errors in his RTK or static-post-processing solution.  If the user has a dual-frequency receiver, then he won’t see much reduction in his ionospheric errors, but will still benefit from reduced tropospheric errors.

    EG: Can you tell me a little bit about the computing platform required for a GNSS L1/L2/L5 receiver?

    TP: I strongly believe that a modern standard PC (four cores) has all the required processing power to do all-in-view L2P(Y) tracking at least with cross-correlation in addition to track the civil signals on L1/L2, but to which extent the computational resources can be exploited strongly depends on the developers’ capabilities. It’s my experience that PhD candidates who typically have a background in geodesy or communications are normally not experts in assembler language. For this type of work an experienced game programmer would eventually be more qualified.

    TH: Right now, a full L1/L2/L5 receiver requires either a multiple-core approach (see the description of the University FAF Munich receiver in the paper) or an FPGA. The wide bandwidth L5 signal drives this requirement. Tracking L5 requires 10 times more computational power than narrow-band tracking of L1 and L2C.

    EG: Do you have a schedule in place to perform the testing described in item 6. A. (from the paper)? Compare the performance of a software GNSS receiver with a traditional ASIC-based receiver?

    TP: A University FAF Munich software receiver will be installed at a EUREF site in Germany in September or October this year. I expect that the data will be available to IGS.

    TH: A dual-frequency version of the Cornell GRID receiver will be tested against traditional dual-frequency receivers in November of this year. It will be deployed to Brazil for ionospheric scintillation study in December of this year.

    Imagine All the Signals, Living in Harmony

    Imagine if you had a GNSS software receiver and a new signal such as L5 comes online. You wouldn’t need to change your receiver hardware (except the antenna), no boxes to unpack, no new hardware to figure out, only load new GNSS processing software into the DSP/FPGA.

    But I think low cost, rather than flexibility; might drive the GNSS software receiver into the commercial markets eventually. Not necessarily on the user equipment side of things such as machine control or portable applications, but rather on the infrastructure side of the business, such as CORS and other regional as well as world-wide networks where power and size can be traded for cost. Like Humphreys said, being 1/10th the cost of traditional GNSS receivers makes it feasible to create very dense networks of reference stations.