GPS World

Tag: Survey Scene

  • What Do Your Colleagues Think?

    Over the past several years, I’ve conducted many webinars on different GPS/GNSS and other geospatial technologies. The audiences have been comprised of hundreds (if not thousands) of participants who have the ability to ask questions and also participate on various polls I conduct during the webinars.The poll results are a powerful tool that illustrates what your colleagues think about GPS/GNSS, their field practices and general attitude about geospatial technology.

    In this column, I’ll published the poll results from last week’s webinar as well as some select polls from previous webinars in an effort to paint a picture of what your colleagues are thinking.

     

    Poll #1 (Nov. 16 webinar): What’s your budget, per unit, for GPS/GIS data collection systems this year?

     

    Gakstatter comment: “It is what it is” in this economy. 32.2% of you have no budget for this., 22%, 11.9%, 16.9% and 16.9% respectively. The good news is that if you scrape and scrap and are able to use some existing hardware/software you might have, you may be able to put together a good quality GPS mapping system a lot less than buying a new system off-the-shelf.

     

     

    Poll #2 (Nov. 16 webinar): Which ergonomic form factor do you prefer?

     

    Gakstatter comment: This is the first time I’ve asked this question in a poll. The reason I asked is because traditionally, the manufacturers have been focused on all-in-one handheld systems, but in the past several years with the emergence of PDA’s, smartphones and tablet computers, there’s a definitely trend towards separating the GPS receiver and the data collector to increase flexibility. For example, with a separate GPS receiver, you can choose to use a PDA or a tablet depending on the project task. With an All-in-One handheld, you don’t have that flexibility. However, an All-in-one handheld certainly has the advantage of being simpler and more ergonomical. The poll result shows almost an even split with Modular at 52.9% and All-in-one handheld at 47.1%

     

    Poll #3 (Nov. 16 webinar): Which category of data collection software do you prefer?

     

    Gakstatter comment: Like Poll #, this is really about flexibility vs. simplicity. In this case, maximum flexibility means that you are selecting software that is not tied to the hardware (hardware-independent). These types of software, like ArcPad, SurvCE, Field CE GIS, etc. work on several hardware platforms and with several different manufacturers of GPS receivers. The risk is that when there’s a problem, there might be finger pointing between hardware and software vendors. The advantage of a single vendor, of course, is that you have a single point of contact for technical support. In the poll, 58.2% of you chose hardware-independent software (Max flexibility) and 41.8% of you chose hardware-dependent software (Single vendor).

     

     

    Poll #4 (Nov. 16 webinar): What accuracy do you require from a GPS/GIS data collection system?

     

    Gakstatter comment: This is sort of a loaded question because the webinar was marketed more towards surveyors/engineers rather than general GIS. I think it skewed the results a bit on this poll, but nonetheless, there is a definite trend towards high-accuracy GIS. The poll results show that 34.5% require 1-2cm accuracy, followed by 23% requiring sub-meter, 20.7% requiring sub-foot, 17.2% requiring 1-3 meters, 3.4% requiring 3-5 meters and only 1.1% are happy with 5-10 meters.

     

     

    Poll #5 (Nov. 16 webinar): How much of your data collection work is under tree canopy?

     

     

    Gakstatter comment: This is another question I asked for the first time. I didn’t know what to expect. Nearly 70% of you work under tree canopy 25% of the time or less.

     

     

    Poll #6 (Nov. 16 webinar): For a data collection device, I prefer a:

     

     

    Gakstatter comment: This is also the first time I’ve asked this question in a poll. The result surprises me a bit due to the emergence of tablet computers and smartphones. However, after thinking about, it’s going to take some time for people to become comfortable with tablets and smartphones for GIS data collection. It’s also going to take time for the industry software vendors to settle down and choose a platform (or develop for all) such as Apple, Windows, Droid, etc. The poll results show that users still prefer handhelds (57.7%) with tablet computers following at 26.9%, then notebook computers a 9%, then smartphones at 6.4%. There is a definite trend, though, towards smartphones. I think we’ll see a substantial increase in popularity over the next couple of years.

     

    Thanks, and see you next time.

    Follow me on Twitter at http://twitter.com/GPSGIS_Eric

     

    Read PART 2 here.

     

  • SBAS (WAAS) and NDGPS Accuracy and Statistics

    There’s something I’ve been wanting to write about since the ION-GNSS conference a few weeks ago. However, a nasty cold, a 10-day trip to Europe (INTERGEO conference), and some jet lag have kept me from it until now.

    Here goes.

    First of all, most of the presentations from the CGSIC meeting are available on the USCG Navigation Center website. You can view them by clicking here. There’s some very good reading and most of it is pretty light-weight and in PDF format.

    One of the presentations at the CGSIC (Civil GPS Service Interface Committee) meeting during the ION-GNSS conference was “Integrating NDGPS and SBAS —
    An Optimal Real-time GPS Mapping Solution,” presented by Jean-Yves Lauture of Geneq, Inc.

    I’m publishing two of the slides from his presentation in order to:

    1. Show the accuracy potential of WAAS and NDGPS given a high performance L1 receiver.
    2. Discuss the statistical names/values used to express GPS accuracy.

    First of all, each of the slides below are at the same scale. Each ellipse is 20 cm with the outside limit (radius) being one meter.

    I’ve known for quite sometime that SBAS (WAAS in this case) is capable of sub-meter precision with a single-frequency GPS receiver. These results are a bit better than what I’ve seen personally, and keep in mind it’s a limited data set of 1,800 continuous epochs, but impressive none the less. Also, keep in mind that the WAAS Performance Analysis Report published quarterly by the FAA’s National Satellite Test Bed shows the 95% horizontal accuracy value for Denver, Colorado, (near where this data was collected) being .547 meters for the quarter ending June 30, 2010 (7,856,354 samples collected over three months).

     

    30 minutes of WAAS-corrected data (each ellipse represents 20cm)

     

    The results I didn’t expect were the slide below, which shows NDGPS-corrected results using the same receiver/antenna. Keep in mind this is a GPS L1 receiver using phase-smoothed pseudorange measurements, not a GPS L1/L2 receiver using a carrier-phase float solution. If you look closely, you’ll see it states the baseline distance is 200 km. Granted, this is a limited data set, and I’ll be interested in seeing further results. If this was a dataset presented by a manufacturer or other party with some sort of interest, I wouldn’t publish it, but this is data collected by an objective entity (a credible U.S. government agency) so that earns, in my mind, a level of credibility.

    The results are pretty impressive. All data points fall within ~20 cm.

    30 minutes of NDGPS-corrected data (each ellipse represents 20cm)

    Keep in mind that this data was collected recently, and we are currently in a period of low ionospheric activity. In other words, data was collected under near-ideal conditions. At the end of the day, my point is that GPS L1 accuracy using SBAS and NDGPS has gotten pretty darned good.

    Accuracy Statistics

    The second reason I’m publishing the slides is to discuss accuracy statistics.

    Look at the small box inside each slide showing 99%, 95%, 68%, and 50% accuracies.

    If you look at the data points, it might not be immediately apparent how those values were arrived at. For example, how could a group of data points all within ~20 cm have a 95% confidence of 37 cm?

    To explain this, there was a good article published in GPS World in 2007 titled “GNSS Accuracy: Lies, Damn Lies, and Statistics” by Frank van Diggelen. It does a good job explaining statistical expressions (RMS, 2DRMS, etc.).

    Keep in mind that most manufacturers express horizontal GPS accuracy specifications based on 68% confidence. When the specification sheet states “sub-meter” HRMS (horizontal RMS) precision, that means 68% of the time; the horizontal accuracy will be less than a meter. In reality, that “sub-meter” receiver won’t consistently deliver sub-meter precision. If you convert the 68% HRMS value and express it with 95% confidence (2D HRMS), the actual horizontal precision for that same receiver will be well over one meter. That’s the precision you can expect from the receiver, not the 68% confidence value.

    Thanks, and see you next time.

    Follow me on Twitter at http://twitter.com/GPSGIS_Eric

  • Tradeshow’s the Appeal at INTERGEO 2010 Conference in Cologne

    This week, I’ve been attending the INTERGEO 2010 conference in Cologne, Germany. It’s a gathering of ~16,500 people interested in geodesy, geoinformation, and land management. It’s the largest event of its kind in the world.

    Although there’s a lot of GIS activity, it’s just as much a surveying/geodesy trade show. I borrowed a little of the following from my Geospatial Weekly newsletter because I think it’s relevant in this newsletter, too. Let me just say that if you’re a land surveyor/engineer/construction contractor/GIS’r, you won’t find a trade show anywhere in the world like this one. To me, two things differentiate it from all other conferences I’ve attended that are related to surveying, engineering, construction, or GIS.

    • The sheer size. 16,500 people buzzing around attracting 504 exhibitors. You can find a solution to any sort of challenge you have regarding surveying, geodesy, construction or GIS. The major GNSS manufacturers (such as Trimble/Spectra, Topcon/Sokkia, Leica, Javad) have enormous exhibit booths that rival the Consumer Electronics Show (CES) held every year in Las Vegas. You don’t see these companies spending this much money to exhibit at conferences in North America.
    • Unlike many of the conferences I attend, the focus at INTERGEO is on the trade show exhibit area. The technical sessions are few and most are in German, so that leaves the vast majority of the attendees to flock to the exhibit area. We’re currently in Day Two of the three-day conference, and the exhibit area attendance seems just as strong as the first day, which is not typical. On top of focusing on the trade show area, INTERGEO makes it inexpensive to attend. A one-day pass to the exhibit area is only EUR 20 (~US$26) and a three-day pass to the same is EUR 48.50 (~US$63). It’s even cheaper if you buy it online in advance.

    The few technical sessions held were presented by University Professors and various Ph.D.s, so although I submitted an abstract to present a paper, I knew there was no chance I’d be presenting in the formal technical sessions. The closest I am to a Ph.D. is my father’s, which he earned 40+ years ago. Anyway, INTERGEO has a stage in the exhibit area called the Trend and Media Forum. It’s sort of an infomercial stage for companies to show their products and services. They scheduled me to present on that stage, which I did earlier today (Wednesday). The title of my presentation was “GNSS is Changing a Lot — the Future of GNSS Mapping and Surveying.” The audience was sparse, but the good thing is that INTERGEO records the presentations and later posts them on their www.intergeo-tv.de site. My presentation is not on the TV site yet, but should be by Thursday. Please don’t laugh when I nearly fall down after stepping off the stage while I’m talking :-). Click on the following image to view my presentation.

     

    Following are some pictures I took of the conference exhibit area, with captions:

       

    Altus Positioning                                     Ashtech                                    Javad GNSS

     

       

    Carlson Software                    CHC Navigation (China)                                   FOIF (China)

     

         

    GeoMax GNSS (Leica)                           Leica Geosystems                                   Geneq   

     

       

    NavCom (John Deere)                  Pacific Crest (Trimble)                                  Sokkia (Topcon)

     

       

    Spectra Precision (Trimble)                                    Topcon                                         Trimble

     

    I’ll post some more photos on our live coverage website tomorrow.

    There were many new product announcements in the past day. I saw one that caught my particular interest. I’ve written before that for years I relied on stand-alone satellite mission planning software. The problem that most folks have is maintaining the software as they change computers or update operating systems. There’s also the pain of having to update the almanac every month or so.

    I’ve become a fan of online satellite mission planning. I’ve mentioned the NavCom Technology website a few times in this column. However, it has a few shortfalls, namely no control over the elevation mask used and no support for GLONASS or SBAS.

    I’m happy to report that today at INTERGEO, Ashtech released an online satellite mission planning tool, and it seems to fit the bill. Among other things, it allows you to adjust the elevation mask, and choose to include GLONASS and SBAS satellites. Of course, since it’s an online tool, you don’t have to worry ab
    out updating the almanac.

    Following are a couple of screenshots from the program.

    Select GPS and/or GLONASS and/or SBAS satellite

     

     

    Give it a try for yourself by clicking here. There’s a really cool plot that’s generated as a 3D visualization in Google Earth, showing each satellite (green = GPS, red= GLONASS and blue = SBAS).

    Follow the rest of my show blogs at INTERGEO at http://stage.globalpositioningnews.com/gis/live-event

    Follow me on Twitter at http://twitter.com/GPSGIS_Eric

  • August 31 Webinar Q&A Follow-up

    Earlier today (August 31), I conducted a webinar entitled “Solar Activity, SBAS and 24+3 GPS Constellation Updates.” Considering we only announced the webinar three weeks ago, we had a fantastic registration numbers, with more than 570 registered. Thank you for attending if you did. If you weren’t able to you’ll be able to download the presentation by registering here. After registering, you’ll be notified when it’s available for download (usually a couple of days after the webinar).

    I had a lot of questions before and during the webinar. As customary, I’d like to address some of those as well as present the poll results here. First, the poll questions and results with accompanying pie charts to illustrate the results.

     

    Poll #1: How concerned are you about solar activity affecting your GNSS operations?

    Total votes: 157

    Gakstatter comment: These numbers don’t surprise me. Personally, I probably fall in the “Somewhat” category, but my GPS/GNSS field work is pretty flexible so I can easily adjust without much inconvenience. However, if I had several crews using GPS/GNSS on a daily or near-daily basis or I had equipment relying on GPS/GNSS, I think I’d be in the “Very” category because the $$ impact would be much higher.

     

    Poll #2: If it was available, would you be interested in receiving alerts/warnings of solar activity that may affect GNSS operations?

    Total votes: 176

    Gakstatter comment: I’m not surprised at these results either. When I initially considered this poll, I was thinking about asking which type of platform you would prefer to receive alerts/warnings with the choices being Droid app, iPhone app, Blackberry app, text message, e-mail, etc. If you have a preference on that, fire off a quick e-mail to me. Secondly, a few of you pointed out that NASA has an app for this, but keep in mind that the system I’m considering is focused specifically on high-performance/precision GPS/GNSS users, which would eliminate a lot of the baggage of the alert/warning systems available today.
    Poll #3: Do any of your GPS receivers use SBAS (WAAS/EGNOS/MSAS) as a primary source of corrections?

    Total votes: 115

     

    Gakstatter comment: Not much to say here except that a substantial number of commercial GPS users are relying on SBAS. This has definitely been the trend over the past five years.

     

    Poll #4: Do you expect that the GPS 24+3 configuration will improve your GPS productivity?

    Total votes: 172

    Gakstatter comment: Like most of you, I have great expectations for the 24+3 configuration. While launching more satellites with L5 would be nice, that’s a long-term effort, whereas the 24+3 configuration is something we will benefit from in a few months and are seeing some marginal benefit now. In January 2011, once all the satellites have arrived at their destination slots, I’ll plot new visibility charts and see where we stand.

     

    Following are some of the questions that were posed by the audience during the webinar:
    Question #1: The blueline ends in late 2009. Any information on up-to-date activity?

    Gakstatter comment: This question was in reference to the Solar Cycle 24 prediction chart I displayed. The chart was probably small and difficult to read when displayed on your computer. Here’s a larger version of it. This was a chart released by the NOAA Space Weather Prediction Center in May 2009. Although sunspots don’t directly affect GPS operations, there is some relationship between sunspots and geomagnetic storms. Below it is an updated chart with actual values through the end of July 2010.

     

     

    Question #2: What tools/online sites can be used to see if there is a TEC anomaly at a specified time, including “today”?

    Gakstatter comment: There is a cool real-time chart of the U.S. on NOAA’s Space Weather Prediction Center website. There are other interesting charts on SWPC’s website like the 10-day trend chart. The JPL had a website that displayed a real-time TEC, but I just checked it and it hasn’t been updated since June. Another website to check is the National Satellite Test Bed that displays a real-time plot of the WAAS ionospheric grid points. Click here to view a global real-time (updated every 60 minutes) TEC chart of the world published by the Australian Space Weather Agency.

     

    Question #3: What is better for a receiver, Differential GPS or dual frequency? Any references on this?

    Gakstatter comment: With respect to performance during periods of heightened solar activity, definitely dual-frequency receivers. Although I don’t have a specific cite for you right now, there has been plenty written on this subject. Single frequency DGPS receivers are the most vulnerable during periods of heightened solar activity.

     

    Question #4: Is the disruption in the sub-meter scale, single-digit meters, or tens of meters?

    Gakstatter comment: It depends on the severity of the geomagnetic storm. During the worst times of the Oct. 2003 event, it was up to 25 meters. That order of magnitude would be rare. Remember, those events occurred in about four days over the 11-year cycle. I have some figures that relate TEC to position error, but I’ll withhold those until I’ve got a better understanding of how practical they are.

     

    Question #5: Is there some type of notification system for GNSS users of major solar events? E-mail alerts? Twitter tweets?

    Gakstatter comment: Following are instructions for signing up for the NOAA alerts/warnings. This is a good start. Stay tuned for my alert/warning system later this fall. Follow me on Twitter at http://twitter.com/GPSGIS_Eric

    Following are detailed instructions for signing up for alerts:

    -Goto the Space Weather Prediction Center website.

    -Click on Email products (under the Support Services menu on the left)

    -Create an account if you don’t have one already (it’s free).

    -Click on Subscribe

    You don’t want to subscribe to everything. Here are the ones specific for GPS operations:

    -Advisories/Space Weather Bulletin

    -Geomagnetic Storm Products/(sign up for both Alerts and Warnings for K6, K7, K8, K9 events.

    -For high latitude (55 degrees and higher) users, als
    o sign up for Alerts and Warnings for K4 and K5 events.

     

    Question #6: There is already an iPhone/iPod application that gives alerts of solar activity.

    Gakstatter comment: Yes, I’m aware of the NASA app and there maybe others, but in my opinion they are too broad for high-performance/high-precision GPS/GNSS users. Personally, I don’t need to know about new sunspots and where they are located on the sun (although it’s cool to see in that app). I need to know when geomagnetic events are occurring that may interrupt or affect my GPS/GNSS fieldwork.

     

    Question #7: Ouch, we’re at 59 degrees north, and 134 west. Seems like these problems are “picking” on Juneau.

    Gakstatter comment: The good news for you is that Alaska has the most dense concentration of WAAS Reference Stations in the entire WAAS coverage area. Well, maybe not Juneau, but certainly “mainland” Alaska :-). Seriously, parts of Alaska produce the best WAAS accuracy due to the high density of WAAS reference stations.

     

    Question #8: Will parts of BC, Canada, be affected by the SBAS outage?

    Gakstatter comment: Not really, except that you’ll have one less WAAS GEO satellite in view for a month or so until PRN 133 is operational in November. I don’t think you’ll notice any change in performance. The exception would be if your receiver uses SBAS ranging. In that case, you’d be tracking one less satellite between the time that PRN 135 becomes unusable and the time PRN 133 becomes operational.

    Following is an elevation plot of the current WAAS GEO satellites (PRN 135 and PRN 138):

     

    Following is an elevation plot of only PRN 138. This is a possible scenario after PRN 135 is unusable in October 2010 and before PRN 133 is placed into service in November 2010.


    Following is an elevation plot of PRN 138 and the new PRN 133 GEO which is expected to be placed into service sometime in November 2010.

     

    Question #9: With the 24+3 configuration, is it that some sats were flying almost in tandem and they are spreading them out more?

    Gakstatter comment: Yes, that is essentially what is happening. Some believe, including me, that a 24+6 configuration would be even better! But, one step at a time. I feel good that the U.S. Air Force is listening and responding.

     

    I addressed many of the questions from the webinar. Some will take a little research on my side to answer properly. I should be able to address those in the mid-September newsletter. Thanks again to those who registered for the webinar. Feel free to send me an e-mail any time with comments, suggestions or questions.

     

    See you next time.

    Follow me on Twitter at

    http://twitter.com/GPSGIS_Eric

     

  • Solar Activity and Powerpoint Presentations

    You might have heard reports this week about a solar storm this week. This is part of the new solar cycle (Solar Cycle 24) that I’ve written about several times. I want to periodically touch on this subject as the solar activity is going to increase over the next few years, and if the solar activity (geomagnetic storms, not sunspots) is severe enough, it will have an effect on GPS accuracy and tracking. Here’s the scoop on this week’s solar activity.

    First of all, I’ll let you in on a secret. I’m working on a new solar activity notification system specifically designed for GPS users. The problem is that people see reports in the mainstream media about solar activity and they automatically assume that it’s going to affect their GPS. Not all solar storms affect GPS; in fact only very specific ones (geomagnetic storms) of sufficient strength will affect GPS operations. I’m working on a notification system that will be tailored to both GPS L1 and GPS L1/L2 users (they are affected differently) so GPS users can have a reliable and specific source of information on solar activity without having to wade through the mainstream media noise.

    Stay tuned for details this fall in this newsletter to learn more about my notification system and how to and access it. If you’ve ever used some of the GPS hardware/software products I helped design, you know my top priority is to make it easy to use and understandable.

    This week’s event was probably the strongest geomagnetic storm of this solar cycle and of recent years (edit: actually, the storm in early April 2010 was a little stronger), maybe since late 2006. It will create some beautiful “northern lights,” but as strong as that may seem, it still wasn’t strong enough to elicit even a “cautionary” warning to GPS users (neither GPS L1 nor GPS L1/L2).

     

    NASA video of sun’s activity on August 2, 2010

     

    The last geomagnetic storm that adversely affected GPS users was in December 2006. It affected some GPS users for 10-15 minutes. For such a short time, most users would not notice or they might attribute it to a local system malfunction. By the time they investigate and reset the system, the event has passed and the user is back in operation. It was barely noticeable, if at all.

    On the other hand, a severe geomagnetic storm such as the one that occurred in October 2003 can last for days and wreak havoc on precision GPS receivers. During extreme geomagnetic storms like that one, GPS accuracy suffers a lot, especially with GPS L1 users. During that event, simulations from the University of Calgary showed that WAAS maximum horizontal error (95th percentile) reached 25 meters while single baseline DGPS maximum horizontal error (95th percentile) reached 18 meters.

    Dual-frequency users aren’t affected as much by extreme events but aren’t immune. Extreme events such as October 2003 can cause a loss of phase lock, especially with L2 on receivers that utilizing codeless and semicodeless techniques, which are virtually all of the dual-frequency GPS receivers on the market as of today.

    For GPS users, nothing can be done to mitigate the effects of a strong geomagnetic storm. The next best step is to try to predict when they will occur so GPS users know what to expect. Fortunately, these storms are not common and scientists can reasonably predict when an event will occur.

    There are some good websites to reference when checking up on solar activity. A great place for Europeans to do this is at the Royal Meteorological Institute of Belgium’s website. The U.S. National Weather Service also operates the Space Weather Prediction Center. The Australian Space Weather Agency operates a Space Weather Prediction Center, too. Also, note that for those users along the equator and at higher latitudes, your area is more susceptible to stronger geomagnetic storm activity.

    The websites listed above are chock full of information and predictive systems on space weather. In fact, I believe it’s too much information for most GPS users to efficiently interpret. The goal with my new initiative is to provide GPS users with a quick summary so they are able to make informed decisions in a few seconds. Again, stay tuned this fall for the rollout.

     

    Conference/Webinar Presentations

    Between webinars and conferences, I’ve put together a fair number of Powerpoint presentations. I’m in the process of uploading many of them, some dating back years, to our website. Currently, I’ve uploaded ones that date back to April 2010. I hope you enjoy them.

    The following presentations have all been converted to PDF format and are copyrighted. Feel free to incorporate them (or parts of them) into your documents if you like, just please remember to attribute each page you use to my name, Eric Gakstatter, and GPS World/Geospatial Solutions.

     

    2010 (July San Diego, California) ESRI Surveying and Engineering GIS Summit luncheon keynote presentation: Get It Surveyed (GIS).

     

    2010 (June, Seattle, Washington) Asia-Pacific Economic Cooperation meeting: Mapping and Surveying with SBAS+GPS.

     

    2010 (June, Portland, Oregon) Webinar: GIS Mapping for Forestry, Agriculture, and Other Natural Resource Professionals.

    Note that for the following webinar, you can also download an audio portion of the webinar free of charge by clicking here.

     

    2010 (April, Portland, Oregon) Webinar: GPS, GLONASS, and SBAS Constellation Updates.

    Note that for the following webinar, you can also download an audio portion of the webinar free of charge by clicking here.

     

    2010 (April, Phoenix, Arizona) ACSM Annual Conference: GNSS Technology Update.

     

    2010 (April, Phoenix, Arizona) GITA Annual Conference: How the Evolution of GPS is Transforming Surveying and Mapping (along with Pamela Fromhertz of NGS).

    Part 1 – GNSS Mapping/Surveying Technology Update

     

    2010 (April, Phoenix, Arizona) GITA Annual Conference: How the Evolution of GPS is Transforming Surveying and Mapping (along with Pamela Fromhertz of NGS).

    Part 2 – Machine Control Using GNSS

     

    2010 (April, Phoenix, Arizona) GITA Annual Conference: How the Evolution of GPS is Transforming Surveying and Mapping (along with Pamela Fromhertz of NGS).

    Part 3 – Sub-Meter Mapping Using GPS

     

    2010 (April, Phoenix, Arizona) GITA Annual Conference: How the Evolution of GPS is Transforming Surveying and Mapping (along with Pamela Fromhertz of NGS).

    Part 4 – Low-Cost GPS Receivers for GIS Mapping

    Thanks, and see you next time.

    Follow me on Twitter at http://twitter.com/GPSGIS_Eric

  • Get It Surveyed: ESRI Surveying and Engineering GIS Summit

    I attended (and presented at) the 2010 ESRI Surveying and Engineering GIS Summit (SEGS) last week, as well as the ESRI International User Conference (UC). I’m telling you, if you’ve never been to the SEGS and UC, just treat yourself one time. Make a mini-vacation out of it. San Diego is a beautiful place to visit. The weather is always moderate with low humidity and warm temperature. It was a little cooler this year than years past, but still absolutely beautiful with tons of sigh-seeing. My wife has accompanied me for the past few years and she always enjoys herself and finds something new every year.

    I believe that if you just go just one time, your vision of surveying, engineering, construction and GIS will change forever. I know it sounds like an advertisement from ESRI, but I think my pitch is even better than theirs :-). Seriously though, there are so many people presenting so many different ideas, and they are all related to the kind of geographic data you work with on a regular basis.

    But, like anything else, it’s not all good. There are some drawbacks, so I’ve come up with my Good, Bad, Ugly list with respect to the conference. I think its pretty objective.

    The Good

    • The single largest gathering (13,000+) of GIS, surveyors and engineers in the world (although one could argue that Europe’s INTERGEO might be larger).
    • A pre-conference (SEGS) that is designed specifically to cater to the land surveying and engineering folks.
    • Ideas and technology are presented that you will not find anywhere else.
    • The opportunity to network and collaborate with a large number of peers that you will not find anywhere else.
    • In 2011, the national ACSM (American Congress on Surveying and Mapping) conference will be combined with the SEGS.
    • San Diego is a beautiful city with beautiful weather and lots to do within walking distance of the convention center.

    The Bad

    • Since it’s a vendor-specific conference, ESRI competitors such as Autodesk, Intergraph, etc., are not invited. In fact, if you tick them off, they might not invite you back next year.
    • A lot of time away from work during prime field season (July).
    • You could be overloaded if you aren’t prepared for the barrage of information and technology.

    The Ugly

    • The whole experience isn’t cheap. The conference registration is expensive and San Diego is an expensive place to visit.
    • The San Diego airport is horrible, but at least it’s a very short ride to the convention center.

    The Surveying and Engineering GIS Summit (SEGS) is held the weekend prior to the massive User Conference (13,000+ people).

    At the end of the SEGS on Sunday (July 11), ESRI and ACSM (American Congress on Surveying and Mapping) announced that next year ACSM will be combining its national conference with SEGS in San Diego. The attendance is expected to be ~1,200.

    I’ve heard rumblings about this for quite awhile. Here are my thoughts.

    The ACSM national conference is dying and needed to do something drastic. This year, it co-located with the GITA (Geospatial Infrastructure Technology Association) national conference in Phoenix, Arizona, back in April. I attended that conference, too. Even though I was disappointed in the lack of coordination between the ACSM and GITA technical programs in Phoenix, the technical content was very good. Attendance, on the other hand, was horrible. It wasn’t sustainable from a business standpoint.

    Because the annual ACSM conference was on a quick road to nowhere; it had to make a move to team up with another conference. Who?

    The GITA conference dissed ACSM (or maybe the other way around) and is flying solo next year in Dallas, Texas. I think the attendance at the GITA conference will be a disaster. They already have a GITA Oil & Gas conference in Houston.

    Another partner choice would be ASPRS, but for some reason, ACSM and ASPRS can’t figure out how to put something together even though the conferences were at the same time this year. Someone’s ego probably got bruised.

    Partner with Autodesk? No way. Autodesk is a $2 billion behemoth. They don’t need or have the time to deal with ACSM.

    That leaves the ESRI SEGS. Attendance-wise, the SEGS has been flat, or even lost ground. It needed a boost. Bringing in ACSM was a smart move, essentially increasing its attendance from 300 to 1,200. For ACSM, it wasn’t the ideal choice, but it was the only choice. It couldn’t afford another solo event in some off-beat city. The bottom line is that conferences need a healthy number of exhibitors and commercial sponsors in order to be financially viable. For companies to be interested there needs to be a healthy number of attendees. It’s a vicious circle. If attendance wanes, then exhibitors and commercial sponsors start to pull out.

    Even though there is some pretty good upside for ACSM and ACSM membership in combining the conferences, I think the general ACSM membership will suffer. The primary reason is because it’s stuck in San Diego for the next three years. The U.S. Mid-Westerners and U.S. East Coaster’s will hesitate to make the trip due to the distance and expense of the conference, especially with the poor U.S. economy. I think what you’ll see are the state association conferences becoming stronger as they have been in the last few years. I wish, somehow, that some of the energy and excitement from the ESRI conferences could make their way to the state conferences.

    I may sound wishy-washy, but in the final analysis, I think this is a good move. For ACSM, it was the only move and for ESRI, a feather in their cap. It’s interesting to note that even though it’s a three-year agreement, either can opt out annually.

    On to the technical part of the SEGS conference

    I blogged about the SEGS while I was in San Diego. Click here to view my summary.

    A few of points I’d like to quickly emphasize:

    Crowd-sourced data. There’s a lot of buzz about this, and rightfully so. SEGS keynote speaker Nancy von Meyer commented on crowd-sourced data and the challenge of “authenticating” it. Crowd-sourced, or third-part,y data is coming in a big way. You can choose to ignore it, but the smart people will take the time to understand it and use it when appropriate.

    On a related point, a Community Basemap initiative was announced at the ESRI UC Plenary. The idea is that you contribute to the “community basemap” and, in return, you receive a better basemap than you started with. Granted, you have the same “data authentication” issues as crowd-sourced data, but if you understand it, there is value.

    Imagery (e.g. ,satellite images, aerial photography). From following t
    he satellite imagery vendors, I’ve known that imagery is progressing. Its quality (pixel resolution) and availability is improving. But, I’ll admit that I was taken back a bit when Lawrie Jordan, founder of ERDAS (he later sold to Leica) said this is the most exciting time in his 40-year career in imagery. He said that in less than five years, every square inch of the Earth will be constantly imaged by satellites. Now, ground truth accuracy is another story…

    On Sunday, I made the keynote presentation during lunch. The title of my presentation was Get It Surveyed (GIS). The title was said tongue-in-cheek of course. There were many directions I could have gone, but I decided on three topics.

    1. A GIS isn’t driven by spatial data accuracy.
    2. GNSS technology in the next 10 years is going to advance significantly faster than the past 10 years.
    3. The land surveyor’s role in the next 10 years is going to change significantly more than the past 10 years.

    You may take offense to some of the details in #3, and I’m sure some of you did. I assure you, my intent was not to offend, but rather stimulate thought and consideration. Some comments I received after my presentation.

    “You said what I’ve wanted to say, but can’t because my RPLS colleagues would kill me” (heard a version this from several people, two of whom are very prominent in the RPLS community).

    “You are spot-on” (heard some version of this several times).

    “Don’t forget about those who specialize in boundary surveys.”

    “Your timeline of 10 years is too conservative; it will be more like five.”

    A criticism I heard (not directly, but through the grapevine), was from someone who was particularly incensed by my presentation. I’m sure there were several people with this attitude. No doubt these criticisms are in reference to my thesis about land surveyors’ practices evolving and/or my comment that most RPLS’s aren’t qualified to manage a GIS. The criticism doesn’t surprise me. I’d be surprised (and probably disappointed) if it didn’t evoke any. Change doesn’t come easy and some will choose to give up rather than change.

    No matter if you were at the live presentation or not, I’d love you hear your comments on it. You can download it by clicking here.

    Lastly, during the Q&A after my presentation, I was caught flat-footed with a question about GIS licensure. I sort of stumbled and then stated that the technology is moving too rapidly and the bureaucracy of licensure couldn’t keep up. It didn’t take long for me to realize, and others to point out, that it wasn’t a very intelligent answer. Several people approached me afterwards and were able to express their opinions more eloquently and clearly. For what it’s worth, not one of them was in favor of GIS licensure. I will dedicate another article to this subject.

    In closing, following are some photos I took at the SEGS. I hope you enjoy them.

    Interesting slide from ESRI’s Brent Jones showing the attendance breakdown at the SEGS

    Countries represented at the SEGS

    Panel Discussion lead by ACSM’s Curt Sumner (Nancy von Meyer – VP Fairview Industries, David Cowen – NGA Committee Member, Wayne Harrison – President NSPS)

     

    Thought-provoking slide from Brent Jones

    Another thought-provoking slide from Brent

    Opportunities for surveyors in GIS according to Brent Jones

     

    Thanks for reading, and see you next time.

    Follow me on Twitter at http://twitter.com/GPSGIS_Eric

  • Follow up: What’s Going to Happen When GPS Accuracy is Cheap?

    I received some interesting e-mails and saw some web comments regarding my newsletter column a couple of weeks ago titled “What’s Going to Happen When High-Accuracy GPS is Cheap?” The comments ranged from “I don’t believe it’s going to happen” to “We’d better adapt to the changes in technology.”

    One comment in particular had me thinking about the title of the original article. Looking back, perhaps I should have used the word “precision” instead of “accuracy” in the title of the article. Accuracy is a tricky subject and a subjective term. What’s accurate to one person may not be to another. Also, you may be precisely correct, but not very accurate at all.

    The point of the commentor was that high-precision GPS equipment in the hands of the general public will create many problems. There’s no doubt that will happen. Is there going to be a new type of service that surveyors can market to in order to clean up the problems that are created? Probably, and quite possibly only a small percentage of today’s surveyors will be qualified to do this type of work. One’s ability to understand and work with spatial data will be critical in helping organizations solve geospatial data problems. Thus, the importance of data management knowledge and skills I’ve mentioned before.

    Geodesy is going to play a big role in the future, regardless if you don’t believe in GPS precision becoming as cheap as I believe. One can’t argue that precision and accuracy are improving, and with that will come geodetic problems with legacy data that need to be solved. Just imagine an electric utility company with its entire distribution system in a GIS (or CAD) that’s been ammended many times over a 30-year period. Imagine the disparate data sources and wildly varying data accuracy in such a system.

    Let’s look at two of the other comments I received. Please note I’ve paraphrased, and sometimes combined, comments for the sake of brevity:

     

    “They thought EDMs, total stations and online GIS were going to change surveying too, but they really didn’t.”

    EDM’s and total stations are complicated and complex instruments (not to say that GPS receivers aren’t). About 10 years ago when my eldest son was nine, I taught him how to map using RTK. Granted, he was a classic “button-pusher,” having no idea what the technology was doing, but he knew which buttons to push to map a soccer field. I taught him to do this in less than 15 minutes. There’s no way I could have taught him to map a soccer field using an EDM or a total station in that amount of time, even if I had a full day. The first difference between GPS and other mapping instruments: it’s very easy to learn and use.

    This subject reminds me of a photo sent to me from Indonesia many years ago. A guy I knew was training a massive number of Indonesian (200+) foresters on how to use handheld GPS/GIS data collectors. They had little or no previous experience with GPS. He had an auditorium set up with a large projection screen. In one of his Powerpoint slides, he had a photo of a chimpanzee sitting next to a GPS receiver. His point was, of course, that anyone can be taught to map using a GPS receiver. At that time, equipment and software wasn’t as easy to use as it is today. For starters, one had to post-process GPS data to improve accuracy, but even then the point he was making was clear. The ending exercise for the class was to locate three $100 bills stashed separately somewhere in Jakarta using only GPS coordinates provided. I thought that was an ingenius way of keeping the class attentive.

    Anyway, back to the topic.

    There are several reasons one can’t view future high-precision GPS L1/L5 receivers the same as EDMs, total stations, or any other automated measurement tool. GPS is simply different and will have a much greater impact on the way surveyors and their clients work.

    1. GPS receivers are orders of magnitude easier to use and more productive than any other surveying measurement tool in history.
    2. GPS is a mainstream consumer electronic technology that is spurring a lot of innovation.
    3. With L5, GPS technology will be very precise (horizontal and vertical) and very inexpensive.

    For these reasons, I think you can view GPS L1/L5 receivers as game-changing and industry-altering technology. The combination of ease-of-use and low-cost will put high-precision GPS in the hands of everyone from the garbage collector to the policeman mapping accident scenes. That wasn’t the case with EDMs, total stations, or any other measurement technology.

     

    “Consumer-grade GPS receivers and survey-grade GPS receivers are not the same quality and never will be.”

    This isn’t the case according to several GNSS receiver designers I’ve spoken to. There’s no reason a “consumer-grade” L1/L5 GPS receiver can’t achieve cm-level precision (horizontally and vertically) with a good quality antenna. Of course, it will need a source of correction, but in the 5-10 year window, RTK corrections will be more available and less expensive than they are today. The RTK corrections will likely be free so the only expense will be the wireless data plan.

    There will be dozens, maybe hundreds of GPS chipsets designed for L1/L5. Many will be open systems where companies will be able to load their own firmware into the receiver to add specific features (e.g., more robust ambiguity resolution for surveying). The baseline L1/L5 GPS receiver may be only a few hundred dollars, but a customized version for specific applications will have a premium of a few hundred, or maybe $1,000+. For example, a GPS L1/L5 receiver that also includes Galileo signal and is customized for machine control with specific features might be $1,500. Commercial users will pay that premium. They already justify paying tens of thousands of dollars for the same performance today. The difference is that a low price point will attract a much larger audience.

    There’s no doubt that there will be boutique, niche GPS L1/L5 receivers that will be able to garner a premium price, but surely the days of many thousands of dollars for high-precision GPS receiver are heading to an end.

     

    This is not the end of land surveying. I didn’t claim it before and I don’t claim it now. That idea is ludicrous. But, you have to ask yourself how much time you spend on projects that will be affected by this technology.

    If 75% of your work is boundary surveys, perhaps you won’t be concerned as much as the company that generates 75% of its revenue from construction work or topographic surveys.

    If 75% of your work is mortgage surveys, you’ve got more to worry about than high-precision GPS.  :-)

    My point is that change is inevitable and that people who have the attitude that this is just another Chicken Little call (the sky is falling!) will be in for a rude awakening when the rubber hits the road. We can have a friendly debate about when this will happen, but there’s absolutely no doubt that it will.

     

    Free Webinar on June 24

    On June 24, Geospatial Solutions will be conducting a free 60-minute webinar, moderated by me, on “GIS Mapping for Forestry, Agriculture, and Other Natural Resource Professionals.” I will discuss GIS mapping software tools/concepts/techniques as well as GIS mapping hardware such as GPS receivers, digital cameras, and laser rangefinders. Although focused on natural resources, it will be relevant for all pe
    ople interested in GIS mapping, which could be utility companies, municipalities, transportation organizations, etc. Sign up now by clicking here and submit questions in advance.

     

    Thanks, and see you next week.

    Follow me on Twitter at https://twitter.com/GPSGIS_Eric

     

  • What’s Going to Happen When High-Accuracy GPS is Cheap?

    Last week, as you may have heard given the multiple launch delays, the United Launch Alliance (a Lockheed and Boeing joint venture), under contract with the U.S. Air Force, successfully rocketed a new GPS satellite into orbit.

    The GPS satellite launched into orbit last week wasn’t just any other GPS satellite. It was the first of a new generation of GPS satellites that are going to change the way surveying, engineering and construction data is collected and processed in the future. Its new features are going to profoundly transform surveying, engineering and construction. I’m not exaggerating.

    Before you stop reading because you think you’ve read this already in my other newsletter, Geospatial Solutions Weekly released earlier this week, hang in there because although some of it is the same, I’ve added some surveying-specific comments.

    First of all, it’s important to understand that this is going to happen. It’s not a matter of if, but rather when. What I mean is the price of high-accuracy GPS is going to be very inexpensive, both horizontal and vertical, and it’s going to dramatically affect your business.

    Here’s why.

    The new L5 signal will eventually (when it’s being broadcast from enough satellites – more on that later) significantly transform GPS receivers in two ways:

    1. It will result in high-accuracy GPS receivers being much cheaper and smaller.
    2. It will make collecting high-accuracy GPS data much more convenient for the average person.

    Let’s examine in more detail.

    Why will high-accuracy GPS receivers be cheaper and smaller?

    Today’s GPS dual-frequency receivers (L1/L2) can achieve a high level of accuracy (1 cm) in a short period of time, as little as a few seconds. But, they are expensive. An entry-level GPS dual-frequency receiver is a few thousand U.S. dollars. The primary reason is because there is a limited number of companies that design GPS dual-frequency receivers for surveying, maybe a dozen or so. Why is there a limited number of manufacturers? The answer is because the original L2 was not an open signal. In the 1980s, some very smart engineers figured out how to utilize L2 (designed for military use only) in commercial receivers. When they developed those techniques, the companies were smart enough to patent them. There are so many patents in place that it makes it very difficult for a new designer to enter the traditional GPS dual-frequency market, whether it’s surveying, machine control, GIS, or whatever.

    Unlike the original L2, L5 is an open signal. Its specification is published for anyone to use. No license fee. No receiver tax. Nothing.

    Without any patent blocks, any company in the world is free to develop a GPS dual-frequency (L1/L5) receiver that would be just as accurate, and arguably more accurate, than today’s L1/L2 GPS dual-frequency receivers.

    Looking back on the history of electronics, within and outside the GPS industry, we know that increased competition usually results in lower prices to the consumer and improved product quality.

    Take, for example, GPS L1 receiver chips used in personal navigation devices and mobile phones. Those chips are available today for less than $3 each. Fifteen years ago, much less powerful GPS L1 receivers were $200 each and 10 times larger.

    Mark my words: you will see a similar trend with high accuracy GPS dual-frequency receivers. GPS dual-frequency receivers will be sold at prices you can’t imagine today, allowing surveyors, engineers, contractors, GIS folks, biologists, ecologists, etc. (and an educated general public) to collect high-accuracy data (horizontal and vertical) very inexpensively.

    The only thing holding this trend back is the availability of L5. It needs to be broadcast by  about 24 GPS satellites. That’s going to happen somewhere between 2018 and 2020. Of course, GPS designers will be working on their receivers long before that.

    Why will collecting high-accuracy GPS data be much more convenient for the average person?

    First of all, the cost of high-accuracy GPS dual-frequency receivers will plummet significantly due to the open L5 signal. This will spur a fantastic amount of innovation and competition among a large number of receiver designers, especially in the consumer electronics market. Surveyors, engineer, contractors, GIS folks, etc. will benefit greatly from the consumer electronics industry because the high volumes in the consumer market will further spur innovation and cost reduction.

    Oddly enough, at that time, the most expensive part of a high-accuracy GPS receiver may be the antenna. The consumer electronics market won’t accept the type of high-accuracy GPS antenna we need (too big/bulky), so the limited number of antennas means you’ll pay a higher price, maybe a $100, maybe $200.

    If you have a minute, you might want to browse this article by Dr. Frank van Diggelen. Essentially, he says that consumer GPS receivers in your mobile phone, PND, etc. can be as accurate as a GPS receivers built for high-accuracy surveying. The reason they aren’t, he says, is due largely to the inferior antenna being used in mobile phones, PNDs, etc. Now, I’m not saying I buy everything he’s writing, but he’s a lot smarter than I am with regards to GPS, and I do have enough experience to know that antennas can make a big difference in receiver performance.

    What you’ll see, eventually, is GPS dual-frequency (L1/L5) receiver technology in consumer electronics, which means high-accuracy positioning at consumer prices. Take it a step further and one can make the statement that high-accuracy positioning will be in the hands of the consumer. A knowledgeable consumer will be able to take a  low-cost, high-accuracy GPS dual-frequency receiver and collect (or have others collect) an amazing amount of valuable data (think high-accuracy vertical) that would otherwise be too expensive to collect using today’s technology.

    That is where we are headed, guaranteed.

    Wildcards

    Other GNSS

    The time-frame estimation I made above (2018-2020) for a full (24-satellite) constellation of GPS satellites broadcasting L5 is based solely on the activities of the U.S. government. Keep in mind that the U.S. government can’t exceed the 2020 deadline because December 31, 2020, is when the U.S. Air Force says it will stop supporting legacy GPS L1/L2 dual-frequency receivers. So, the end of 2020 is the worst-case scenario.

    Of course, the U.S. isn’t the only country working on GNSS. Europe’s Galileo system also utilizes L1 and L5. It’s possible that in the 2014 timeframe, the U.S. could have a dozen GPS satellites broadcasting L1/L5 and Galileo could have a dozen Galileo satellites broadcasting L1/L5. Because the U.S. and Europe have been working so closely together to ensure GPS and Galileo work together seamlessly, having 12 Galileo satellites broadcasting L1/L5 is the same as GPS broadcasting L1/L5.

    China is also working on a GNSS called Compass/BeiDou. Although China is very tight-lipped with its intentions, it’s possible China could launch some satellites in orbit that may contribute to an L1/L5 solution, but China is a serious wildcard.

    L2C

    Some of you may be wondering why I haven’t included GPS L2C in the discussion. L2C is an open GPS signal much like L5. There are currently seven GPS satellites broadcasting L2
    C. Not including Galileo, there will be 24 GPS satellites broadcasting L2C before there are 24 GPS satellites broadcasting L5. In fact, some designers may decide to develop L1/L2C receivers. However, Galileo isn’t supporting L2 so while there will probably be triple-frequency receivers (L1/L2C/L5), my guess is that the standard will be L1/L5, because the third frequency isn’t going to buy you much.

    Conclusion

    No other conclusion can be drawn but that in the future, as soon as 2014 and as late as 2020, high-accuracy GPS receivers (cm-level in both horizontal and vertical) will be in the hands of anyone with a few hundred dollars to spend. This will be consumers as well as surveyors, engineers, contractors, GIS folks, and many other folks who see value in spatial data. They will have easy access to a fantastic new tool that will allow them to collect high-accuracy, horizontal and vertical data, at a very low cost and very conveniently. I keep referring to vertical accuracy because accurate vertical data is much more expensive to acquire with the technology that exists today, GPS and otherwise. Not so in the future. When one really thinks about the value of accurate low-cost vertical data, the numbers of applications are mind-boggling and will certainly send all disciplines that use spatial data in a new direction.

    Perhaps no discipline will be more affected by this technology advancement than surveying. If you’re retiring in five years, you can probably get away with not thinking about this. But, if you’ve got more than that left in your career, you really need to consider what direction you want to go.

    The bad news is that you have to change. Change is stressful, especially at mid-career, but you don’t have a choice if you want to enjoy a career in surveying. Technology is transforming surveying. You know it because you’ve been feeling the squeeze. You’ve seen that engineers and contractors have acquired technology tools to bring some activities in-house. Machine control is an obvious one. In just a few years, you likely won’t be doing the same sorts of tasks you’re doing today. There will be much more emphasis on data management and data analysis than on data collection (less field time, more office time). Of course, there will still be a need for people in the field, but that’s not where the professional wage is going to be earned. Those in the field will only have jobs, not careers. The well-paying careers will be in the office (either home office or business office or mobile office).

    The good news is that there’s more opportunity than ever before. I can’t count the number of times I’ve had people from different organizations (public and private) ask me if I knew someone who could help solve their geospatial problem. Sometimes, it’s a problem combining data sets. Sometimes, it’s a problem interpreting the data they have as well as finding or collecting new data. Guess what? They aren’t looking in the telephone book (yellow pages) to find someone to help solve their problem. In fact, in some cases they don’t even care if you live in the same country as they do. True, you may have to travel to their office, but they don’t care as long as you solve their problems. I realize this may be a strange concept to many of you, but the Internet has made the world a lot smaller than it used to be. Your clients don’t have to be located within 200 miles of your office. You can have clients in different counties, states, provinces, and even countries! When you start letting go of the idea that your clients need to be geographically close to you, suddenly your business prospects start to look bright. When you limit your ten-person company to clients located within 100 miles in rural Alabama in this economy, you’re going to starve. When you release that limit and start thinking and acting regionally, statewide, nationwide, or worldwide, all of the sudden there’s a lot more opportunity to keep your employees working.

    One important note

    In order to take advantage of the opportunities I mentioned above, you have to expand your knowledgebase. There’s no choice. It’s either that or you’re bagging groceries at Walmart. Technology is changing and its forcing changes in your business, so you must adapt to those changes. Recently, I wrote about a technical session at the ACSM/GITA conference I attended called the Surveying Body of Knowledge (SBoK). Although I may have some differences with some of the SBoK committee member’s intentions, the concept is right. SBoK does a good job of defining the different disciplines in which surveyors can diversify. Briefly, the five areas are:

    1. Positioning (field data collection)
    2. Imaging (photogrammetry/remote sensing/3D scanners/LiDAR/)
    3. GIS (mapping/cartography)
    4. Law (boundary/real property/business law)
    5. Land development (construction/planning/development)

    The idea is that if one discipline is weak, such as positioning, in the current economy, then you could shift your business in another direction where you are qualified, such as GIS or imaging. You certainly don’t need to be qualified in all five disciplines, but having three or four in your pocket gives you a lot of flexibility when the economy is as weak as it is now.

     

    Thanks, and see you next time.

    Free Webinar on June 24th

    On June 24 (was originally scheduled for June 22), I will be conducting a free 60-minute webinar on “GIS Mapping for Forestry, Agriculture, and Other Natural Resource Professionals.” I will discuss GIS mapping software tools/concepts/techniques as well as GIS mapping hardware such as GPS receivers, digital cameras, and laser rangefinders. Although focused on natural resources, it will be relevant for all people interested in GIS mapping, which could be utility companies, municipalities, transportation organizations, etc.  Sign up now by clicking here and submit questions in advance.

    Follow me on Twitter at

    https://twitter.com/GPSGIS_Eric

  • GPS, GLONASS, and SBAS Webinar Follow-up

    Normally, my column following a webinar is dedicated to Q&A follow-up from the webinar. However, immediately following the April 22 webinar, I traveled to Phoenix, Arizona, to attend the ACSM/GITA conference, which I wrote about earlier this month.

    This column is dedicated to answering questions I didn’t address during the webinar. Also, I always find the results from the polls I conduct during the webinar very interesting.

    Poll #1: Have you or your work crews had to stop or alter your work pattern due to the lack of GPS satellites?

    Total votes: 128, Yes: 73%, No: 27%

    Gakstatter comment: This is consistent with other polls I’ve conducted regarding GPS satellite availability. The new GPS 24+3 configuration will help mitigate this problem. Read more about the new GPS 24+3 configuration in a three-part series I wrote earlier this year.

     

    Poll #2: How often do you upgrade your GPS equipment?

    Total votes: 113

    Gakstatter comment: There’s no clear pattern here except to say that 46% of the users wait until at least 3 years before they consider upgrading their GPS equipment. That makes sense to me.

     

    Poll #3: Does any of your GNSS equipment utilize GLONASS?

    Total votes: 115, Yes: 39%, No: 61%

    Gakstatter comment: When considering the result of this poll, keep in mind that there are very few “mapping-grade” receivers that are designed to utilize GLONASS. For example, there are very few, if any, sub-meter receivers that utilize GLONASS, primarily due to the lack of correction sources. SBAS doesn’t support GLONASS, DGPS (radiobeacon) doesn’t support GLONASS, and most CORS do not support GLONASS. Only recently did OmniSTAR begin supporting GLONASS. I think this trend will continue, although I doubt that SBAS or DGPS (radiobeacon) will support GLONASS in the foreseeable future.

    Poll #4: Does any of your GNSS equipment utilize SBAS (WAAS/EGNOS/MSAS) as a primary source of corrections?

    Total votes: 111, Yes: 60.5%, No: 39.5%

    Gakstatter comment: This poll result doesn’t surprise me. Given that SBAS corrections are widely available, free of charge, reasonably accurate, and require no action by the user, it makes a lot of sense they are being used.

    Following are some of the questions that were posed by the audience during the webinar:

    Question #1: I am not sure, but when you say you’re “pushing” something out to us, it sounds like your trying to “push” something on us. Just a comment.

    Gakstatter: I’m sorry about the webinar-speak. When I say “pushing the next slide,” that means I’m changing slides. I may change the way I say this. Thanks for your comment.

    Question #2: Can you correct GLONASS signals with WAAS or other real-time technologies?

    Gakstatter: WAAS (or any SBAS) doesn’t support GLONASS. Neither does DGPS (radiobeacon). This doesn’t mean that GLONASS measurement can’t be used, but you’ll be using uncorrected measurements to augment SBAS-corrected measurements. A case where it may be useful is when you’re mapping in an environment where there are a lot of trees. You might only have four GPS satellites visible that are being corrected via SBAS. In that scenario, there might be value in utilizing measurements from GLONASS satellites just to improve the PDOP, even though the GLONASS measurements are uncorrected.

    Question #3: Do you feel manufacturers will begin to release lower-end mapping-grade GPS receivers with L2C and L5 functionality in the future?

    Gakstatter: Yes, I do, but it will be a few years before there are enough satellites broadcasting an L5 signal. I think what you’ll end up seeing are inexpensive L1/L5 receivers (Galileo doesn’t support L2). They will not only be able to provide mapping-grade sub-meter, decimeter) but also RTK accuracies (cm-level). Since L2C and L5 are open civil signals, you won’t see the patent blocks that restrict competition for L1/L2 receivers like you do today.

    I’m not saying L2C will not be supported at all. I think there will be L1/L2C/L5 receivers, but I think you’ll see L1/L5 on lower-end receivers.

    Question #4: There is apparently some degradation of accuracy when using GPS and GLONASS for RTK. Have there been any rigorous studies quantifying this that you are aware of?

    Gakstatter: I’m not sure I’d say I believe there is degradation in accuracy, but I wouldn’t count on GLONASS to improve accuracy. The value of GLONASS is improving productivity. Since it adds several satellite signals to the solution, it effectively eliminates GPS “brown-out” periods so RTK can be used 24/7. There was a rigorous study released by The Survey Association in the UK. The report focused on network RTK. They tested both GPS and GPS+GLONASS. You can download a copy of the report here.

    Question #5: Does using GLONASS-capable receivers shorten the observation time required for fast-static points?

    Gakstatter: My first thought is yes since generally more observables equates to shorter occupation time, but I would check with the manufacturer and follow their recommendations. Honestly, I’ve only used fast-static with GPS-only receivers so I don’t have any personal experience with your scenario.

    Question #6: When is GLONASS-K launch scheduled? When can we receiver a valid CDMA signal?

    Gakstatter: The first GLONASS-K satellite is scheduled for launch later this year. I haven’t seen a launch schedule beyond that. A representative from the Russian Space Agency is scheduled to present at the Institute of Navigation (ION) GNSS conference in September, so I’ll probably learn more at that point. However, it’s a lengthy process. It’s not just a matter of launching satellites. There are many other variables and unknowns such as the control segment and user equipment compatibility. I think it’s safe to say that we are a few years away from having a minimal GLONASS satellite constellation broadcasting CDMA.

    Question #7: The visibility plots show one extra satellite in the “after” plots. Was that intentional? I would have expected there to be an improved number of satellites visible when one more was added to the plotted constellation.

    Gakstatter: Good catch. In the “after” scenario, I set SVN-49 healthy, which it is currently not. The reason I did this was because SVN-49 is in an important slot in the 24+3 configuration. The status of SVN-49 is still undecided, but if they decide to not set it healthy they will move another satellite to take its place in the 24+3 configuration. If I would have kept it unhealthy in the “after” scenario, it would have only s
    hown a 24+2 configuration. Clear as mud?

    Question #8: Is 24+3 the solution to the blackout problem from now to 2014 stated by the GAO Report from last year?

    Gakstatter: The definition of the 24+3 configuration had been around before the GAO Report. Personally, I don’t think the GAO Report had anything to do with 24+3. The 24+3 configuration just helps optimize the current satellites in orbit, whereas the GAO Report addresses the attrition of GPS satellites outpacing the addition of GPS satellites.

    Question #9: Cellphone question: Is the move to 24+3 likely to degrade indoor GPS coverage – fewer peak sats => lower probability of seeing 4+ sats indoors?

    Gakstatter: Interesting question. My first thought is probably so, although I think it would be a temporary problem. Assuming Galileo keeps pushing forward, that would be a big help for cellphone users, both indoors and outdoors.

    Question #10: GPS Satellites are getting beyond the design life…is the USA behind schedule in satellite updates?

    Gakstatter: GPS satellites have been unbelievably reliable. PRN-24, the oldest operational satellite, has been in operation since August 30, 1991. Since they have been so reliable, there hasn’t been as much pressure to launch GPS satellites. Prior to the 24+3 initiative, the minimum guaranteed constellation was 24 satellites. It costs $50-60 million to build each GPS satellite and another $150-200 million to launch it. With the GPS constellation hovering around 30 satellites these past few years, and government budgets tightening, I think it’s clear that the pressure to save money has resulted in a more relaxed launch schedule.

    The delay in the Block IIF satellite (the first one being launched this week) was not a result of the above, but rather technical and program management mis-steps. The GAO Report was particularly critical of the IIF development.

    Question #11: Do you see any future for ground-based free systems such as those broadcasting corrections in LF/MF radio, like the Coast Guard broadcasts?

    Gakstatter:     There is an interesting debate between DGPS (what you mention) and SBAS. The DGPS infrastructure has been in place and working reliably for mariners for better than a decade. Funding for DGPS seems solid for marine navigation, but less stable for inland-based applications (like the U.S. NDGPS system). I think the future of DGPS for mariners is solid for the next 10 years. Once there is a full constellation of satellites broadcasting GPS L5, the value of DGPS will be questioned.

    Question #12: Will WAAS, EGNOS, etc. be needed after L1/L5 receivers can measure the iono effects themselves?

    Gakstatter: I think it comes down to integrity. If the L1/L5 combo can deliver integrity that safety-of-life applications require (such as aviation), then one has to question the value of SBAS. My gut feeling is that the L1/L5 combo can’t and that some sort of augmentation will be needed to attain the integrity level required.

    Question #13: What are your thoughts concerning Compass? Do you feel this will eventually be applicable for public use as part of a functioning GNSS?

    Gakstatter: Compass is the GNSS wildcard. Since the Chinese aren’t particularly forthcoming with their plans, it’s hard to say. But I’m not sure that matters. With a full constellation of GPS, GLONASS (CDMA), and Galileo satellites in the future, that’s around an average of 25+ satellites in view at any one time during the day. If China doesn’t play well with others in a timely fashion, the user community won’t care what Compass brings to the table.

    Question #14: If my current GPS receiver is not ready for L2C and L5, do I have to buy a new GPS or I can upgrade software/firmware later so that I can still use it?

    Gakstatter: You’ll have to trade-in. Some might be upgradable to L2C, but L5 is a different story. It’s a completely different frequency. That affects the receiver as well as the antenna.

    I wasn’t able to address all of the questions here, so look for more in the next newsletter. Particularly I’ll cover some discussion about reference frames, SBAS and L5.

    Look for announcements in the next day or so about the Block IIF GPS satellite launch. It’s scheduled for Friday, May 21. It’s a new era with the first GPS satellite to broadcast an operational L5 signal.

    Thanks, and see you next time.

    Follow me on Twitter at http://twitter.com/GPSGIS_Eric

  • ACSM/GITA Conference Coverage

    The annual ACSM (American Congress on Surveying and Mapping) isn’t what it used to be. Attendance was way down and the number of exhibitors is way down. The technical content, however, was still pretty good. In fact, I’ve included links to several videos I recorded at the ACSM/GITA conference.

    This year, the ACSM conference was co-located with the GITA (Geospatial Infrastructure & Technology Association) annual conference. This made the trip worthwhile. By themselves, both conferences are becoming too small for most attendees (and therefore, exhibitors) to attend.

    GITA is a GIS conference targeted at the global geospatial community, but in reality it attracts infrastructure geospatial users such as electric/gas/water utilities and local government.

    This mix of ACSM and GITA is interesting and was a great opportunity for surveyors. While the economy is starving surveyors who are in the typical boundary and land development markets, the GITA crowd, in my estimation, are in dire need of a GIS-versed land surveyor.

    There are many topics that were interesting and I thoroughly enjoyed most of the ones I attended, but there are two points I want to address about this conference:

    1. Surveying/GIS collaboration discussion
    2. Surveying Body of Knowledge discussion

    If I can write fast enough, there is a third I’d like to tackle regarding the Driven By Data discussion. If not in this column, I’m sure I will touch on it in a future column or maybe in my Geospatial Solutions Weekly column.

    Surveying/GIS Collaboration

    One of the major benefits of co-locating the ACSM and GITA conferences is that it gives attendees a chance to mix it up with the “other side.” History has consistently demonstrated that it’s always easier to view the “other side” with a certain level of antipathy from afar. However, when one learns more intimately about the adversary’s intentions and struggles, that antipathy eventually turns towards empathy and appreciation. I recall listening to a US Veteran of World War II talking about fighting the enemy. I’m paraphrasing, but it went something like this:

    “I believed in what we were doing and fighting the enemy was just doing my job. In those circumstances, we were enemies. Under peaceful circumstances, however, we may have been neighbors and we may have even been good friends.”

    Land surveyors and GIS folks should be good friends. They both have a lot to gain from a positive relationship and a lot to lose with an adversarial relationship, with the former standing to lose the most.

    Rudy Stricklin presented a very good session entitled “Professional Land Surveyors and Geospatial Professionals Building Bridges in Arizona.” In the presentation, he describes the process surveyors and GIS folks went through in Arizona to collaborate and find a common ground to work from. I’m not saying I necessarily agree with everything that was presented or enacted in Arizona, but Rudy’s consistent and often used terms like “collaboration” and “inclusive” certainly conveyed the team-building spirit and positive attitude needed to build a long-term relationship. The bridge-building process presented by Rudy is a model that would be difficult to go wrong with in a similar endeavor by another state, province or local/regional government.

    I recorded the presentation in its entirety. It’s in five parts with each being about 10 minutes in length. I suggest listening to the first segment as he paints the broad picture. However, the entire presentation is well worth your time.

    Part 1 – Professional Land Surveyors and Geospatial Professionals Building Bridges in Arizona (9:10 minutes)

    Part 2 – Professional Land Surveyors and Geospatial Professionals Building Bridges in Arizona (9:23 minutes)

    Part 3 – Professional Land Surveyors and Geospatial Professionals Building Bridges in Arizona (9:39 minutes)

    Part 4 – Professional Land Surveyors and Geospatial Professionals Building Bridges in Arizona (9:12 minutes)

    Part 5 – Professional Land Surveyors and Geospatial Professionals Building Bridges in Arizona (9:59 minutes)

    There was also a discussion panel entitled “GIS/Surveying Geospatial Collaboration.” On the panel was Gene Trobia, Arizona State Cartographer, Jack Avis, PLS, and Bill Coleman, PLS. Jack and Bill are both land surveyors who offer GIS services.

    Gene has some great stories about the early ESRI years and GIS challenges. He recalled there were 37 people at the first ESRI User Conference he attended.

    Watch this 85 second description by Gene of the challenge faced by GIS managers explaining why some are myopic.

    I posed a couple of questions to the panel.

    The first was the subject of a National Parcel Database with references to the First American parcel database.

    Part 1 – National Parcel Database discussion (2:26 minutes)

    Part 2 – National Parcel Database discussion (8:36 minutes)

    The second question I posed was how can a small surveying firm that is focused on boundary and mortgage surveys (and is starving) can transition to offering GIS services.

    How Can a Small Surveying Firm Transition to Offering GIS Services (9:55 minutes)

     

    Surveying Body of Knowledge (BoK) discussion

    • Josh Greenfeld, Ph.D., PLS
    • Earl Burkholder, PLS, PE (New Mexico State Univ)
    • Wendy Lathrop, PLS (Private practice)
    • Joe Paiva, Ph.D., PLS (Geomatics consultant)

    The focus of this presentation/discussion was to define the role (Body of Knowledge) of professional surveyors in the 21st century.

    Why develop a Surveying Body of Knowledge (BoK)?

    According to the committee (the folks above plus Bob Burton, PLS, PE and Bob Dahn, PLS), the Surveying BoK was developed to:

    1. Formulate a scope of the surveying profession.
    2. Promote recognition for the need for college education.
    3. To help surveyors in business development.
    4. To develop a surveying scholarship
    5. To help promote the surveying profession.
    6. To define the distinctiveness of the surveying profession.

    The Surveying BoK Committee has defined the surveying profession to encompass the following disciplines:

    • Positioning
    • Imaging
    • GIS
    • Law
    • Land development

    The discussion was led by Josh Greenfeld with Earl and Joe presenting on Positioning, Josh presenting for Robert Burtch on Imaging, Wendy presenting on Law, Josh presenting on GIS, and Wendy presenting on Land Development.

    Often referred to as the world’s second-oldest profession, it’s ironic that land surveyors are trying to redefine themselves after thousands of years. But, technology has forced them to face reality. I can’t say I wouldn’t do the same thing. I would say, however, that it’s late in the game for this. Of course, hindsight is 20-20, but this effort really should have begun 10 years ago. Someone dropped the ball.

    Regardless, I think they’ve got the right idea. The BoK committee consists of pe
    ople who are highly respected in the surveying profession. The BoK document is not perfect (and they recognize that and are looking for input), but it’s a step in defining the future of the surveying professional.
    I think expanding the horizons of the land surveyor to include the five disciplines (positioning, imaging, GIS, law and land development) is a great idea. This would expand the profession significantly as it would paint a much more current and accurate picture of the knowledge and skillset a student could strive to achieve if they chose surveying as a profession to pursue. A Surveying Body of Knowledge (BoK) doesn’t exist today so it’s difficult to paint a picture and describe the knowledge and skillset much beyond that of boundary surveyor.

    Kudos to the committee for devoting the time and energy to assemble the BoK document. Although I don’t have a link to the detailed Surveying BoK that was handed out at the presentation, click here to view a Surveying BoK paper that Dr. Greenfeld presented at the FIG (International Federation of Surveyors) conference about one month ago.

    However, I want to make what I feel is a very important point

    I mentioned this during the discussion and I’ll write it here. If one of the purposes of this document is to take it and run to the state legislature to have it legally define the land surveyor’s domain (and therefore eliminate others from operating in that space), I would vehemently oppose it. Honestly, I got that weird feeling when Dr. Greenfeld made a comment early in his presentation that one of the Surveying BoK purposes was to be used “to define the distinctiveness of the profession against those who are trying to encroach on our profession [because] there are a lot of cases like this.” In other words, he’d like positioning, imaging, GIS, law (as related to surveying) and land development to be the exclusive domain of the land surveyor. That would be a mistake, a HUGE mistake. After the discussion group, I asked Dr. Greenfeld about this remark. He dismissed the premise with the thought that laws can be changed and that a larger group with more resources could overturn such a law if there was enough dissent.

    The reason I think it would be a huge mistake is because it limits competition. It’s common knowledge that competition breeds innovation. Henry Ford said “you can have any color (automobile) you want, as long as it’s black.” Without competition, you may still be driving a black automobile without air conditioning. Of course, all-out competition is not the answer either. Just like in politics, the right answer is not at either extreme, but somewhere in the middle.

    As a side note, here is a short clip from the audience regarding the importance of communication skills in the education of land surveyors.

    The importance of land surveyor communication skills (4:36 minutes)

     

    To give you a flavor of the rest of the conference content, following is a partial list of technical presentations at both conferences.

    ACSM:

    • The Surveyor’s Role in the FEMA Flood Insurance Program
    • Hydrographic Surveying
    • Understanding the Statistics Used in GPS Surveying
    • Development, Implementation, and Future of the National Spatial Reference System
    • The Surveying Body of Knowledge
    • The Surveyor’s Role in Boundary Conflict Resolution
    • Introduction to GIS for Surveyors
    • GIS, Geodesy, and the Ghost in the Machine: A Workshop for Surveyors and GIS Professionals
    • Professional Land Surveyors and Geospatial Professionals Building Bridges in Arizona
    • Panel Discussion: Driven by Data: Who Pays? Who Plays?
    • GNSS Technology Update (presented by Yours Truly)
    • The Truth about an RTK Localization/Calibration

    GITA:

    • How the Evolution of GPS is Transforming Surveying and Mapping (presented by Yours Truly along with Pam Fromhertz of NGS)
    • Geospatial Solutions to Address Aging Infrastructure
    • GIS/Surveying Geospatial Collaboration
    • Geospatial Solutions for Preparing and Responding to Natural Disasters
    • Spatial Analysis in a CAD-driven GIS
    • Geodata Creation and Sharing
    • Location, OGC, and the Smart Grid
    • Spatial Law and Policy
    • Building a Facilities Information Infrastructure to Support Public Safety
    • Offshore Wind Energy GIS Development for the Gulf of Maine
    • Haiti, Open Source Mapping, and the Collaborative Environment
    • Phoenix Sky Harbor Airport Enterprise GIS – Managing Signage Infrastructure and Content
    • Streamlined Methods to Collect and Maintain GPS and Attribute Information for Utility Assets

     

    Lastly, if you’re interested, here’s a link to my “GNSS Technology Update” presentation I made at the ACSM Technical Session.

    GNSS Technology Update

    Thanks and see you next time.

     

    Follow me on Twitter at http://twitter.com/GPSGIS_Eric

     

  • SBAS Crashing

    It’s been a tough couple of weeks for SBAS (Satellite-Based Augmentation System), namely the USA’s WAAS program and India’s GAGAN program. WAAS and GAGAN have taken big hits recently that threaten the integrity of the programs. Both events were totally unexpected and are causing disruptions of GPS correction services.

     

    Let’s Start with WAAS

    First of all, consider the following infrastructure graphic describing WAAS.

    WAAS Infrastructure (note: GEO satellites positioning not geographically correct in graphic)

    At the moment, WAAS uses two geostationary satellites (referred to as GEOs) to broadcast GPS corrections throughout the WAAS service area, which covers the U.S., Mexico, and most of Canada. The user’s GPS receiver must be able to “see” at least one of the WAAS GEOs in order to receive the GPS corrections. Currently, one WAAS GEO (PRN 135) is located at 133°W longitude and one (PRN 138) is located at 107°W longitude. They are positioned, for the most part, to provide “dual coverage” in case one fails as the following graphic illustrates. The solid line represents the visibility above the horizon of PRN 138 (107°W). The dashed line represents the visibility above the horizon of PRN 135 (133°W). In New York, for example, PRN 138 is visible at 30°+ above the horizon while PRN 135 is visible at ~15° above the horizon.

    WAAS GEO Footprint Coverage (Dashed = PRN 135, Solid = PRN 138)

    The Federal Aviation Administration (FAA) is the WAAS steward. WAAS (and SBAS) was designed for aviation use and paid for by the FAA. The fact that surveying and mapping users benefit from WAAS is a by-product. The FAA owns and controls most of the WAAS infrastructure, such as the 38 WAAS reference stations located throughout the U.S., Canada, and Mexico. About the only thing they don’t own are the WAAS GEO satellites, and this has been the source of most of the problems with WAAS in the past few years.

    Lease vs. Buy

    It would be prohibitively expensive for the FAA to own GEO satellites that were exclusively used by WAAS. Instead, the agency leases bandwidth from owners of commercial satellites. These are the same commercial satellite owners who lease bandwidth to media (e.g., television) customers. It’s not unlike a utility pole you see along the road with many different wires and devices attached to the pole from different companies who pay to lease space on the pole, except it’s a very expensive pole orbiting in space.

    If you’ve been using WAAS for a number of years, you’ll remember back in 2006 there was a hiccup with the WAAS GEOs at that time. The FAA was leasing space on two Inmarsat satellites (AOR-W and POR). They began transitioning to the current WAAS GEOs but before the transition was complete, Inmarsat began moving AOR-W. This was a headache for some WAAS users and really showed the vulnerability of WAAS.

    Losing Control

    The vulnerability reared its ugly head again last week when one of the commercial satellite operators (Intelsat) that the FAA leases space from announced it had lost contact with its Galaxy 15 (G-15) satellite, which is the GEO that WAAS PRN 135 is broadcast from. Intelsat reported it had lost the ability to send commands to G-15. Without the ability to control the satellite, it will slowly drift out of orbit until it becomes unusable. The FAA estimates this will occur in one to three weeks.

    Solutions?

    Intelsat’s answer was to bring in an older generation backup satellite (G-12), which was in a backup orbit at 122°W. It arrived at 133°W around April 14. Intelsat said that G-12 has virtually an identical C-band package as the G-15 and they could transfer C-band customers to the G-12. The problem is that there is no L-band package (which WAAS needs) on the G-12, so the FAA was out of luck.

    Since Intelsat’s G-12 backup won’t help WAAS, the FAA is looking at other alternatives:

    1. Contract with Inmarsat to bring back POR (178°E). The FAA says that will take 12-18 months. Personally, I don’t think it’s a good solution. It’s too far to the east to help much at all. Its coverage footprint barely covers the western U.S.
    2. Speed up the testing on the new PRN 133 (98°W) and bring it into service more quickly than the original December 2010 schedule. The FAA says it can accelerate testing by one to two months. This is good and I see the benefit, but it still doesn’t help Alaskan users.
    3. The replacement backup satellite being moved to 122°W to backup G-12 may be a solution. It will be a few weeks before it is known what is possible. That would be the best scenario from a coverage footprint standpoint. The question is how long it would take to bring it into service.

    On another note, the FAA stated that with the money they are saving with G-15 going out of service, they will be able to accelerate the acquisition of another WAAS GEO. I have no doubt that this has put a new level of fear into the FAA folks, and they have to realize that they can’t be running thin on WAAS GEOs. If you weren’t aware, the future of aviation navigation is based on GPS, WAAS, LAAS, etc. These sorts of hiccups would be an absolute nightmare if the National Airspace System (NAS) was already dependent on GPS.

    GAGAN

    GAGAN (GPS-Aided Geo Augmentation Navigation) is India’s SBAS. It has been under development for many years and is quite far along in development. It is funded through implementation by the Airport Authority of India with the Indian Space Research Organization. In 2008, GAGAN was broadcasting a test signal from an Inmarsat GEO with reasonable results.

    India’s intent was to launch its new GSAT-4 communication satellite with part of its purpose being a GAGAN GEO satellite. GSAT-4 was to be India’s first rocket with an Indian-designed and built cryogenic-fueled third stage. Apparently it is a very difficult technology to master as it reportedly took India 16 years to develop.

    Last week, after much anticipation, the rocket with GSAT-4 onboard was brought to the launch pad. Liftoff was reportedly flawless. At 8:25 minutes into flight, the rocket failed and the entire rocket, GSAT-4 and all, ended up splashing into the Bay of Bengal. It’s a crushing blow to India’s GAGAN SBAS program, which has suffered a number of delays.

    P.S. Veeraraghavan, director of the Vikram Sarabhai Space Centre in Thiruvananthapuram, said “Our target is to fly a GSLV with our indigenous cryogenic engine within one year. But it will be tough.”

    Following is a video report from an India news organization describing the event:

     

     

     

     

     

     

     

     

     

     

    Webinar Tomorrow

    If you don’t receive this too late (or you can access the archive if you do miss it), you might want to catch my 60-minute webinar “GPS, GLONASS and SBAS Constellation Updates.” It’s free and full of the latest information. I’ll also be answering a number of questions from people who registered. I hope to see you there!

     

    GITA and ACSM Conferences Next Week

    Next week, I’ll be blogging and such from the Geospatial Infrastructure Technology Association (GITA) annual conference and American Congress on Surveying and Mapping (ACSM) annual conference in Phoenix, Arizona. In addition to presenting at both conferences, I’ve got a number of interviews scheduled with interesting people. Follow my blog on the Geospatial Solution’s website Live Event Blog area.

     

    Thanks, and see you next week.

    Follow me on Twitter at

    http://twitter.com/GPSGIS_Eric

  • Solar Activity and RFID Technology

    Updated: Friday, April 9 11:00am US Pacific. I added more specific information regarding signing up for Space Weather Prediction Center email alerts. See below.

     

    It’s time to touch on the solar activity subject again, as there was an event earlier this week and rumors began to fly. The mainstream press jumped on a story back in January when the first solar flare of Solar Cycle 24 occurred. Of course, journalists were writing about worst-case scenarios in the event of extreme solar events that could cause power grids to fail, GPS to stop working, etc.

    While that is true, it’s a real stretch and the typical “sky is falling” reporting. In reality, the solar flare back in January had no effect on GPS operations. In fact, it would take an event 10-20 times stronger than last January’s to begin to notice any effect on GPS operations. Earlier this week (Monday 0800 GMT), the first geomagnetic storm of Solar Cycle 24 occurred.

    Geomagnetic storms are the ones that will give GPS users problems, although this one didn’t because it was relatively minor. The last geomagnetic storm strong enough to noticeably affect GPS users occurred in December 2006. During such an event, it might interrupt your GPS receiver for 10-15 minutes. Most users would not notice or they might attribute it to a local system malfunction. By the time they investigate and reset the system, the event would have passed and the user is back in operation. It would be barely noticeable, if at all.

    According to Joe Kunches of the NOAA Space Weather Prediction Center, a geomagnetic storm is a global event (as opposed to a regional event) that is caused by a highly energized solar wind that is fast and embedded with a strong magnetic field. In the following chart, you can see how this week’s event illustrates this.

    Source: NOAA Space Weather Prediction Center

    In the above chart, the top panel illustrates how the magnetic field becomes much more turbulent starting at 0700 GMT. The fourth panel on the chart denotes the solar wind speed, which ramped up to approximately 2,000,000 mph (3,218,688 kph) at its peak.

     

    Extreme geomagnetic storms = Dynamic TEC = GPS interruptions

    There needs to be very turbulent solar wind that disturbs the Earth’s geomagnetic field in order for GPS operations to be affected. For those of you who are familiar with the Total Electron Count (TEC), a dynamic TEC density in the ionosphere is what really messes up GPS operations. If the TEC is stable, the ionospheric models work fine and we get really good GPS performance like we’ve seen in the past few years in between solar cycles.

    GPS L1 users are affected most by a dynamic TEC density in the ionosphere. These are users of WAAS, DGPS, and commercial L1 correction services like OmniSTAR VBS (not their XP or HP service). During the extreme geomagnetic event in October 2003, published simulations (Yousuf, Skone, Coster, University of Calgary, ION NTM 2005) that illustrated the WAAS maximum horizontal error (95th percentile) blew out to 25 meters while single baseline DGPS maximum horizontal error (95th percentile) blew out to 18 meters. This extreme event lasted for several days.

    This doesn’t mean you’re going to have major problems in the future if you are using WAAS (or another SBAS) or DGPS, but just that high-performance GPS L1 receivers are the most susceptible to extreme solar events. In the case of the December 2006 event, SBAS and DGPS users might have experienced 10-15 minutes of unusual behavior depending on their locations. According to Kunches, high latitude geographic regions (60+ degrees latitude) and the region within 10 degrees of the geomagnetic equator (as opposed to the geographic equator) are affected the most by geomagnetic storms.

    GPS L1/L2 receivers are less susceptible to extreme solar events because they can actively model the affects of the ionosphere, but they are not immune. Extreme events such as in October 2003 can cause a loss of phase lock, especially on L2 with GPS receivers that utilize codeless/semicodeless techniques, which are virtually all of the dual-frequency GPS receivers on the market today. The L2 signal-to-noise (SNR) ratio on L2 is quite a bit lower due to the codeless/semicodeless technique so it is more susceptible.

    GPS L1/L2 receivers using L2C will be less affected (assuming a sufficient number of GPS satellites are broadcasting L2C) due to a stronger SNR.

     

    Not the time to panic

    The reason I wrote this article is to share what I’ve learned about the effects of solar storms on GPS operations from speaking with a number of different scientists. This isn’t meant to be a warning of impending doom for GPS users or anything or that sort. Extreme events typically occur near the solar peak and then again during the decline of the cycle. The peak is estimated to occur around May 2013, so the typical extreme events affecting GPS would likely occur in 2013, 2014, and 2015. It’s too early to start worrying much about it now.

    However, as Solar Cycle 24 ramps up, we’ll see more and more geomagnetic storm activity. If you’re a high-performance GPS user (meter or sub-meter level GPS L1 and GPS L1/L2), I think it’s a good idea to monitor space weather now. Fortunately, the NOAA Space Weather Prediction Center (where Kunches works) provides a service that will notify you of unusual space weather by e-mail. You can sign up to receive e-mail alerts at http://www.swpc.noaa.gov

    Following are detailed instructions for signing up for alerts:

    -Goto the Space Weather Prediction Center website.

    -Click on Email products (under the Support Services menu on the left)

    -Create an account if you don’t have one already (it’s free).

    -Click on Subscribe

    You don’t want to subscribe to everything. Here are the ones specific for GPS operations:

    -Advisories/Space Weather Bulletin

    -Geomagnetic Storm Products/(sign up for both Alerts and Warnings for K6, K7, K8, K9 events.

    -For high latitude (55 degrees and higher) users, also sign up for Alerts and Warnings for K4 and K5 events.

     

    Following are some good reference links regarding the Solar Cycle and TEC:

    GPS World article in January 2010 (scroll to end of article)

    GPS World article in October 2009 (follow-up to other October 2009 article)

    GPS World article in October 2009

    GPS World article in May 2003

    Latest NOAA prediction on Solar Cycle 24

    Solar Cycle 24 page

    Real-time TEC plot from the Jet Propulsion Lab

    Wikipedia description of the Ionosphere

    Wikipedia description of the Total Electron Content (TEC)

     

    RF ID (Radio frequency Identification) in Survey Monuments

    If you haven’t been followi
    ng my Geospatial Solutions Weekly newsletter (sign up here for free), you might want to sign up and read the article I wrote on how RF ID is going to be a technology very much used by surveyors in the future. You can read the article by clicking here.

     

    Webinar later this month (April 22, 10 a.m. Pacific time, 6 p.m. GMT): GPS, GLONASS, and SBAS Constellation Updates

    There’s been a lot of infrastructure changes with GPS, GLONASS, and SBAS in the past six months. We’ve already got several hundred people registered for this webinar. It’s going to be a good one. Here are some of the questions I’ve received already and will be addressing:

    1. When and where will the new FAA WAAS GPS Satellite cover?
    2. Will the accuracy of hand-held units be increased with these latest changes?
    3. What developments will make GPS & GLONASS work better together? In terms of RTK accuracy.

    There have been some questions as to whether you can receive continuing education credit (PDH, CEUs, etc.) by attending the webinar. Please e-mail me directly with these requests and I will do my best to accomodate.

     

    See you next time.

    Follow me on Twitter at http://twitter.com/GPSGIS_Eric