When I arrived in Denver, my plan was to meet Tim Smith (GPS Coordinator for the U.S. National Park Service) and travel to the Bakerville GPS test site in the Rocky Mountains, which was at about ~11,000 feet in elevation. My intent was to test the CORS Streaming and PBO real-time streaming that I discussed last month to better understand the accuracy and reliability of those services.

I arrived at the Denver airport early on a Monday ready to rock and roll into the Rockies with some high-precision GNSS equipment. As it turned out, I was denied. In Colorado, the weather is dynamic. It was quickly degrading when I arrived in Denver. Snow was definitely in my future for the next few days. Tim made the decision that we shouldn’t travel to Bakerville. The reason for Tim’s trepidation wasn’t necessarily due to the weather in Bakerville, but rather that the I-70 Interstate might turn into a parking lot and we’d be stuck in traffic for a few hours. Fair enough. The backup plan was to do some local testing in the parking lot adjacent to Tim’s office in Denver.

Tim invited Mel Philbrook to join us. Mel is a long-time GNSS technologist who works for the local Trimble dealer. He brought an SUV full of Trimble GNSS equipment, including one of the new R10 GNSS units as well as a GeoXH handheld with an external antenna.

Tim Smith using a Trimble R10 with CORS Streaming RTK data.

Mel and Eric with some of the GNSS gear.

Mel also had an Intuicom RTK Bridge in the trunk of his SUV that facilitated the different sources of RTK reference data we could use. He could switch from CORS Streaming to the local VRS via NTRIP to UHF at the flip of a switch, sending corrections to both the R10 and the GeoXH. I was particularly interested in seeing how the units performed using CORS Streaming, which is/was a free RTK service (single baseline) that was in beta test phase. In Oregon, I don’t have access to CORS Streaming because the only CORS Streaming station west of the Mississippi River is in Boulder, Colorado. The station is TMGO (Table Mountain CORS).

The baseline distance from TMGO to our location was about 55 km. The R10 was reporting a horizontal precision of about 4 cm. Not bad for a 55-km baseline. I didn’t compare the results to a survey mark (shame on me, but keep reading because I get to that) so I’m trusting the R10’s precision estimate. Tim said he’s run the test before using a GeoXH and a longer baseline and saw sub 10-cm horizontal precision. It’s not what the typical person using short baseline or RTK network is accustomed to, but for the high-precision GIS user who’s mapping utility, transportation, and infrastructure, that’s pretty darn good.

Tim, Mel and I spent an hour or so messing around with the equipment before packing it up. Not a very scientific study, but it confirmed that CORS Streaming was accessible via NTRIP and reasonably accurate.

In the meantime, the snow wasn’t letting up. This is the view as I was leaving Tim’s office to head to Boulder for the Space Weather Workshop:

Leaving Tim’s office. There was no snow when I arrived.

I wasn’t finished with my CORS Streaming testing yet. My experience at Tim’s office gave me enough confidence to allocate time later in the week to conduct a more detailed test after the Space Weather Workshop. Hopefully, the weather would cooperate (call me a fair-weather field guy).

Space Weather Workshop

Every April, NOAA’s Space Weather Prediction Center in Boulder hosts the Space Weather Workshop (SWW), a gathering that has evolved into the leading conference in the U.S. for space weather-related topics. It attracts attendees, experts and speakers from all over the world. The discussion isn’t centered on GNSS, but GNSS certainly is a topic that is discussed. This year’s central topic was the electric power grid. You can view the SWW program here.

Believe it or not, this month (May 2013) was the predicted “solar maximum” for the current solar cycle (Solar Cycle 24, an 11-year cycle). However, Solar Cycle 24 has been unexpectedly weak. See the following slide presented by Doug Bisecker of the Space Weather Prediction Center. Doug is the Chairman of the Solar Cycle 24 Prediction Panel. His question, “Is there any chance we can still salvage some respectability?” speaks volumes about the difficulty in predicting space weather.

Source: Doug Bisecker presentation at the 2013 Space Weather Workshop

From the above, you can see the actual number of sun spot occurrence has been significantly less than predicted. Although sun spots aren’t what cause GNSS receivers to have problems, sun spots can indicate the amount of solar activity, which can be related to geomagnetic storms. Geomagnetic storms disturb the ionosphere and are the events that cause the most problems for GNSS receivers. Looking at the top chart above, you can see the difference in activity between the last solar maximum (peaked in early 2002) and today. The difference is clearly significant.

Does this mean we, the high-precision GNSS users, get a free pass on Solar Cycle 24?

Not at all.

Historically speaking, the most extreme geomagnetic storms (e.g., Oct/Nov 2002) have occurred after the solar maximum so our sensitivity to this issue should be keen for the next two years. Furthermore, there are orders of magnitude more high-precision GNSS receivers being used than ever before, and in mission-critical applications such as auto-steer in machine control (agriculture, construction, etc.). Most GNSS high-precision users today haven’t experienced the effects of an extreme geomagnetic storm. For a short primer on the effects of solar activity on GNSS/GPS, you might want to take a look at this article I wrote in 2008 as well Richard Langley’s 2011 Innovation column “GNSS and the Ionosphere.” In addition to the content, they both contain some valuable links to relevant articles.

In line with a goal of the workshop, a panel of GNSS professionals looked at issues that users face as they go about their business at solar max. The panel was “Global Navigation Satellite System (GNSS) Services: Research Needed to Fill Operational Gaps.” Joe Kunches (SWPC) moderated the panel that included Dr. Geoff Crowley (Astra), Dr. Anthea Coster (MIT), Capt. Steven Miller (USAF) and myself. We highlighted precision GNSS, satellite navigation for commercial aviation (ADS-B), and current work to better understand the errors the ionosphere imposes on user activities.

Something else I learned at the conference was how tough ionospheric scintillation is on GNSS receivers in Brazil. I feel for those users. When I mentioned I was traveling to Chile for an RTK project, the scientists said it is worse in Chile than the U.S., but still not as bad as Brazil. I’ll be very interested to experience how different it is than the U.S. (or other parts of the world where I’ve traveled).

I keep a pretty close eye on space weather and in contact with NOAA’s Space Weather Prediction Center. When I hear of a space weather event that may affect high-precision GNSS/GPS receivers, I send out a Tweet with the hashtag #SolarActivity. You can follow me on Twitter at https://twitter.com/GPSGIS_Eric.

From Space Weather Back to Local Weather

As the week progressed during the Space Weather Workshop, the snow continued. Boulder looked like Christmas in April.

Christmas in April, Boulder, Colorado.

I really wanted to spend some more time in the field to test the accuracy of the NGS’s CORS Streaming service and I was running out of time. In order to perform the test the way I wanted, I needed to find a local NGS survey mark that was observed using GPS. I checked out the NGS survey mark database and got lucky. There was one (PID = KK2060) located on a vista point parking area off of Highway 36 on the way from my hotel to the Space Weather Workshop. I couldn’t have asked for a better or more convenient survey mark location. I was planning to use a Bluetooth GNSS receiver so I could actually collect data while sitting in my car.

KK2060 Survey Mark along Highway 36

On Thursday morning, Mother Nature cleared her skies for me so I drove to the vista point. Remember, there’s a couple of feet of snow on the ground, so I was really hoping to see some kind of wood lathe that would get me close to the survey mark (no, I didn’t preload the KK2060 coords in my GPS L). Fortunately, a wood stake was near the survey mark. However, I didn’t have a shovel or a metal detector so it was either using my hands to shovel and search under two feet of snow for the mark, or…thanks to the rental car company, the car came with a healthy-sized windshield scraper. After 15 minutes of digging in the snow with a windshield scraper, I found KK2060. I’m sure to the people parked on the vista enjoying the view; I looked very suspicious using a windshield scraper to dig a hole in the snow. I wouldn’t have been surprised if a state trooper had shown up.

KK2060 recovered from under two feet of snow with a windshield scraper.

My final challenge was…no tripod or tribrach. I travel light and didn’t want to pack a set and, of course, I forgot to ask Tim if I could borrow a set. It’s never a good idea to set a GNSS antenna directly on the ground, but the antenna was small (<3” in diameter) and I did have a 5” diameter ground plane with about a 1” post. I was able to place it over the survey mark with reasonable confidence.

3″ diameter L1/L2/GLONASS antenna on a 5″ ground plane centered over KK2060.

As I mentioned before, I was using a Bluetooth GNSS receiver (GPS L1/L2, GLONASS), the SXBlue III GNSS.

SXBlue III GNSS bluetooth receiver

To collect the data, I was using an SXPad handheld with an AT&T SIM card for the Internet connection. For data-collection software, I used VisualGPSce, a free GPS data-collection program that collects and displays raw NMEA data. Although it doesn’t display enough digits of precision for the horizontal position, it accomplishes the simple task of collecting NMEA-formatted data without applying any transformation so I get the raw NMEA-formatted data from the receiver. It also displays some useful information such as PDOP, RTK indicator and elevation.

VisualGPSce running on an SXPad data collector collecting RTK data.

The last piece of data-collection software I used was a free NTRIP client software written by the SXBlue people called SXBlue RTN. I needed an NTRIP client software to access the CORS Streaming mount point. The software manages the IP address, port and login/pwd of the CORS Streaming system.

Logging into the NGS CORS Streaming site was painless, and within a few seconds I had an RTK FIXed position from the GNSS receiver, all from the comfort of my rental car, thanks to long-range Bluetooth. I collected ~45 minutes of NMEA data (1-Hz data rate) without interruption.

When I returned to the office, I began the process of comparing the results from CORS Streaming to the NGS survey mark coordinate. I checked with NGS and they reported that CORS Streaming is referenced to the ITRF00 (epoch 1997.0) datum. The KK2060 coordinate is published in NAD83/2011 (epoch 2010.0). I needed to reconcile the datum difference before performing any analysis so I used the NGS HTDP (Horizontal Time Dependent Positioning) online tool to accomplish this.

Finally, I used NMEA Analyzer (custom-built software for performing statistical analysis on GNSS NMEA data to NSSDA horizontal accuracy standards) to calculate accuracy (not precision) values of the data. I set up the NMEA Analyzer software to randomly select 200 epochs out of the ~2,700 collected to mitigate any bias due to filtering or other receiver “tricks”. Following are the horizontal results:

Not bad for an antenna sitting on the ground and an 18-km baseline using a $6,000 GNSS receiver and a free RTK base station. Folks, this is the direction that GNSS technology is heading. The continued proliferation of high-precision GNSS infrastructure (RTK networks, real-time PPP, etc.) and the falling prices of RTK GNSS receivers will dramatically increase the availability of high-precision technology to those who previously could not afford to make the investment.

I didn’t get a chance to test the PBO real-time streaming while I was in Colorado, but fortunately there are many PBO real-time stations that I can test from the comfort of my home office here in Oregon. In fact, there are so many in Oregon and Washington that I can test many different baseline distances to understand what accuracy users can expect. Look for my test results on that sometime this summer.

National Geodetic Survey (NGS) Suffering

It’s likely that you aren’t an NDGPS user, but you might still be affected if the NDGPS is decommissioned. There are a total of 86 NDGPS stations across the Continental U.S., Alaska and Hawaii. As well as being NDGPS signal broadcasters, they are also part of the NGS CORS program that is used by the NGS’s OPUS online post-processing service. If you are using OPUS or NGS CORS for post-processing, you might be using NDGPS CORS data and not realize it. Following is a map of all NDGPS stations in the U.S.:

U.S. NDGPS coverage map.

If you’re interested in reading an explanation from the U.S. Coast Guard and Department of Transportation about the request for public comment and submitting a comment, click here. To be considered, comments must be submitted by July 15.

Then, towards the late ’90s, there were enough publicly available GPS CORS in the U.S. that you could collect data in the field without knowing where the closest base station was located, but you knew GPS base stations were so prolific that you could find one close enough to use for post-processing without prior planning/coordinating.

Then, sources of real-time GPS corrections started through the same progression. In the ’90s, if you wanted real-time corrections, you either had to operate your own GPS base station and wireless datalink or, if you were lucky you were close to a U.S. Coast Guard beacon transmitter, which were few a far between. OmniSTAR was an option, but subscription was a quite a bit more expensive back then and the equipment was bulky.

Today, post-processing is a no brainer. You don’t even need to have to license post-processing software. Through the National Geodetic Survey’s OPUS, Austraila’s AUSPOS and Canada’s CSRS-PPP, you can collect GPS data anywhere in the world, submit it to one of these free, online processing centers, and have the answer in your email inbox in a few minutes. But, as I’ve lamented more than once over the years, post-processing is a dinosaur. Mind you, it will never go away completely, but it doesn’t belong in the typical mainstream data collection workflow. It just doesn’t make sense.

As it was 20 years ago and as it is today, the challenge with real-time GPS/GNSS data collection is the wireless datalink. If you’ve ever worked with real-time GPS/GNSS data collection and had a unreliable wireless data link between the base and your receiver, you know what I mean. It’s exceedingly frustrating and unproductive. However, when everything is working as designed, the real-time GPS/GNSS data collection workflow is a thing of beauty.

Sources of high-precision real-time GPS/GNSS corrections are still a rather disparate group of public and commercial services that depend heavily on geography and communications infrastructure. For example, in the U.S. there is plenty of wireless coverage (GSM, CDMA, Wi-Fi) in metro areas and along major interstate roads, but there are still vast areas of rural farmland, prairie and desert where wireless networks don’t reach, leaving the choice of either satellite-based communications or setting up your own private wireless communications (UHF/VHF/900 MHz) between a base station and your receiver.

That said, there are more choices for real-time, high-precision GPS/GNSS corrections than ever before. In fact, just last week, the International GNSS Service (IGS) announced that it has started to offer a global real-time PPP data stream for high-precision, dual-frequency GPS receivers via NTRIP. That means anyone with a dual-frequency GPS receiver and an Internet connection can achieve sub-decimeter accuracy anywhere in the world, free of charge. How exciting is that! I think about the regions of the world like South America, Central and Southern Africa, Australia, and parts of Asia that aren’t served well by public SBAS or other free sources of high-precision GPS/GNSS corrections. This service will open up those regions to a new level of real-time, high-precision positioning. There’s one catch though; GPS/GNSS receiver designers have to implement special firmware to use the IGS RT PPP service. Some manufacturers are talking about implementing this, which would be a boon for the high-precision GNSS user community. Global IGS RT accuracy = ~10 cm.

Of course, OmniSTAR, Fugro, Starfire, Veripos have been providing real-time PPP for years  (as well as Terrastar and Trimble more recently) in their respective vertical markets (land and offshore) but it requires an annual subscription fee and specialty hardware (L-band) to receive the signal. The receiver hardware can be prohibitively expensive for some potential users, and their coverage, based on leased communications satellite footprint, isn’t dependent on local Internet connectivity. However, I will say that OmniSTAR subscription pricing is very competitive now, and that a public service like what IGS is offering has no guarantees of availability or accuracy. On the other hand, since commercial services like OmniSTAR are collecting a fee, they have an obligation to service their users. Nevertheless, public, sub-meter SBAS services like WAAS, EGNOS, MSAS, GAGAN, and SDCM are offered to non-aviation users on the same terms as IGS, and those services have worked out very well for our surveying and mapping user community.

Global IGS GPS/GNSS Stations use for Real-time PPP Streaming
Source: European Space Agency (ESA).
http://igsac-cnes.cls.fr/documents/egu11/01_Caissy_IGS_RealTimePilotProject_EGU2011.pdf

Other public sources of high-precision GPS/GNSS corrections are on the rise:

RTK Networks. RTK networks continue to proliferate. In the U.S., many states offer free access to their centimeter-level statewide RTK networks. These are somewhat well-known within the surveying and agriculture community, but not as well known within the GIS community. Many countries also offer regional and country-wide RTK networks. RTK network accuracy = 1-2 cm.

Washington State RTK Network
Source: Washington State Reference Network. http://www.wsrn3.org/

PBO real-time streaming. In the western U.S., UNAVCO’s Plate Boundary Observatory (PBO) maintains more than 1,000 GNSS base stations with many of them broadcasting RTCM3-formatted data. If you’re in California, Oregon, Washington, and the surrounding states, you should take a look at its website. The only requirement is that you have a receiver capable of handling RTCM3 data and you have Internet access in the field. You’ll also need an NTRIP client software (there are free ones available) running on your data collector (smartphone, handheld, tablet). Note that these are single baseline solutions (as opposed to the RTK network solution), so the further you are from the base station, the more error will be introduced. One caveat: be sure you understand which horizontal datum and epoch the particular PBO base station is streaming. PBO real-time streaming accuracy within 20 km = 1-2 cm.

PBO Station Streaming Map
Source: UNAVCO Plate Boundary Observatory. http://pbo.unavco.org/data/gps/realtime

CORS Streaming. The National Geodetic Survey (NGS) is testing real-time streaming from nearly a couple of dozen CORS sites, mostly in the Eastern U.S. This is very similar to PBO real-time streaming. If you are 50-75 km from the base station, you’ll still be under 10 cm. If you’re within 20 km, you’ll be down to 1-2 cm.

CORS Streaming Station Map
Source: National Geodetic Survey. http://beta.ngs.noaa.gov/NGSRealtimeGNSS/statusmap.jsp

SBAS. SBAS (WAAS/EGNOS/MSAS/GAGAN/SDCM) was the first true source of public, country-wide high-precision GPS corrections. What make SBAS so easy is its ergonomics. It’s become such a standard that virtually every high-performance GPS/GNSS receiver designed today has SBAS capability built-in. You don’t need to purchase any extra hardware or software to use it. SBAS accuracy = sub-meter (with a receiver designed to optimize WAAS).

Global SBAS Coverage Map
Source: Geneq, Inc. www.sxbluegps.com

There’s no doubt that years from now, we’ll look back and be amused at how “difficult” and expensive real-time, high-precision positioning was. Today, there are many more sources of high-precision, real-time GPS/GNSS corrections than there were ten years ago. In ten years, there may or may not be many more choices for high-precision GPS/GNSS corrections, but certainly the sources will be less complex, more ubiquitous and more convenient than they are today.

For the latest GPS/GNSS news, follow me on Twitter by clicking here.

Thanks, and see you next month.

• Trimble
• Leica/Novatel
• Topcon/Sokkia
• Hemisphere GNSS
• JAVAD GNSS
• Septentrio
• Ashtech (owned by Trimble)
• Navcom Technology (owned by Deere & Co.)

Some of you may think that I should include “consumer” GNSS chipset designers like GlobalLocate/Broadcomm, SiRF/CSR, u-blox, NVS Technologies, etc. While some of the engineers at consumer GNSS chip companies clearly have the knowledge (and experience in some cases) of RTK design, none of these chipsets are integrated into commercial RTK products. Yes, I know some of you have “made RTK work” with consumer GNSS chipsets, and I think that speaks volumes about where RTK capability will end up, but it’s not quite there yet with respect to a reliable commercial implementation.

Regardless of consumer GNSS chipsets, the multi-constellation, multi-frequency RTK GNSS receiver landscape is changing quickly, even before the deployment of the new L5 signal and Galileo as I’ve written about previously (Why the Price of Precision Receivers Will Drop). This is because of the proliferation of RTK GNSS receiver “boards” such as the Trimble BD series, Novatel OEM series, Hemisphere GNSS P series, and Septentrio AsteRx series. System integrators like Altus, Geneq, CHCNav, Stonex, FOIF, Carlson, etc., are scooping up these proven receiver boards and designing their own systems around them.

There are more RTK GNSS system integrators in China than any other geographic region in the world. It makes sense because the Chinese market for RTK GNSS receivers is larger (much larger) than any other market in the world. Even though you don’t see many Chinese-made RTK GNSS receivers sold in North America (you do see them sold in Africa, Europe and South America), they sell a huge number of them within China. I would even go as far as to say that the North American market is likely considered a “leftover” market since the North American RTK GNSS receiver sales volumes are so low in comparison. In other words, North America is such a small market for RTK GNSS receivers, it’s not worth the marketing/selling effort it requires. That said, some companies, like CHCNav, are ramping up their marketing and selling efforts in North America.

To put it in perspective, let’s take a look at some of the new RTK GNSS products (and services) introduced in the past ~6 months (in alphabetical order). I’m sure I’ve left some out because there are so many on the market, but this gives you an idea of the broad range of RTK GNSS receivers available. Again, these are products introduced just in the past ~6 months.

Altus APS-3L

Key benefit: Integrates Terrastar’s new 10cm real-time precise positioning service. Uses a Septentrio GNSS receiver board.

Carlson SuperG

Key benefit: Tablet-based RTK GNSS system capable of 1cm real-time accuracy. Uses a Novatel RTK GNSS receiver board.

CHCNav X900+ GNSS

Key benefit: Low-cost RTK GNSS made in China. Uses a Novatel RTK GNSS receiver board.

FOIF A30

Key benefit: Low-cost RTK GNSS made in China. Uses a Trimble RTK GNSS receiver board.

Geneq SXBlue III-L

Key benefit: Low-cost, palm-sized receiver integrates OmniSTAR’s G2/HP/XP 10cm service and also 1cm RTK capability. Uses a Hemisphere GNSS receiver board.

Hemisphere A325 GNSS Smart Antenna

Key benefit: All-purpose, low-cost RTK GNSS receiver.

Javad J-Shield

Key benefit: Innovative radio frequency (RF) interference visualization (onboard spectrum analyzer) and interference reporting feature.

Leica CS25 GNSS

Key benefit: Tablet-based RTK GNSS system capable of <10cm real-time accuracy.

Navcom StarFire Over IP

Key benefit: 5cm (horizontal RMS) real-time correction service delivered via IP (Internet Protocol) as an alternative to delivering via satellite communications.

Sokkia GRX-2

Key benefit: Low-cost, lightweight (1.00kg) RTK GNSS receiver. Same as Topcon HiPer V.

Topcon HiPer SR

Key benefit: Palm-sized, lightweight (.85kg) RTK GNSS receiver capable of surviving a two meter drop.

Spectra Precision ProMark 700

Key benefit: Lightweight (.65kg) RTK GNSS receiver. Uses Trimble RTK GNSS receiver board.

Stonex S9III

Key benefit: Lightweight (1.2kg) RTK GNSS receiver. Uses Trimble RTK GNSS receiver board.

Terrastar Terrastar-D Satellite Correction Service

Key benefit: World-wide, real-time 10cm (horizontal 2DRMS) GNSS correction service delivered via satellite.

Trimble R-10

Key benefit: Lightweight (1.12kg) RTK GNSS receiver.

Trimble RTX

Key benefit: World-wide, real-time 4cm GNSS correction service delivered via satellite.

Looking at this list, there are two key trends:

1. RTK GNSS receivers are becoming smaller. Moore’s Law, or a GNSS version of it, is definitely in effect.
2. The price of RTK GNSS receivers is falling, as low as US$7,000 (retail price) for a full RTK GNSS receiver in North America and likely less than that in other parts of the globe.

Another clear trend is the advancement of global GNSS augmentation services (OmniSTAR, StarFire, Terrastar, Trimble). RTK networks are great when you have access to them, but in many places of the world, RTK networks aren’t available or there isn’t a data link (wireless network) available to receive corrections. This has created an opportunity for satellite-based (and Internet-based) global correction services. Whereas OmniSTAR (serving the agriculture and mapping markets) and StarFire (serving primarily the agriculture market) have been long-term players in this market, Terrastar recently announced its entry into the market and Trimble (who also owns OmniSTAR) announced its new RTX service.

The advantage of satellite-based correction services is that you can receive them virtually anywhere in the world as long as you have a clear view of the sky. The disadvantage is that the initialization time it takes to achieve the stated real-time accuracy (<10 cm) is up to one hour if you aren’t starting on a known point. The addition of GLONASS helps reduce the initialization time, but it’s still much longer convenient than RTK initialization due to the sparse network of reference GNSS receivers used.

Furthermore, the accuracy provided by the satellite-based correction vendors isn’t as good as RTK. OmniSTAR and Terrastar advertise 10-cm (horizontal 2DRMS) real-time accuracy. StarFire advertises 5-cm (horizontal RMS, as opposed to 2DRMS values given for competing services) real-time accuracy, and Trimble RTX advertises 4-cm (horizontal 2DRMS) real-time accuracy. RTK accuracy is solid at 2-cm or less.

Lastly, in order to access satellite-based correction services, GNSS receivers must be specifically designed (additional hardware is required), so the reality is that few receivers on the market are capable of utilizing these services. But, if you’re performing mapping work across a large geographic area where RTK networks aren’t consistently available and you don’t want the go through the pain of owning, maintaining, and setting up your own RTK base station, the satellite-based correction service is a solid solution.

For more information on these satellite and internet-based correction services, GPS World’s Tony Murfin published a detailed article this month entitled “Look, No Base-Station! — Precise Point Positioning (PPP)“. Tony offers some detailed insight into these services.

Nightmare on GIS Street: Accuracy, Datums, and Geospatial Data

Changing the subject a bit, but highly related to RTK GNSS receivers, is the subject of datums and geospatial data. Last month, I wrote an article for Geospatial Solutions that is a first in what promises to be a very interesting and complex discussion. I received quite a bit of email on the article with many good points made. If you think you know how to handle horizontal datums in a GIS environment, you might want to take a look at the article and follow the thread over the next few months. You can read the article by clicking here.

Thanks and see you next month

Follow me on Twitter by clicking here.

Eric Gakstatter

For quite some time, I’ve been writing in GPS World magazine and speaking at conferences about the declining prices of high-precision GNSS receivers and how the cost of high-precision data (especially vertical) is going to decline substantially. For my colleagues in Asia, Africa, Europe, and South America, you’ve already seen this. Dual-frequency, multi-constellation GNSS receiver prices in those areas are significantly lower than in the United States and Canada.

Previously, I’ve presented to you that I think dual-frequency (L1/L5), dual-constellation (GPS/Galileo) GNSS receivers will be  inexpensive in the future. My reasoning, simply, is that L5 is an open signal (legacy L2 is not) and supported by both GPS and Galileo. Furthermore, both GPS and Galileo use a CDMA radio technology, so designing a GPS/Galileo receiver is a heck of a lot easier than a GPS/GLONASS receiver. Therefore, unlike today’s GNSS receiver competitive landscape of only a dozen or so manufacturers of high-precision GNSS receivers, there will be dozensssss (emphasis on s) and maybe hundreds of high-precision GNSS receiver manufacturers, based on oodles of L1/L5 GNSS chipsets that are sure to come.

Will all GNSS chipset designers decide to expend the extra energy it takes to optimize their chipset for RTK FIX or Float solution? No, but certainly there will be “boutique” GNSS chip designers that will specialize in high-precision designs. It likely won’t be the companies selling a $3 GNSS chip to Apple or Samsung  today. Those companies rely on selling tens (or hundreds) of millions of GNSS chips per year. I’m talking about companies that can survive on selling hundreds of thousands of high-precision GNSS chipsets for $50-100 each.

However, Galileo is still at least two years from a minimal usable constellation and the GPS operator, the U.S. Air Force, is in no hurry to launch GPS satellites with new capabilities (for example, L5) — so low-cost, high-precision GNSS chipsets are still a couple of years away. If this is the case, then why are high-precision GNSS receiver prices declining in some areas today?

As I mentioned before, our colleagues in Asia, Africa, Europe, and South America are already seeing lower-cost high-precision GNSS receivers. There are brands offered in those geographic regions that aren’t known (or are very little known) in the U.S. and Canada. Brands like Stonex, FOIF, BHCNav, CHCNav, and others market themselves outside of the U.S. and Canadian markets, but not much in the United States or Canada. The increased competition in those foreign markets has driven high-precision GNSS prices down.

The CHC booth at Intergeo 2012.

The reason high-precision GNSS prices are still high in the U.S. and Canadian markets are because it’s still primarily a Trimble, Leica, Topcon game. Yes, there are other brands like Ashtech/Spectra-Precision, SXBlue, Javad, Sokkia, Hemisphere, Altus, and Navcom, that may offer entry-level entry points, but the Big Three still dominate the U.S. and Canadian markets, partly because of their broader product lines and mostly because they have the best network of dealers. Differing from the others in this mix is Navcom, a subsidiary of John Deere & Co. Navcom’s GNSS technology is distributed by Deere & Co, and is focused almost exclusively on the agriculture market.

In the United States and Canada, high-precision GNSS receiver users are still willing to pay a premium for leading brand-name products and their dealer networks. You might think that there’s a lot of price pressure from the other brands. There is some, but some of the other brands are owned by the big boys. Trimble owns Spectra-Precision and Ashtech. Topcon owns Sokkia.

Spectra Precision (here at Intergeo 2012) is owned by Trimble.

For there to be serious price movement in the United States and Canada as there has been in other areas of the world requires more competition. I think we’re going to start to see more of that.

I know you don’t want to hear this, but the competition for high-precision GNSS receivers is coming from China — and it’s serious competition. Chinese GNSS receiver manufacturers are already well-established in Africa, Europe, and Asia (of course). Their high-precision GNSS gear is coming soon to a place near you.

What exactly is a Chinese-made GNSS receiver? Mostly, they are receivers made using the guts (GNSS receiver boards) from mainstream GNSS receiver designers like Trimble, Topcon, NovAtel, and Hemisphere. The Chinese companies buy these receiver boards and design their own cases, battery packs, and other supporting systems around the GNSS receiver board. The finished products, like the CHCNav X91, look much like what you see from Trimble/Topcon/Leica today, and it sports a Trimble or Novatel GNSS receiver inside, for fraction of the price you’ll pay for the equivalent Trimble GNSS receiver.

Of course, you wouldn’t benefit from Trimble (or whomever) dealer network support, and you would be risking that the manufacturer has designed a reliable system around the GNSS receiver board. What happens if the receiver needs service? Where’s the nearest support center? Who do you call? These are all very valid questions that any prudent businessperson would ask themself before making a significant equipment purchase.

Some of the Chinese manufacturers rely on low price to attract your attention and then offer minimal customer support. Others, like CHCNav, are addressing this by setting up regional centers around the globe for support and repair. Can they produce high-quality GNSS products that will meet the expectations of U.S. and Canadian buyers? The reputation of Chinese manufactured products in the surveying market is not very good. Will they have the staying power to hang on for a few years, long enough to gain the confidence of U.S. and Canadian users?

In their favor is their home market. China is the largest consumer of high-precision GNSS receivers in the world. In fact, it’s been said that more high-precision receivers are sold in China than in the rest of the world combined. Even if that’s not an accurate statement, it’s not incorrect by very much. That tells you something about the size of the Chinese market for high-precision receivers. With a market that size, I think it’s safe to say that Chinese receiver manufacturers are gaining a lot of experience in designing and manufacturing GNSS receivers, and one can assume that the next-generation receiver design is better than the previous one.

While they haven’t quite ventured into offering their own GNSS receiver designs (still buying GNSS receiver “guts” from established manufacturers), last week one Chinese manufacturer took a step closer to doing so. On January 31, Hemisphere GPS announced that Beijing UniStrong Science & Technology Co Ltd. is acquiring Hemisphere’s core GPS design/manufacturing business. Hemisphere has chosen to divest itself of all non-agriculture related businesses and rename the company AgJunction, the same name as a software company it acquired recently. Of course, GNSS technology is highly related to agriculture, and there’s no doubt that AgJunction will continue to use GNSS technology, but clearly the AgJunction management team doesn’t think it’s an important enough technology to have to own it.

UniStrong is no stranger to the GPS/GNSS business and is no small fry. It’s been in business since the mid-1990s and boasts more than 1,000 employees, offering a wide variety of high-precision GPS/GNSS receiver solutions from handheld GIS receivers to full-blown RTK GNSS receivers. With this acquisition (US $15 million), it becomes the first Chinese-owned GNSS receiver design/manufacturing group in North America.

Thanks, and see you next time.
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Navcom, a subsidiary of John Deere, focuses on the ag market.

Let’s take a look at some of the technologies and events that were significant in 2012 and some that will be significant in 2013 for high-precision GNSS users.

LightSquared

House Representative Anna Eshoo, ranking member on the House Subcommittee on Communications and Technology, who in September 2011 wrote to the NTIA’s Larry Strickland asking Strickland to find a way for LightSquared and GPS to coexist, said it best a year later (November 2012):

“What happened to LightSquared is disappointing, but unfortunately that ship has sailed.”

Now all that’s left are negotiations regarding GNSS receiver standards and/or a frequency guard band around GPS L1, both of which are moving at a snail’s pace. Regardless, you can bet that GNSS receiver designers are taking this experience to heart and tightening up their filtering as much as possible. The more difficult problem to solve is the augmentation services offered in the MSS band (such as Trimble’s OmniSTAR, Deere’s Starfire and just-introduced Terrastar), all of which broadcast their correction signals in the MSS band at low-power satcom power levels (as opposed to high-power terrestrial power levels).

You can pretty much dismiss the LightSquared-proposed spectrum sharing proposal from last fall. It’s just another desperate move from a desperate company. If you have a few minutes, you can listen to the NSPS (formerly ASCM) Radio Hour show I participated in on October 8, 2012, where we discuss this issue.

FCC UHF/VHF Narrowbanding Rule

Hidden behind the LightSquared issue over the past two years has been the FCC narrow-banding ruling that took effect on January 1, 2013. Initially adopted in 1995, the narrowbanding ruling has been around for a number of years. In fact, equipment suppliers have been required to offer narrowbanded (12.5kHz vs. 25kHz spacing) radios since 1997. In 2004, the FCC set the January 1, 2013 deadline for users to comply.

The FCC’s webpage on the narrowbanding ruling shed some light on the rationale behind it, but narrowbanding doesn’t specifically target RTK users so there’s not any RTK-specific information contained in the FCC documents. The bottom line is that the FCC is trying to allow more users in the same spectrum, similar to trying to fit more cars on a highway by splitting lanes in two. The problem with this, from a user standpoint, is that some vehicles won’t fit in the new, narrower lanes and therefore aren’t legal to use any longer. That’s the case with most UHF/VHF RTK base stations.

To be clear, the narrowbanding ruling doesn’t affect UHF/VHF radios on your rover (receiving radio) GPS/GNSS receiver. I’m talking about the base station UHF/VHF radio. The ruling states that your UHF/VHF base station radio must be able to broadcast at 12.5kHz vs. 25kHz, essentially utilizing half the spectrum. Your UHF/VHF base radio can still broadcast at 25kHz if it broadcasts at 19,200 baud. Since January 1, 2013, it is illegal to broadcast at 4,800 or 9,600 using 25kHz spacing. The reality is that it becomes complicated when trying to broadcast at 19,200 baud at 25kHz spacing. Radio range is reduced and communication protocols (compatibility) become an issue. The reality is that you’ll likely need to replace your UHF/VHF base radio in order to stay compliant with the FCC rules.

Just a few weeks ago (January 7, 2013), I was a guest on the NSPS Radio Hour to discuss the FCC narrowbanding rule. I invited Charlie Branch from Pacific Crest Corporation, a major supplier of VHF/UHF radios for RTK users, and Mark Silver from IGAGE Corp, a Pacific Crest dealer, to discuss their thoughts on the FCC narrowbanding rule and their experience with equipment compatibility. It is a great discussion on the subject and well worth listening to if you’re interested in learning more about the narrowbanding rule and how it affects RTK users.

Lastly, you might also be interested in this presentation from Charlie Branch on the FCC narrowbanding rule.

Low-Cost RTK Receivers

At the GPS World dinner during the Institute of Navigation GNSS conference last September, Dr. Todd Humphreys predicted that RTK GNSS would be available in mobile phones by the year 2020. As I’ve written before, the challenge with this is not really the quality of the GPS receiver used in mobile phones (some of the key engineers at Broadcomm, who supply the GNSS chip to Apple, used to design RTK receivers at Ashtech), but rather the poor quality antennas that mobile phone designers choose to use. Instead of RTK inside the mobile phone, I think small RTK “pucks,” a few inches in diameter, are more practical and realistic and will become common and easily interfaced to mobile phones (or other mobile devices) via Bluetooth. I think you will start seeing these within the next three years.

Galileo

With four Galileo IOV (in-orbit validation) test satellites in orbit that will be converted to operational satellites, Europe’s Galileo is on its way to becoming a viable satellite navigation system for high-precision apps. Launch of production satellites is scheduled to begin later this year and scheduled to occur every three months, launching in pairs. With an aggressive launch schedule, 18 satellites are predicted to be in orbit by the end of 2015, a little more than two years from now.

I’m very bullish on Galileo because, like GPS, it supports the new L5 signal, which will lead to less expensive dual-frequency, dual-constellation receivers. It’s clear that the European Union is committed to Galileo, and it would be difficult for them to shut down the project after advancing as far as they have.

GPS Modernization

Modernizing GPS, on the other hand, is moving very slowly. Galileo already has more L5-capable satellites in orbit than GPS. My 2010 prediction that 18 Galileo satellites and 12 GPS satellites would provide the high-precision user community with a full 30-satellite constellation broadcasting L1/L5 signals by 2015 may not materialize. However, the weak link might end up being delays with the GPS program rather than a lack of commitment from the European Union with its Galileo program.

Last August at a CGSIC (Civil GPS Service Interface Committee) meeting, I heard rumblings of three GPS launches this year (2013). Sadly, I don’t think this is going to materialize. I think we’re on pace for a single launch this year, again. Budget, launch pad scheduling and a healthy GPS constellation continue to be the culprits.

There’s also a bit of second-guessing happening with respect to GPS signals. Earlier this month, Don Jewell wrote a piece entitled “2C or not 2C: An Important Signal Question.” While the delay in launching next-generation GPS satellites may have saved the U.S. government some money, I think it has put the L2C signal in peril. There were high hopes for L2C, as the second civil GPS signal, when it was conceived in the 1990s. But it’s been seven long years since the signal was deployed on the first GPS II-RM satellite in 2005, and there are only a total of 10 GPS satellites broadcasting L2C today. That’s not enough, and it’s hard for receiver manufacturers and the civilian user community to take L2C seriously when it appears the U.S. government is not taking it seriously.

Some sort of positive traction with L2C must happen soon, or it will risk being ignored as it is overtaken by the new L5 signal that is supported by up-and-coming GNSS like Galileo and Compass/BeiDou.

UAVs (Unmanned Aerial Vehicles)

The United States is the last major geographic region (that I’m aware of) where UAVs are illegal to use by commercial entities. Service companies in other countries are going crazy with UAVs in offering mapping services (for instance, in mining and agriculture). The Federal Aviation Administration (FAA) is working on establishing rules by 2015 that will allow commercial entities to utilize UAVs in the U.S. This will turn the market for digital mapping imagery upside down. It will become very easy and inexpensive for people to obtain quick-n-dirty imagery for mapping purposes with a very quick turnaround.

Thanks, and see you next month.

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Portland | Oregon | United States (USA)

Eric Gakstatter, GPS World’s editor for survey and Geospatial Solutions Weekly, will be a keynote speaker at the Second Annual Field Technology Conference (FTC 2012). FTC 2012 is hosted by the Western Forestry and Conservation Association (WFCA), GPS World magazine, and Geospatial Solutions Weekly.

The conference will be held September 26-27 at the Holiday Inn Convention Center in Portland, Oregon. This unique conference, centered around geospatial technology, features tracks on field devices (handhelds/tablets, GPS, lasers, 3D scanning), remote sensing (aerial photography, satellite imagery, airborne lidar), and mapping software (mobile GIS, open source GIS, datum conversions).

The opening general plenary session will feature world-class experts in emerging geospatial technologies of Unmanned Aerial Vehicles/Systems (UAV/UAS), Mobile GIS, Open Source GIS, and GPS/GNSS. The keynote speakers will discuss how these emerging technologies are changing the way geospatial data is collected and managed. Besides Gakstatter, featured speakers include:

• Dr. Joe Paiva – Paiva Consulting
• Jeff Shaner – Esri Mobile Technology Program Manager
• David Percy – Portland State University GIS Research Faculty

“Audience feedback from last year’s conference was very good,” said keynote/moderator Eric Gakstatter. ”Attendees said they appreciated our intimate and focused content as well as expert analysis of technology trends. Listening to feedback from last year’s attendees, we’ve expanded a bit this year to include outdoor demonstration sessions with UAVs, handhelds/tablets, laser rangefinders, mobile phones, and GPS units. We’ve also attracted more experts from around the country to present their work and thought leadership.”

Registration for the Second Annual Field Technology Conference (FTC) is now open. 2011 attendees included representatives from federal, state, and local government, Fortune 1000 companies, Native American tribes, higher education, and natural resource consultancies.

The registration fee is $245 if registered by September 21, and $295 if registered after September 21, 2012. The registration fee includes lunch on both days as well as refreshments during breaks. The conference room rate is $99/night plus tax. After September 5, the reduced rate will be subject to availability.

For more information as well as a draft of the conference agenda, visit the website.

Sponsorship opportunities are available. Contact Richard Zabel.

The Civil GPS Service Interface Committee (CGSIC) was established to facilitate communication among civilian GPS users, identify civilian user community needs, and report to the Office of the Assistant Secretary for Transportation. The U.S. state and local government subcommittee meeting moves around to different parts of the U.S. The next meeting is the annual CGSIC meeting, typically held the two days prior to the Institute of Navigation (ION) GNSS conference. This year it’s being held in Nashville, Tennessee.

Gakstatter reports on how GNSS receiver technology is moving much faster than GPS policymakers can keep up with, the National Telcommunications and Information Administration’s efforts to execute the National Broadband Plan, and a whether illegal jamming has been on the rise.

The Civil GPS Service Interface Committee (CGSIC) was established to facilitate communication among civilian GPS users, identify civilian user community needs, and report to the Office of the Assistant Secretary for Transportation. You are welcome to attend any of the CGSIC meetings. The U.S. state and local government subcommittee meeting moves around to different parts of the U.S. The next meeting is the annual CGSIC meeting that’s typically held the two days prior to the Institute of Navigation (ION) GNSS conference. This year it’s being held in Nashville, Tennessee.

You can view the agenda for this week’s meeting by clicking here.

Some take-away bullet point observations from this week:

1. GNSS receiver technology is moving much faster than GPS policymakers can keep up with. If the policymakers can keep the various GNSS from interfering with each other, can protect the spectrum used by GNSS, and do their best to mitigate jamming/interference (intentional and unintentional), they’ve done their job.

Rather than try to cage the GNSS animal, let it run wild and it will explore so many apps. Some will fail and many will succeed, but either way it’s a given that GNSS technology will contribute significantly to the world’s economy. With the introduction of the L5 civilian signal by the U.S. and Europeans, a new era of high-precision GNSS technology will emerge, along with countless new apps.

2. The NTIA (National Telcommunications and Information Administration), while seemingly our friend when they recommended to the FCC last February that LightSquared not be allowed to move forward, did so because they had no choice. Make no mistake; the NTIA is trying to figure out a way to execute President Obama’s National Broadband Plan (which includes finding 500 MHz of wireless spectrum for high-speed Internet), which may mean trying to draw a tight box around the GNSS spectrum, via receiver standards. On the other hand, the FAA (Federal Aviation Administration) and RITA (Research and Innovative Technology Administration) are taking a different approach by developing a Spectrum Protection Plan. Which one will move faster? Likely the NTIA due to political pressure. While the LightSquared debate is seemingly on indefinite hold for now, the spectrum discussion is far from over. We might see draft proposal (for public comment) from the NTIA and FAA/RITA as soon as the end of this year, but could easily slip into 2013. Stay tuned.

3. With all the talk about illegal GPS jammers and “jammagedon,” as Gavin Schrock (PLS) jokingly coins it, it was reported at the CGSIC meeting that there’s been no increase in reported incidences of GPS jamming and has stayed at the “couple of events” per year level. People are still talking about the 2007 San Diego event and the Newark airport event as the major ones. Unless the DoD is keeping something from us, jamming (intentional or unintentional) hasn’t panned out like one might have thought. The FCC is certainly cracking down on the distribution of GPS jammers (and cell-phone jammers). It is illegal to manufacture, import, distribute, and use GPS jammers in the United States.

Not that jamming doesn’t occur and we shouldn’t be aware of it, but when your receiver isn’t working the way you think it should, jamming and solar activity shouldn’t be the first thoughts that cross your mind.

4. Of the 12 Block IIF GPS satellites being built, two are in orbit with the first being launched in 2010 and the second one last year. A third is scheduled to launch later this year. That equates to one launch per year. Clearly, this pace cannot continue or it would be the year 2022 before all twelve were in orbit. What’s the problem? Part of the problem is that the legacy Block IIA model satellites have performed so well. In fact, one has been operational for 22 years. That’s an incredible feat for a satellite that was designed with an expected life of 7.5 years. Unfortunately for the IIF program (and the high-precision user community), it means that congress can defer a few hundred million dollars per year by delaying the IIF launches. In these budget-conscious economic times, it’s not difficult to understand the reasoning that if there are 31 operational GPS satellites in orbit, why spend $150-200M to launch each GPS satellite when we don’t need it yet? But, that won’t last for long. The many legacy GPS satellites are one component failure away from being unusable. That said, the word at the CGSIC meeting is that three IIF satellites will be launched in 2013.

How important is the IIF satellite to the high-precision user community? It brings the new L5 civil GPS signal, which has huge implications on high-precision receiver performance and cost. Read here for more thoughts on L5.

If you looked at the meeting agenda, you can see that I was on the agenda to make a 20-minute presentation. During my presentation, one of the messages I wanted to be clear on is that GPS is not in competition with GLONASS, Compass/BeiDou, Galileo, or any other GNSS. The GPS user community needs the other GNSS to succeed and the GPS program needs the other GNSS to succeed just as much as the other GNSS rely on GPS. Other GNSS, along with GPS, clearly provide a better solution for the user community than any one of them used by itself.

I think it’s pretty clear, at this point in time, that the days of GPS-only receivers are numbered. Of course, they’ll still be around for a few years, but the trend is clear that even mobile phones are beginning to use GPS/GLONASS receivers.

If you’re interested, click below and you can view a PDF of my presentation.

Thanks, and see you next time.

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