As a quick overview — L-band is just like WAAS, but with privately owned assets, rather than provided by a state agency. WAAS focuses on high integrity and accuracy, while L-band corrections are largely more focused on providing accuracy to users. A geographically distributed ground network of base stations sends receiver data to one or more central processing facilities, which formulate wide area corrections. A number of uplink stations then send these corrections up to geostationary satellite transponders (time on a number of satellites is often rented, but L-band companies could also own and operate their own satellites), and the transponders transmit the wide area corrections at L-band frequency for reception by suitably configured user receivers. Users are able to buy subscriptions that enable them to receive corrections for a period of time — and that’s how the private L-band suppliers make money. The accuracy a user can achieve depends on the service, but anything from a few meters to a few centimeters is now possible.

Before WAAS was fully operation in the U.S., L-band corrections supplied by private companies were already available. It became possible to regularly get meter-level accuracies without base-stations, and it was clear that this could well turn into a major benefit for users. Operations like agricultural automation, asset tracking, mining, marine navigation, and others that could get by with a few meters of accuracy began to rely on L-band corrections. Geographic Information Systems (GIS) could even work without base stations, and vehicle tracking could determine which side of the road a truck was on. Then with expanding worldwide ground networks, more satellites and ever-improving clock and orbit algorithms, we started talking about corrections that gave us decimeter accuracies. That’s when PPP began to outpace WAAS for some applications requiring higher precision.

Never quite got the significance of why the original marine PPP companies were spinning off land-focused providers from their marine businesses, but the original marine correction providers now have successfully established “land-only” provider companies. It makes sense to have a supplier talk to you in marine terms if you’re running a shipping company, and for that provider to focus on providing higher integrity corrections to your shipping fleet. Land-based machine control, GIS and vehicle tracking outfits, on the other hand, want their own land-based support networks and don’t want to talk in marine terms. So we now have a number of providers supplying different sets of PPP corrections. It’s also possible that segment pricing for the different markets might have played a role in these spin-offs.

The granddaddy system would seem to be Fugro’s OminSTAR — whose services are now marketed by Trimble following acquisition of OminSTAR marketing rights by Trimble in 2011, while Fugro retained its marine services. OminSTAR HP, G2, XP and VBS services are available courtesy of a worldwide network of reference stations, data networks, carrier-phase measurements and sophisticated “clocks and orbits” correction algorithms which provide sub-meter thru 10-cm capability to users.

The OmniSTAR network.

And of course Trimble is also running its own RTX service alongside OmniSTAR. With a world-wide reference station network, and a number of concentrated regional networks, CenterPoint RTX is regularly achieving less than 4cm for users. RTX is available over regular L-band satellite and over internet. Overall an impressive PPP capability.

The CenterPoint RTX network, by Trimble.

Then NavCom — and Deere & Co, its parent company — fielded the StarFire system for both NavCom and John Deere customers, who not surprisingly use it mainly for agriculture. However, use of the system has grown since it was introduced in 1999 and currently around 10 percent of customers are in markets other than ag — in offshore, survey, construction, aerial, GIS, and government/military applications. The StarFire signal is available worldwide but NavCom offers two differently priced services: “Land Only” and “All Area” for non-ag applications. You have to have Navcom or John Deere equipment to be able to use it, but the network and the receivers come from the same people, so the system has been optimized for peak performance and there shouldn’t be concerns about third-party integrators or service providers.

In 2001 in collaboration with JPL, Real Time GIPSY (RTG) was combined with the existing StarFire clocks and orbits algorithms and a StarFire GPS 10-cm service was offered. Nowadays StarFire GNSS has evolved out of that original correction service and claims impressive 5-cm accuracies using its multi-constellation GPS and GLONASS corrections.

The Starfire GNSS network.

StarFire also uses over 80 reference stations with mostly GPS/GLONASS receivers providing carrier phase data for redundant processing and distribution by L-band transmissions over the Inmarsat satellite network.

Then we come to the latest entrant into the land PPP business – TERRASTAR. The parent company Veripos has been around since 1989 and has been extremely successful in its marine business, going public in 2012 on the Oslo stock exchange. Veripos recently launched TERRASTAR to better address the land market for all the same good reasons discussed earlier. TERRASTAR provides two correction services: –M is meter level DGNSS and –D is a decimeter solution using both GPS and GLONASS. All the 80+ owned and operated reference sites around the world have dual-frequency GPS/GLONASS receivers, and there are plans to add Galileo and even COMPASS in the future.

Dual-redundant processing and network servers ensure uninterrupted distribution of GPS and GLONASS orbit and clock corrections, enabling decimeter accuracy for users. TERRASTAR distributes corrections over all seven Inmarsat GEOs, providing most land users with redundant L-band visibility.

Correction quality and availability are largely dependent on the number of reference stations that track the same GNSS satellite. The figures below show the location of satellites at a given time and the number of stations simultaneously tracking those satellites. For the TERRASTAR ground network, there are often more than 30 stations tracking the same satellite. This makes for high-quality clock and orbit corrections, and TERRASTAR-D claims to provide consistent, stable horizontal 5-10 cm and vertical 10-15 cm performance.

The TERRASTAR network.

As a new player, TERRASTAR has yet to corner a whole bunch of customers, but it already has some significant customer applications. It “GEO-Gates” its corrections like other providers to ensure usage on land, but it extends coverage to land areas plus about 6 km beyond the coastline — termed “nearshore.” So TERRASTAR has been able to capture in-shore dredging and construction business in Europe that otherwise might have had to go to more expensive marine correction services.

In addition, a new customer is using TERRASTAR for airborne geophysical applications. There are also ongoing trials on excavators in road construction, on trains, in oil and gas, for GIS/surveying, and with integrated agricultural sprayer-control and harvesters. TERRASTAR plans shortly to offer a web-based e-Commerce System for users to control their subscriptions. TERRASTAR and Septentrio/Altus have long-term relationships for receivers/systems, and Septentrio and Altus also retail the TERRASTAR service.

So, just when you think you have a good picture of PPP, another option for users has started to show up. PPP over internet — or iPPP as Nexteq Navigation in Calgary, Canada terms their service – is designed to provide similar corrections as PPP, but over cellular phone or Wi-Fi connection to the internet, rather than over satellite. With single frequency GPS, Nexteq claims accuracies of around 50cm, and 10cm with dual frequency, although their T5 and T5A handhelds only currently support L1. Of course Trimble has had corrections over the internet for a number of years.

So its clear that PPP services continue to evolve and become more and more sophisticated to match the growing complexity of customer applications. And as achievable accuracies improve, we’re seeing use in higher precision applications which would have seemed impossible just a few years ago, where local RTK base-stations and radio links would have been the only way to go.

With several very capable sources to choose from, GNSS industry customers have several options to carefully assess and fit to their business. Each PPP supplier has specific advantages and features available to meet customer expectations. The market now appears to be large and specialized enough that its inviting for new entrants. And each new entrant seems to bring with them new twists and capabilities which sell their services. As a customer, it’s a good time to trial new precision applications with PPP.

Tony Murfin
GNSS Aerospace

By Don Jewell

It had to happen sometime. I just thought or hoped it might take a few more years.

But I guess I should not be surprised since I experienced a wonderful 30-year U.S. Air Force (USAF) career and that has been over for more than a decade. I have been working GPS issues since 1978. So I guess it should not have come as a surprise when just a couple of weeks ago a wet-behind-the-ears USAF 2^nd Lieutenant actually inquired of me, in a public GPS-related forum no less, “So, what did you do in the war, granddad?”

Several irreverent and potentially satisfying responses immediately came to mind:

1. I am not your granddad.
2. Where do you get off asking me a question in that tone of voice?
3. Frankly, it is none of your business.

Instead, I simply inquired, “Which one?” This obviously unexpected response necessitated a long pause while the offender, a now obviously-easily-confused 2^nd Lieutenant, ruminated about which war(s) to inquire. For my part I was ready to hit him over the head with my cane if he responded with WWII. Of course I would probably have been accused of child abuse, so he saved the day and a possible court date when he replied in a questioning falsetto, “Vietnam?”

I won’t bore you with my response. However, since that unfortunate “age discrimination” incident (from both parties), it has occurred to me that many of us who were privileged to experience GPS in its infancy are certainly not spring chickens. Indeed, many (Dr. Ivan Getting for one) have passed on to their great reward. Remember, Professor (Colonel) USAF Ret. Bradford Parkinson, who created and ran the NAVSTAR GPS Joint Program Office from 1972 to 1978, was a full colonel in 1972. However, that says nothing about commitment or expertise. Most of us, Brad included, are still as engaged and passionate about the future of GPS as we ever were. Consider that the first satellite in the system, Navstar 1, was launched February 22, 1978. In just a few months the GPS operational constellation will be 35 years old, and Air Force Space Command is celebrating its 30^th anniversary this year. My point being that few operational space systems, if any, engender this type of lifelong loyalty, passion and dedication. Plus, those of us who count ourselves among the original sojourners on this amazing journey, especially those who are graying and threatening to beat impertinent whippersnappers with canes, are actually very proud of the fact that we are still engaged, and even more amazed and heartened that there’s a generation of young USAF and other military personnel, engineers, scientists, inventors, and everyday believers to follow in our footsteps. I highlight the USAF personnel because they are the official stewards of GPS.

Indeed, at the recent ION GNSS Conference held it Nashville, Tennessee, it was apparent that many of the youngsters (many of whom are Ph.D.s) are just as engaged as we are. They see a future for GPS and PNT (position, navigation and timing) systems that we may never have imagined. As prescient as many of us “seniors” claim to be, I have no doubt, indeed I fervently hope, that the young men and women following in our footsteps will achieve feats with GPS and PNT systems of which we never dared dream.

ION GNSS 2012 – Nashville

I state here without equivocation or worry of being challenged that the plenary at this year’s event, which was titled “GNSS Revolution, the Catalyst of the New Information Age,” was the best I have ever encountered at any ION event in the past twenty years. Dr. Jade Morton from Miami University was an excellent moderator and kept the program moving along, but it was the presenters, their evident, extensible passion for their subjects and their excellent presentations (see list below) that made the night unforgettable:

GPS and Agriculture

Tony Thelen, the first presenter from John Deere — yes, the people who make green farm and lawn tractors among other things — actually made GPS and agriculture sound interesting. His presentation was top notch. It certainly kept my interest, and he left me wanting to know more about GPS and agriculture! Of course, I am being a bit disingenuous, since one of my most requested columns, titled “The Farmer in Finland,” concerns the unparalleled John Deere StarFire system, which probably deserves another column soon. Conversations with plenary attendees after his excellent presentation indicate that Tony managed to ignite that spark and interest again for many in the audience. The effect that GPS and companies like John Deere have had on agriculture is simply amazing, and the quantifiable benefits almost beyond belief. Plus, according to Tony Thelen, there is good reason to believe we will continue to be astounded at what the future holds for GPS and agriculture. I encourage you to visit the ION website and review not only Tony’s excellent presentation, but all the ION GNSS 2012 Plenary presentations.

GPS Forensics

When you have three excellent and inspiring speakers lined up for an evening of edification, you always face the conundrum of order. Should the featured or most entertaining speaker be in the middle, or should you risk losing some of your audience early and build toward a climax? With this audience Dr. Jade Morton made the wise decision, and put the most anticipated speaker in the middle of the lineup. There is always great expectation on my part, and I expect from most of the audience, when Professor David Last is scheduled to speak. At Nashville, he certainly did not disappoint. Only the infamous tonal chimes from “Law and Order” could have made his presentation any more dramatic.

For my part, I kept expecting to hear those infamous tones whenever David transitioned to a new slide. David’s presentation was a perfect combination of “Law and Order” combined with “The World of Stupid Criminals.” With material like that, how could it have not been a roaring success? Add the dulcet British Public School accent and perfect comic timing and delivery and you can’t fail. Indeed, anyone listening outside the auditorium that night would have thought they had stumbled upon a standup comic convention instead of a bunch of staid scientists and engineers listening to a presentation on GPS forensics.

David is always interesting, but that night he was competing for and in my book won the ION GNSS Emmy. If you ever have the chance to hear Professor David Last speak publicly, don’t miss it. And criminals in the UK should just surrender — they don’t stand a chance in court against a consulting engineer and expert witness like Professor Last. I dare say even Sherlock Holmes, the famous consulting detective, would be proud of Professor Last.

Cold Atom Interferometry

None of this lessens the impact or obvious passion for his subject displayed by Professor Mark Kasevich from Stanford University. It is not that I don’t have a passion for cold atom interferometry, it’s just that two weeks later I am still trying to figure out what he said and how it applies. I have no doubt that you can, excuse me, that Professor Mark Kasevich can, construct a cold atom interferometer that can be used to determine a position or a fix; I am just trying to figure out how that 10-cubic-foot rack is going to fit into anything remotely mobile. But, of course, even the optimistic Professor Kasevich admitted that mobile or handheld atom interferometers of this caliber are probably 10 years in the future.

So, at this years’ ION GNSS Plenary event, the audience was treated to a down-to-earth and yet exciting look at the future of GPS and agriculture: the comedic and yet brilliant GPS forensic expertise of a passionate John Cleese wannabee, a caped crusader who is feared by criminals everywhere, and the futuristic “Star Trek” look at cold atoms and interferometry. What more could you ask for? This was an evening that for me elucidates the best ION GNSS Plenary ever. My hat is off to ION Executive Director Lisa Beaty and Plenary Program Director Dr. Jade Morton for an excellent program, but mostly I applaud all three speakers for a wonderfully educational and entertaining evening. How often do you get to combine those adjectives?

GPS World Leadership Dinner and Annual Awards Ceremony

However, for myself and many others the highlight of the ION GNSS event for the past several years has been the annual GPS World Gala and Dinner, now known as the annual GPS World Leadership Dinner and Awards Ceremony. This wonderful and prestigious event is the brainchild of Alan Cameron, our beloved editor-in-chief and now publisher of GPS World. Every year the event just gets better and better. The venues are always palatial, and this year was no exception as we held the event at the beautiful Nashville Hermitage Hotel. The stained-glass ceiling in the lobby was astounding.

Stained-glass ceiling in the Hermitage Hotel, location of this year’s GPS World Leadership Dinner and Annual Awards Ceremony.

I won’t say much more since Alan wrote a complete review of the evenings events, except to caution you that invitations to this wonderful event are extremely hard to come by, and if you are nice to me, who knows? You might receive an invitation next year. It reminds me of the admonition from my daughter, a PsyD in Psychology and a practicing clinical psychologist, when she says: “You should always be nice to me Dad. Remember, I get to pick your nursing home!”

Kudos and Final Thoughts on ION GNSS 2012

I can’t complete my comments on ION GNSS this year without pointing out that the venue, Nashville or Music City, and the Renaissance Hotel by Marriott were both outstanding. The ambience of the entire event was professional yet also warm and friendly, and the ION staff as well as the staff at the Renaissance could not do enough to make my stay more memorable. The Renaissance staff was extremely professional and attentive, working hard to make the event a success. I am already looking forward to next year’s conference, which will be held at the same location September 16-20, 2013. Book early and arrive early for reasons I elucidate next.

Lest we forget, while the ION GNSS is the main performance, the center ring if you will, it is historically preceded by the Civil GPS Service Interface Committee (CGSIC) meeting, which is co-chaired by the United States Coast Guard (USCG) NAVCEN/CC. The CGSIC has been around for 52 years, and was outstanding this year. Yes, the title sounds incredibly dry and boring, but CGSIC meetings are actually very informative, down to earth, informal and even occasionally entertaining. The new USCG NAVCEN commander, Captain William Burns, and his NAVCEN team did an excellent job putting the event together. So, again, I highly recommend arriving a couple of days early for next year’s ION GNSS in Nashville, so you too can attend the CGSIC. You will find it worthwhile.

LightSquared

As much as I hate to close my column on a downer I must unfortunately inform you that the amnesiacs at LightSquared (LSQ) are at it again. Not exactly the same amnesiacs, of course, as their CEO resigned in February, and Philip Falcone from Harbinger, whose solipsistic behavior resulted in a federal security SEC indictment for fraud, joined the LightSquared board recently. The U.S. Securities and Exchange Commission recently filed securities fraud charges against Falcone and Harbinger Capital Partners. However, this has not slowed LSQ as it subsequently on Septembert 28 submitted two proposed spectrum sharing filings with the FCC, proposing to utilize the lower 5 MHz of LSQ’s non-existent broadband network in a form that was not initially sanctioned or envisioned and, according to the filings, will not interfere with GPS signals. LSQ did not submit any evidence or test data to prove the lack of interference, just conjecture. These filings, of course, are in addition to LSQ’s recent filing for Chapter 11, better known as a bankruptcy filing. Plus, Philip Falcone has publicly alerted the FCC that LightSquared will not go away!

Where have you heard this song and dance before? I have read both filings very carefully, and they are filled with the same flawed technology and total refusal to adhere to the laws of physics as their previous filings. LSQ fails to understand that you cannot abrogate the laws of physics merely because they are inconvenient and interfere with your grand scheme. Previous test results have determined that transmitters as powerful as the ones proposed by LSQ will interfere with GPS signals no matter what portion of the immediately adjacent spectrum bands are proposed.

The latest filings clearly seem to be a last-gasp effort of a dying company that is attempting to snatch victory from the jaws of defeat. LSQ must think the U.S. government has an incredibly short attention span. In my humble opinion, if the FCC were to approve either of the proposed filings, pilots, airlines and passengers at Ronald Reagan National Airport and other major airports on the East Coast would be unable to use GPS to fly out of or navigate to the airports. LSQ continues to think it is more important to be able to tweet, “I just saw Elvis” than it is to navigate safely to your destination. However, as improbable as the acceptance of these LSQ filings may be, in a recent memo I warned my GPS/PNT colleagues, via notable quotes you may recognize,  “…unfortunately this is not over, ‘prepare for boarders’ and remember ‘we have not yet begun to fight’.”

GPS II-F 3

Fortunately, I won’t end on a down note after all. As I write this, the third GPS IIF satellite, designated SVN-65, is on orbit being checked out by the 19^th SOPS (Space Operations Squadron) with LADO (Launch, Anomaly, and Disposal Operations) software developed by Braxton Technologies. My hat is off to AFSPC (Air Force Space Command), SMC (Space & Missile Systems Center), Boeing, ULA (United Launch Alliance), the 50^th Space Wing, and Braxton Technologies for a successful launch and hopefully a quick and flawless checkout. It has been a long 15 months since the last IIF launch, and this is the only launch in calendar and FY12. Plus, technically the satellite on orbit is actually satellite vehicle (SV) four, as SV three is undergoing some necessary changes. Most experts expect a minimum 30-day checkout. However, my sources tell me it could be as long as 90 days. Wouldn’t it be great if it were sooner? We will just have to wait and see. Stay tuned to GPS World for the latest news on GPS IIF-3. The good news is we have another GPS IIF on orbit.

Until next time, happy navigating, and remember all of us at GPS World now have new email addresses in the following format. If you wish to email me please do so at djewell@gpsworld.com. I look forward to your comments.

Today’s demand for a wide range of unmanned aerial systems (UAS) has resulted in a lots of different types flying today in many applications. With no apparent standard avionics fit or uniform safety standards, each UAS type is basically configured for specific tasks. As commercial applications for UAS emerge, major market growth is anticipated. One forecast indicates that the UAS market could reach $7.26 billion this year alone. The promise of new and better ways to reduce costs, improve safety, and for more efficient operations is feeding a real market expansion.

However, in the U.S. the FAA currently requires each UAS commercial project desiring access to controlled airspace to obtain an FAA-approved Certificate of Authorization (CoA). While the FAA has made efforts to speed up approvals, this process has put a damper on widespread commercial adoption of UAS. Nevertheless, opportunities abound in pipeline and transmission line inspection, crop spraying, expanded law enforcement/security, and hundreds of other applications. The FAA may have felt some pressure to move forward, because Congress has put in place the Modernization and Reform Act of 2012, which calls on the FAA to fully integrate unmanned systems, including those for commercial use, into the national airspace by September 2015.

Cadence Technologies SR-20.

Meanwhile, a project called the Unmanned Aircraft Systems Integration in the National Airspace System (or UAS in the NAS) undertaken by NASA’s Dryden Flight Research Center at Edwards Air Force Base, California, seeks to reduce technical barriers related to safety and operational challenges associated with enabling routine UAS access to the NAS.

Civil aircraft and UAS may co-exist after September 2015.

NASA Predator test vehicle.

Europe is also undertaking a study on the integration of unmanned aerial systems (UAS) in non-segregated airspace for the future “Single European Sky”. The study, known as ICONUS (Initial CON OPS for UAS in SESAR), will be carried out by a consortium within the European air traffic management program called SESAR. The group is led by France’s ONERA, and includes AVTECH (Sweden), CIRA and Deep Blue (Italy), ENAC (France), and INTA (Spain) — all have significant experience with UAS. The study will allow the definition of the requirements, capabilities, and the equipment that UAS will need to operate safely and efficiently in the coming European SESAR environment.

In the U.S., the RTCA SC-203 committee is busy drafting UAS operational requirements, and there has been significant progress towards ultimately publishing Minimum Aviation Performance Standards (MASPS), including requirements for navigation. Europe also has similar activities under way aimed at improving UAS access to their airspace.

The big picture is that requirements for unmanned aircraft are being brought into conformance with the standards applied to the performance and behavior of manned aircraft. Navigation requirements for UAS are expected to specify that systems will need to be qualified to Minimum Operational Performance Standards (MOPS). This means that on-board electronics, including GNSS systems, will probably need to be FAA TSO qualified, just as they are now for manned aircraft.

But why do we need to investigate certified avionics now? In the scheme of things, +2 years of breathing space to certify UAS avionics systems is not long before the September 2015 deadline. FAA airborne software and hardware qualification will take mucho time and effort to implement, and reconfiguration of systems, interfaces, and operating procedures may take even longer.

UAS manufacturers have the option to move forward in stages — for instance, by selecting a few existing airborne qualified OEM avionics, they could minimize the internal effort to comply. And as the first UAS with certified avionics emerge, they will probbaly get good support from FAA to adopt the rules of operating in the U.S. NAS. Embedding an existing certified GPS receiver in UAS avionics will reduce the level of internal work needed and will allow more effort for developing commercial market opportunities which are looking to quickly adopt UAS.

And while this is going on, efforts are in full swing to change the navigation landscape in the U.S. and Europe over the next few years. So it would be better to be ready with a capable GNSS receiver that is already built to meet the challenges of the FAA NextGen and SESAR environments.

The L5 civil GPS frequency may likely be operational around the time that UAS unrestricted access becomes possible. GPS L1/L5 dual-frequency operations will enable higher navigation accuracy, reliablity, and integrity. The FAA is already developing NexGen WAAS to include L5, and revisions to the GPS MOPS to include L5 are anticipated to begin shortly, in time for a usable GPS L5 constellation in 2015/2016.

The FAA is already preparing for L5 avionics, and industry investigative work is under way. It’s possible that GPS L1/L5 may well meet the accuracy and integrity requirements for CAT II/III automated landings. And in Europe, Eurocae work is expected to gain momentum for the Galileo E1/E5a MOPS as the Galileo satellite navigation system is launched and becomes operational.

The new GNSS environment also includes WAAS/SBAS precision approach (LPV) capability — LPV is available now in the US and will soon be in wider operation in Europe. And Automatic Dependendant Surveillance (ADS-B) is being rolled out in the U.S. and around the world. ADS-B is being mandated within the U.S. NAS as the means for air traffic control to track all aircraft, so UAS avionics will need to include certified ADS-B Out capability.

The Septentrio AiRx2 receiver comes out of the box as a certified L1 GPS with ADS-B and WAAS LVP, but is also ready for GPS L5 and Galileo E1/E5a.

Septentrio L1/L5 AiRx2 airborne receiver.

And yet, even as greater steps forward are being taken to enhance how GNSS is used in this wider definition of aviation, which will soon include UAS, a team at the University of Texas was busy demonstrating how a UAV could be maliciously side-tracked (see article in the August issue of GPS World). Their recent tests at White Sands Missile Range used a spoofing set-up built in their lab to significantly affect the trajectory of a Hornet Mini UAV. Admittedly, the GPS on this vehicle was not a qualified airborne receiver, but there were other sensors on board the vehicle which may have been able to indicate that the GPS had been hijacked. The spoofing set-up used a high-power directional signal to overwhelm the real GPS signals and “distract” the GPS on-board receiver. Nevertheless, they were able to force the hovering UAV down towards the ground — somewhat reminiscent of the Iranian downing of a U.S. surveillance drone in December last year.

How could this happen when there was also an inertial sensor and a radio-altimeter on the UAV? A good question, which UAV manufacturers will need to consider when they implement their on-board Kalman filters, knowing that spoofing is now an additional threat to combat. But, couldn’t we detect that high-power RF spoofing signal at the front-end of the GPS receiver? Even if only to tell the on-board systems that there could be Hazardous Misleading Information (HMI) about? Or run separate GPS and GPS/inertial position solutions, detect significant divergence, and set the same warning flag? And multi-constellation, multi-frequency receivers, and even controlled radiation pattern antennas — all things to investigate, and even more effort for the aviation receiver guys who are always working tirelessly to improve the integrity of GNSS positioning.

Of course, if you hijack a UAV with a high-power spoofer, you are also spoofing civil transports operating in the same airspace — so now there is the potential to trigger a federal investigation. And it will probably be easier to detect this stuff with moving airborne sensors rather than the fixed ground equipment used to find jammers on trucks at Newark Airport, and lots of pilots likely providing real-time location information on radios if their GPS goes even a little haywire — all would help to quickly locate and shut down any spoofer. Nevertheless, it’s a threat to be mitigated.

In South Korea, the effects of intermittent North Korean jamming of GPS to disrupt navigation at sea, on land, and in the air in the south may have contributed to the recent fatal crash of a Schiebel Camcopter S-100 drone — a 150-kilogram rotorcraft capable of 220 km/h flight, which should have coped with loss of GPS as the Camcopter has multiple inertial measurement units that “allow safe operation and recovery in the absence of GPS signals.”

Schiebel Camcopter S-100.

Schiebel, however, has indicated that information recovered to date indicates that after the loss of GPS signals to the aircraft’s receivers, there may have been incorrect handling and operator errors which resulted in an unfortunate chain of events that ultimately led to the crash.

Emergency procedures “to ensure a safe recovery in such a situation” do not appear to have been “correctly and adequately followed,” Schiebel alleges.

NovAtel may have found one way to help mitigate spoofing on UAVs — they just released a combined civil/SAASM GPS receiver, the OEM625S, aimed specifically at UAVs. Granted, the idea is to add SAASM anti-spoofing capability to a number of UAVs which currently use NovAtel commercial receivers — mostly in military systems. And of course that may well be motivated by the desire to avoid any further Iranian incidents!

BAE Systems has obviously been thinking of giving GPS a back-up for just those situations where jamming or even spoofing is detected. BAE’s system was just announced at the Farnborough Air Show in the UK and is still in the research phase, but looks extremely promising. Known as Navigation via Signals of Opportunity (NAVSOP), it interrogates the radio environment for the ID and signal strength of local digital TV and radio signals, plus air traffic control radars, with finer-grained adjustments coming from cellphone masts and Wi-Fi routers. Mapping the locations of all these sources might be quite an undertaking, and given that these are all non-safety-of-life commercial signals, the sources are subject to the vagaries of power outages, regular maintenance, and breakdowns. Nevertheless, with such a multitude of signals, NAVSOP could well turn out to be a viable back-up for GNSS.

Aerostar 5C UAS.

Meanwhile, the Association for Unmanned Vehicle Systems International (AUVSI) big show is set to run August 6-9 in Las Vegas. With more than 500 exhibitors, attendance is expected to be more than 8,000 people from all over the world. All the key manufacturers, suppliers, and users of UAS are expected to be there, so it’s a great opportunity to meet people working with UAS and see some of the hardware and systems. Hopefully we will be able to get a feel for how the industry sees the onset of commercial market opportunities and the changes this may mean to systems and vehicles. It will be my first time walking round all these exhibits and seeing the live demos, so I’m very excited to be able to find out even a little about what makes this industry tick! More on this later…

So, shared access to civil airspace, wider applications in commercial operations, and changes in equipment qualification — along with potential solutions for GNSS jamming and spoofing — lots to consider for the UAS industry.

Tony Murfin
GNSS Aerospace

Across transportation, agriculture, industry, commerce, and finance, GPS has replaced earlier technologies, opened up innovative applications, and led to new ways of doing old things. GPS now plays a key role in the critical infrastructures of all industrialized nations, from the most sophisticated telecommunications system to the production of a simple loaf of bread.

Wheat is the world’s second staple food, and bread its main product. Bakers have been around for 30,000 years. GPS, among its manifold other duties, now also helps bring us our breakfast toast and midday sandwich.

British farmers sow 2 million hectares (5 million acres) of wheat per year, harvest 8 tonnes per hectare (3.6 U.S. tons per acre) and sell it at £150 a tonne ($214 per U.S. ton), making their harvest worth £2.5 billion ($3.9 billion). Nearly a billion pounds-worth ($1.6 billion) goes to make bread.

We use Britain as an example because we are British, but this same truth holds, at much grander scale, when you consider the United States, Russia, and many other European nations.

A vital value chain wends its way from farm to mill to bakery to store to home: in the UK, 99 percent of households buy bread, 99 percent of which is made in this country, 80 percent of it from domestic flour. This relatively closed value chain lets us see how GPS is used, and that its loss would increase the price of a loaf and translate into inflation.

GPS serves as the basis of the precision agriculture, cutting fuel costs and enabling selective and variable rate optimized application of fertilizers. It lets farmers use less manpower, reduces soil compaction, and even minimizes operator fatigue. Farmers now spend much more time on yield monitoring and within-paddock zone management than leaning on gates chewing straws. Though the capital cost of precision agriculture is high, the annual benefits are comparable with the investment. Losing GPS-based precision agriculture would increase the price of bread by at least 2 percent.

Transport logistics is the glue that joins our value chain together. GPS in fleet management optimizes routings, accelerates dispatching, prevents theft, improves driver behavior, and delivers fuel efficiencies. Loss of GPS in the transport links in our chain would increase fuel costs alone by 13 percent.

On top of all this, GPS is the ultimate source of precision timing supporting telecommunications links at every stage of the value chain, from wheat futures trading and banking transactions to voice, data, and Internet traffic.

The sudden loss of GPS in farming, transportation, communications, business management, and retail distribution, would substantially raise the price of bread, hit every household, and impact the national economy.

What applies to a traditional  and at first glance low-technology product like bread applies across the board. The recent report on GNSS vulnerabilities by the Royal Academy of Engineering says that GPS and other satellite navigation services have applications so pervasive that there is now a real threat to global security if the systems should fail — or be interfered with. The signals are used by almost every industry: rail, road, aviation, space, maritime, agriculture, energy, surveying, construction, law enforcement and communications.

Dependence on GNSS connects many otherwise independent services into a so-called accidental system — with a single point of failure, the satellite signal. And a satellite signal, says the report, is a weak foundation for important services, since it can fail in dozens of ways.

GPS is no longer the only GNSS, of course, as many nations, recognizing its political and economic value, have developed their own systems, and augmentations to enhance accuracy and integrity. Over the next few years, the number of navigation satellites may approach 150. This will help reduce vulnerability to the loss of GPS and so will be a benefit in the short term.

But the long term is a very different matter. All these systems now use, or shortly will use, essentially the same technology. And, crucially, the same radio frequency bands.

In those frequency bands, GNSS is threatened by rising levels of radio interference. This threat has several strands that are being recognized separately and handled individually, but which taken together will determine the future of GNSS.

We face a Triple Whammy!

The First Threat

The first component of the Triple Whammy comes from the new satellite systems themselves. Each satellite transmitting in the GPS frequency band increases the noise level there. Satellite navigation receivers must find and lock onto the extremely weak signal that reaches the Earth, digging it out from the background noise of the cosmos. And the other GPS satellites add to the noise level.

Günther Hein of the European Space Agency shows this remarkable diagram (Figure 1): as the number of systems increases and the number of satellites heads for that 150, up rises the noise they make, the blue-green line. More than about 70 of them, and satellite noise exceeds the cosmic noise floor in red and becomes the main source of noise. The more satellites, the worse the reception as GNSS interferes with itself. Too many satellites, and you’d pick up none at all! The first threat of the triple whammy is self-inflicted.

Figure 1. The first threat of the Triple Whammy: new satellite systems. Source: Günther Hein.

The Second Threat

Conflicts between nations as their new GNSSs compete for radio spectrum also threaten GNSS viability.

The frequency bands available to satellite navigation are essentially L2, L5, and the principal one we use currently, L1. On L1, the European Galileo system and the Chinese Compass system occupy the same areas. Now, that’s very desirable if the two systems are to share receivers. But they also compete for that spectrum, and there is conflict between Compass and Galileo.

This battle for spectrum is a highly complex engineering problem. But chiefly, the spectrum wars are political, even emotional.

Chinese satellites fly across American skies broadcasting signals that interfere with European receivers. Spectrum wars have everything to do with relationships between nations and little to do with battles between engineers. They are developing into a classic tragedy of the commons: a situation in which self-interest determines how a limited resource — here the radio spectrum — is to be shared in a regime in which regulation is weak. The International Telecommunication Union sets standards and registers claims. The UN Office for Outer Space Affairs seeks to mediate. But neither is a policeman; sovereign governments may sometimes be penniless, but they are very powerful.

The second threat of the Triple Whammy is also self-inflicted.

The Third Threat

Communications systems compete with GNSS for spectrum: witness the current LightSquared case of a powerful new broadband system. For existing receivers, including those in government systems and aviation, it seems there is no fix for its devastating interference. LightSquared is driven by rich and powerful commercial forces; it could well win this fight.

Communication technologies will continue to press upon the satellite navigation spectrum. LightSquared will likely erode spectrum gaps between communications and navigation services, the so-called guard bands.

Satellite navigation has become highly political. The intense use of GNSS across our economies makes them vulnerable. GNSS is threatened by a Triple Whammy, by jamming, and by spoofing. These increase the risks to our security and our economies, both in probability and impact. The solution of detecting jammers and making ownership illegal will help with local problems in local areas. But the Triple Whammy threats are not local; they are national and international, world-wide.

Today’s spectrum wars affect us all. That the loss of GPS would increase the price of a loaf — the very trigger for the French Revolution — brings this down to earth.

These are not technical issues, they determine the price of our food! They constitute a real and present danger to our societies — down to the mundane yet very real level of our daily bread.

David Last is a past-president of the Royal Institute of Navigation, a consultant and expert witness on radio-navigation and communications systems to companies, governmental and international organizations, and criminal investigators.

Sally Basker, former director of research and radionavigation at the General Lighthouse Authorities of the UK and Ireland, has opened Traxis Ltd: management, business, and technology advice with expertise in navigation service provision. See www.traxis.co.uk.

This article is adapted from a presentation at the European Navigation Conference, London, November 2011. A longer version of the talk appears in the Royal institute of Navigation News.

By Rob Lorimer

Open-pit mining (also called open-cut, open-cast, and strip mining) has historically been an early and innovative adopter of new positioning technologies. Some of the earliest examples of fitting GPS to heavy earth-moving machinery occurred in the U.S., Australian, and Canadian mining industries in the 1990s. Miners were also quick to adopt the first GPS/GLONASS systems. The trend continues today with trials of new radio positioning technologies such as the Novariant Terralite XPS and the Locata system.

Phase 2 of a global mining boom is underway, driven by an apparently insatiable appetite for primary resources from developing economies such as China and India. Indeed, according to one study by Access Economics, to meet projected demand the production of some commodities such as nickel and zinc will need to double in the period 2000-2020; others, including coal and iron ore, will need to increase by 40-60% over the same period.

The response from the mining industry is two-fold. First, increase the productivity of existing mines; second, explore and develop new mining territories. Both these responses increase the demand for positioning systems, but we will focus here on first response.

Increased Productivity. Increasing the productivity of existing mines can take several forms, including extending the life of the mine and extracting the commodity more effectively. The former is generally driven by higher commodity prices (previously marginal deposits become viable); the latter is driven by adopting improved practices and new technologies, including those incorporating positioning components.

Productivity gains from new technology are multiplied by the scale of the mining operation, so it is no surprise that the largest mines were the first to experiment with and adopt new position-based systems, particularly in earth moving and commodity handling. The scope for productivity improvement is huge — there are more than 100 open-pit mines that move more than 1 million tonnes of material per week, about half of which are in Australia, Canada, and the U.S. Another 600-700 open-pit mines worldwide move between 10-50 million tonnes/annum, and a further 1,500 or so move 1-10 million tonnes/annum. On top of these there are tens of thousands of smaller mines and quarries, although to date most of these do not use innovative practices or technologies.

Just as new practices were usually adopted first in the super-mines and then progressivity smaller operations, there was a similar trend to apply new positioning-based solutions first to the largest earth-moving machines and then to progressively smaller machines and vehicles. As this process unfolded during the 1990s and 2000s, a number of companies emerged as global technology suppliers for mining, including the Caterpillar/Trimble Joint venture, Modular Mining (owned by Komatsu), and Leica Geosystems. However, there remains a vibrant small- to medium-enterprise (SME) positioning-based solutions sector in mining, most of which is focused on technology niches (for example, Novariant, APS, and Accumine.

Collision Avoidance. As positioning-based solutions progressively made their way onto heavy machinery (such as draglines, excavators, and dozers), and haul trucks and auxiliary equipment (drills and explosives trucks) for production purposes, another set of suppliers were eying up positioning technologies for a different reason.

As mines increase production from existing operations, site traffic increases and so does the risk of collisions. Of particular concern are collisions between heavy and light vehicles, which have a high probability of serious injury or fatality. There are many safety issues to be addressed: mining machinery and haul trucks have extensive operator blind spots, haul roads are unsealed and need constant maintenance, blind corners are common and intersections change frequently. Add to these issues 24-hour working, driver fatigue, frequent poor visibility caused by dust or snow, and the requirements for safety systems becomes apparent. The second wave of suppliers adopted GPS, RFID, lasers, radar, and other technologies to develop a range of driver adherence, situational awareness, proximity detection, and collision avoidance systems. These companies include Caterpillar, SafeMine, AMT, 3DP, and others (see the Professional OEM newsletter from July 2009 for a fuller discussion on GPS-based safety systems in mining).

When we add together the positioning requirements for both production and safety systems, we start to get a feel for the variety of positioning solutions applied on large open-pit mines today as illustrated by the table below. Indeed, on some of the most advanced mines virtually everything that moves, or can be moved, is fitted with some sort of positioning device for production, operational, logistics, or safety reasons.

TABLE 1. Positioning options for open-pit mining. GPS remains a popular choice.

As the table illustrates, despite its limitations in deep open-pit mines, GPS remains a popular choice for positioning and can be found on most platforms from people to heavy machinery. GPS/GLONASS (GNSS) receivers have largely replaced GPS-only receivers for heavy machinery, haul trucks, and auxiliary equipment (such as drills) as it delivers improved availability over GPS. However, the cost of GNSS receivers has meant they are not as popular on the more numerous light vehicle fleets. With low-cost GNSS chipsets coming on the market, we can expect this situation to change quickly over the coming years.

Both high-end (HI Inertial) and low-cost (LO Inertial) technology are deployed in open-pit mining, usually in conjunction with GPS or GNSS. High-end inertial systems tend to be in machine control systems; the low-cost devices, including electromagnetic compasses and accelerometers, are more often used in vehicle and personal safety devices.

In the table above, I have distinguished between radio positioning and radio location technologies. The former are dedicated positioning systems such as the Novariant Terralite and Locata, which deliver precise positioning from planned networks of transponders on site. The latter derive location from communications systems, and are generally accurate to a few meters (for example, the 3DP systems built on a Motorola Motomesh backbone).

Radio Frequency Identification (RFID) location is well established in the mining industry for both underground and open-pit operations. Although not used for high-precision machine control applications, RFID can be found on all platform classes for safety, operational, and logistics purposes.

Both Electronic Distance Measuring (EDM) and laser technology are used to position machines and haul trucks. As these are line-of-sight systems, they tend to be deployed in close proximity to work areas. Laser technology is used with roadside beacons to locate and navigate trucks along haul roads.

Finally, radar is used in several safety systems for proximity detection and collision avoidance, but can also be used with roadside beacons for navigation and location.

Positioning Mix. The reali
ty is no single technology has the right mix of precision, availability, and cost to meet all the production, operational, logistical, and safety applications within open-pit mining today. System integrators are experimenting with different combinations, with many claims and counter claims about which mix is superior. What may well be a deciding factor for success is which positioning technologies (or technology combinations) are scalable to non-mining applications; that’s where GPS, GNSS, and RFID have a distinct advantage today.

To learn more about positioning technology in mining, including a more detailed look at one of the new radio positioning technologies, tune into my webinar at 1 p.m. PST May 20, or download it post event.

A deeply cut open-pit mine. (Image courtesy of Brendon Lilly.)

Digging for Accuracy

By Geoff Roberts, Leica Geosystems

A reality of open-pit mining is the challenge of GPS positioning coverage as the mine is cut deeper into the earth, and with the price of minerals rising, miners are digging deeper than ever before. Reduced sky view to satellites, especially where machinery is working near pit walls, can cause signals to become obstructed. With high-precision machine-control systems heavily utilized on mining equipment, a loss of positioning signal affects mine productivity. For years, Leica Geosystems has addressed sky-view issues by offering hybrid positioning for its high-precision mining machine control systems, using GPS and GNSS signals. While this has seen great advantages, GPS and GNSS share the same weakness as the pit is cut deeper or when operating against a high wall.

Recent developments aimed at making systems less dependent on satellite signals has resulted in the successful integration of a “local positioning constellation,” through technology developed by Locata Corporation. LocataLites are positioned around the rim of the pit and transmit to machinery-mounted receivers integrated into Leica Geosystems’ high-precision machine-control system, acting as local satellites with the advantage of being visible to machine-control systems, independent of GPS/GNSS coverage.

With this integration, blast-hole drills, dozers, and shovels can continue operating to centimeter accuracy when GPS/GNSS is unavailable. LocataLites self survey using GPS at the surface level where coverage is trouble free, and can easily be moved around a site to cover holes in coverage. Locata positioning becomes more accurate as the pit is dug deeper due to gaining sufficient vertical geometry for 3D positioning, a great advantage as the pit grows down. Rigorous testing of Leica Geosystems’ Locata integrated system has been conducted at one of Australia’s largest mines over the last six months. Results have proven reliable and accurate, while delivering significant productivity gains through reduced downtime caused by GPS/GNSS coverage holes.