This will be known as the day in geospatial history that the floodgates were opened for small drones to be used for business. On that day, the Federal Aviation Administration (FAA) officially introduced new rules (so-called Part 107) that allow businesses to fly small (under 55 pounds) unmanned aerial vehicles (UAVs) in the U.S. airspace for business purposes.
There are still a few rules that need to be adhered to, but no longer do “wannabe” UAV pilots need to go through the painful FAA 333 Exemption process to begin flying UAVs for business purposes. The FAA has created a pilot certificate specifically for UAV pilots called the “Remote Pilot Certificate” that does not require any manned aircraft training.
Previously, UAV pilots authorized by the FAA were required to at least have an FAA Sport Pilot Certificate, which required at least 20 hours of manned flight training, among other things. Deployment of the new Remote Pilot Certificate will begin just two months from now, in August 2016, according to this announcement by the FAA.
In a nutshell, following is the operating environment under the new Remote Pilot (Part 107) rules:
Remote Pilot Certificate.
Be at least 16 years old. Pass a three-hour aeronautical knowledge test at an FAA Knowledge Test Center, requiring about 20 hours of study. Pay a $150 fee. The certificate is valid for two years.
Complete FAA Form 8710-13.
Maximum operating altitude is 400 feet AGL, or 400 feet AGL (above ground level) from a structure (e.g. building, roof).
Visual observer (VO) is now optional (was required under 333 Exemption) except if the pilot uses First Person View technology, then a VO is required.
UAV must weigh less than 55 pounds.
UAV must fly less than 100 miles per hour.
You can’t fly over anyone who is not directly participating in the operation, and not under a covered structure.
You can pilot a UAV from a moving vehicle in “sparsely populated” areas, but otherwise must be stationary (e.g. no piloting from other aircraft).
Daylight-only operations.
Pilot can only operate one UAV at a time.
Operations in Class G airspace are allowed without air traffic control (ATC) permission. Operations in Class B, C, D and E airspace need ATC approval. See description of US airspace here.
Operator does not have to be a certificated pilot if a certificated pilot is along side the operator.
Pilot must maintain VLOS (visual line of sight) of the UAS at all times.
If you have a requirement that exceeds one of more of the above restrictions, the FAA says that as long as you can show that your operation can be carried out in a safe manner, you can request a waiver (Certificate of Waiver and Authorization – CoA) via an FAA portal.
The remaining major hurdle for commercial operations is the requirement to maintain VLOS, which still is required under the new rules. With a rotary UAV (e.g. quad-copter) like what I fly, this requirement is easy to adhere to since the UAV isn’t traveling very fast and if you simply let go of the control sticks, it will hover. With a fixed-wing (conventional airplane airframe) UAV, this is not so easy. A fixed-wing can travel 30 to 40 mph, and can be out of VLOS within one minute, and it’s always moving. Nonetheless, even with the VLOS rule still in place, the new Part 107 rules grant a new, easily accessible and powerful tool to collect high-precision geospatial data.
The good news for geospatial professionals is that more UAV companies are focusing on the professional marketplace.
In 2009, 3D Robotics started targeting the DIY (do-it-yourself) UAV market, then the consumer market, and now are focusing on the professional markets like GIS, construction, etc.
Because the rules have opened up to a much broader audience, expect more vendors to offer more products and services for professional UAV operators. For example, at the Esri International User Conference this week in San Diego, Esri showcased its Drone2Map software product that allows Esri software users to process and consume UAV data into the ArcGIS ecosystem.
It’s no longer hype, folks. UAVs are here to stay, and they are becoming an increasingly powerful tool in the geospatial toolbox. The great news is that will all the UAV hype over the last few years, there’s many different vendors offering UAV hardware and softwares for you to choose from. All that competition will be reflected in the quality and price of UAVs on the market, benefitting the consumer.
This will be known as the day in geospatial history that the floodgates were opened for small drones to be used for business. On that day, the Federal Aviation Administration (FAA) officially introduced new rules (so-called Part 107) that allow businesses to fly small (under 55 pounds) unmanned aerial vehicles (UAVs) in the U.S. airspace for business purposes.
There are still a few rules that need to be adhered to, but no longer do “wannabe” UAV pilots need to go through the painful FAA 333 Exemption process to begin flying UAVs for business purposes. The FAA has created a pilot certificate specifically for UAV pilots called the “Remote Pilot Certificate” that does not require any manned aircraft training.
Previously, UAV pilots authorized by the FAA were required to at least have an FAA Sport Pilot Certificate, which required at least 20 hours of manned flight training, among other things. Deployment of the new Remote Pilot Certificate will begin just two months from now, in August 2016, according to this announcement by the FAA.
In a nutshell, following is the operating environment under the new Remote Pilot (Part 107) rules:
Remote Pilot Certificate.
Be at least 16 years old. Pass a three-hour aeronautical knowledge test at an FAA Knowledge Test Center, requiring about 20 hours of study. Pay a $150 fee. The certificate is valid for two years.
Complete FAA Form 8710-13.
Maximum operating altitude is 400 feet AGL, or 400 feet AGL (above ground level) from a structure (e.g. building, roof).
Visual observer (VO) is now optional (was required under 333 Exemption) except if the pilot uses First Person View technology, then a VO is required.
UAV must weigh less than 55 pounds.
UAV must fly less than 100 miles per hour.
You can’t fly over anyone who is not directly participating in the operation, and not under a covered structure.
You can pilot a UAV from a moving vehicle in “sparsely populated” areas, but otherwise must be stationary (e.g. no piloting from other aircraft).
Daylight-only operations.
Pilot can only operate one UAV at a time.
Operations in Class G airspace are allowed without air traffic control (ATC) permission. Operations in Class B, C, D and E airspace need ATC approval. See description of US airspace here.
Operator does not have to be a certificated pilot if a certificated pilot is along side the operator.
Pilot must maintain VLOS (visual line of sight) of the UAS at all times.
If you have a requirement that exceeds one of more of the above restrictions, the FAA says that as long as you can show that your operation can be carried out in a safe manner, you can request a waiver (Certificate of Waiver and Authorization – CoA) via an FAA portal.
The remaining major hurdle for commercial operations is the requirement to maintain VLOS, which still is required under the new rules. With a rotary UAV (e.g. quad-copter) like what I fly, this requirement is easy to adhere to since the UAV isn’t traveling very fast and if you simply let go of the control sticks, it will hover. With a fixed-wing (conventional airplane airframe) UAV, this is not so easy. A fixed-wing can travel 30 to 40 mph, and can be out of VLOS within one minute, and it’s always moving. Nonetheless, even with the VLOS rule still in place, the new Part 107 rules grant a new, easily accessible and powerful tool to collect high-precision geospatial data.
The good news for geospatial professionals is that more UAV companies are focusing on the professional marketplace.
In 2009, 3D Robotics started targeting the DIY (do-it-yourself) UAV market, then the consumer market, and now are focusing on the professional markets like GIS, construction, etc.
Because the rules have opened up to a much broader audience, expect more vendors to offer more products and services for professional UAV operators. For example, at the Esri International User Conference this week in San Diego, Esri showcased its Drone2Map software product that allows Esri software users to process and consume UAV data into the ArcGIS ecosystem.
It’s no longer hype, folks. UAVs are here to stay, and they are becoming an increasingly powerful tool in the geospatial toolbox. The great news is that will all the UAV hype over the last few years, there’s many different vendors offering UAV hardware and softwares for you to choose from. All that competition will be reflected in the quality and price of UAVs on the market, benefitting the consumer.
The eighth edition of the Geospatial World Forum took place May 23–26 in Rotterdam, The Netherlands, attracting professionals from the surveying and geospatial information system (GIS) sectors. I attended the event on May 24 and took part in a workshop that looked at the benefits of Galileo and EGNOS in geospatial applications in the context of the imminent launch of Galileo initial services.
An industry survey undertaken by the GSA indicates that already more than 80 percent of GNSS receivers for surveying and mapping use are EGNOS-enabled, while 77 percent of geospatial reference network providers have enough information to upgrade Galileo and will be ready to provide a service by 2017. All good news. On the less positive side, more than 60% of professional surveyors did not know about EGNOS!
The workshop also talked up the potential for synergies between Galileo GNSS and Copernicus Earth Observation (EO) systems — a topic of immense interest at the European Space Solutions as well. Hans Dufourmont from the European Environment Agency (EEA) highlighted the use of GNSS to track animal species and monitor migration paths when considering development opportunities. He saw a huge potential for synergies between geopositioning and surface imaging going forward.
Maurice Barbieri, president of the Council of European Geodetic Surveyors (CLGE), also saw a “clear role for Galileo” in the surveying community with its potential ability to meet centimeter accuracy requirements much more than for EGNOS.
He also speculated about the value of establishing a European Geoinformatic Agency that might coordinate the provision of European GNSS and EO data. He felt the private business community would appreciate such simplification.
Let’s look through the other end of the telescope this month. The satellites are nattering along, lining up in orderly fashion at the rocket pad, extending their solar arms smoothly in space once they arrive on orbit. The constellations accrue and new signals inch closer to maturity.
The only blips on the horizon come from Ligado’s terrestrial impulse and a looming gap in GPS ground control. Just possibly, the latter might coincide with activation of the full European constellation and Galileo could come to the rescue of suitably equipped users who hunger for greater accuracy. This has been Galileo’s raison d’etre for two decades now, and it may actually be on the cusp of coming true.
At any rate, back to the telescope’s other end. What might that be? Facebook.
“When you think back to the beginning of online advertising, this is what advertisers have been waiting for.” That is Facebook’s director of monetization product marketing — an actual job title, and a powerful one in time to come.
All this — what advertisers have been waiting for — is made possible by GPS. Soon, by all GNSS. And by your smartphone.
From a GNSS Design & Test point of view, this means we are about to see some real money come available for constellations. Fast-multiplying applications of position, navigation and timing data have always shaped GNSS evolution, to some degree. Making this latest development different by a degree of magnitude is its potential to alter the way GNSS policy is shaped and the way GNSS funding is provided.
Facebook will soon roll out a new Store Visits metric for business clients: location data and purchases correlated to Facebook ad performance. Partnerships with point-of-sale systems like Square and Marketo will “prove” (let’s use that word loosely for now) who bought what after seeing Facebook ads.
The way the company tells it, “While people use mobile in 45 percent of all shopping journeys, more than 90% of sales still happen in brick-and-mortar businesses.”
Even if you don’t buy something, Facebook will know that you — assuming, and this is a big jump, that you are a Facebook user — visited a store by aligning GPS, beacon, Wi-Fi and other radio-frequency signals and cell-tower locations with brick-and-mortar coordinates. You may not be a Facebook user, but I’ll bet one of your loved ones is.
With the new feature, instead of having to (gasp!) leave Facebook to visit an unfamiliar website for a store locator, users can view the address, hours, phone number and estimated travel time without exiting the social network.
I know people who rarely or never leave Facebook. Do you? This is a plus for them.
Facebook, one of the new corporate mega-giants, duels with Google, Apple and Microsoft over various pieces of digital turf. One of the most hotly contested treasures — the Holy Grail, in marketing execs’ terms — is the capture and use of user data. It is getting more than a little bit creepy.
To date, the even-bigger giant that is advertising has used metrics such as ad views and clicks to measure effectiveness: how much an ad actually inspires purchase or response to other calls to action. I know this because I use these metrics, or someone in my organization does. Such metrics are now deemed “flimsy” by the standards of aligning GPS, beacon, Wi-Fi data and so on as outlined above.
Facebook is not alone in exploring the fertile ground. Google recently launched ads that show maps of nearby locations, and the others surely do not lag far behind. For the moment, these massive integrators aggregate and anonymize the data to protect privacy, but that’s not to guarantee they would always do so. Currently, there’s no specific opt-out other than turning off location services for the app on the user’s device, which people might be reluctant to do if it degrades other app functionality.
Let’s shield our eyes from the dark side for the moment, and consider what this means for GNSS.
We, you and I, those of us in the PNT industry, have known for some time how integral to critical infrastructure GPS is and GNSS soon will be. But the vast public does not. And lawmakers, bless their little hearts, largely do not either. That will change when the desperate craving of large companies to reach billions of buyers enters the PNT arena.
We can envision mega-marketing bolstered by alliance with the transportation industry, both ground and air, as driverless vehicles and drones become more commonplace. With powerful lobbying interests behind it, GPS might finally get some respect, and other systems around the world with it. Modernization might proceed more smoothly and quickly, without funding hiccups and capability gaps. That’s the bright side of all this.
It reminds me of nothing so much as an old rock’n’roll song. In “Top of the Pops,” the Kinks sang:
Now my agent called me on the telephone He said, son your record’s just got to number 1 And you know what this means?
Amazon and Walmart are making plans toward faster delivery of goods by drone, while TV dramas bring drones into their stories. And evaluation and test of technologies to protect airports and aircraft from unwanted drone incursions is picking up speed — while sense-and-avoid technology takes big steps forward toward integration of drones in the U.S. National Airspace.
Amazon and Walmart. Amazon is working hard to enable deliveries using drones — even advocating a “high-speed” transit zone 200-400 feet above ground level. Delivery drones can then zoom between warehouse and customer carrying goods so orders show up super quick, right on your doorstep.
Proposed Amazon drone-traffic-control system.
Drone-traffic-control would be automated — too many drones over too many cities to use conventional air-traffic control. With a buffer zone of 100ft above drone traffic and regular manned aircraft, and no-fly zones around airports, low speed localized drone-traffic would transit from the high speed area to the delivery point. And recreational model aircraft and other drones would be limited to flying in designated areas, or up to 200ft within drone-traffic-control segments. Amazon seems to indicate that the technology to enable all this is already pretty well there — it’s selling the concept and developing the regulations which will take the most time.
So not wanting to miss out on automation using drones, Walmart is now talking about using drones in warehouses to monitor stock levels. Inventory control currently uses manual stock-taking which takes up to a month for just one pass through a large facility — while a complete stock count is possible in one day using hi-res drone-camera data.
Walmart warehouse.
To keep pace with the competition for its on-line business, its essential for Walmart to avoid out-of-stock and overstocked items, and tight, rapid inventory control is the key. So drones in warehouses, and data analytics is where they are headed.
Walmart is already looking for approval from the U.S. Federal Aviation Administration (FAA) to test home delivery using drones, so it may not be long before their drones get out of the warehouses and start testing how to fulfill online orders, too.
NCIS New Orleans. I was just thinking about this month’s drone update article while imitating a couch potato watching TV last evening, when NCIS New Orleans airs a show built around drones. A Predator pilot uses his day-time skills frying drone operations to search for a missing person. He buys an “undetectable drone” from a couple of drone geeks and makes aerial maps around his base. There were segments of simulated Predator operations, protests about overseas drone operations, an octocopter on the street in New Orleans and a DJI hobby drone flown on camera by a young boy. Other than a couple of technical errors, the show demonstrated just how much drones are now becoming part of our daily life, and how much the public is hearing about UAV technology.
And talking about undetectable drones — the FAA is using its Pathfinder Program to investigate a defensive system to protect airports from drone incursions. The FAA will evaluate a UK system known as Anti-UAV Defence System (AUDS) developed by Blighter Surveillance, Chess Dynamics and Enterprise Control Systems— the system is claimed to be able to detect, track, disrupt and defeat drones.
AUDS system.
National Airspace. Increasingly concerned about reports of UAVs flying too close to an airport or to manned aircraft the FAA and the Department of Homeland Security (DHS) have been searching for a system that can defend against drones.
The AUDS system uses electronic scanning radar, precision infrared, daylight cameras and specialist video tracking software to detect and track even small drones up to six miles away. An inhibitor then disrupts the drone radio control signals. The whole sequence of detect, track, disrupt, defeat process typically only takes 8-15 seconds. And the system has already undergone over 400 hours of ‘live’ testing against small UAVs.
In addition, the MITRE Corporation — a technical service organization which supports several U.S. government agencies — is investigating products and technology to detect and stop drones, through a funded competition called “Countering UAS Challenge”. Eligible solutions need to detect small airborne UAS, and discern and interdict those that are perceived as threats, forcing them to be recovered safely with an intact payload. MITRE has now selected eight finalists who will compete in live flight tests in August to determine the winners of a $100,000 prize package.
So although efforts are underway to protect airports and aircraft from wayward drones, the bad press that drones have been getting recently might not all be appropriate. The FAA recently released drone sighting data for March this year which has now been analyzed in some detail by the Academy of Model Aeronautics (AMA). AMA found that within the 582 drone sightings reported only 3.3% appear to involve near-misses or close calls.
Drone Sightings. Given that over a million drones were sold during the 2015 Thanksgiving-Christmas holiday season, it does appear that drone “sightings” are on the decline, and related reports to law enforcement also appear to be going down. So its possible that the FAA drone registration program, and the industry-FAA Know Before You Fly have positively improved the operation of drones by the public.
And while we’re all looking for ways to detect and deter drones from the ground, General Atomics (GA) has announced the successful operational testing of an airborne anti-collision radar system which includes GA’s Due Regard Radar (DRR) and Honeywell’s Traffic Alert and Collision Avoidance System (TCAS) and Sensor Tracker. Tests were carried out aboard a U.S. Customs and Border Protection (CBP) Guardian UAS, a maritime variant of the Predator B.
GA’s Due Regard Radar (DRR) drone.
During encounters with a Cessna fixed wing aircraft and a Blackhawk helicopter, safe separation was ensured between the UAV and the other traffic. Overland testing began at the GA facility near Palmdale, California, and concluded over the eastern Pacific Ocean. The tests confirmed that the pilot of the UAV had as a clear picture of surrounding air traffic as if he was flying in the cockpit of a manned aircraft. The tests also confirmed operational compatibility between the DRR radar and the maritime surface search radar carried by the Guardian UAV.
This is a significant step forward — albeit on a military drone — towards technologies which will ultimately enable integration of UAVs into the U.S. National Airspace. If we are also getting recreational operators to be more mindful of safely operating their hobby drones, and we can also prevent unwanted encroachment on airports and manned aircraft, then plans for delivery drones might also begin to make some progress.
A: PNT accuracy, availability and assurance will increase in importance. UAV payloads for military applications routinely require precise PNT information to geolocate sensor data for intelligence, surveillance and reconnaissance missions. High-end commercial applications for survey and mapping will require similarly high levels of accuracy and availability. As commercial UAV operations enter the national airspace, PNT assurance levels will increase with the need for GNSS receivers designed for safety critical applications.
A: Whether for military or commercial use, the accuracy requirements of a UAV’s positioning, navigation and timing system depend on the UAV’s size/weight, the mission duration and complexity, and the information being gathered. Commercial UAV applications such as mobile survey, mapping, surveillance and virtual imagery real-time overlays require higher levels of accuracy, particularly for UAVs in urban or heavily populated areas with tight restrictions. Many higher-end UAV accuracy requirements dictate the use of FOG-based inertial systems.
A: As the growth of small UAS operations increase in the National Airspace System, it will be interesting to track how PNT standards and certifications evolve in order to adapt to a more versatile UAV aircraft certification system. Likely a tiered system will be required to map PNT requirements for lower risk, lower accuracy and lower cost applications to higher risk systems or those which require higher precision due to their mission profiles.
A few weeks ago, I attended GEOINT 2016. It was quite different from my first GEOINT in 2007. Back then, GIS and imagery were the focus of most exhibitors and presentations, with points, line and polygons plotted on paper being the norm. This year the tradecraft seems to have evolved exponentially to a broad and significantly more sophisticated collection of technologies both on the EXPO floor and in most presentations.
New terms have solidly entered the geospatial lexicon: big data, big data analytics, exploiting social media, machine learning, activity based intelligence (ABI), predictive analytics (see my column last month), the internet of things (IoT) (see my January column), small sats, object based intelligence (OBI), cyber, human geography, open source, deep learning, machine to machine tipping & cueing, survivable space assets and the list continues to grow.
I was pleased to hear something I believed for quite a while. There is a growing consensus that Cyber attacks need to be displayed as events with geospatial components (location of servers, nodes, networks, etc.). That kind of visualization should provide valuable insight into these growing and complex attacks.
Keynotes
National Intelligence Director James Clapper.
The 75-year-old Director of National Intelligence (DNI) James Clapper poked fun at himself indicating that this would be his last year as DNI and he was counting down the days. He said that he was taught to always respect his elders but finding one was getting increasingly difficult. He also highlighted the same feeling I had that the GEOINT community has gone through some significant changes.
Computers have evolved from IBM’s 1997 Deep Blue winning only one of four chess games against Gary Kasperov to the recent contest of Google AlphaGo against the world master of the much more complex Chinese board game “Go.” AlphaGo won four of five games primarily with moves that experts called inspired genius. It did that because it was programed not to just play but to learn as it played. So “machine learning” was a frequent topic at GEOINT with it becoming a real game changer in national intelligence work.
Even imagery, the long standing bread and butter of GEOINT, is going through a revolutionary change. Citing NGA Director Cardillo, DNI Clapper indicated that we will soon evolve from limited overhead imagery available in certain locations at certain times to imagery of every spot on the globe every day of the year. You can watch Director Clapper’s full keynote.
Five awards were presented for 2016. Two of them had special interest for me — the Industry award winner ABACO Group shown in the EXPO section below and GeoHuntsville. Here is more information about the five USGIF award winners.
Community Support Achievement Award for the GeoHunstville Exemplar City program
The GeoHunstville Exemplar City program helps cities deal with disasters using new technology. Shown receiving the award for the GeoHunstville team are Chris Johnson and Joe Francica.
I was thrilled to see my adopted geospatial city, Huntsville, win the Community Support Achievement Award. The GeoHunstville Exemplar City program which assists local governments in preparing, responding, mitigating and avoiding natural and manmade disasters using new technology.
The system leverages geospatial tools including the new NGA open source collaboration environment GeoQ, UAVs and a broad array of internet accessible sensors through the IoT.
Exhibit Hall Expo
The conference attendance was over 4,000 with 250 exhibitors on the EXPO floor. You can view the full list of exhibitors at the GEOINT2016 website or by downloading the GEOINT 2016 smart phone app. The app has more information about the exhibitors including descriptions of their technology, contact info and website links. Here are samples of booths I found especially interesting.
ABACO Group:ABACO of in the United Kingdom and Italy, was given the 2016 USGIF Industry Achievement Award. ABACO received the award for their augmented reality (AR) “Farm Visor,” to help farmers access big data. One aspect that caught a lot of attention was their very elegant “X-ray” tablet viewer. The user holds the tablet up and adjust the “Transparency” of the wall they are viewing and it looks like you are looking through the wall. In reality you are viewing a geo-registered image of the surrounding area that seems like you are looking through the wall. Because of exhibit hall lights and screen reflections the
CYVIZ: CYVIZ builds easy to configure tactical operations centers that can display mixed media both classified and unclassified content in a common environment.
DIFFEO: DIFFEO is an automated search assistant that uses proprietary algorithms to speed searches of Big Data even if the operator does not know what key words need to be searched.
Hewlett Packard Enterprise Software:HP had a virtual off road driving experience. IT was not as enjoyable as Birdly, a little sickening in fact. I was told by one of the users that the reason was poor synchronization between the goggle imagery and head movement.
International Spy Museum:The International Spy Museum, currently located on F Street in Washington DC will soon be building a much larger facility just south of the mall. They have also received considerable new material and collections for their exhibits.
Lead’Air: Lead’Air shows several hardware configurations to capture lidar, ortho and oblique imagery.
LizardTech:LizardTech highlighted the new ability to handle LiDAR data and display it in various ways including DEMs.
PitneyBowes:PitneyBowes was showing their latest lossless imagery compression tools along with extensive business intelligence data.
PLW Modelworks and Birdly: Most users consider PLW Modelworks the gold standard of digital 3D models. The PLW booth combined their superb 3B models with a virtual reality “flying machine” called Birdly. The machine uses Occulus Rift goggles with earphones for sound and even a fan blowing wind in your face to create a fairly realistic urban flight experience. The user can bank and turn or soar by flapping the wings. I tried it and it was nice.
SigmaSpace:SigmaSpace was showing their single photon LiDAR. Their system is supposed to do a much better job discerning first and second level returns so collecting true ground elevation under a tree canopies is faster, more accurate with greater point density. Being a green laser it may also prove more effective in littoral work.
TerraGo:TerraGo was demonstrating Edge as a tool to simplify data collection in the field using mobile devices.
Prince’s death on April 21 highlights a fatal flaw in the United States’ antiquated 911 emergency system. When you call from cell phone, 911 doesn’t automatically know where you are. 911 often can’t determine the location of an emergency, even when the call for help comes from a GPS-equipped smartphone. Often the 911 operator can only zero in the nearest cell tower, which can be several miles away or in the next county.
In the transcript of the 911 call from Prince’s house comes this exchange:
911 operator: OK, what’s the address?
Caller: We’re at Prince’s house.
911 operator: OK, does anybody know the address? OK, your cell phone’s not going to tell me where you’re at, so I need you to find me an address … OK, have you found an address yet?
Caller: Yeah, um, I’m so sorry, I’m so sorry. (The caller is heard asking others if they know the address.)
911 operator: Is there any mail around that you could look at?
While a quicker response may not have saved Prince’s life, some experts estimate that cutting 911 response by one minute could save one person every hour every day nationwide.
The FCC and the four largest cellphone carriers say they’re doing their best to address the problem. One possible solution is LaaSer, a technology suite that runs in the cloud. LaaSer updates your precise location at the exact same time that the call to 911 is being made, so that the answering operator is immediately presented with your information.
With Laaser, any mobile device delivers accurate location information about the caller to 911 operators immediately. It does this using existing infrastructure, so carriers, handset manufacturers and 911 call centers wouldn’t have to change their systems to receive the benefits.
Unlike current 911 mobile phone technology, LaaSer takes advantage of all of the location information already available in smartphones, including GPS, Wi-Fi, Bluetooth, near-field communications (NFC)/RFID, compass, accelerometer, barometer and more.
How many times have you heard of a nearly 20-year-old space constellation being modified with a new technology? It almost never happens.
I will never forget when the general slid the sensitive Iridium folder across my desk; I knew from his facial expression that he was not happy. The folder contained a controversial civilian plan to de-orbit the entire multi-billion dollar Iridium communications satellite constellation less than a year after it was launched.
Fortunately, the folder also contained a proposed military, U.S. government (USG) and joint civilian proposal to sustain the constellation, with the only caveats being that a buyer be found and that the military and/or USG provide “indemnity” (insurance policy) for the Iridium constellation if it were to be utilized by the USG and our Allies, especially during wartime. At the time I was serving as the deputy chief scientist at Air Force Space Command headquarters. Our job was to determine the technical feasibility of both proposals and make a recommendation.
Iridium satellites
Replica of Iridium satellite. (Photo courtesy of Iridium)
Launched in 1998 by Motorola, Iridium is a satellite communications constellation that is a “technological marvel,” as John Bloom writes in his new book about Iridium, Eccentric Orbits. Additionally, Iridium was and remains a capability sorely needed by the USG that in many ways revolutionized global communications — unfortunately, just not in the manner or time frame Motorola originally envisioned.
Indeed, eventually not 66 or 77, or even 88, Iridium satellites would be launched, as you will read in many places. Rather, a total of 95 Iridium satellites have been launched to date, which should give the constellation the name Americium, since 95 is the atomic number for the element americium. But I digress.
The problem with Iridium was not technical or even space-related. Motorola, which developed the technology and launched the constellation into low Earth orbit (LEO) — an amazing feat in so many respects — totally missed the correct marketing strategy. Motorola developed Iridium as a quick (five-year lifetime) money-making capability and profit center when in fact it proved to be a much longer term project. Today, there are Iridium satellites that are fully expected to be on orbit and fully functioning for more than 20 years.
The original Iridium satellite was — and still is — a technological marvel that broke almost all the so-called rules for manufacturing spacecraft:
The satellites were built without any fully space qualified or certified parts.
The satellites were not built in a clean room.
The satellites were built “horizontally” on a moving assembly line, like automobiles, versus vertically, individually and historically as a stationery static device. The moving assembly line produced a satellite every five days by a little-known company that eventually became part of Lockheed Martin (LMCO).
The satellites were launched by nearly every space-faring nation that had a launch capability at the time.
The original Iridium satellites were built for a projected lifetime of five years — that was more than 18 years ago. The current Iridium constellation of 66-plus satellites (remember, 95 have been launched) has exceeded its projected lifetime by nearly 400 percent, and is still going strong.
In 2010, Iridium Communications entered into a long-term agreement with Boeing for maintenance, operations and support of the satellite network. Boeing operates the constellation and provides support for Iridium’s satellite control system (SCS).
How many times have you heard of an almost 20-year-old space constellation being modified with a new technology? It almost never happens.
The constellation’s legacy
Amazingly, the only reason the Iridium constellation still exists today, in several respects, is due to the intervention of the USG and a major program that suffered a production failure. Originally Motorola contracted for an additional hosted payload that just never came to fruition. The nameless company developed an Iridium test program, on which it failed to deliver. This “major glitch” caused a weight and balance problem for the Iridium satellites, which Danny Stamp, an Iridium program engineer, solved at the time by recommending a quick fix: adding an additional fuel load of the same weight as the failed payload to the satellite. It was a simple fix just to get the satellites launched on time that no one thought much about at the time. However, the result was a key component — remaining or residual fuel — that ensures the satellites are still in orbit, and can be maneuvered and working properly today.
As I mentioned earlier, one of the major reasons the entire Iridium constellation was not de-orbited was because the USG decided it was a necessary tactical capability during wartime for our warfighters, as well as being an amazing R&R tool for morale purposes. (The Iridium system enabled conversations with loved ones back home.)
Add to that a civilian plan put together by some true visionaries, individuals such as Dan Colussy and corporate partners such as Boeing, that were able to purchase the entire constellation for pennies on the dollar, and you have an incredible success story.
The result is one of the most successful — certainly the largest and most well known — satellite communication constellations ever flown. Plus, as I mentioned earlier, Iridium has proposed a brand-new capability that, if it comes to fruition, has the potential be a huge boon for GPS by serving as a key global PNT augmentation.
The way ahead
Just last week, Iridium announced that it is proposing, or has developed, in conjunction with other companies, an augmentation or compliment to GPS. Reuters quoted the CEO of Iridium Communications, Matthew Desch as saying the new technology used chips that were the size of a postage stamp, and could ultimately be integrated into other devices, heavy machinery, automobiles and the power grid.
The system, known as STL or Iridium Satellite Time and Location System, transmits signals via Iridium’s satellite constellation, delivering codes to ground positions that are independently authenticated, Reuters reported.
Both Iridium and the private firm Satelles said STL as a system has been demonstrated in military, academic and commercial applications. The Reuters article didn’t provide specific details on the exact nature of the devices or any launch customers. (Satelles and Boeing entered into a patent and technology license agreement for STL in 2013).
Iridium NEXT, Iridium’s next-generation global satellite constellation, will support the STL solution. Iridium NEXT is scheduled for completion by late 2017. Along with supporting the current Iridium constellation, Boeing is under contract from prime contractor Thales Alenia Space to provide system integration and testing support for Iridium NEXT.
So, while STL is far from concrete, it makes for an interesting possibility that Iridium is proposing or has apparently built an on-orbit satellite augmentation to GPS, and PNT in general. My government inquires brought the to-be-expected, “We can neither confirm or deny” response. As far as Iridium and Satelles are concerned, I suppose it is a wait-and-see proposal.
Still, it is good to see company internal R&D funding being used to further support our global PNT infrastructure. Now that the word is out, we can look for more details on the horizon. So stay tuned. By the way, many of you may remember that this is not the first time Iridium has gone down this path; perhaps this time it will actually work.
Yes, sometimes 18 years ago seems just like yesterday.
Abstract: The iGPS high-integrity precision navigation system combines carrier-phase ranging measurements from GPS and low-Earth orbit Iridium telecommunication satellites. Large geometry variations generated by fast moving Iridium spacecraft enable the rapid floating estimation of cycle ambiguities. Augmentation of GPS with Iridium satellites also guarantees signal redundancy, which enables fault-detection using carrier phase Receiver Autonomous Integrity Monitoring (RAIM). Over short time periods, the temporal correlation of measurement error sources can be exploited to establish reliable error models, hence relaxing requirements on differential corrections.
In this paper, a new ionospheric error model is derived to account for Iridium satellite signals crossing large sections of the sky within short periods of time. Then, a fixed-interval positioning and cycle ambiguity estimation algorithm is introduced to process Iridium and GPS code and carrier-phase observations. A residual-based carrier phase RAIM detection algorithm is described and evaluated against single-satellite step and ramp-type faults of all magnitudes and start-times. Finally, a sensitivity analysis focused on ionosphere-related system design variables (ionospheric error model parameters, code-carrier divergence, single and dual-frequency implementations) explores the potential of iGPS to fulfill some of the most stringent navigation integrity requirements with coverage at continental scales.
ION Joint Navigation Conference
The highly anticipated and always rewarding Institute of Navigation Joint Navigation Conference (ION JNC) kicks off this week, June 6-9, at the Convention Center in Dayton, Ohio, and at Wright Paterson Air Force Base.
There are the expected technical and joint presentations, along with a classified day (U.S. only) and a Warrior Panel. It all sounds like a great time and an educational experience. Be sure to visit the National Museum of the U.S. Air Force, including the website where you can take a virtual tour; it is an amazing venue. Also take time to visit the Wright Brothers exhibits in the “Birthplace of Aviation” while you are there.
Wright Brothers 1901 Wind Tunnel on display in the Early Years Gallery at the National Museum of the United States Air Force. (Photo: U.S. Air Force)
ION always puts on a great event. I hope many of you are there to participate.
Until next time, happy navigating, and remember: GPS is brought to you free of charge, courtesy of the United States Air Force.
It’s funny sometimes how things work out. I had just been preparing to take up in this column an issue raised last September at the ION-GNSS+ Plenary Session. Literally at the very moment I set pen to paper, notice of an extremely positive response to the problem arrived in my inbox. Hypercoincidental as it may be, market forces can and do work in mysterious ways, inexorably driving forward progress.
The issue arose during “lightning talks” as track chairs gave brief overviews of material to be presented in the following days. That’s when Paul McBurney tackled the gorillas.
A former eRide co-founder and now CEO of GopherHush Corp., a location analytics company, he chaired the Mass Market Application track. As he described market players — GNSS chip providers, sensor providers, indoor location providers, app providers and operating system (OS) providers — he made this statement: “The OS providers are the 800-pound gorillas that we have a hard time getting into this room. They have to support their fusion layers over a wide range of handsets and devices. They often end up competing with the apps makers they enable.”
A couple of those gorillas were in the room, in fact, and at least one more prominent GNSS figure has since joined their band. We’re talking Google and Apple, in case you hadn’t guessed.
McBurney’s point, as he later elaborated to me: “The OS manufacturers are really driving/owning the requirements/feature set of the mass-market chip providers. If they wanted carrier phase to drive RTK in the OS, everyone would have to step up to provide it, and these chip makers would lose their advantage in providing that to higher paying customers. If chip makers aren’t able to play, they are relegated to the crumbs of the rest of the market. Even car navigation is barely 1/10th of mobile. OS providers also dictate where/how sensor fusion/indoor location is performed. Sensor chip providers are in the same boat.”
I’d been thinking on and off about this situation since September, and as said was about to trumpet a call for the gorillas to come down out of the mist — or wherever they reside — to collaboratively and constructively join the PNT community. That’s when this message popped in through the electronic transom:
“Google I/O was this week and we announced we will open pseudoranges (raw GPS measurements) to application developers. If you want, I can do a blog post for you on this for the next magazine.”
Well, you bet I do! Look for it in the July issue. This is big news indeed. Check the website for a bit of elaboration in the meantime, and for the link to a YouTube video of the Google I/O announcement.
McBurney has further thoughts on this development, and you’ll see some of those next month as well. For now, he opines, “I was thinking that Google opening up pseudoranges shows that, while they wield huge power, they still understand the advantage of being open. A clear distinction from Apple.”
Basic procedures and tools for determining valid NAVD 88 heights for constraints
To date, the six parts of “Establishing Orthometric Heights Using GNSS” have provided the reader with basic concepts, routines and procedures for understanding, analyzing, evaluating and estimating GNSS-derived ellipsoid and orthometric heights.
In Part 5 of this series, we discussed National Geodetic Survey’s NGS 59 guidelines and methods for evaluating the results of the GNSS-derived orthometric height project. It provided methods for evaluating the results of the project and identifying stations with valid North American Vertical Datum of 1988 (NAVD 88) published heights.
In Part 6, we continued to analyze the changes in adjusted heights due to different NAVD 88 height constraints and compared the results to the published NAVD 88 orthometric heights. We demonstrated that every constraint has an influence on the final set of adjusted heights so determining valid published NAVD 88 heights is important. With that, when incorporating new geodetic data into the National Spatial Reference System (NSRS), it is important to maintain consistency between neighboring stations. If the station has moved since the last time its height was established, then not constraining the published value and superseding the height is the appropriate action to take. As it was mentioned and emphasized in Part 6, if the difference is not due to movement and is due to some other reason such as the results of a previous adjustment distribution correction then superseding the height may not be the appropriate action to take.
In this part of the series, we will look at the network design of the NAVD 88 project and estimate the potential NAVD 88 distribution correction between two benchmarks involved with the original NAVD 88 adjustment.
First, we need to address the network design in the area that was used in the General Adjustment of the North American Vertical Datum of 1988 (NAVD 88). The NAVD 88 was a major leveling network adjustment project performed by the National Geodetic Survey (NGS) that was started in the early 1970s and completed in the early 1990s. NGS provides a summary of vertical datums. The excerpt (below) from the website describes the major attributes of the NAVD 88.
North American Vertical Datum of 1988 (NAVD 88) consists of a leveling network on the North American Continent, ranging from Alaska, through Canada, across the United States, affixed to a single origin point on the continent:
Tide Station & Location = Pointe-au-Pere,Rimouski, Quebec, Canada
PID = TY5255
GSD* Designation = 54L071
Bench Mark = 1250 G
Ht above LMSL(Meters) = 6.271
* Geodetic Survey of Canada = GSD
In 1993, NAVD 88 was affirmed as the official vertical datum in the National Spatial Reference System (NSRS) for the Conterminous United States and Alaska. Although many papers on NAVD 88 exist, no single document serves as the official defining document for that datum.
Abstract from the NAVD 88 Special Report Special Report Results of the General Adjustment of the North American Vertical Datum of 1988 David B. Zilkoski, John H. Richards, and Gary M. Young
American Congress on Surveying and Mapping Surveying and Land Information Systems, Vol. 52, No. 3, 1992, pp.133-149
ABSTRACT. For the new general adjustment of the North American Vertical Datum of 1988 (NAVD 88), a minimum-constraint adjustment of Canadian-Mexican-U.S. leveling observations was performed holding fixed the height of the primary tidal benchmark, referenced to the new International Great Lakes Datum of 1985 (IGLD 85) local mean sea level height value, at Father Point/Rimouski, Quebec, Canada. IGLD 85 and NAVD 88 are now one and the same. Father Point/Rimouski is an IGLD water-level station located at the mouth of the St. Lawrence River, and is the reference station used for IGLD 85. This constraint satisfies the requirements of shifting the datum vertically to minimize the impact of NAVD 88 on U.S. Geological Survey mapping products, and provides the datum point desired by the IGLD Coordinating Committee for IGLD 85. The only difference between IGLD 85 and NAVD 88 is that IGLD 85 benchmark values are given in dynamic height units, and NAVD 88 values are given in Helmert orthometric height units. The geopotential numbers of benchmarks are the same in both systems. Preliminary analyses indicate differences for the conterminous United States between orthometric heights referred to NAVD 88 and to the National Geodetic Vertical Datum of 1929 (NGVD 29) range from -40 cm to +150 cm. In Alaska, the differences range from +94 cm to +240 cm. However, in most “stable” areas, relative height changes between adjacent benchmarks appear to be less than 1 cm. In many areas, a single bias factor, describing the difference between NGVD 29 and NAVD 88, can be estimated and used for most mapping applications. The overall differences between dynamic heights referred to IGLD 85 and to International Great Lakes Datum of 1955 will range from 1 cm to 40 cm. The use of Global Positioning System (GPS) data and a high-resolution geoid model to estimate accurate GPS-derived orthometric heights will be directly associated with the implementation of NAVD 88 and IGLD 85. It is important that users initiate a project to convert their products to NAVD 88 and IGLD 85. The conversion process is not a difficult task, but will require time and resources.
More than one million kilometers of leveling data were analyzed during the NAVD 88 project. The design of the leveling network involved in the NAVD 88 project is shown in Figure 1.
Figure 1. Leveling Network Design Used in the General Adjustment of the North American Vertical Datum of 1988 (Figure 3 from the NAVD88 report).
Not all of the leveling data depicted in Figure 1 were used in the general adjustment. Some of the older leveling data were not consistent with the newer data so these older data were not included in the adjustment. When proper procedures are followed, leveling data is very precise and accurate over short distances but the leveling network design usually does not provide a lot of redundancy. That’s why it is important to design a leveling network with many connecting loops. The loops provide the redundancy required to ensure that the leveling data does not contain any remaining significant systematic errors and/or blunders. At a minimum, the connected loops help to control and/or localize the remaining errors. Some of the older leveling data that were not included in the general adjustment were incorporated into the NAVD 88 after the general adjustment and were loaded into the NGS database. These stations are denoted as POSTed monuments on the NGS datasheet, shown in the highlighted section below in the excerpt labeled “NAVD 88 General Adjustment: What Does This Really Mean?”
NAVD 88 General Adjustment: What Does This Really Mean?
The general adjustment of NAVD 88 was completed in June 1991. All heights from the general adjustment were loaded into the NGS geodetic database in September 1991. This means that benchmarks included in the NAVD 88 Helmert blocking phase (approximately 80% of the total) have final NAVD 88 heights available for distribution to the public.
The remaining 20% of the benchmarks in “stable” areas were removed from the adjustment (denoted as “POSTed” benchmarks), because older data were inconsistent with newer data. NAVD 88 heights for these posted benchmarks will be determined from these older data during 1992-93. This task involves analyzing the data associated with the posted benchmarks to determine the best estimate of their NAVD 88 heights.
“POSTed” benchmarks in large crustal movement areas (e.g., southern Alaska, southern California, Phoenix, Houston, and southern Louisiana) will be published as special reports. This is a long-term task that started in January. It is important to note that some benchmarks in crustal-movement areas (i.e., benchmarks that were included in the NAVD 88 Helmert blocking phase) are available now. The heights of these benchmarks were usually based on the latest available data, but still may be influenced by crustal movement effects. In some areas, these benchmarks were not based on the latest available data, because this would have forced large distribution corrections into good, but older, adjacent leveling data.
In addition, there are approximately 500,000 USGS third-order benchmarks for which NGS does not yet have any data.
The NGS datasheet provides the date the station’s NAVD 88 orthometric height was adjusted so a user can determine if the station was part of the general adjustment of NAVD 88 or if the station was readjusted or incorporated in the NAVD 88 after the general adjustment. Station V 49 (PID = FA0151) is an example of a station that was involved in the general adjustment and published in 1991. The highlighted statement “The orthometric height was determined by differential leveling and adjusted by the NATIONAL GEODETIC SURVEY in June 1991” in the text portion of the datasheet indicates that this station’s adjusted height was established in the general adjustment of NAVD 88, as shown in the highlighted section in excerpt from “NGS datasheet for station V 49″ below.
Station Phaniel is an example of a station that was incorporated into NAVD 88 after the general adjustment. Phaniel’s datasheet has the following statement, highlighted below: “The orthometric height was determined by differential leveling and adjusted by the NATIONAL GEODETIC SURVEY in January 2005.”
So why is this important?
It is important to realize that just because the leveling data is newer than the rest of the leveling network around it, it doesn’t necessarily mean its absolute height value is more accurate or more reliable than the stations it was established from. The newer leveling data most likely is associated with an older leveling survey used in the general adjustment of NAVD 88. This older leveling data may have been affected by crustal movement and could be inconsistent with its neighbors 5-15 kilometers away. If proper procedures were adhered to, such as the FGCS geodetic leveling procedures, then the new leveling should have been connected to the NAVD 88 through a two- or three-mark leveling validation check leveling procedure, shown in the excerpt from “FGCS Specifications and Procedures to Incorporate Electronic Digital/Bar-Code Leveling Systems” below.
FGCS Specifications and Procedures to Incorporate Electronic Digital/Bar-Code Leveling Systems*
3.5 Geodetic Leveling
Geodetic leveling is a measurement system comprised of elevation differences observed between nearby rods. Geodetic leveling is used to extend vertical control.
Network Geometry
Order Class
First I
First II
Second I
Second II
Third
Bench mark spacing not more than (km)
3
3
3
3
3
Average bench mark spacing not more than (km)
1.6
1.6
1.6
3.0
3.0
Line length between networkcontrol points not more than (km)
300a
100a
50a
50a
25b
Minimum bench mark ties
6
6
4
4
4
aElectronic Digital/Bar-Code Leveling Systems, 25 km bElectronic Digital/Bar-Code Leveling Systems, 10 km
As specified in above table, new surveys are required to tie to existing network bench marks at the beginning and end of the leveling line. These network bench marks must have an order (and class) equivalent to or better than the intended order (and class) of the new survey.
First-order surveys are required to perform valid check connections to a minimum of six bench marks, three at each end. All other surveys require a minimum of four valid check connections, two at each end.
A valid “check connection” means that the observed elevation difference agrees with the published adjusted elevation difference within the tolerance limit of the new survey. Checking the elevation difference between two bench marks located on the same structure, or so close together that both may have been affected by the same localized disturbance, is not considered a proper check.
In addition, the survey is required to connect to any network control points within 3 km of its path. However, if the survey is run parallel to existing control, then the following table specifies the maximum spacing of extra connections between the survey and the existing control.
When using Electronic Digital/Bar-Code Leveling Systems for area projects, there must be at least 4 contiguous loops and the loop size must not exceed 25 km. (Note: This specification may be amended at a future date after sufficient data have been evaluated and it is proven that there are no significant uncorrected systematic errors remaining in Electronic Digital/Bar-Code Leveling Systems.)
* NGS’ analyses of the data will be the final determination if the data meet the desired FGCS order and class standards.
The validation check leveling procedure ensures that the new leveling is consistent with the local stations it’s connected to. However, if the local area around these monuments all moved together than the validation check leveling procedure may meet the allowable tolerances but the new heights could still be inconsistent with neighbors 5 to 15 kilometers away. Similarly, if the validation check leveling stations were involved in a large distribution correction in the NAVD 88, than, once again, the validation check leveling may meet the allowable tolerances but the new heights could still be inconsistent with neighbors 5-15 kilometers away. This is not to say that the older leveling or published heights of the stations are bad or incorrect; all it is ensuring is that the new leveling is consistent with the adjusted heights in the local area surrounding the new leveling project.
Another statement on the NGS datasheet that should be explained is “No vertical observational check was made to this station,” shown in the highlighted statement from the excerpt of Phaniel’s datasheet, below. This means that the station was determined on a leveling line that is known as a spur level line. This means that the leveling data were not involved in a loop. This is important because the lack of redundancy means that there is no check on the adjusted heights of these stations other than the checks performed during the double running procedure. The double-running procedure is very important but the procedure may not detect, reduce, and/or eliminate all systematic errors and/or blunders. The GNSS-derived values may be the first check on the published height of these stations. When performing GNSS-derived orthometric height adjustments the users should investigate all stations that seem to be inconsistent with its neighboring stations especially stations that their published datasheet contains the statement “No vertical observational check was made to this station” such as station Phaniel.
When analyzing GNSS projects, it is helpful to understand how the NAVD 88 height of the station was established and what year it was leveled. Figures 2 and 3 depict the original leveling network design used in the general adjustment of the NAVD 88 in the Rowan County, North Carolina, project area, and Figures 4 and 5 depict the current NAVD 88 leveling network design. Looking at Figures 2 and 3, it appears that the leveling network used in the general adjustment of NAVD 88 in Rowan County was fairly sparse and mostly consisted of leveling data observed in the 1930s and 1960s.
Figures 4 and 5 show the amount of leveling data incorporated into the NAVD 88 after the general adjustment. The red stars on Figure 4 are the stations that have been incorporated into the NAVD 88 since the general adjustment. Figure 5 depicts the dates of the leveling lines that were used to establish the new NAVD 88 heights. All of these new stations will have adjustment dates after June 1991. Having a different adjustment date than the general adjustment date of 1991 is not an issue, it’s just a way of informing the user that the station was incorporated into NAVD 88 and constrained to previously published NAVD 88 heights. The user should know the adjustment date of the control they are using in their GNSS project because the accumulated NAVD 88 distribution correction could be large especially between stations with different adjustment dates in areas with old leveling data and large loops.
Figure 2. Leveling Network Design Used in the General Adjustment of the North American Vertical Datum of 1988 (Green stations are stations established in the NAVD 88 and published in June 1991).Figure 3. Dates of the Original Leveling Network Design in the Vinicity of the Rowan County, North Carolina, Height Modernization Project.Figure 4. Leveling Network Design Incorporated into the General Adjustment of the North American Vertical Datum of 1988 (Red stars are stations that were incorporated in NAVD 88 after June 1991).Figure 5. Dates of the Current Leveling Network Design in the Vinicity of the Rowan County, North Carolina, Height Modernization Project.
As depicted in Figure 3, the original leveling data used in NAVD 88 in southern Rowan County, NC, was an east-west leveling line performed in 1935. It was connected at both ends of the line to leveling data performed in the 1970s. The validation check leveling procedure was performed and met the required tolerances. The loops that the 1935 leveling line was involved in are fairly large, around 175 kilometers. The leveling data involved in the loops consists of first- and second-order data. The allowable loop closure would have been based on the amount of leveling of each order and class involved in the loop. The allowable loop closure for the older second-order, class 0 leveling line would have been based on 8.4 mm times the square root of the length of loop in kilometers. In this case, a loop 175 kilometers would have an allowable closure of 111 mm. The allowable loop closure for first-order, class 2 leveling is 4 mm times the square root of the length of loop in kilometers. In this case, a loop 175 kilometers would have an allowable closure of 53 mm. Since this is based on a mixture of order and classes of leveling data, the allowable loop closure would have been somewhere in between.
For this column, I decided to estimate the NAVD 88 distribution correction between two benchmarks involved with the older leveling lines in southern Rowan County. The observed Helmert orthometric height difference between station V 49 and T 78 is -6.850 meters, and the Published NAVD 88 Helmert orthometric height difference from the NAVD 88 general adjustment is -6.891 meters. This means that the distribution correction between stations V 49 (FA0151) and T 78 (FA0295) is 0.041 meters (4.1 cm).
Figure 6 depicts the location of the stations and the leveling route used to estimate the NAVD 88 distribution correction. Since the leveling distance between these two stations is approximately 60 kilometers, the distribution correction is less than 1 mm per kilometer (0.7 mm/km). This is a very reasonable distribution correction because it only modifies each leveling section observation by about 1 mm per kilometer allowing users to check their local leveling projects. This, however, may be an issue with some GNSS surveys that extend over a large area were the leveling network consists of old leveling data with large loops. The GNSS-derived orthometric heights may be more accurate than the leveling-derived orthometric heights. As shown in Figure 6, stations V 49 and T 78 are involved in large loops and were established using older leveling data in the original NAVD 88 resulting in a distribution correction of 4.1 cm.
Figure 6. Example of an estimate of the NAVD 88 distribution correction between two stations established with old leveling data and large loops.
Station V 49 was used in this analysis because the station was occupied during the Rowan County GNSS project. The shortest leveling distance between station V 49 and T 78 was used to estimate the NAVD 88 distribution correction. Station T 78 was selected because it is the junction station for the leveling line that was used to incorporate station Buffalo 2 into the NAVD 88 in January 2005. Since T 78 was the junction station and its height changed 4.1 cm, 4.1 cm was applied to station Buffalo 2’s height to obtain its modified height. This is not the most rigorous way to estimate the effects of the distribution correction but it provides a quick method to determine an estimate of the NAVD 88 distribution correction between two stations.
Figure 7 is a plot that depicts the differences at station Buffalo 2 using the modified NAVD 88 height. The difference between the GNSS-derived orthometric adjusted height and the new NAVD 88 height decreased from 3.5 cm to -0.6 cm. This difference agrees to within 1 cm with the results of station V 49 (see Figure 7). It should be noted that one of the recommendations in the National Geodetic Survey’s NGS 59 document is to occupy valid NAVD 88 stations every 20 km. Following this procedure can help reduce the number of stations that need to be investigated due to NAVD 88 distribution corrections from the general adjustment.
Figure 7. Example of the possible effect of the NAVD 88 distribution correction on an adjusted GNSS-derived orthometric height.
Three stations were identified as potential outliers in Part 6 — Phaniel, Plaza, and Row 3. As mentioned in Part 5 (February 2016), station Phaniel has a large difference between the adjusted GNSS-derived orthometric height and the published NAVD 88 orthometric height value (-4.2 cm); indicating an issue with the ellipsoid height and/or orthometric height (see Figure 8). However, Phaniel’s published NAD 83 (2011) ellipsoid height and the Rowan County minimum-constraint adjusted height of Phaniel only differed by 0.8 cm. The comparison of adjusted ellipsoid heights and published ellipsoid heights for the Rowan County GNSS project were provided in Part 4 (December 2015). This is an indication that the GNSS-derived ellipsoid height of station Phaniel is not an issue and that the station hasn’t moved since the original GNSS survey and the 2015 Rowan County GNSS survey. It should be noted that the leveling project used to incorporate station Phaniel into NAVD 88 was performed in 2001 which was in between the two GNSS surveys.
Two other stations (Row 17 and Row 16) were leveled on the same leveling line as Phaniel and their adjusted GNSS-derived orthometric height and the published NAVD 88 orthometric height values agree to 1.6 cm and 1.7 cm respectively; this is an indication that the leveling data and GNSS data are consistent from the main level line to these two stations. Phaniel’s datasheet has the statement “No vertical observational check was made to this station,” indicating the station’s height was established on a spur leveling line and therefore has a lack of redundancy and reliability. Based on the information up to now, I would not recommend constraining station Phaniel in the final adjustment. Saying that, before it is superseded by the GNSS project, the benchmarks between Phaniel and Row 17 should be re-leveled to determine if a leveling error was made between these stations in 2001.
Figure 8. NAVD 88 leveling network design involving station Phaniel.
The geodetic data and information for station Plaza is listed below:
As described in Part 6 (April 2016), station Plaza and station Fifth have a large relative difference between the adjusted GNSS-derived orthometric height and the published NAVD 88 orthometric height value (-3.2 cm); (See Figure 9.);
Four other stations in the vicinity have small relative differences between the adjusted GNSS-derived orthometric heights and the published NAVD 88 orthometric heights values, 37 DRD (0.6 cm), Midtown (-0.1 cm), Midway (1.0 cm), and J 181 (1.1 cm) – indicating a problem with station Plaza;
Station Fifth and Plaza are only 400 meters apart, and their adjusted heights were established in two different adjustments: station Fifth was leveled in 2013 (adjustment date of March 2015) and station Plaza was leveled to in 1989 (adjustment date of September 1997) – indicating a potential inconsistency between adjustments;
Plaza’s datasheet states that “the station was recovered as described in 2012 except the area between the curb and sidewalk has been filled with concrete. Mark is now part of the sidewalk but does not appear to have been disturbed.”
Based on the available information to date, I would not recommend constraining the published height of station Plaza in the final adjustment. Once again, this station’s published height should not be superseded by the GNSS project until new leveling has been performed between station Fifth and Plaza.
Figure 9. NAVD 88 leveling network design involving station Plaza.
Figure 10 depicts the leveling network involving station Row 3. As described in Part 6 (April 2016), station Row 3 has a large difference between the adjusted GNSS-derived orthometric height and the published NAVD 88 orthometric height value, -3.8 cm (see Figure 10.). Except for station AE4540 (382 JAS), all of the differences between the adjusted GNSS-derived orthometric height and the published NAVD 88 orthometric height value at the other nearby stations are all less than 1.7 cm; as a matter of fact, most of the differences are less than +/- 0.5 cm.
I could not find any leveling data in NGS’ database involving station AE4540 (382 JAS). (See Figure 11.) As far as I could determine, this station was not leveled to by NGS and leveling data were not submitted to NGS for inclusion in the NAVD 88. You can retrieve all project identifiers for those projects with observations to or from a station using the stations’s PID. The station’s PID is provided on the NGS datasheet. The input and output for PID AE4540 is shown below. There are no identifiers listed under the sections labeled “Vert_Obs,” “Lev_Obs,” or “Level_Obs” indicating that this station does not have any leveling observations in NGS database.
Based on the available information so far, I would not recommend constraining the published heights of station Row 3 or 382 JAS (AE4540) since they will distort the adjusted heights of surrounding stations (see Part 6, Figure 10). If no supporting leveling data can be found for station 382 JAS then I would recommend superseding that station’s height with the GNSS-derived value. As for station Row 3, I wouldn’t recommend superseding the published height with the GNSS-derived height until a leveling check has been made between Row 3 (DG5673) and a nearby station such as station 384 JAS (FA0564).
I realize that by not constraining a station and not superseding the published height that an inconsistency between the leveled NAVD 88 height and the NAVD 88 GNSS-derived orthometric height may occur. This information needs to be noted in the project report with an explanation of why you made certain decisions in your final adjustment. The analysis and plots provided in these columns are the types of information that should be provided in the final report.
All of the analysis and recommendations have been based on using the latest scientific geoid model xGeoid15b. However, in practice, GNSS-derived orthometric heights are incorporated into the NAVD 88 using the latest hybrid geoid model GEOID12B. I recommend first performing the analysis using the scientific geoid model because the hybrid geoid model has been warped to be consistent with the published NAVD 88 values. This was described in detail in my Part 3 (October 2015). The analysis using the scientific geoid should be included in the report especially if the user finds significant differences between the results using the two different geoid models. Saying that, maintaining consistency between closely spaced stations is extremely important when incorporating data into an existing network. Based on the information so far and the results using GEOID12B, I would not recommend constraining the published NAVD 88 heights of stations Phaniel and Plaza in the final NAVD 88 GNSS-derived orthometric height adjustment. These two stations resulted in significant changes in relative adjusted heights when they were constrained. (See Part 6, April 2016.)
It was noted in Part 5 (February 2016) that ten of the 2015 GNSS Rowan County Height Modernization project’s stations have published NAVD 88 GNSS-derived orthometric heights. These station are important because they are on the edge of the network where there’s a void of published NAVD 88 leveling-derived orthometric heights. In the next column, we will look at these stations and the differences between their minimum-constraint least squares adjusted GNSS-derived orthometric heights and their published NAVD 88 GNSS-derived orthometric height.
These columns have provided a lot of routines and procedures for analyzing and estimating GNSS-derived orthometric heights. My intent was to provide the analyst with tools for documenting the results of the analysis and providing a basis for making recommendations associated with the GNSS project. A future column will address what information should be included in a project report.
Locatalite transceiver installation in the White Sands Missile Range Ultra High-Accuracy Reference System, provided by the U.S. Air Force for testing equipment under conditions of GPS jamming.
A new dimension in real-world PNT testing has arrived. One of the most critical things to predict for chips, receivers and devices using alternative or back-up PNT technologies is how they will actually perform without GPS.
Filling this need, the U.S. Air Force 746th Test Squadron has declared Initial Operational Capability (IOC) for its new truth reference, the Ultra High-Accuracy Reference System (UHARS) at the White Sands Missile Range in New Mexico. Even when GPS — or any other GNSS system — is being completely jammed, UHARS provides extremely accurate positioning, navigation and time (PNT) over the large area that the system was designed to cover.
“Initial testing shows that UHARS delivers accurate independent PNT as good as, or better than, the Air Force’s current Central Inertial and GPS Test Facility (CIGTF) Reference System (CRS), so it is perfectly able to support current customer requirements,” said Dr. Jim Brewer, Chief Scientist of the 746th Test Squadron. “However, more data are required to tune the UHARS filter and optimize its accuracy to meet even tighter PNT requirements, which is our objective. When this is achieved, UHARS will deliver truth accuracy for next-generation military capabilities, and we will declare UHARS Full Operational Capability.”
“UHARS is a rack-mounted, tightly integrated system of improved navigation sensors, a data acquisition system (DAS) and a new post-mission Kalman filter, all of which need to work together,” explained John Cao, Technical Director of the 746th Test Squadron. “It’s working very well, but once we completely measure and characterize the individual components and then tune and validate the filter, the complete system will provide a significantly more accurate reference solution for future airborne and land-based test vehicles in navigation warfare environments where modernized and legacy GPS signals are jammed from friendly or hostile systems.”
To achieve these accurate reference solutions, UHARS requires a core Non-GPS Based Positioning System (NGBPS) component capable of operating and providing sub-meter position accuracy in a GPS-denied (jamming) environment. The NGBPS subsystem of the UHARS program employs a network of ground-based LocataLite transceivers and test vehicle receivers manufactured by the Locata Corporation. The Locata network deliver centimeter-level positioning and navigation as well as nanosecond-level synchronization, which may be useful for military applications requiring precise time transfer in GPS-denied environments.
White Sands Missile Range (WSMR) is a United States Army rocket range of almost 3,200 sq mi (8,300 sq km) in parts of five counties in southern New Mexico. It is the largest military installation in the United States.
The importance and uniqueness of the WSMR as GPS test facility spring from the fact that it is illegal to jam GPS elsewhere without a special permit. Thus it is extremely difficult to create a real-world test scenario for various GPS and other PNT devices, to see how they perform under denied or restricted circumstances. This is of critical importance for flight testing (UAVs and other avionics) for which the UHARS was primarily designed and optimized.
The LocataNet truth reference system can also provide a 2D solution to support ground vehicle testing. Reportedly, the 2D solution, while also very good, has not yet been fully characterized. Once the filter has been fully tuned in this respect, WSMR could serve as a test facility for autonomous driving. There are many miles of paved highway on the WSMR, possibly in the hundreds of miles.
History of UHARS Development. Based on successful results of the original technical demonstration at WSMR in a real-world end-to-end environment, the USAF proceeded to the NGBPS production and fielding phase in 2012. The Locata Corporation was contracted to provide production ground transceivers and receivers, navigation algorithms required for data analysis and subject matter expertise. The TMC Design Corporation, the integrating contractor for this program, was tasked to develop the production hardware to house the Locata hardware, develop the command and control hardware and software, and field the production hardware at WSMR. The Locata network was fielded in September 2014, and its NGBPS capability is now core to the UHARS that is replacing the CRS.
“Our team is thrilled to be part of this historic USAF capability,” said Nunzio Gambale, CEO and co-founder of Locata Corporation. “Locata products developed and fielded by important commercial partners like Hexagon and Perrone Robotics routinely prove our technology is a game-changer for positioning over industrial-sized areas. However, leveraging Locata technology as the core non-GPS-based PNT solution over a vast military area when GPS is jammed instantly elevates our achievements into a completely new league. Clearly, we are witnessing the arrival of one of the most important technology developments for the future of the entire PNT industry.”
Customers wishing to leverage UHARS into their test programs should contact the 746th Test Squadron at (575) 679-2123 or [email protected] for scheduling information.
Prince’s death on April 21 highlights a fatal flaw in the United States’ antiquated 911 emergency system. When you call from cell phone, 911 doesn’t automatically know where you are. 911 often can’t determine the location of an emergency, even when the call for help comes from a GPS-equipped smartphone. Often the 911 operator can only zero in the nearest cell tower, which can be several miles away or in the next county.
It’s funny sometimes how things work out. I had just been preparing to take up in this column an issue raised last September at the ION-GNSS+ Plenary Session. Literally at the very moment I set pen to paper, notice of an extremely positive response to the problem arrived in my inbox. Hypercoincidental as it may be, market forces can and do work in mysterious ways, inexorably driving forward progress.
