GPS World

Category: Opinions

  • Respect the facts: March for Science

    Respect the facts: March for Science

    Photo: Petr Kratochvil
    Photo: Petr Kratochvil

    In life, few things are certain. In family, love and friendship, fewer. Add more people — workplace, groups, associations, government, society, nations, war — and the complications multiply, the certainties become more scarce.

    Some things, however, remain fixed, and true. We call them facts. They are not subject to denial or claims of fakery. They can sometimes be distorted, or their interpretation disputed, but at the end of the day they remain what they were at the beginning. Facts. True.

    They do not require a majority to believe in them, nor even a powerful minority. They exist outside belief, heedless of the powers of persuasion, cajolery, hucksterism.

    The facts do not always, to their detriment, speak for themselves. Reason does not always prevail. But the facts continue to exist, ruling the operations of the universe.

    It has been said that journalism’s duty is to print the facts and raise hell (Chicago Times, 1861). I submit to you that it is a scientist’s duty — and an engineer is a scientist — to live and practice by the facts, to preserve the facts if necessary. To raise hell? That may be a matter of taste or personal style. But to see that the facts are known, shared, publicly available — that can be undertaken without uncomfortable or unpleasant hell-raising.

    Guerrilla archiving and data rescues have mushroomed across the U.S., in response to fear that the U.S. government will remove facts it dislikes from its own websites. All-day hackathons are organized by volunteers; the events focus on downloading federal science data sets, particularly those related to climate change, from government websites and uploading them to a new site, datarefuge.org, an alternative source for data. They’re also feeding tens of thousands of government web pages into the Internet Archive, a nonprofit digital library with the mission of “universal access to all knowledge.” And of course someone has devised a custom-built app specifically for this purpose.

    Climate-change data has a geospatial aspect, and much of it was collected with GPS equipment. Positioning coordinates lie at the heart of so much key information. So an attack on carefully assembled, scientifically overseen data can be interpreted as an attack on the validity of global positioning technology. Whether or not we take it personally, we should be wary of any attempt to deny or abolish any facts, anywhere.

    We’ve seen this before, in other forms. The LightSquared episode in 2011–12 produced blatant denials of the physics of radio-frequency waveforms, for personal and institutional profit. We don’t yet know if this is happening again, whether government data has been erased or simply moved elsewhere.

    Whether or wherever they appear or disappear, the facts continue to exist, and perhaps they deserve more respect than they’ve been getting.

    MarchforScience.com, April 22.

  • GeoHuntsville 2017: Huntsville and NGA partner to advance the tradecraft

    Last year, Huntsville, Alabama, was the site of the National Geospatial-intelligence Agency’s (NGA’s) first HackAThon — just one outreach event to take advantage of talent and skills outside the agency that could enrich the efforts of NGA.

    The HackAThon was an initiative of both previous NGA Director Letitia Long and current Director Robert Cardillo. It was so successful that NGA had four other HackAThons in major cities, including New York, Boston and San Francisco, with a repeat this year in Huntsville.

    The weekend HackAThon led up to the GeoHuntsville Summit, a geospatial conference that has been an annual event for more than 10 years. The conference was opened by long-time geospatial professional and advocate Chris Johnson and Huntsville Mayor Tommy Battle, who both have had supportive connections with NGA. The mayor highlighted the fact that for its size, Huntsville was somewhat unique in that it had a higher per capita population of Ph.D.s and engineers than any other city in the U.S. That same wealth of talent extends into geospatial, with more than 70 geospatial firms in the area.

    New GeoHuntsville Director

     

    GeoHuntsville Executive Director Jorge Garcia
    GeoHuntsville Executive Director Jorge Garcia

    Chris then introduced Jorge Garcia, who is taking over as the GeoHuntsville Executive Director. Jorge retired from the FBI, where he served as assistant director, Directorate of Intelligence. His 16-year military career includes combat tours in Iraq, which preceded 21 years with the FBI, and later intelligence work in Iraq during Operation Iraqi Freedom.

    Jorge highlighted the goals of GeoHuntsville that were his marching orders, including the advancement of geospatial tools to prevent and/or mitigate natural and manmade threats to the region while fostering research, development and education of the geospatial tradecraft.

    Presentation Highlights

     

    Ken Graham, Director, Platform Services Division, National Geospatial Intelligence Agency (NGA)

    As a sponsor of the event, and active part of GeoHuntsville, there was heavy participation by NGA staff, including NGA recruiters eyeing the 15,000-plus geospatial talent located in Huntsville. Ken discussed the success of the HackAThons and other outreach efforts developed by NGA’s Enterprise Innovation Office. Its focus on unclassified open source tools is changing the culture away from “that’s the way we always did it” to completely out-of-the-box thinking including “Shark Tank”-like evaluations of tools developed outside the agency, without the very slow and expensive procurement methods that took years to place new innovations into the hand of NGA users.

    Ken explained that rather than NGA developing exact descriptions and specification of what the agency wanted, it instead describes a problem or need. The NGA then leaves it up to the creativity of outside developers to think of new approaches and solutions to the problem.

    Most of the solutions can be created in unclassified environments and then tested by NGA staff using real agency data. In many cases, this negates the need for outside developers to have TS/SCI clearances, which are expensive and time consuming to obtain. The NGA goal, which sounds very ambitious, is to be able to get new tools into the hands of users less than 24 hours after a problem is identified!

    Dan Koch, Oak Ridge National Laboratory (ORNL)

    Koch demonstrated a system developed by ORNL that integrates various GIS tools in one easy-to-use environment called the Incident Management Preparedness Coordination Tool Kit, or IMPACT for short. This system was initially designed for EOD use during potential bombing events, but the system also proved useful to a broad audience of first responders.

    The system can be used with web services, but also can operate in a disconnected environment, since much of the needed data resides locally. IMPACT includes traditional GIS tools and external data access augmented with bomb-blast patterns, crowd evacuation animations, plume models, contagion spread simulations, active shooter view-sheds, antenna placements and patterns and real-time live data feeds.

    The afternoon breakout sessions included a detailed demonstration of IMPACT. You can see a demonstration of IMPACT in this youtube video. Some of the attendees mentioned that the system would be even nicer if it used the new CESIUM WebGL virtual globe to show 3D data.

    Alabama Department of Transportation (ALDOT)

    J.D. D’Arville of the ALDOT explained ALDOT’s use of off-the-shelf UAVs (DJI Phantom 3s and  4s) with eMotion software and senseFly S.O.D.A. cameras to capture very high-quality aerial imagery in multiple spectrums (see the senseFly video.} The imagery was then assembled into metric 3D models using Pix4D that permitted them to monitor contractor work. One early success was discovering poor “cut and fill” procedures by a contractor.

    John Russell of ALDOT then explained survey data collection using what I believe is very disruptive technology —AeroPoints, developed by Propeller Aero. AeroPoints is a very accurate automated system that uses UAVs with innovative ground control pads to capture 2-cm-accurate aerial imagery. See a video of it in operation here.

    Mike Botts, OpenSensorHub

    Botts presented the latest examples of work he and his colleagues have done to advance the practical use of remote sensors. He pointed out a key advantage of working with GeoHuntsville, in that both developers and end users had the ability to learn from each other.

    One example he cited was showing the display of live UAV video on a static map to a participating local fire chief. Since the video was related to the geography but not accurately geo-referenced, the fire chief said that it wouldn’t be useful. He explained that trying to figure out exactly what he was looking at and from which direction would be too time-consuming and potentially confusing. Botts and his staff took the problem in hand and developed a simple way to place the video footprint in the exact location and orientation that was spatially correct. This had been done before with high-end military systems, but never so simply and effectively.

    UAVs

    There were also several presentations by UAV users and the UAV users’ group that addressed both hardware and software. However, the UAV topics that still dominate the discussions are the administrative and legal issues that still cloud the use of the technology.

    These were only the highlights of the conference. Although lasting one day, this was an information-rich conference worth attending.

  • GNSS plays prominent role at Mobile World Congress

    Global navigation satellite system (GNSS) technology found its way into products ranging from autonomous vehicles to wearables at this year’s Mobile World Congress in Barcelona, Spain.

    One company says it is tailoring a GNSS receiver chip to meet the demands of mobile devices that require high levels of speed and position accuracy. Thalwil, Switzerland-based u-blox said its new low-power UBX-M8230-CT GNSS receiver chip can not only be used for smartwatch development, but for tracking people, animals and assets.

    “The highlight of the chip is that it has much better balance, while maintaining the accuracy of a traditional, full-power receiver,” said Florian Bousquet, u-blox market development manager. “It can work in the most difficult urban canyon environments. It works well in sports watches, smartwatches, activity trackers and other wearables — and just about anything portable that has a battery.”

    Bousquet said the chip, in what the company calls a Super-E mode, uses GPS with either GLONASS or BeiDou. This mode allows batching location data on the chip, which reduces power consumption, he said.

    Bousquet said the chip is available now, in an evaluation kit, for around $120. He said the chip will be manufactured in volume this summer.

    It took u-blox a year-and-a-half to develop the GNSS chip, Bousquet said. “It took time for our development team to optimize the system and field test the infrastructure to make sure the product performed in different scenarios and environments.”

    Another company, Racelogic, exhibited its LabSat 3 Wideband GNSS simulator, which is used by u-blox and others to help test and develop products. Some applications include drones, autonomous vehicles, survey equipment, personal monitoring devices, aerospace and end-of-the-line product testing, the company said.

    The newer L2C, L5 and L1C signals give companies the opportunity to develop products that are compatible with new receivers as they come to market, said Mark Sampson, LabSat product/sales manager.

    The company also showed off its SatGen v3 simulator software that allows users to create a data file to be replayed on the LabSat GNSS simulator. The software allows companies to define a complicated route, and then import it into the software.

    Company tests eCall and ERA-GLONASS modules

    Both the European Union (EU) and Russian Federation are requiring governments to have intelligent telematics-based safety systems. In case of a serious accident, these systems automatically call for local medical services.

    Technology to meet the requirements of eCall and ERA-GLONASS include an antenna, GNSS receiver, crash sensors and other components.

    To reproduce end-to-end and standard-compliant testing of the eCall and ERA-GLONASS modules, Rohde & Schwarz offers two products. One is the CMW-KA094 eCall application software. The other is the CMW-KA095 extension for ERA-GLONASS to simulate a public safety answering point (PSAP) to emulate a cellular network in a lab.

    “It’s pretty important testing because of the safety of life. We have set up implementation of it in our labs,” said Christian Hof, Rohde & Schwarz senior product manager for mobile radio testers.

    CMW_ERA-Glonass_eCall_T
    CMW500 simulator by Rohde & Schwarz. Photo: Rohde & Schwarz

    During testing, governments and companies can use the CMW500 platform, which identifies Internet of Things (IoT) and mobile communications devices’ IP connection security issues, Hof said.

    The company believes, since many IoT platforms are proprietary as standardization is still in progress, security gaps are frequently reported.

    Spirent rolls out new simulator

    Spirent Communications displayed its Elevate IoT Device Test Solution, a new cellular test designed to support IoT applications. These applications include end-to-end cloud server connectivity, security-vulnerability assessment and battery-life measurement.

    The new unit is available through the company’s Spirent Elevate platform, which addresses areas affected when designing 3G, LTE and new narrowband wireless technologies for IoT devices.

    Overall, Spirent is finding many use cases and applications in the IoT and mobile industry.

    “We are finding that smaller companies developing software and services want to test GNSS, but don’t have the capabilities to do so. These could include small projects such as people and pet trackers,” said Simon Loe, Spirent’s head of marketing solutions and services. “We are trying to democratize the technology. Another trend we are seeing is growing importance on GNSS in network timing.”

    Not everything is about drab simulation. Far from it. Spirent last year teamed with Aston Martin Racing to evaluate automotive technologies on the 2016 V8 Vantage GTE race cars.

    This includes the accuracy and performance of GPS receivers and interference monitoring, said Julian Kemp, Spirent product manager, custom solutions.

    Antenna market for IoT, autonomous vehicles robust

    Taoglas is offering GNSS antennas that support IoT products, unmanned aerial vehicles (UAVs) and future autonomous vehicles, said Ronan Quinlan, company co-founder.

    The company is offering lightweight antennas for mass-market unmanned UAVs, which had a growing presence at Mobile World Congress this year.

    The future markets for Taoglas will be in connected and autonomous vehicles, Quinlan said. “We found out years ago that we missed out on the rise of 2G, but we did not miss the rise of 4G. The advent of 5G and GNSS will lead to the development of the autonomous vehicle,” he said.

    Antenna costs associated with the rise of autonomous vehicles will have to be reduced, Quinlan said. “Some antennas that were $100 solutions have to go down to $20 solutions once they get into a car,” he said.

    In other Mobile World Congress news:

    • Fraunhofer IIS displayed its Enhanced Voice Services (EVS), the Third Generation Partnership Project (3GPP) communication protocol designed specifically for voice over LTE (VoLTE) services.
    • Telit said it is expanding its relationship with Tele2 on Pan-European long-term evolution (LTE) IoT connectivity services. Telit and Tele2 now offer custom data plans with predictable pricing, no hidden fees or roaming charges for high bandwidth IoT applications, the company said. Services include video monitoring, digital signage or real-time asset tracking.

  • GNSS and the Surveyor: Take Me to School

    The adaptation of GPS for civilian use is the single greatest step taken by  the land surveyor, more specifically the advance to  real-time kinematic networks. Now unmanned aerial vehicles enable data collection in places thought impossible previously, and laser/LiDAR scanners are on the horizon as the next game-changer. But how did we get here? An understanding of our history can be help us prepare for the future.

    The land surveyor has been practicing this occupation since man first claimed rights to physical property. In similar fashion with almost all other professions and trades, forward progress in knowledge and technology has increased educational requirements for even the most mundane of surveying tasks. An environment in which a simple survey is completed by manual measurements and depicted on a hand-drawn plat still exists but will continue to decrease as technological acceptance and governmental requirements become increased. The challenge will be a continual advancement to educate the surveying community as a whole.

    Today, the average age of the professional land surveyor approaches that of a sexagenarian (no worries, it’s just a fancy word for being in your sixties). Here’s a rundown of how we got there:

    Boots on the Ground

    In a previous article, I wrote of my journey to becoming a professional land surveyor (GPS World November 2015) and how it was possible for a high school graduate to be introduced to this wonderful profession with little to no formal training. Even though my introduction into land surveying started in the early 1980’s, it was still during what I refer to the early “high tech” surveying era. While electronics were evolving the surveying industry from the late 1960’s to my beginning days, it didn’t change the career path for the surveyor.

    At the time of my surveying opportunity, an entry level employee didn’t require the knowledge of higher level math, science and geodesy to gain a position as a chainman on a three-man survey crew. At a minimum, the employee was instructed to hold the measuring tape (known as the “chain”) at specific locations as directed by the survey party chief. The employee also was utilized as a pack mule to carry equipment and staking materials, so physical conditioning and stamina were much more important characteristics that knowledge of the profession.

    Over time (and usually through employee attrition), the chainman could learn to run the surveying equipment, which included transits, levels, and theodolites. Total stations with integrated electronic distance meters (EDM) were just becoming mainstream during my early days as an instrument person but little additional knowledge was necessary other than on-the-job training. The benefit of the EDM allowed the survey crew to measure further and faster than previous manual methods.

    An additional benefit of the total station was the digital readout of the horizontal and vertical angles and the elimination of the time-consuming need of reading the angular verniers.  These electronic advancements were great but didn’t affect the procedures for calculating survey figures and boundary analysis; they only increased the productivity of the field crew.

    Once an instrument man became more knowledgeable in the math and processes of land surveys, it was possible to advance further as a party chief. This path included many days on construction sites, hand calculating staking points and alignments, squaring up buildings and running traverses under the direction of a party chief, who in many cases, had become a professional land surveyor by these methods as well.

    Most of the knowledge obtained for career advancement was still on-the-job, but now also included some office tasks to compute boundary calculations and staking calculations through simple geometry/trigonometry means. Not rocket science but still required a good head for math and problem solving; this step also provided a potential career roadblock. This meant an occupational ceiling for some and advancement for others.

    Most of those who continued to advance were the ones with the stronger mathematical aptitude and capability to evolve with the knowledge they were gaining during their experiences as an apprentice land surveyor. The success of these future professional land surveyors depended greatly on successful mentoring capabilities of his/her previous supervisors. For those fortunate enough to learn under a great mentor, many more facets of the profession were introduced to them to gather experience. They were provided with time and care to explain and demonstrate proper methods and procedures for many surveying tasks, along with an example of how paying it forward helps everyone in the process.

    There are those, however, that received limited personal and professional training from their supervisors. These supervisors/managers possessed little experience in formal education or training methods. While these superiors excelled well enough to pass the licensing requirements at the time, the fast-paced movement of the surveying profession has left them in the dust. It is also these individuals who lack the necessary knowledge to successfully train and mentor the next generation of professional land surveyors.

    Old School versus New School

    The point here is that all of this was possible for the “old world” way of surveying. Several of my professional land surveyor contemporaries came up through this pathway of apprenticeship and mentoring with little to no formal education or training, yet have succeeded in business very well for themselves. But I caution you; they are not the norm. This minority of forward thinking professional land surveyors are the ones who remain visible in our business environment and continue to push themselves toward improvement for personal and professional gain.

    Where does this leave everyone else? Like so many other professions that have existed for centuries, the system of learning the craft of land surveying is based upon being self-serving. A historical look at the profession will reveal a long list of generational lines of land surveyors (yours truly included…) and have passed down the occupation somewhat like a family crest. But like so many vocations that get passed down like a family heirloom, if the means and methods of the occupation don’t progress with the times, it will eventually falter.

    The earlier example of the career of the land surveyor was possible until the early 1990’s; that’s when the electronic modernization of our profession picked up steam and the survey equipment manufacturers began revolutionizing our measuring and data collection methods. Couple the hardware enhancements with the boost in drafting capabilities of several drafting packages and that starts us down the road of needing staff with more educational requirements. Because of the advancements in both the field and office tasks of land surveying, we must look at each to understand how technology must be embraced to succeed as a profession.

    Not Your Father’s Transit & Chain (or Theodolite or Total Station…)

    I believe the field portion of the land surveying revolution started in the mid-1990’s with the rapid change in technology. Geodimeter led the conventional instrument innovation with servo-driven theodolites and robotic total stations that increased field productivity along with reducing errors. Along with the advancement of data collectors, these improvements greatly modernized a manual method of locating information. It also gave surveying firms an opportunity to reduce the number of staff members necessary on a field crew and spread their work out to more customers.

    The continuing improvement of the software on the data collector also made it more user friendly but also providing a “dumbing down” of the way the information is collected. While the data collection is now more efficient, the overall calculation process hasn’t changed much. But when this information is incorporated into various datums and coordinate systems, it gets much more complicated. We’ll cover this area more later.

    As stated in my previous articles, it is my opinion that the adaptation of the global positioning system created by the United Stated Department of Defense for civilian use is the single greatest improvement for the land surveyor (GPS World May 2016), more specifically the advancement to the real-time kinematic network. Couple this now with the exploding market of the unmanned aerial vehicle (UAV) with GNSS location capability, the surveying community now can collect data in places though impossible previously.

    The use of GNSS is a big part of that equation (no pun intended) and having the right balance of education and experience with its use will be key to our profession’s success. The continued to use of all facets of GNSS by surveyors worldwide will require the need for more responsible field staff. They will need to have the proper education and experience to comprehend the technology and calculations behind the data.

    I would be remiss if I didn’t mention laser/LiDAR scanners as tools for surveyors. There are companies who utilize these devices on a regular basis but they haven’t become the game changer like other technologies. These will come more into play as technology makes them smaller and the price point for entry into potential purchase is more affordable. The learning curve for processing the field data in point clouds is long and tedious but will evolve like everything else.

    It’s Always Warm and Dry in the Office

    Equally as important requiring proper training, education and mentoring are the land surveying tasks completed by office staff. As I stated in the opening paragraph, the norm used to be hand-drafted maps and plats depicting the results of field surveys from the notes of the party chief. Many drafters came through high school vocational programs and were hired directly after graduation. Simple angles, distances and direct measurements between entities were easy to portray and didn’t take much training. The introduction of the personal computer in the late 1970’s/early 1980’s also brought various platforms of computer-aided drafting (CAD) so another level of training was now necessary to learn both the software and the computer. Early versions were simplistic and mostly line-based but as technology increased the capability, it become more clear that a high school graduate didn’t have enough formal training to keep up with it.

    In addition to the drafting packages, computation software has become increasingly complex. These systems have developed into incredibly capable programs with a multitude of surveying solutions. This category includes aerial photography rectifying systems, point cloud manipulation and control network planning/computation systems that were only available previously on mainframe computers. While they are user friendly, they are well above the general education level of the high school graduate. The requirement to stay pertinent in the surveying environment must be centered around education.

    This Is Supposed to Be about GPS; How Do All These Things Fit In?

    I wrote in my last column regarding geolocation and how relied upon it has become in our society, (GPS World January 2017), and the land surveying community is no exception. The story here becomes about how quickly we can train the entire surveying profession to recognize the importance of location in our vocation or get left in the dust.

    It used to be location only mattered to explorers and mappers. Even with the creation of the latitude/longitude system, it was embraced more for the those who were traveling and giving directions to those planning to do so. Early surveys only related to surrounding properties and didn’t give much mind to specifically where it was located on the face of the earth. The surveys and related legal descriptions relied on physical monuments and avoiding hindrances versus actual measurements. That’s one reason why in the surveyor’s Rule of Construction that monuments carry significantly more weight that distance or direction in a legal description. The early settlers of the American Colonies relied on this system for conveyance of properties.

    It was only when the United States wanted to sell the lands gained from the Revolutionary War and Louisiana Purchase did they come up with a system for dividing the land. The Land Ordinance of 1785 was the beginning of the Public Land Survey System (PLSS) with the Surveyor General sending his staff westward to begin the task of establishing the sectional system.

    Fast forward to the 20th century and the rapid expansion of civilization worldwide. In the post-WW2 timeframe, our world was going places. Highway systems were increasing and the need to map it all was becoming more important on much larger scales. These entities charged with this mapping needed a much bigger method of planning and charting to depict where information was being located. The implementation of state plane coordinate systems was utilized to help with this task but involved high-order surveying along with brain-numbing geodesy. Very few individuals and firms were capable of doing this work but it provided a needed baseline for future endeavors.

    Fast forward to the past 20 years and think of the technological explosion of geolocation in the surveying and engineering fields. What used to be simple plat and plans has become a georeferenced dataset relied upon by clients, contractors, governing bodies and our firms. There are many geographical information systems in place now (from cities/counties/states down to rural utility companies) that all rely on geolocation. It would be easy to sit back and state I’m just a surveyor and this geolocation thing doesn’t come across my radar, but I would be greatly mistaken. Geolocation is an important factor of my profession and must be considered for almost all of my work going forward.

    Education Is the Key

    The professional land surveyor is uniquely qualified to provide accurate measurement for platting and mapping purposes. Our main focus throughout history has been to provide guidance and knowledge on boundary matters worldwide. Our background, knowledge and experience is not only in the physical location of the boundary but of the legal precedent and standing within the court system. Only the professional land surveyor can provide the legal opinion of where a boundary line lies; a judge or jury are not permitted to do that under law. The judge can rule whether to accept your opinion as fact but cannot make the determination themselves. We have an incredible duty and responsibility to the public; now we have the opportunity to instill more trust from them regarding geolocation.

    These statements are not intending to water down the importance of any of the Rules of Construction for surveys. It is intended to bring it in a brighter light so that surveyors see they have another role to fill, and that is the role of providing locations for the world in a spatial context. All of those tasks we provide can now be referenced in another view; data location in relation to the world.

    The professional land surveyor and their use of GNSS provides the basis of all real and potential mapping. Our inherent background in geodesy, technology and analysis of survey data leads the way as promoting our capability as the geolocation experts. While I still believe that conventional instruments will be utilized for a significant portion of our work, it will be the GNSS portion that will further define us as the experts in geolocation.

    All surveyors, both existing and future ones, need to get on board and embrace the future. This means additional education for us old timers along with planting the seeds in the junior high and high school age students who don’t know what a surveyor is or does. It means supporting the programs that train future surveyors; from the Boy Scouts through the collegiate level.

    Here is where the big difference in land surveying from past generations to now lies: education. I was fortunate enough to have started during a generation that allowed me to gain the necessary on-the-job education and training to become a professional land surveyor. I will also be the first to tell you that path is not the proper one for today’s surveying environment. Higher level math, science, and surveying training topics along with specific knowledge of geodesy, GNSS concepts, and environmental conditions are among the necessary tools for becoming a successful professional land surveyor in today’s world.

    Because of the family and financial barriers to formal schooling, there is a movement to roll back the educational requirements for professional land surveyors. I’m here to state for the record that surveying is much harder than when I began my career, so I can’t imagine trying to break into the profession now without the proper formal training. Just as many other occupations have need to adapt to stay current, the surveying profession need to do the same. There is too much at risk to not properly train our staffs to not just operate the equipment and software but to understand the concepts and results that are gained by it.

    While I became interested in land surveying for different reasons, my focus on geolocation as a subset of my boundary knowledge has me more energized for our profession. It is this enthusiasm that I ask that you help me spread to the world but also help provide the education and guidance that will be necessary for these young future professionals. In the end, the professional land surveyor through the use of GNSS can lead the charge with geolocation. All it takes is the proper education, training and guidance; after that, everything is easy.

  • Recommendations: RTCM on BeiDou use, DHS on critical timing receivers

    Two documents of interest and importance to GNSS designers and manufacturers have been published, one from the Radio Technical Commission for Maritime Services (RTCM) and one from the U.S. Department of Homeland Security (DHS).
    Improving_the_Operation_and_Development_of_Global_Positioning_System_(GPS)_Equipment_Used_by_Critical_Infrastructure_S508C-cover

    The latter document is the subject of a news story concerning receivers used in critical infrastructure, with an emphasis on timing receivers. It provides owners, operators, researchers, designers and manufacturers with information to improve the security and resilience of PNT equipment across the spectrum of equipment development, deployment and use. It makes specific recommendations.

    The first-mentioned document is a white paper issued by the RTCM. It follows here, largely verbatim. It is titled “GNSS Community Benefit from Strong International Coordination and Cooperation,” and it addresses an important issue for GNSS receiver manufacturers and others concerning use of BeiDou signals. The authors believe that early publication and dissemination of the recommendation is needed to prevent possible confusion down the line.

    GNSS Community Benefit from Strong International Coordination and Cooperation

    Introduction

    The ephemeris broadcast by China’s BeiDou Navigation Satellites do not directly provide unique identifiers that are similar to the GPS’s “Issue of Data, Ephemeris” (IODE) and “Issue of Data, Clock” (IODC) values. Special Committee #104 (SC-104) of the Radio Technical Commission for Maritime Services (RTCM) has been working with the China Satellite Navigation Office (CSNO) to ensure that equivalent BeiDou IODE and IODC values can be generated.

    This paper presents the BeiDou IODE and IODC calculation algorithms that were developed by RTCM’s SC-104 and are being shared with the GNSS community in an effort to promote consistent BeiDou IODE and IODC computational approaches within the community.

    Background

    Most GNSS position and timing related algorithms need to know exactly where the satellite was at the moment the signal component of interest was transmitted. The signal sent from these satellites also contain messages, which contain parameters used to calculate the position and clock errors of that satellite for a moment of interest within the validity period of those orbital parameters. Because this validity period is relatively short (e.g., +/-4 hours of the current time), the satellites are periodically broadcasting new orbital parameters. These orbital parameters are often referred to as the satellite broadcast ephemeris. Plots from the different broadcast ephemeris for the same satellite do not directly overlay each other because there are forces acting on those satellites (such as solar wind, ionospheric drag, and gravitational anomalies) that do not permit long term exact prediction of orbits and clocks.

    Many differential correction services require both the correction generator system (e.g., reference station and reference networks) and the correction consumer (e.g., GNSS rover receivers) know and use the exact same orbital parameters. That is, the consumer of the corrections needs to apply those corrections using the exact same orbital parameters as those used to create the corrections. Failure to do so results in errors and biases for reasons earlier described. In such correction services, the correction message contains information enabling the consumer to uniquely identify the orbital parameters used by the generator.

    Correction services need a mechanism to uniquely identify the orbit parameters used by the correction generator system. The GPS Broadcast ephemeris messages are uniquely identified for a certain period of time by what are known as the “Issue Of Data, Ephemeris” (IODE) and the “Issue of Data, Clock” (IODC). Other GNSS constellations have similar concepts, or at least other parameters that can be used for similar purposes. Unfortunately, the 2011, 2012 and 2013 BeiDou Signal-In-Space Interface Control Documents (BDS-SIS-ICD) have offered no information enabling one to develop some mechanism for such a unique identification.

    In 2013 RTCM SC-104 created the BeiDou Working Group (BDS WG). Since then, the BDS WG has worked closely with the China Satellite Navigation Office (CSNO) to ensure proper inclusion of BeiDou in RTCM standards and recommendations. As part of this effort, RTCM SC-104 and the CSNO explored several avenues concerning equivalent BeiDou values of IODE and IODC. Ultimately an approach was selected by the CSNO. The selected approach stems from a ground-segment based approach which does not require a change to the BeiDou broadcast message format. However, it does then require that the users of BeiDou needing IODE and/or IODC values ensure that they employ the exact same algorithm to compute those values from the data available in the broadcast ephemeris.

    In May 2016, Kendall Ferguson (RTCM SC-104 Chair), Shaowei Han (Wuhan Navigation and LBS, Ltd. and Chair of the RTCM SC-104 BDS WG), and Dr. Hui Liu (Wuhan University /Wuhan Navigation and LBS, Ltd. and co-Chair of the RTCM SC-104 BDS WG) met with the Deputy Director of the CSNO. In that meeting, the CSNO Deputy Director indicated that a soon to be release BDS-SIS-ICD would provide information that would enable calculation of equivalent BeiDou IODE and IODC values. In November 2016, the CSNO released the BDS-SIS-ICD, Version 2.1, and that ICD contains the needed information.

    The language in the new BDS-SIS-ICD indicates that the normal ephemeris update (i.e., with new ephemeris parameters) will occur every hour on the hour when everything is normal.  If new parameters are needed for whatever reason, they will occur on 12 minute slots within the hour.  Any parameter that is changed in a broadcast ephemeris that is related to toc will result in a new toc (coincident with the 12-minute slot of the hour).  Likewise, any parameter that is changed in a broadcast ephemeris that is related to toe will result in a new toe (coincident with the 12-minute slot of the hour).  Whenever toc changes so will toe.  There will be no repeated toc or toe values within a week.

    On February 3, 2017, RTCM SC-104 formally approved algorithms for BeiDou ephemeris unique identifiers that can be computed by both message generators and message consumers. The reason for announcing this approval is to proactively prevent a wide variety of BeiDou IODE/IODC algorithms from emerging throughout the GNSS community.

    These RTCM BeiDou IODE and IODC algorithms are:

    BDS IODC=mod (toc / 720, 240)

    BDS IODE=mod (toe / 720, 240)

    The modulo 240 gives an 8-bit IODE (and an 8-bit IODC) that provides 2 days of uniqueness and which offers the smaller bit size needed for correction messages.   The values from 240 to 255 thus offer some future expansion should additional cases be needed.

    Unlike the relationship between the GPS IODE and GPS IODC, the BDS IODC may not be equal to the BDS IODE. The BDS IODC may be updated much more often than BDS IODE. However, whenever the BDS IODE is changed, the BDS IODC is also changed at the same time. Thus, RTCM will be using the BDS IODC as the unique ephemeris identifier in its messages.

    Conclusions

    Special Committee #104 (SC-104) of the Radio Technical Commission for Maritime Services (RTCM) has been working with the China Satellite Navigation Office (CSNO) seeking methods where by BeiDou equivalents of the GPS IODE and IODC might become available. The BDS-SIS-ICD, Version 2.1, released November 2016, provides information about the constellation allowing computation of IODE and IODC values from its broadcast ephemeris. In February 2017, RTCM SC-104 approved the algorithms it will use to compute unique ephemeris identifiers that will be contained in its messages, thus allowing the recipients of RTCM BeiDou related messages to identify the ephemeris used by the sender of such messages. RTCM is announcing these algorithms in an effort to prevent a variety of such algorithms from emerging and thus causing community confusion.

     

  • New book explains GPS for the rest of us

    I’ve absorbed the basics of how GPS works in the decade since I joined the staff of GPS World magazine, when I barely gave the positioning system a thought. But in those first few months, this is the book I wish I’d had.

    Terms I needed to learn back then included pseudorange (nothing to do with juicy fruit), geodesy (not an undiscovered work by Homer) and multipath (not a forking trail in a park).

    All of these and more are described in the new book GPS for Everyone: You Are Here by Pratap Misra. Pratap is Professor of the Practice, Department of Mechanical Engineering at Tufts University, and he sent me his new book for review. As a non-engineer, I have found it a great resource — Pratap explains complex subjects in an entertaining, highly readable narrative, accompanied by photos, illustrations and even a few cartoons.

    Even if I’m not looking for a little background, I find myself engaged in the story of GPS: its history, its uses today (location-based services, defense, UAVs), privacy concerns and more.

    For instance, I hadn’t given much thought to how general relativity had to be taken into account in designing the clocks for GPS satellites. If the clocks hadn’t been designed with an offset, GPS would lose 38 milliseconds a day. So much for an accurate timing reference.

    Aother interesting story was the rescue of U.S. pilot Captain O’Grady, downed during the Bosnian conflict in the 1990s and quickly rescued because he was able to provide his coordinates from his handheld Flightmate GPS receiver. Today, of course, military receivers would automatically provide the location, and rescue would be even faster.

    Pratap also co-authored with Per Enge of Stanford a graduate-level engineering textbook on GNSS. But for the rest of us, GPS for Everyone: You Are Here is available through bookstores everywhere.

  • UAV industry demonstrates innovation

    A new system using RF detection of drone radio transmissions to warn of incoming drones is just one of several interesting developments in the unmanned systems sector this month.

    While UAS, or drones, continue to proliferate around the world, the majority appear to be used in meaningful and useful applications — earning money, helping disaster relief and in public service applications such as firefighting and police monitoring/tracking the bad guys. And there are those who fly them from the beach, just to get good overheads of the expensive neighborhood — lots of harmless, non-intrusive backyard, conscientious home-grown operations.

    But every now and again some bright spark tries to get the best possible picture of a passenger jet on approach or during regular air-traffic maneuvers. Air France just cried foul on Thursday, Feb. 9, when a Boeing 777 on approach into Washington-Dulles Airport caught sight of UAV estimated to be only 100 feet above the aircraft.

    Airport Close Call

    Now, why would a huge 240-foot-long, 250-ton B-777 even be bothered by a skinny 10- to 15-pound baby drone? Because on approach, an aircraft is dumping lift, reducing altitude, balancing speed — maneuvering a huge beast like a 777 can be quite a delicate operation. Its huge turbofan engines are also spinning really fast even at flight idle, and they still suck in an awful lot of air, so sucking in a stray quadrotor isn’t difficult. They do test these engines for bird ingestion during qualification, but I don’t think anyone has yet put anything like a DJI drone through an engine to see if the engine survives — frozen chickens don’t have any of the hard bits that drones have — and the whirling supersonic blades inside the compressor sections will not take well to foreign objects made of plastic, fiberglass, silicon and metal. Power loss low on approach can easily lead to disaster.

    Not to mention that at 700 feet, it’s probably bad news for the ~300 passengers if an engine quits or the guy driving has to unexpectedly jink the aircraft sideways to avoid a darn drone. This low-energy phase of flight involves a delicate balancing act of many parameters, and we don’t need pilots to be distracted from their focus of bringing their aircraft down a narrow landing corridor safely to the runway. Never mind the damage that even a small UAV can do to a multi-million-dollar aircraft. The Federal Aviation Administration (FAA) has mandated that drones fly below 400 feet and stay several miles away from airports for a reason.

    Detection and Disabling Drones

    Which brings us once again to equipment intended for the detection and disabling of drones. Keeping these pesky, unwelcome intruders away from penetrating airport protection boundaries — or other sensitive areas — is starting to become a business for which significant growth is being forecast, even paralleling the growth of drone sales.

    Several significant European agencies have already put Sensofusion radar equipment to work defending their facilities, or are undertaking joint R&D efforts with the company. Installations such as prisons, government, military and community security sites have benefited from a hybrid detection and location solution system known as Airfence.

    And, to the point, Sensofusion from Finland was also recently included in a group of companies selected by the U.S. FAA for a cooperative program aimed at the development of drone protection, location and prevention for airports. The other companies added to the FAA Pathfinder Program at the same time were Gryphon Sensors and Liteye Systems. The FAA’s objective is to find a system to deploy to “spot, block and drop the unwanted unmanned aircraft systems” before they get anywhere near the boundary fence, never mind into controlled airport airspace.

    The Airfence system starts by using RF detection of drone radio transmissions from over six miles away and immediately raises the alarm in case of an intrusion — even notifying controllers on their smartphones. The system then triangulates the location of the incoming drone and uses what appears to be directional high-power RF transmissions to disrupt the drone’s control link.

    For an example of how attention is turning to anti-drone systems, Dedrone in San Francisco, which develops software products designed to detect drones and protect high-value airspace from drone threats, recently secured a whopping $15 million during a round seeking investment funding.

    Army’s Shadow Disappears

    It could be that a roaming drone might not be wandering at the hands of someone intent on mischief. Operators of a $1.5-million U.S. Army Shadow fixed-wing UAV lost contact during a training flight recently, and it was presumed to have crashed in Southern Arizona within the area of operations.

    Shadow launch.
    Shadow launch.

    The Army went looking for the bits, but extensive searches found no trace of the elusive Shadow. Turns out that the UAV was eventually found by a hiker stuck up a tree several hundred miles away in Colorado, in the foothills west of Denver. The Army sent local troops and police to recover the errant drone.

    So, it seems that it’s not just malicious operators who may cause problems in commercial airspace. When things go wrong, we may also need a means to bring down an off-flight-plan drone. The side-trip for the Shadow apparently may have been brought on by unusually warm, gusty winds blowing into Colorado from the desert southwest on the day the aircraft went missing. Just as well that the tree caught the drone, as Shadows have a flight endurance of eight to nine hours.

    General Atomics Seeks Non-Military Opportunities

    And now General Atomics (GA) — one of the best-known UAV manufacturers of them all and their turboprop powered Predator — both are looking for opportunities in the “less-military, semi-commercial” world. The UAV that most people picture when someone says drone is probably the Predator, or its successor known as the Reaper.

    SkyGuardian UAV.
    SkyGuardian UAV.

    GA recently announced that its new SkyGuardian UAV is intended to be certifiable to airworthiness requirements. Given that no civilian standards yet exist for this class of large UAV, GA is using published military NATO, UK and German standards and recommendations for its early certification activities. SkyGuardian has benefited from a five-year-long company-funded effort to develop a certifiable UAV. Given that the existing military Predator fleet has altogether flown for almost four million hours, GA should already be ahead of the curve when it comes to proving airframe and systems reliability. The first production aircraft is planned for 2018.

    While its clear that GA is using largely military qualification standards and the target market seems to be in support of ground forces, its also aimed at non-military applications, such as border patrol, and quasi-military operations such as police, related security agencies and disaster relief. A maritime patrol version is also planned for coastal and open-water coast-guard applications. SkyGuardian has a lengthy 35-hour endurance, can fly at up to 240 mph and reach altitudes of around 46,000 feet.

    Flying Packages?

    And Amazon keeps pumping out patents, which give us some indication of what they might be planning for their much-publicized drone delivery system. Its latest patent has Amazon delivery drones arriving at their delivery point, but instead of landing to drop off a package, the package is dropped from the drone in flight.

    To ensure that the order doesn’t land in the neighbor’s pool, the package’s descent is controlled by small parachutes, a landing flap or compressed air release. This implies that the package has radio communications with the drone, so the flying packaging isn’t inexpensive. Aerobraking, maneuvering packages — what’s next?

    Patent drawing of flying package and parachutes.
    Patent drawing of flying package and parachutes.

    These flying packages or their carrier drone are not intended to interfere with commercial aircraft on take-off or approach because Amazon has also supported a drone delivery highway below 400 feet with its own air-traffic control system. But I can’t help thinking that flying packages might be a bit of a stretch. But who knows? The drone industry is demonstrating nothing but innovation!

    Tony Murfin
    GNSS Areospace

  • Expert Opinions: The effect of LEO constellations on GNSS services

    Expert Opinions: The effect of LEO constellations on GNSS services

    Q: What is the potential for low-Earth orbit constellations to augment services provided by the four medium-Earth orbit GNSS?

    Doug Taggart, President, Overlook Systems Technologies, Inc.
    Doug Taggart, President, Overlook Systems Technologies, Inc.

    A: With more than one hundred GNSS satellites broadcasting on three or more frequencies, our international constellation of medium-Earth orbiting (MEO) satellites will provide a combination of path diversity and frequency diversity. However, satellites in low-Earth orbit (LEO) should be added to our MEO mélange to provide orbital diversity and thus cyber safety. The LEO satellites would have 20 dB less path loss and compel jammers and spoofers to become conspicuous. Even with only one LEO in view, we would be able to use the LEO signal as a hot clock to improve the robustness of GNSS signal acquisition by our users. For timing applications, a solitary LEO satellite would enable time transfer to fixed locations worldwide.

    Per Enge, Professor and Director, Stanford university Center for Position Navigation and Time
    Per Enge, Professor and Director, Stanford university Center for Position Navigation and Time

    A: While it is prudent to take advantage of multiple PNT sources, the devil is in the details. Are users seeking more availability, accuracy, integrity and/or resilience to fill gaps? What is the complexity and cost for integration in user equipment, the reliability compared to other augmentations, the applications to be supported, vulnerability to interference, and so on? Additionally, all things from space may not be the best solution when all user needs and vulnerabilities are factored in.

  • Agricultural robot market impacted by urbanization, less land

     

    Robots are way cool. Anyone three or older knows that. And agricultural robots were among the first envisioned civilian applications of GPS. When Brad Parkinson went to Stanford in 1984, one of the earliest demonstrations he and his bright new students conducted was fully automatic GPS control of farm tractors on a rough field to an accuracy of 2 inches. Now it’s a bazillion global industry. See “Agriculture robots market projected to reach US$5.7 billion by 2024” for a few figures on that.

    The market report underpinning that story contained a couple unquantified yet provocative assertions. Here’s one: Rural flight to the cities is a big force in this market’s growth.

    “Progress . . . has primarily driven a growing number of people towards the urban areas and the suburbs. . . . This, in turn, has caused a twofold need for the incorporation of agriculture robots in several countries. Firstly, the growing global population — a lot of it being urban — is pressuring countries to increase food production while steadily reducing the hands available for the agriculture industry. Secondly, the overall land slotted for agriculture in nearly all countries is reducing, thanks to the burgeoning industrial sector and residential construction projects.”

    I find this a bit chilling, a bit 1984-ish, and goodness knows we’ve got enough of that going on already. Will our future trips through the countryside, the shrinking countryside, take us through landscapes populated by nothing by smoothly chuffing engines? Will the term “bucolic” lose all meaning?

    A second factor driving the agricultural robots market is “the increasingly accepted modes of corporate farming.” Now, I know that multitudes must be fed. Still, personally, I buy my food from small, local farmers as much as possible. It simply tastes better. That is indisputable. Arguments rage about whether it’s better for you; I believe that it is.

    I hope the small farmers that my family and neighbors depend on benefit from GPS even though they don’t have huge expensive pieces of equipment. I’ll have to ask them next time I go on a visit. Meanwhile if any GPS and/or robotics manufacturers supply products to the artisanal, shall we say, as opposed to the corporate side of farming, I’d like to hear from you.

  • The changing face of defense PNT

    I have mixed emotions as I write this column. Delighted, absolutely, to be given the opportunity to write for GPS World on topics that I am so passionate about; but also sad that we will not see any more articles from Don Jewell, whose excellent columns I followed so religiously over the years. I never had the opportunity to meet Don personally but, to me, he is irreplaceable. But let’s talk about the changing face of defense positioning, navigation and timing (PNT) — not in the editorial sense, but in the technology sense.

    As we all know, PNT and GPS are no longer synonymous. With a host of innovative technologies on the horizon, PNT is about so much more than GPS these days, and the military knows it. Sure, GPS has been the workhorse of PNT for many years, and it’s not going anywhere anytime soon. I’ll be clear on that: GPS is not going anywhere. But it’s not a complete solution either.

    Let me paraphrase what a friend in the infantry tells me, by saying GPS is a 60 percent solution to their navigation needs. What does that mean? Well, it goes something like this:

    • 60 percent of the time: GPS is great, it does what we need.
    • 20 percent of the time: We are indoors or underground, and GPS is simply not available.
    • 15 percent of the time: We’re in an urban canyon. GPS availability is intermittent, and the accuracy is poor.
    • 4 percent of the time: We’re in forests or dense vegetation, and GPS is sporadic.
    • 1 percent of the time: GPS is jammed.

    You can argue the numbers depending on the mission, but you get the idea. What, then, is the answer for the soldier? Well, first things first: We don’t want to reinvent the good 60 percent so, once again, GPS is here to stay. The question is how do we push past that 60 percent figure and get ourselves closer to 100 percent? Let’s go from the bottom up, and address GPS jamming.

    Overcoming interference

    The classic solution to jamming is an adaptive antenna, also known as a controlled radiation pattern antenna (CRPA). More on this another time but, for now, suffice it to say that CRPAs are a well-understood and mature technology, and can offer very high levels of jamming resistance.

    The often-cited disadvantage of a CRPA antenna is its size, weight and power: As CRPAs employ multiple antenna elements, they are inherently larger and heavier. The electronics can pretty much be covered by a single chip these days, leaving the antennas themselves as the problematic aspect, but advances in antenna technology have also made big hurdles.

    For airborne platforms, conformal antennas designed as part of the structure or fuselage can be used; whilst for the dismounted soldier, the trend is towards wearables, where the antennas may be an inherent part of the clothing or helmet design.

    Aside from adaptive antennas there are a whole host of other techniques in your anti-jam kit bag, including receiver-based techniques.

    It’s a numbers game

    For forests and urban canyons, this is where multi-frequency multi-GNSS comes into its own. It really is a numbers game: The more constellations you use, the more satellites you can choose from, and the greater your chances of seeing enough satellites to derive a reasonable navigation solution. You also have more options for mitigating the effects of multipath and other errors.

    Of course, this gives rise to a potentially difficult question for some governments: In defense applications, do you want to rely on foreign GNSS constellations as part of your PNT solution? The attitude here depends on your own country’s policy and a trade-off of perceived gains against perceived threats. The UK, for example, has chosen to embrace all available constellations and frequencies in future military navigation systems.

    That’s probably about as far as GNSS gets you, because now we’re looking at the 20 percent of the time where the user is indoors or underground. In other words, environments where GNSS simply isn’t available. This 20 percent is perhaps more tricky to address, and is the realm of alternative and complementary PNT technologies.

    Beyond GNSS

    Fusing different sensor modalities to create a combined navigation solution is anything but a new idea. The benefits of combining GPS with an inertial sensor were recognized a long time ago, and this classic pairing continues to be the subject of research today.

    The two technologies are highly complementary in various ways: GNSS offers absolute position, low short-term accuracy, and high long-term accuracy. On the other hand, an inertial sensor offers the opposite: relative position, high short-term accuracy, and low long-term accuracy. It’s a match made in heaven.

    But whilst GNSS plus inertial may be a good choice for, say, airborne platforms, it doesn’t solve the in-building and underground problem. Without GNSS, you need something else.

    Indoor navigation has been one of the hottest research topics of recent times, but there are really two types of indoor scenario: the first is when you’re in a shopping mall or airport. You can use an inertial sensor, Wi-Fi, mobile base stations, and various other bits of infrastructure to help you navigate.

    The second scenario is the military one: You’re in an unfamiliar enemy compound or underground tunnel complex. In this case, there is no GNSS, no Wi-Fi, no mobile communications; and, for navigation, you can only really rely on the sensors you bring with you.

    So what other sensor works underground, and complements inertial?

    Visual/inertial integration

    Visual odometry is an established, yet often overlooked, navigation technology that is undergoing a resurgence of interest, in both military and civilian applications. In simple terms, visual odometry uses sequential camera images to determine motion in a six degrees of freedom reference frame. Using either single or multiple cameras a platform can estimate both its 3D position and orientation, providing much the same information as an inertial sensor — but with a few added benefits.

    Visual/inertial sensing allows 3D reconstruction of a road incident (https://www.youtube.com/watch?v=eBw-DH2p5uo&t=2s)
    Visual/inertial sensing allows 3D reconstruction of a road incident. (Screenshot: Roke)

    Because cameras and associated vision-processing algorithms are capable of detecting corners and features, a 3D model of the environment in which the soldier is operating can also be built up. In other words, we can perform simultaneous localization and mapping (SLAM).

    But like any navigation technology, visual odometry has its limitations. It likes well-defined features in the environment, such as corners, but can get confused by moving objects like trees and clouds. Its performance also depends on factors such as the quality of the camera and lens, and how well the system is calibrated. Like an inertial sensor, it provides a relative positioning solution and is subject to accumulation of errors over time. It’s a great technique, but it really comes into its own when combined with another navigation sensor, such as an inertial unit.

    And it’s not just the military guys who are taking advantage of visual/inertial integration. Just take a look at Google’s Tango project, or what Qualcomm is doing, or Roke’s black box for driverless cars, to name but a few examples.

    Bringing it all together

    Over the course of the last decade or two, the operational landscape for soldiers has changed significantly, with far greater focus on urban warfare. The military realized some years ago that the answer to robust navigation for dismounted soldiers was going to require a range of sensor modalities: no single navigation technology is ideal in all environments. That’s why this has been the focus of so many defense programs of recent years.

    By way of example, the UK Ministry of Defence (MoD) initiated a research program in 2013 called Dismounted Close Combat Sensors (DCCS). The contract addressed a range of soldier capabilities, one of which was the ability to provide reliable soldier position and orientation in all environments.

    The DCCS programme evaluated a whole bunch of technologies, but eventually converged to an integration of three primary sensors: multi-constellation GNSS, a low-cost inertial measurement unit (IMU) and a video camera. The single monocular video camera was used to strap down the IMU, in a very tightly-coupled system. It makes sense: when GNSS is available, use it. When GNSS isn’t available, the integrated visual/inertial navigation sensor continues to provide both location and orientation for the duration of the mission. As it should be for a tightly integrated navigation system, the performance of the combined system outperforms any individual sensor in isolation.

    Whilst integrated sensor systems enable our soldiers to position, orientate and navigate themselves, the performance of individual sensors continues to be pushed to new limits. Inertial technology is advancing all the time, and defense is again pushing the boundaries. Take a look at what DARPA is up to, as an example.

    The missing ‘T’

    Haven’t we missed something? Ah yes, there’s a “T” in PNT. So whilst there would seem to be various options for achieving a robust positioning and navigation solution, we mustn’t forget precise timing for those applications that need it. Quantum technology is flavor of the month here and, once more, the defense agencies are furthering developments: DARPA with its ACES program, and MOD/DSTL via the Quantum Technology Program, to illustrate just a couple of examples.

    So whilst GPS will continue to remain the workhorse, defense PNT is migrating from GPS-only to being a many-faced beast. And I haven’t even gotten started on pseudolites, signals of opportunity, eLoran, and cooperative navigation.

    The future of defense PNT looks pretty good to me.

  • Establishing orthometric heights using GNSS — Part 11

    Establishing orthometric heights using GNSS — Part 11

    Strategically Occupying Stations to Support NGS’ GPS on Bench Marks Program

    This is the 11th segment in my series on “Establishing Orthometric Height Using GNSS.” Each column has focused on a specific topic and provided procedures and tools for analyzing that topic. The columns are meant to build on each other. When addressing a topic that has been discussed in a previous column, web links are provided so the reader can review the previous columns.

    The last column, December 2016, highlighted NGS plans for the 2022 Vertical Reference Datum and provided approximate height differences that users can expect to see. It also provided a little history behind the differences between the NGVD 29 and NAVD 88, and how each replacement of the United States’ National vertical reference datum is improving the user’s ability to obtain the most accurate orthometric height. The October 2016 column demonstrated how to use the GPS on BMs dataset to identify potential issues in published NAVD 88 and NAD 83 (2011) heights. It focused on analyzing the NGS’ GPS on BM data set that was used to create NGS’ GEOID12B hybrid geoid model. It provided procedures that users could employ when analyzing the differences between the modeled geoid values and the computed geoid values using GNSS/Leveling data (GNSS-derived ellipsoid height minus leveling-derived orthometric height). The October 2016 column provided several examples of large relative differences in residuals between neighboring stations. Each example represented stations that should be investigated based on different reasons, such as a weak NAVD 88 leveling network design in the region, the station’s published height attribute code implies that the station was not rigorously adjusted into the NAVD 88, and station pairs have different adjustment dates indicating a possible adjustment distribution correction issue or movement.

    The following questions still need to be addressed: (1) Is the large difference due to an issue with the NAVD 88 orthometric height or the NAD 83 (2011) ellipsoid height? and (2) Should the station be included in the development of NGS’ hybrid geoid models? This column will provide suggestions on how users can assist NGS in determining the reason for the large difference between the modeled hybrid geoid value and computed GNSS/leveling geoid computed value. This information will be useful to NGS when developing hybrid geoid models and the 2022 Vertical Transformation model.

    At this moment, the user is limited to what they can do to assist in identifying the problem. There are basically two options: (1) perform precise leveling observations between two or more stations and/or (2) perform accurate GNSS observations between two or more stations. Performing geodetic leveling between two stations is the desired option but is very expensive and time consuming; however, performing accurate GNSS observations between the two stations is relatively inexpensive and, if NGS’ OPUS-Projects is used to process the data then it is relatively simple to determine accurate NAD 83 (2011) ellipsoid heights and height differences. Even if the project is not submitted to NGS for inclusion into NAD 83 (2011), OPUS-Projects provides a easy and traceable mechanism for others to analyze the results and make their own decision.

    First, let’s look at what NGS provides the user on their GPS on Bench Mark Program. The October 2016 column discussed the GPS on Bench Mark dataset used to create GEOID12B. It provided basic information about the program and provided links to websites that address the program. This column will provide additional information that will be useful for those individuals that desire to participate in the GPS on Bench Mark program. The website provides information on bench mark reconnaissance and recovery. NGS outlines to the user how to use their data files to perform a desktop reconnaissance. They provide eight steps that they believe will be helpful to the user when supporting the GPS on Bench Mark program. (See box titled “NGS’ Suggested Eight Steps for Users to Follow When Participating in the GPS on Bench Mark Program.”)

    NGS’ Suggested Eight Steps for Users to Follow When Participating in the GPS on Bench Mark Program

    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:

    1. Desktop reconnaissance
    2. Reconnaissance materials
    3. Reconnaissance equipment
    4. Bench Mark Hunting
    5. Photos
    6. Observe and record
    7. Plan for Survey Observation
    8. Add your Planned Observation to the ArcGIS Online Map

    Each step has a short narrative that provides helpful information for users that want to participate in the program. This column will focus on the first step titled Desktop reconnaissance. (See box titled “Excerpt from the National Geodetic Survey on Bench Mark Reconnaissance and Recovery.”)

    Excerpt from the National Geodetic Survey on Bench Mark Reconnaissance and Recovery

    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:

    1. Desktop reconnaissance

    Bench marks of First and Second order leveling are targeted for GPS observations. Identify where you are looking for survey control. Generally surveyors try to tie into the NSRS without traveling too far from their project areas. Once you have determined your area of interest, use mapping applications to find marks that meet your criteria. The two recommended mapping applications are the NGS Data Explorer and DSWorld. The NGS database does not always get updated when geocachers recover marks on their web site, but DSWorld does provide information from their web site by showing a when it has been recovered.

    To help assist surveyors and geocachers we have also created an ArcGIS Map Package , a zip file for non ArcGIS users and an ArcGIS Online (AGOL) Web Map available using the links below. The Web Map Application is available using any browser and the Map Package and zip file is for users interested in performing their own analysis.

    GPS-on-bench-marks-agol-map
    GPS on Bench Marks AGOL Map

    ngs-gps-on-bench-marks-esri-map-package
    NGS GPS on Bench Marks
Esri Map Package (~178 MB)

    NGS GPS on Bench Marks
Shapes/rasters (~88 MB)

    NGS GPS on Bench Marks
Shapes/rasters (~88 MB)

    These datasets provide the bench marks that were used in the creation of Geoid12B as well as the new GPS on bench marks that have been incorporated into NAD 83 (2011) since the creation of Geoid12B. This is useful information for those that want to occupy different bench marks than those previously observed with GNSS, and it is especially useful for identifying areas of the country that do not have enough bench marks occupied by GNSS. However, as I mentioned in my October 2016 column, the GPS on Bench Mark dataset can also be useful for identifying issues with NAVD 88 orthometric heights and NAD 83 (2011) ellipsoid heights. In the October 2016 column, I recommended that users perform an analysis of the differences between the published Geoid12B values and computed values from the NGS datasheet. (See box titled “Excerpt from October 2016 column – Analyzing Stations in the GPSBM Table.”)

    Excerpt from October 2016 column – Analyzing Stations in the GPSBM Table.

    So, what should the user do with the GPSBM table? I recommend that users perform the following steps when analyzing the stations in the GPSBM table.

    1. Compare the modeled GEOID12B (N12B) value to the computed GPS/Leveling (h minus H) value using the following formula: Published N12B from the NGS data sheet minus (ellipsoid height from the GPSBM table minus orthometric height from the GPSBM table). We discussed this procedure a year ago in column 3 (October 2015). It should be noted that the orthometric height in the GPSBM table may be different than the published NAVD 88 height on the NGS data sheet if the station has been readjusted since the GPSBM table was created.
    2. Repeat the procedure in Step 1 using the latest NGS experimental geoid model, e.g. xGeoid16b. At this time, NGS only provides the experimental geoid models referenced to IGS08 so the user will have to use NGS’ xGeoid16 web tool to obtain the station’s IGS08 ellipsoid height and xGeoid16b value. The input to the tool is the station’s NAD 83 (2011) coordinates (latitude, Longitude, and ellipsoid height). [An example of using the xGeoid16 web tool is provided in the box titled “Example of Using NGS xGeoid16 Web Tool.”] As discussed in column 3 (October 2015), the user will have to remove a bias and trend based on the differences in the region.
    3. Use the station’s data sheet to identify how the station’s orthometric height was determined; for example, was it rigorously adjusted into the NAVD 88 (published height attribute – Adjusted). We discussed the attributes of the NGS data sheet in column 5 (February 2016). A summary of the attributes from the NGS data sheet DSDATA.TXT file is provided in the box titled “Extracted from NGS’ DSDATA.TXT.” I have highlighted the most common attributes of the stations involved in making GEOID12B.
    4. Use the station’s NGS data sheet to determine the adjustment date of the station’s published NAVD 88 orthometric height. We discussed this in column 7 (June 2016). As mentioned in column 7, if the station has a different adjustment date than other stations nearby, there could be inconsistencies due to adjustment distribution corrections and/or movement.

    If you download the Zip file or the Esri Map Package, you should have a layer titled “NGS_Bench_Marks.” This layer contains all the bench marks from the NGS database that have NAVD 88 orthometric heights with the attribute “ADJUSTED.” It should be noted that this is not the complete list of stations used to create the hybrid geoid model GEOID12B. This file only contains bench marks that were established using precise geodetic leveling procedures and incorporated into NAVD 88 using NGS’ leveling adjustment program. The list of attributes and their meaning was provided in my February 2016 column. The ArcGIS NGS_Bench_Marks layer contains a NAVD 88 orthometric height, a Geoid12B value, and an ellipsoid height if the station was occupied in a GNSS project. The ArcGIS user can select all bench marks that have a NAD 83 (2011) ellipsoid height in their state by using an ESRI query builder statement; for example, “STATE” = ‘NC’ AND “DATUM_TAG” = ‘(2011)’ AND “POS_DATUM” = ‘NAD 83’. Now the user can compute the GPS on BMs residual using the following formula: GPS on BMs Residual = Geoid12B value minus [NAD 83 (2011) Ellipsoid Height – NAVD 88 Orthometric Height)]. The user can perform this operation in the ESRI ArcGIS program or download the ArcGIS “NGS_Bench_Marks.dbf” file into Excel (or another spreadsheet program) and compute the computation in that spreadsheet program. The user can then import the file back into ArcGIS or their own GIS software. Once you have the GPS on BMs Residuals you can plot them and look for outliers. This is what I denote as “Strategically Occupying Stations to Support the GPS on Bench Mark Program.” I performed the above operation for the entire “NGS_Bench_Marks” file.

    The file can be downloaded as an Excel document here and as a text document here.

    So, what do I really mean by strategically occupying station to support the GPS on Bench Mark Program. Once you plot the GPS on Bench Marks residuals, the user should use the plots to identify stations that should be re-occupied because of large residuals or new stations that should be occupied in areas void of control. Figure 1 is an example of the GPS on BMs residuals for the State of North Carolina.

    Figure 1 – GPS on Bench Marks Residuals using GEOID12B computed using NGS GPS on Bench Marks Shapes/rasters
    Figure 1 – GPS on Bench Marks Residuals using GEOID12B computed using NGS GPS on Bench Marks Shapes/rasters

    Looking at figure 1, the reader should notice some large red circles (negative GPS on BMs residuals) are located near some large blue circles (positive GPS on BMs residuals). In my opinion, these regions should be analyzed to determine if stations should be re-observed during a GPS on Bench Mark campaign. This doesn’t mean that if other stations are occupied that they will not help improve the hybrid geoid model and the NAVD 88 transformation model to the new 2022 Vertical Reference Datum, it just means that these previously occupied stations are questionable and re-observing these stations may help to explain why the residuals are so large. I’ve provided a couple of examples in North Carolina to explain what I mean.

    Figure 2 depicts a station with a large negative residual (-7.9 cm) surrounded by stations with smaller residuals (mostly positive residuals). This station’s published NAVD 88 height may be an invalid height; that is, the station may have moved after the leveling-derived orthometric height was determined. In my opinion, this station should not be used in the development of a hybrid geoid model or any transformation model from NAVD 88 to another vertical reference datum. It would be useful information to know if the NAVD 88 orthometric height is invalid. In this example, the user could re-observe station Z 183 (PID = FA0997) with a long GNSS session, or simultaneously observe station FA0997 and another nearby station (such as AH5641) during the same long session. The second option allows the user to estimate a new ellipsoid height difference between the two stations that can be compared with the published ellipsoid height difference.

    Figure 2 – Large Negative Residual Surrounded by Smaller Residuals – Station FA0997
    Figure 2 – Large Negative Residual Surrounded by Smaller Residuals – Station FA0997

    The ArcGIS NGS_Bench_Marks layer includes when the station was first recovered (e.g.,1967) and last recovered (e.g., 2009), and the condition of the station (e.g., good condition). The NGS dataset provides the network and local accuracies for published NAD 83 (2011) stations. (See box titled “Excerpt from NGS’ Datasheets for Stations FA0997 and AH5641.”) We discussed NGS’ datasheet and published local and network accuracy values in the August 2015 column.

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    ngs-datasheet-excerpt-2

    The stations’ local and network accuracy values are highlighted in the box titled “Excerpt from NGS’ Datasheets for Stations FA0997 and AH5641.” Station AH5641 local ellipsoid standard error value (0.51 cm) is much better than station’s FA0997 value (2.47 cm). Next, we should look at the local network accuracies to determine which stations were simultaneously observed during a GNSS survey. Once again, these options on the NGS’ datasheets were discussed in the August 2015 column.

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    The box titled “Excerpt from NGS’ The Local and Network Accuracy Data Sheet for Stations FA0997 and AH5641” provides the local and network accuracy data sheet for stations FA0997 and AH56412. The readers should notice that Station FA0997 only has one local accuracy to another station and that station is not AH5641. This implies that these two stations were not observed during the same session. The large relative difference in residual could be due to an invalid NAVD 88 orthometric height but it could also be due to an undetected error in the ellipsoid height due to a weak GNSS survey design. Let’s look at another example where there’s more than one outlier in a small group.

    Figure 3 depicts two stations (AI7070 and AI7073) that appear to be inconsistent with their neighboring stations (FB3216 and FB3222). If we look at the datasheets for these stations, it can be determined that stations AI7070 and AI7073 were observed in the same session but neither station was occupied in a session with FB3216 or FB3222. The datasheets do indicate that FB3216 and FB3222 were observed during the same session. In this case, I would recommend simultaneously observing stations FB3222 and AI7073 to determine an accurate ellipsoid height difference to determine if the relative ellipsoid height difference computed from the published ellipsoid heights are really as accurate as their published network and local accuracy values. If these stations do not get re-observed, I would not recommend using stations AI7070 and AI7073 in the hybrid geoid model.

    Figure 3 – Several Large Negative Residual Surrounded by Smaller Positive Residuals – Stations AI7070 and AI7073
    Figure 3 – Several Large Negative Residual Surrounded by Smaller Positive Residuals – Stations AI7070 and AI7073

    I have focused on North Carolina but this analysis can be performed on any state or region. Figure 4 is a plot of GPS on BMs residuals using Geoid 12B for the State of Florida. Looking at figure 4, there appears to be a lot of stations with large GPS on Bench Mark residuals.

    Figure 4 – GPS on BMs residuals using GEOID12B for the State of Florida
    Figure 4 – GPS on BMs residuals using GEOID12B for the State of Florida

    Figure 5 is a plot of the GPS on Bench Mark residuals using GEOID12B in the Lynn Haven, Florida, area. Looking at figure 5, the reader can see that station BE1497 has a large relative difference between its neighbors (BE0604 and AA9918). This station and one of its neighboring station should be re-observed in a GNSS survey. In my opinion, if this station is not re-observed then it should be rejected and not included in the development of the hybrid geoid model.

    Figure 5 – GPS on BMs residuals using GEOID12B for Lynn Haven, Florida, Area
    Figure 5 – GPS on BMs residuals using GEOID12B for Lynn Haven, Florida, Area

    Some States have enough bench marks that have been occupied by GPS that re-observing a station may not improve the hybrid geoid model. It may be sufficient to reject the station so it doesn’t distort the hybrid geoid model. Figure 6 is a plot of the GPS on BMs for the State of Missouri. If you compare figure 1 (plot of GPS on BMs in North Carolina) with figure 6 (plot of GPS on BMS in Missouri), it’s obvious that the State of North Carolina has more bench marks occupied by GPS than Missouri. Most of the residuals in figure 6 seem reasonable but the user should investigate those stations that are greater than +/- 5 cm. An example of a station that should be re-observed is station C 10 (KD0210). Figure 7 is a plot of the GPS on BMs surrounding station C 10 (KD0210). The NGS data sheet for station C 10 states that the station was incorporated into NAD 83 (2011) in May 2015; therefore, it wasn’t used in the creation of GEOID 12B. The data sheet also provides the Network and Local Accuracy values for the station. [See the box titled “Excerpt from NGS’ Datasheets for Station KD0210.”] The network and local ellipsoid height accuracy values (6.49 cm) are larger than most published NAD 83 (2011) stations.

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    Figure 6 – GPS on BMs residuals using GEOID12B for the State of Missouri
    Figure 6 – GPS on BMs residuals using GEOID12B for the State of Missouri
    Figure 7 – GPS on BMs residuals using GEOID12B Surrounding Station KD0210 (C 12)
    Figure 7 – GPS on BMs residuals using GEOID12B Surrounding Station KD0210 (C 12)

    This is an area that is void of GPS on bench mark control so this station is extremely important. However, this station has a large GPS on BM residual and a large local accuracy value which makes the station’s published orthometric height and ellipsoid height questionable. I would recommend that this bench mark and several nearby bench marks be observed in a GNSS survey to provide additional estimates of the relationship between the NAVD 88 orthometric heights and NAD 83 (2011) ellipsoid heights in this area. Saying that, it is very important that users perform procedures that result in an accurate GNSS-derived ellipsoid height. This means that users may have to observe stations for several hours and repeat observations on different days and at different times of the day. Of course, I realize that this may be too expensive for most surveyors but the end result may not be sufficient to determine why the station has a large GPS on BM residual.

    I stated in my October 2016 column that step 2 was to use the latest experimental geoid model in the analysis. (See box titled “Excerpt from October 2016 column – Analyzing Stations in the GPSBM Table.”) I have focused this column on using data that can easily be obtained from the NGS’ website. Saying that, in my next example I have computed the GPS on Bench Marks residuals using a detrended xGeoid16b that is consistent with NAD 83 (2011) [i.e., a bias and trend has been removed from the differences]. This information is not currently available from NGS’ website but I want to show the differences between the hybrid model residuals and the experimental geoid model, xGeoid16b.

    It’s very difficult, if not impossible, to identify how much the hybrid geoid model has been distorted to fit a GPS/Leveling station by looking at published data from NGS data sheets. Figures 8 and 9 demonstrate how some large GPS on Bench Marks residuals using GEOID12B may be distorting the hybrid geoid model. Figure 8 is a plot of the GPS on BM residuals using GEOID 12B in an area in Rockbridge County, Virginia, and Figure 9 is a plot of the same stations using a detrended scientific geoid model xGeoid16b that is consistent with NAD 83 (2011). Looking at figure 8, stations GW2113 and GW0934 appear to be large outliers, -8.8 cm and 11.8 cm, respectively. Station GW0934 was rejected by the geoid team. However, looking at figure 9, using a detrended xGeoid 16b model, the GPS on BM residual of station GW2113 is -19.3 cm and the residual of station GW0934 is only 3.4 cm. What is very important to notice on figure 8 is that nearby stations GW1042 and GW0822 residuals are only -3.3 cm and -2.0 cm, respectively; but, on figure 9, using the detrended xGeoid16b model, the residuals of stations GW1042 and GW0822 are -12.2 cm and -11.5 cm, respectively. Some of these stations need to be re-observed to determine if the NAVD 88 orthometric heights are no longer valid or if there are undetected errors in the published ellipsoid heights. This is why the experimental geoid model should also be used when analyzing GPS on Bench Mark residuals; and why some GPS on BM stations that are inconsistent with their neighboring stations should not be included in the development of a hybrid geoid model. This means that analyzing GPS on Bench Marks residuals using just the hybrid geoid model will only identify outliers that are significantly different from their neighbors. Some outliers will be missed but the procedure does help to prioritize those stations that should be re-observed to help support NGS’ GPS on Bench Mark Program.

    Figure 8 – GPS on BMs residuals using GEOID12B for a Large Outlier in Rockbridge County, Virginia (PID =GW2113)
    Figure 8 – GPS on BMs residuals using GEOID12B for a Large Outlier in Rockbridge County, Virginia (PID =GW2113)

    Figure 9 – GPS on BMs Residuals Using a Detrended GEOID16b [consistent with NAD 83 (2011), bias and trend removed] for a Large Outlier in Rockbridge County, Virginia (PID =GW2113)
    Figure 9 – GPS on BMs Residuals Using a Detrended GEOID16b [consistent with NAD 83 (2011), bias and trend removed] for a Large Outlier in Rockbridge County, Virginia (PID =GW2113)
    It should be noted that many of these large GPS on BM residuals could be due to an invalid NAVD 88 published height because the bench mark moved since the last time the height of the bench mark was adjusted and published, and/or an undetected error in an ellipsoid height due to a weak GNSS project design. Either way, in my opinion, most of these stations with large GPS on BMs residuals don’t accurately represent the current NAVD 88. When performing a geodetic survey, these stations would be identified as bench marks with invalid heights when following the appropriate Federal geodetic survey guidelines, procedures, and specifications. These bench marks should not be used in the hybrid geoid model just like they would not be used in controlling geodetic surveys. I want to emphasize that I’m not criticizing NGS process for creating their hybrid geoid model. NGS’ goal is to create a hybrid geoid model that is consistent with published NAVD 88 values. I believe NGS is using all the data and information available to them. I am trying to emphasize to users the importance to strategically occupy stations to help support the GPS on Bench Marks Program and create a hybrid geoid model that accurately represents the current NAVD 88.

    This column focused on addressing the following questions: (1) Is the large GPS on BM residual due to an issue with the NAVD 88 orthometric height or the NAD 83 (2011) ellipsoid height? and (2) Should stations with large GMS on BM residuals be included in the development of NGS’ hybrid geoid models? The column provided suggestions on how users can assist NGS in determining the reason for the large difference between the modeled hybrid geoid value and computed GNSS/leveling geoid computed value. This information will be useful to NGS when developing hybrid geoid models and the 2022 Vertical Transformation model.

  • CNN explores space warfare, US military’s use of GPS

    shiyan-grabbing-cnn-space-warfare
    Photo: Shiyan

    A spaceborne laser zaps a GPS satellite, disabling it.

    A “kamikaze” satellite hits and destroys other nations’ critical satellites.

    Another satellite moves beside an Intelsat bird — and listens in.

    A new CNN special considers all of these possibilities in an exploration of an arms race in space, showcasing the devastation that would be caused by space warfare and how the U.S. military is preparing.

    “War in Space: The Next Battlefield” premiered Nov. 29 on CNN. It provides the general public with an understanding of the critical nature of GPS, ranging from mundane activities such as daily commutes and withdrawing money from a bank, to the reliance on GPS for soldiers and intelligence agencies defending the U.S.

    The documentary explores the belief by many in the military and civilian experts that war in space is inevitable, with particular attention to methods China and Russia might use to interfere with or disable GPS.

    CNN goes inside Lockheed Martin’s facility, where it is building the next-generation GPS III satellite, as well as U.S. Space Command at Peterson Air Force Base, and visits the 2SOPS team at Schriever Air Force Base.

    CNN national security correspondent Jim Sciutto interviews the chain of command for space warfare, including Gen. William L. Shelton and Gen. John Hyten, both former commanders of Air Force Space Command. (Gen. Hyten is now commander of U.S. Strategic Command).

    Also interviewed are Adm. Cecil Haney (Ret.), former commander of U.S. Strategic Command; Lt. Gen. David Buck, commander of the Joint Functional Component Command for Space; and Defensive Duty Officer 1st Lt. Andrew Engle, a newly created position to monitor threats in space.

    If you haven’t seen this documentary, you can still watch it through on demand on cable and via the CNNgo app.