GPS World

Category: Applications

  • Innovation: Low-cost single-frequency positioning approach

    Innovation: Low-cost single-frequency positioning approach

    INNOVATION INSIGHTS with Richard Langley

    GPS + BDS RTK

    Even a GNSS receiver that can supply raw pseudorange and carrier-phase measurements now costs only a few hundred dollars, and in this month’s column, a couple of researchers from Down Under pit a couple of these receivers up against a couple of survey-grade receivers. Did this cheap receiver turn out to be a good thing?

    By Robert Odolinski and Peter J.G. Teunissen

    ALL GOOD THINGS ARE CHEAP; ALL BAD ARE VERY DEAR. That’s what the famous American essayist (and surveyor) Henry David Thoreau wrote in his diary on March 3, 1841. He was likely referring, in part, to the cheapness of the things he came across in nature such as birdsong or the plants and trees on the shores of Walden Pond and the dearness of some luxuries and comforts of civilization, which he tended to eschew. But what has that got to do with GPS, you might ask?

    When they were first introduced in the late 1970s and early 1980s, GPS receivers were very dear. Many of them sold for anywhere from $50,000 to $250,000, which would be equivalent to about twice those amounts in today’s dollars. The first civilian receivers were large bulky affairs. As I documented in this column in April 1990 (“Smaller and Smaller: The Evolution of the GPS Receiver”), the “first commercially available GPS receiver was the STI-5010 built by Stanford Telecommunications Inc. It was a dual-frequency, C/A- and P-code, slow-sequencing receiver. Cycling through four satellites took about five minutes, and the receiver unit alone required about 30 centimeters of rack space. External counters, also requiring rack space, made pseudorange measurements. An external computer controlled the receiver and computed positions.” While it could be transported in a small truck (and some were), it was not designed for portability and ease of use by surveyors or geodesists.

    Then, in 1982, Texas Instruments introduced the first relatively compact civil GPS receiver, the TI 4100, also known as the Navstar Navigator. And as I also noted in that column more than 15 years ago, this “receiver could make both C/A- and P-code measurements along with carrier-phase measurements on both L1 and L2 frequencies. Its single hardware channel could track four satellites simultaneously through a multiplexing arrangement. The 37 × 45 × 21-centimeter receiver/processor had a handheld control and display unit and an optional dual-cassette data recorder for saving measurements for post-processing. The unit, although portable, weighed 25 kilograms and consumed 110 watts of power (the receiver doubled as a hand warmer). Field operation required a supply of automobile batteries.”

    My, how things have changed. Beginning around 1990, receivers steadily got smaller and smaller and cheaper and cheaper. Survey-grade GNSS (not just GPS) receivers can now be purchased for well under $10,000 and consumer-grade units sell for as little as a hundred dollars or less. And, of course, the GNSS modules inside smartphones and other devices cost manufacturers only a couple of dollars or so.

    But even a GNSS receiver that can supply raw pseudorange and carrier-phase measurements now costs only a few hundred dollars, and in this month’s column, a couple of researchers from Down Under pit a couple of these receivers up against a couple of survey-grade receivers. Did this cheap receiver turn out to be a good thing?

    Read on to find out.

    GPS has been the number-one positioning tool for a range of applications during the past few decades. The integration of the emerging global navigation satellite systems, such as the Chinese BeiDou Navigation Satellite System (BDS), can give improved precise (millimeter- to centimeter-level) real-time kinematic (RTK) positioning. When BDS is combined with GPS, about double the number of satellites are visible in the Asia-Pacific region, which can make single-frequency RTK and low-cost receiver RTK positioning possible.

    In this article, we will analyze the performance of L1 GPS + B1 BDS in Dunedin, New Zealand, using low-cost receivers. We compare their performance to that of L1+L2 GPS survey-grade receivers.

    First, we describe the GPS+BDS functional and stochastic models and the data used for our evaluations. Least-squares variance component estimation (LS-VCE) is used as a means to determine the code and phase (co)variances to formulate a realistic stochastic model. (An incorrect stochastic model will deteriorate the ambiguity resolution and consequently the achievable positioning precisions.)

    Having correctly defined the stochastic model, we focus on the positioning performance. We investigated the ambiguity resolution and positioning performance, both formally and empirically, for customary and high-elevation cut-off angles. The high cut-off angles are used to mimic situations when low-elevation multipath is to be avoided. Lastly, we compared all our results between using low-cost and survey-grade antennas.

    GPS+BDS POSITIONING MODEL

    The model that we used for positioning is given as follows. Assume that sG + 1 GPS satellites are tracked on fG frequencies and sB + 1 BDS satellites on fB frequencies. As we apply system-specific double-differencing (DD), one pivot satellite is used per system. The total number of DD phase and code observations per epoch then equals 2 fG sG + 2 fB sB. We assume for now that cross-correlation between frequencies as well as code and phase is absent. The combined multi-frequency short-baseline GPS+BDS model is then defined as follows.

    The system-specific DD phase and code observation vectors are denoted as φ* and p*, respectively, with * = {G, B} where G = GPS and B = BDS. The single-epoch GNSS model of the combined system is given as

     (1)

    and

     (2)
    in which

     is the combined phase vector,

    is the combined code vector,

     is the combined integer ambiguity vector,
    is the real-valued baseline vector,

     is the combined phase random observation noise vector,

     is the combined code random observation noise vector, and

    D[.] denotes the dispersion operator.

    The entries of the baseline design and wavelength matrices are given as

    where    is the  x 1 vector of 1s,  is the   differencing matrix,   is the  unit matrix, the geometry-matrices GG  and GB  contain the undifferenced receiver-satellite unit direction vectors for GPS and BDS, respectively,   is the wavelength of frequency  ,   denotes the Kronecker product, and “diag” and “blkdiag” indicate diagonal and block diagonal matrices, respectively. The entries of the positive definite variance matrices are given as

     (3)

    where  ,     denote the phase and code standard deviation, respectively, and    the satellite elevation-angle-dependent weight.

    The model in Equation 1 applies to short baselines, and thus the ionospheric and tropospheric delays are assumed absent. The broadcast ephemerides are used to obtain the satellite coordinates. Further, the Least-squares AMBiguity Decorrelation Adjustment (LAMBDA) technique is used to estimate the integer ambiguities a. The observation noise vectors ε and e, respectively, are zero-mean vectors, provided that no multipath is present in Equation 1.

    EXPERIMENT SETUP

    The GNSS receivers we used are depicted in FIGURE 1. Firstly, two low-cost single-frequency receivers were set up to collect L1+B1 GPS+BDS data for two days. These receivers cost a few hundred U.S. dollars. Since the patch antennas we used have been shown to have less effective signal reception and multipath suppression in comparison to survey-grade antennas, the receivers that collected data for two days were additionally connected to such antennas. These antennas have a cost of slightly more than US$1,000 per antenna. To compare the low-cost solution to a survey-grade receiver-solution, two such receivers (which cost several thousand U.S. dollars) were connected to the same survey-grade antennas through splitters and collected L1+L2 GPS data. A detection, identification and adaption procedure was used to eliminate any outliers.

    FIGURE 1. Low-cost single-frequency receivers collecting GPS+BDS data for single-baseline RTK, with patch antennas (left) and survey-grade antennas (right) on Jan. 4–6 and Jan. 6–8, 2016, respectively. Survey-grade dual- frequency GPS receivers were connected to the same survey-grade antennas simultaneously to truly track the same GPS constellation.

    FIGURE 2 depicts the corresponding redundancy of the two receiver models (that is, the number of observations minus the number of estimated unknowns) together with the number of satellites over 48 hours (30-second epoch interval). The number of BDS satellites (magenta lines) is overall smaller than when compared to GPS (blue lines) in Dunedin. However, Figure 2 also shows that the model strength of L1+B1 GPS+BDS, as measured by its redundancy, is almost similar to that of L1+L2 GPS except for some hours at the middle of the two days. This implies that the two receiver models can potentially give competitive RTK ambiguity resolution and positioning performance. This is however only true if the receiver code and phase observation noise would be of similar magnitude between the receivers used, hence the need for an analysis of the receiver observation precision.

    FIGURE 2. Redundancy (left) and number of satellites (right) of L1+B1 GPS+BDS and L1+L2 GPS during Jan. 6–8, 2016, (48 hours) for an elevation cut-off angle of 10°.

    In our receiver evaluations, we determined a set of reference ambiguities by using a known baseline and treating them as time-constant parameters over the two days in a dynamic model.

    LOW-COST RTK POSITIONING

    The code and phase variances were estimated by LS-VCE using data independent from the data used for the following positioning analysis. The variances are needed to formulate a realistic stochastic model, whereas an incorrect stochastic model will deteriorate the ambiguity resolution and consequently the achievable positioning precisions. TABLE 1 depicts the corresponding estimated standard deviations (STDs) used for our positioning models.

    TAB LE 1. Zenith-referenced undifferenced code and phase standard deviations estimated by least-squares variance component estimation.

    Table 1 shows that the code precision of L1 GPS and B1 BDS improves significantly when the survey-grade antennas are used instead of patch antennas (49 centimeters STD for L1/B1 that decreases to about 30 centimeters), due to their better signal reception and multipath suppression abilities. For testing our stochastic model, we used data that is independent from the data used to estimate the code/phase precision.

    Positioning Performance. The single-epoch (instantaneous) RTK positioning results for 24 hours data are shown in FIGURE 3, with ambiguity-float solutions shown at the top and ambiguity-fixed solutions at the bottom. Only the correctly fixed solutions are depicted as determined by comparing the instantaneously estimated ambiguities to the set of reference ambiguities. The 95% empirical and formal confidence ellipses and intervals are shown in green and red, respectively. They were computed from the empirical and formal position variance matrices. The empirical variance matrix was estimated from the positioning errors as obtained from comparing the estimated positions to precise benchmark coordinates. The formal variance matrix used was determined from the mean of all single-epoch formal variance matrices.

    FIGURE 3. Horizontal (north (N), east (E)) position scatter and corresponding vertical (U) time series of the float (top) and correctly fixed (bottom) L1+B1 GPS+BDS single-epoch RTK solutions for an elevation cut-off angle of 10°. The 95% empirical and formal confidence ellipses and intervals are shown in green and red, respectively. The 24 hour (30 second) period is 22:00-22:00 UTC Jan. 5-6, 2016, for patch antennas in (a) and 21:48-21:48 UTC Jan. 8-9, 2016, for survey-grade antennas in (b), which are periods independent of the periods used to determine the stochastic model through the code/phase STDs in Table 1.

    Figure 3 shows a good fit between the formal and empirical confidence ellipses/intervals, which thus illustrates realistic LS-VCE STDs in Table 1 that were used in the stochastic model. Note also the two-order of magnitude improvement when going from float to fixed solutions, and that the low-cost receiver plus survey-grade antenna has the most precise ambiguity-float positioning solutions.

    Ambiguity Resolution and Positioning Performance for Higher Cut-Off Angles. We subsequently investigated the low-cost L1+B1 GPS+BDS performance for high elevation cut-off angles, so as to mimic situations in urban canyon environments or when low-elevation-angle multipath is present and is to be avoided. We have made comparisons to the survey-grade L1+L2 GPS results. It has been shown that a good ambiguity resolution performance does not necessarily imply a good positioning performance, so we investigated what effect this has on our positioning models.

    The following integer least-squares (ILS) success rates (SRs) are thus computed based on epochs with the condition of positional dilution of precision (PDOP) ≤ 10 and averaged over all epochs over two days of data. By including and excluding epochs with large PDOPs, we can show how the positioning performance of the different models is affected by poor receiver-satellite geometries. To better understand how this exclusion of epochs with large PDOPs also influenced the empirical ambiguity-correctly-fixed positioning performance, we constructed TABLE 2, which shows the corresponding positioning STDs for two days of data. These STDs were computed by comparing the estimated positions to precise benchmark coordinates. In addition to the positioning performance, we depict in Table 2 the corresponding empirical ILS SR for full ambiguity-resolution, which is given by the ratio of the number of correctly fixed epochs to the total number of epochs.

    TABLE 2. Single-epoch empirical STDs (N, E, U) of correctly fixed positions for the three positioning models together with their ILS SR for four elevation cut-off angles and 48 hours of data (Jan. 4–6 and Jan. 6–8, 2016). The empirical STDs and ILS SRs are also shown when conditioned on PDOP ≤ 10.

    Table 2 shows that the L1+B1 low-cost receiver plus patch antenna combination has (as expected) smaller SRs in comparison to those when the survey-grade antenna is used. This latter combination has comparable SRs to the (PDOP-conditioned) SRs of the survey-grade L1+L2 GPS receiver for cut-off angles up to 25°.

    In support of better understanding Table 2, FIGURE 4 shows typical positioning results for the different receiver and antenna combinations with elevation cut-off angles of 10° (top two rows) and 25° (bottom two rows). The first and third rows show the local horizontal (N, E) positioning scatterplots and the second and fourth rows the vertical (U) time series over two days of data. The float solutions are depicted in gray, and incorrectly and correctly fixed solutions in red and green, respectively. The zoom-in is given to better show the spread of the correctly fixed solutions with millimeter-centimeter level precisions. The formal ambiguity-float STDs are also shown under the up time series to reflect consistency between the empirical and formal positioning results.

    FIGURE 4. Horizontal (N, E) scatterplots and vertical (U) time series for L1+B1 low-cost receiver with patch antenna (first column) with 99.5% (89.8%) ILS SR, L1+B1 low-cost receiver with survey-grade antenna (second column) with 100% (97.8%) ILS SR, and survey-grade L1+L2 GPS (third column) with 100% (94.1%) ILS SR, using 10° (top two rows) and 25° (bottom two rows) cut-off angles respectively (Jan. 4–6, 2016, for low-cost receiver with patch antenna and Jan. 7–8, 2016, for the low-cost and survey-grade receivers with survey-grade antennas). The SRs are conditioned on PDOP ≤ 10 and computed based on all epochs. Below the vertical time series, the ADOP is depicted in blue color, the 0.12-cycles level as red, and ambiguity-float vertical formal STDs are shown in gray.

    We also depict in Figure 4 the ambiguity dilution of precision (ADOP) as an easy-to-compute scalar diagnostic to measure the intrinsic model strength for successful ambiguity resolution. The ADOP is defined as

       (cycles)   (4)

    with n being the dimension of the ambiguity vector,    the ambiguity variance matrix, and |.| denoting the determinant. ADOP gives a good approximation to the average precision of the ambiguities, and it also provides for a good approximation to the ILS SR. The rule-of-thumb is that an ADOP smaller than about 0.12 cycles corresponds to an ambiguity SR larger than 99.9%.

    Figure 4 shows that more solutions are incorrectly fixed (red dots) when the ADOPs (blue lines) are larger than the 0.12 cycle level (red dashed lines). The figure also reveals that the L1+B1 low-cost receiver plus patch antenna combination achieves an ILS SR (99.5%) similar to that of the survey-grade L1+L2 GPS receiver (SR of 100%) for the cut-off angle of 10°. This ILS SR corresponds to the availability of correctly fixed solutions (green dots) with millimeter-centimeter level positioning precision over the two days. The L1+L2 GPS receiver has, moreover, large ambiguity-fixed positioning excursions at the same time as the formal STDs are large for the cut-off angle of 25° due the poor GPS-only receiver-satellite geometry for this high cut-off angle. This is also reflected by the corresponding relatively large ambiguity-fixed STDs depicted in Table 2 that are improved from decimeter- to millimeter-level when the PDOP ≤ 10 condition is applied. Figure 4 also shows that the L1+B1 low-cost receiver with the survey-grade antenna has a larger SR of 97.8% when compared to the PDOP-conditioned SR for L1+L2 GPS of 94.1% for the cut-off angle of 25° (see also Table 2), owing to the use of BDS that significantly improves the receiver-satellite geometry.

    Finally, we also tested the low-cost receiver-solution (with survey-grade antennas) for a baseline length of 7 kilometers, where (small) residual slant ionospheric delays are present. It was shown that this combination still has the potential to achieve ambiguity resolution and positioning performance competitive with the survey-grade receiver-solution.

    CONCLUSIONS

    In this article, we evaluated a low-cost L1+B1 GPS+BDS RTK setup and compared its ambiguity resolution and positioning performance to a survey-grade L1+L2 GPS solution in Dunedin, New Zealand. The LS-VCE procedure was used to determine the variances of the low-cost receivers. The estimated variances are needed so as to formulate a realistic stochastic model, otherwise the ambiguity resolution and hence the achievable positioning precisions would deteriorate.

    Since we analyzed a short baseline, the LS-VCE variances were shown to likely be affected by multipath. To mitigate multipath we connected the low-cost receivers to survey-grade antennas with better signal reception and multipath suppression abilities. It was shown that the survey-grade antennas can significantly improve the performance for the low-cost receivers so that the code/phase noise estimates more resemble that of survey-grade receivers. The LS-VCE STDs were furthermore shown to be realistically estimated for an independent time period.

    We also demonstrated that the low-cost receivers can give competitive instantaneous ambiguity resolution and positioning performance to that of the survey-grade receivers. This is particularly true when the low-cost receivers are connected to survey-grade antennas.

    ACKNOWLEDGMENTS

    This article is based on the paper “On the Performance of a Low-cost Single-frequency GPS+BDS RTK Positioning Model” presented at the 2017 International Technical Meeting of The Institute of Navigation held Jan. 30-Feb. 1, 2017, in Monterey, California.

    Ryan Cambridge at the School of Surveying, University of Otago, collected the low-cost receiver data. Author Peter J.G. Teunissen was supported by an Australian Research Council Federation Fellowship. All of this support is gratefully acknowledged.

    MANUFACTURERS

    The low-cost receivers used in the research were u-blox EVK-M8T receivers. The survey-grade receivers were Trimble NetRS receivers. The patch antennas were u-blox ANN-MS antennas, while the survey-grade antennas were Trimble Zephyr 2 GNSS antennas.

    ROBERT ODOLINSKI conducted his Ph.D. studies at Curtin University, Perth, Australia, from 2011 to 2014. His research focus is next-generation multi-GNSS integer ambiguity resolution enabled precise positioning. In 2015, Odolinski started his position as a lecturer/research fellow in geodesy/GNSS at the School of Surveying, University of Otago, New Zealand.

    PETER J.G. TEUNISSEN is a professor of geodesy and navigation and the head of the Curtin GNSS Research Centre, Curtin University. He is also with the Department of Geoscience and Remote Sensing, Delft University of Technology, Delft, The Netherlands. His research interests include multiple GNSS and the modeling of next-generation GNSS for high-precision positioning, navigation and timing applications.

    FURTHER READING

    • Authors’ Conference Paper

    “On the Performance of a Low-cost Single-frequency GPS+BDS RTK Positioning Model” by R. Odolinski and P.J.G. Teunissen in Proceedings of the 2017 International Technical Meeting of The Institute of Navigation, Monterey, California, Jan. 30 – 1 Feb., 2017, pp. 745–753.

    • Authors’ Related Work

    “Single-Frequency, Dual-GNSS Versus Dual-frequency, Single-GNSS: A Low-cost and High-grade Receivers GPS-BDS RTK Analysis” by R. Odolinski and P.J.G. Teunissen in Journal of Geodesy, Vol. 90, No. 11, 2016, pp. 1255–1278, doi:10.1007/s00190-016-0921-x.

    “Combined BDS, Galileo, QZSS and GPS Single-frequency RTK” by R. Odolinski, P.J.G. Teunissen and D. Odijk in GPS Solutions, Vol. 19, No. 1, 2015, pp. 151–163, doi:10.1007/s10291-014-0376-6.

    “Instantaneous BeiDou+GPS RTK Positioning With High Cut-off Elevation Angles” by P.J.G. Teunissen, R. Odolinski and D. Odijk in Journal of Geodesy, Vol. 88, No. 4, 2014, pp. 335–350, doi: 10.1007/s00190-013-0686-4.

    “The Future of Single-Frequency Integer Ambiguity Resolution” by S. Verhagen, P.J.G. Teunissen and D. Odijk in Proceedings of the VII Hotine-Marussi Symposium on Mathematical Geodesy, Rome, June 6–10, 2009, edited by N. Sneeuw, P. Novák, M. Crespi and F. Sanso, International Association of Geodesy Symposia, Vol. 137, 2012, pp. 33–38, doi:10.1007/978-3-642-22078-4 5.

    • Mass-Market Single-Frequency Positioning

    “Precision GNSS for Everyone: Precise Positioning Using Raw GPS Measurements from Android Smartphones” by S. Banville and F. Van Diggelen in GPS World, Vol. 27, No. 11, Nov. 2016, pp. 43–48.

    “Centimeter-Level Positioning for UAVs and Other Mass-Market Applications” by C. Mongredien, J.-P. Doyen, M. Strom and D. Ammann in Proceedings of ION GNSS+ 2016, the 29th International Technical Meeting of the Satellite Division of The Institute of Navigation, Portland, Oregon, Sept. 12–16, 2016, pp. 1441–1454.

    “Accuracy in the Palm of Your Hand: Centimeter Positioning with a Smartphone-Quality GNSS Antenna” by K.M. Pesyna, Jr., R.W. Heath, Jr., and T.E. Humphreys in GPS World, Vol. 26, No. 2, February 2015, pp. 16–18, 27–31.

    • BeiDou Navigation Satellite System

    “Initial Assessment of the COMPASS/BeiDou-2 Regional Navigation Satellite System” by O. Montenbruck, A. Hauschild, P. Steigenberger, U. Hugentobler, P.J.G. Teunissen and S. Nakamura in GPS Solutions, Vol. 17, No. 2, 2013, pp. 211–222, doi:10.1007/s10291-012-0272-x.

    • LAMBDA

    “On the Reliability of Integer Ambiguity Resolution” by S. Verhagen in Navigation, Vol. 52, No. 2, Summer 2005, pp. 99–110, doi: 10.1002/j.2161-4296.2005.tb01736.x.

    “Fixing the Ambiguities: Are You Sure They’re Right?” by P. Joosten and C. Tiberius in GPS World, Vol. 11, No. 5, May 2000, pp. 46–51.

    “A New Way to Fix Carrier-Phase Ambiguities” by P.J.G. Teunissen, P.J. de Jonge and C.C.J.M. Tiberius in GPS World, Vol. 6, No. 4, April 1995, pp. 58–61.

    • Ambiguity Dilution of Precision

    “ADOP in Closed Form for a Hierarchy of Multi-frequency Single-baseline GNSS Models” by D. Odijk and P.J.G. Teunissen in Journal of Geodesy, Vol. 82, 2008, pp. 473–492, doi: 10.1007/s00190-007-0197-2.

    • GNSS Antennas

    “GNSS Antennas: An Introduction to Bandwidth, Gain Pattern, Polarization and All That” by G.J.K. Moernaut and D. Orban in GPS World, Vol. 21, No. 2, February 2009, pp. 42–48.

  • Boomerang system locates gunfire on the battlefield

    Boomerang system locates gunfire on the battlefield

    Surrounding sounds may not be a common way of determining location. But on the battlefield, warfighters need to know the direction of gunshots to enable a proper response.

    Weighing 12 ounces, the Boomerang Warrior-X by Raytheon BBN Technologies provides immediate hostile fire location awareness to individual soldiers and gives unit leaders shooter grid coordinates, according to the company. These situational awareness enhancements improve coordinated team responses to hostile fire.

    Incoming shot announcements are transmitted to a built-in speaker or an earpiece while a lightweight display provides range and azimuth of the shooter position. As the soldier moves, the system compensates for the soldier’s motion and continually updates the threat’s location on a wrist display.

    The Boomerang Warrior X system.

    This summer, an undisclosed Gulf nation has awarded a direct commercial sales contract to Raytheon BBN Technologies valued at more than $10 million for the delivery of 2,000 Boomerang Warrior-X systems during the next 12 months.

    “This technology is a proven life saver on the battlefield,” said Ed Campbell, president of Raytheon BBN Technologies. “Boomerang delivers the best performance of any available shooter detection system today at the lowest cost.”

    Raytheon BBN Technologies is a wholly owned subsidiary of Raytheon Company.

  • German Defense chooses Rockwell Collins NavHub system for GNSS

    German Defense chooses Rockwell Collins NavHub system for GNSS

    (Photo: Rockwell Collins)

    The German Ministry of Defense selected Rockwell Collins’ NavHub navigation system to provide GNSS availability to a variety of its military vehicles.

    The NavHub system serves as a next-generation GNSS- and Military-code (M-code)-enabled solution for the German Armed Forces.

    Customizable for ground and maritime platforms, NavHub provides a variety of vehicle interfaces, meets the standards required by military vehicle operators, and allows users to receive data from multiple secure and open-service GNSS constellations to simultaneously confirm the navigational solution.

    Access to multi-constellation GNSS and GPS M-Code will provide a significantly enhanced navigational solution over the current GPS-only solution.

    Work under the contract will be performed in Rockwell Collins’ facilities in in Europe.

    About the NavHub GNSS navigation system

    NavHub (Image:: Rockwell Collins)

    Based on Rockwell Collins Selective Availability/Anti-Spoofing Module (SAASM) GPS receivers, NavHub is strategically designed to meetfast-moving and demanding combat environments.

    Through the use of dual-installed GNSS receivers, NavHub provides an assured navigational solution, interfaces and GNSS upgrade path to support modern operations platforms.

    Features include:

    • Dual receiver card slots, enabling multi-constellation reception
    • SAASM security (expansion to M-code), expansion to multi constellation GNSS
    • Extended platform interfaces, including Ethernet, USB and CAN
    • Extended performance in a jammed environment (i.e., 41 dB while tracking and 24 dB during initial acquisition)

    “NavHub meets the critical mission need for accurate navigation support for fast-moving platforms and challenging environments,” said Claude Alber, vice president and managing director, Europe, Middle East and Africa for Rockwell Collins. “Our military GNSS receivers will provide significantly enhanced navigational capabilities to military vehicles and will mitigate terrain, forest and urban degradation as it will raise the number of satellites used from 28 to well over 100.”

     

  • Taoglas launches RF filter division for IoT, mobile apps

    Taoglas is launching a new RF Filter division specifically developed for Internet of Things (IoT) and mobile applications.

    Taoglas, a provider of IoT and M2M antenna products, made the announcement at at Mobile World Congress Americas this week.

    Taoglas aims to provide high-quality, small-form-factor, cost-effective and easy-to-implement RF filters.

    The new filter division will feature a range of off-the-shelf filters for a variety of applications, including filters for emerging license-free bands used for IoT, L1/L2 and L1/L5 GNSS applications.

    Taoglas can also work with customers to develop custom filter solutions.

    “Today’s mobile and IoT applications require high-performance RF filters, in a form factor and cost that makes sense for our customers,” said Dermot O’Shea, co-CEO at Taoglas. “We’ve seen the frustrations our own engineers have had in quickly sourcing reliable components for active antenna and electronic designs. Taoglas is eliminating that frustration with its own filter division, applying the same principles for success that we’ve demonstrated with our antenna business.”

    The filters are manufactured in Taoglas’ purpose-built production facilities in Taiwan, and shipped immediately anywhere worldwide. Support is available from any Taoglas location globally. Filters are available through regular Taoglas sales and distribution channels.

  • Defense, academia test systems for GPS denial at NAVFEST

    Defense, academia test systems for GPS denial at NAVFEST

    By Christopher Ball, 412th Test Wing Public Affairs

    What happens when GPS isn’t available?

    A collection of U.S. Department of Defense units and universities found out when they gathered at Edwards Air Force Base, California, to evaluate various aerial platforms in a degraded GPS environment this summer.

    The week-long test event called DT NAVFEST — short for Developmental Test Navigation Festival — was the first large-scale program of its kind, according to James Cook, KC-46A project manager with the 418th Flight Test Squadron.

    “DT NAVFEST was established to provide a locally more realistic GPS jamming environment in which aircraft platforms and unmanned aerial vehicles could evaluate their performance under a degraded GPS signal,” Cook said. “Other locations around the U.S. provide such environments, but having it locally allowed for direct program input and cost savings to customers by not having to deal with the logistics costs of deploying to those locations.”

    Cole Johnson, technical lead for NAVFEST, explained how they create a degraded GPS environment.

    “GPS signals are super faint,” he said. “Imagine a 30-watt lightbulb 12,000 miles in space. So it doesn’t take much interference for your smartphone’s GPS to lose lock on such a low power signal. Interference could occur from walking in a dense forest, through a canyon, inside a building, driving among skyscrapers, or from GPS jammers. The end effects of GPS jammers aren’t much different than the other causes of interference, they all make it harder for your GPS receiver to pick out faint GPS signals from the air, except jammers do it by adding noise to the environment.”

    Teams from the University of Illinois Champagne Urbana and Stanford University were invited to the first-ever DT NAVFEST at Edwards Air Force Base to test their projects in a GPS degraded environment. (Photo: U.S. Air Force/Wei Lee)

    Units that tested assets at Edwards included the Emerging Technologies Combined Test Force, the 411th 416th, 419th and 461st Flight Test Squadrons. Two universities — Stanford University and the University of Illinois — and the U.S. Army’s Special Operations Command also participated.

    The GPS jammers and support came from the 746th Test Squadron at Holloman Air Force Base, New Mexico.

    According to Wei Lee, test safety engineer with the 412th Test Wing, the universities were invited to participate in DT NAVFEST on a trial basis with the hope of expanding to other institutions in the future.

    “Live GPS jamming data is extremely difficult for academic labs to obtain due to the complexity of working with the Federal Aviation Administration and regional first responders,” Lee said. “It is crucial that the Department of Defense support basic research and development that is ongoing in our nation’s top academic institutions. Many of the low technology readiness level projects will eventually migrate from academic labs to defense industry and military applications. Allowing the labs to participate on a non-interference basis is a win-win situation.”

    To minimize the effect on the local community and air traffic, planning of the GPS jamming was initiated months in advance. According to Johnson, the GPS jammers had a vertical reach of upwards of 30,000 feet, so the first step was contacting the FAA, which provided a list of “green” times when commercial air traffic was at its lowest. This led to the testing being performed between 1 and 6 a.m. on test days.

    Johnson said the team performed extensive modeling and simulation to identify how far the GPS interference would reach. “Not just at 30,000 feet, but ground level as well.”

    The models suggested a small part of the Antelope Valley — a couple of small towns around Edwards — could be affected. “We wanted to err on the side of caution, so we constructed a huge list of emergency services from the Antelope Valley to contact.”

    The team also set up phone lines the FAA and any emergency service could call up during testing and request the jammers to be turned off.

    The 746th Test Squadron from Holloman Air Force Base, New Mexico, provided an array of GPS jamming equipment and support for DT NAVFEST at Edwards Air Force Base. The jammers provided a degraded GPS environment for testing multiple aerial platforms throughout the week. Testing was done from 1 to 6 a.m. each day to minimize impact on the community and civilian air traffic. (Photo: U.S. Air Force/Cole Johnson)

    Cook said the event was extremely successful, judging by the feedback from the customers.

    “For a first-of-its-kind event, it executed fairly smoothly, thanks to the test team and customers’ direct involvement,” he said. “The technical knowledge and support from the 746th TS was awesome. And the support given to this program from 412th Test Wing all the way down to the Airman on the ground providing direct support.”

  • Lockheed Martin awarded GPS M-code early-use ground system upgrade

    Lockheed Martin awarded GPS M-code early-use ground system upgrade

    The U.S. Air Force has awarded Lockheed Martin a $45.5 million contract to provide military code (M-code) early use (MCEU) capability to the Global Positioning System (GPS).

    Part of the Air Force’s overall modernization plan for the GPS, M-code is an advanced, new signal designed to improve anti-jamming and protection from spoofing — as well as increased secure access — to military GPS signals for U.S. and allied armed forces.

    MCEU will provide command and control of M-code capability to eight GPS IIR-M and 12 GPS IIF satellites on orbit, as well as future GPS III satellites, which the Air Force expects will begin launching in 2018.

    MCEU is envisioned as a way to accelerate M-code’s deployment to support testing and fielding of modernized user equipment in support of the warfighter.

    The Military Code (M-Code) Early Use (MCEU) contract will accelerate deployment of command and control of M-code capability to GPS IIR-M and GPS IIF satellites currently on orbit, as well as future GPS III satellites (like GPS III SV02 above). (Photo: Lockheed Martin)

    The U.S. Air Force’s MCEU contract directs Lockheed Martin to upgrade the existing Architecture Evolution Plan (AEP) Operational Control System (OCS), allowing it to task, upload and monitor M-code within the GPS constellation. The contract includes new software and hardware development that will be deployed in 2019 to worldwide ground facilities that support the Air Force’s GPS.

    “When people think of GPS, they often think of the satellites that provide the signals, but do not remember the important ground system behind it,” said Mark Stewart, Lockheed Martin’s vice president for Navigation Systems. “We recognize the ‘ground’ is critical for any major space mission constellation and we are proud that we can help the Air Force with this part of their GPS modernization plan.”

    The AEP OCS — maintained by Lockheed Martin under the GPS Control Segment (GCS) Sustainment Contract — controls the 12 GPS IIR, 8 IIR-M and 12 IIF satellites in orbit today. The company has successfully implemented several recent projects to modernize and sustain the system for the Air Force.

    In June, Lockheed Martin deployed the first of its state-of-the-art GPS Monitor Station Technology Improvement Capability (MSTIC) receivers at Cape Canaveral Air Force Station. The software-defined MSTIC system replaces 30-year-old hardware, positioning the Air Force to take advantage of commercial off-the-shelf technology enhancements in processing power, reliability and cybersecurity in the future. Six Air Force AEP OCS monitoring stations around the world will receive the MSTIC upgrade by the end of 2017.

    In February 2016, the Air Force awarded Lockheed Martin the GPS III Contingency Operations (COps) contract to upgrade the AEP OCS with new capabilities so it could support the more powerful, next-generation GPS Block III satellites. The COps program passed a successful Critical Design Review milestone with the Air Force in December 2016.

    Also in 2016, under the GCS contract, Lockheed Martin completed the commercial off-the-shelf upgrade No. 2 (CUP2) project — part of a multi-year plan to modernize the AEP OCS’ technology and enhance the system’s ability to protect data and infrastructure from internal and external cyber threats, as well as improve its overall sustainability and operability. CUP2 is now fully operational and managing the current GPS constellation.

  • EagleView capturing Hurricane Irma imagery to speed response

    EagleView capturing Hurricane Irma imagery to speed response

    EagleView Technologies is actively flying to acquire post-storm imagery in Florida following Hurricane Irma. With more than 20 planes staged or in the air, EagleView is continuously capturing high-resolution aerial imagery to enable rapid assessment and response to Hurricane Irma relief efforts.

    EagleView is a provider of aerial imagery and property analytics for the government, insurance and commercial sectors.

    Using both fixed-wing aircraft and drones, EagleView imagery supports post-hurricane insurance claims adjusting, property assessment, public safety and land surveying professionals.

    “With these hurricanes affecting so many Americans, we’re putting our planes in the air as soon as possible to begin the image capture process,” said EagleView President Rishi Daga. “From our unique high-resolution post-event imagery to our industry-leading machine learning capabilities, EagleView’s technology can massively accelerate recovery efforts and because of this, we find it crucial to take flight immediately once permitted into the airspace.”

    EagleView’s historical image library, dating back to 2002 in Florida, offers insurance carriers, first responders, non-profit organizations and local government agencies the ability to analyze the impact of the storm on homes, commercial buildings and infrastructure by comparing previously captured imagery with the latest post-event images.

    Image capture and processing post-Hurricane Irma will take place continuously over several weeks, with EagleView making constant updates to its nearly four-petabyte imagery and data library.

    “We have access to an impressive amount of resources in Florida and the surrounding areas, allowing us to provide the largest post-storm image capture capabilities to our clients,” said Jay Martin, senior vice president of operations for EagleView. “Our team is working around the clock to deliver imagery to those who need it most following these devastating weather events.”

    EagleView is capturing varying types of aerial imagery throughout Florida. This includes its ultra-high-resolution (UHR) imagery, also known as Reveal imagery, which is the highest resolution aerial imagery available on the market today.

  • Systems Engineering Group to demonstrate UAV tech at naval event

    Telephonics Corporation’s subsidiary, Systems Engineering Group (SEG), will demonstrate autonomous UAV control and PULSEbox this month during the Annual Naval Technology Exercise (ANTX), Dahlgren (Virginia) Division event.

    ANTX-Dahlgren, being held Sept. 13-14, is a two-day event providing a low-risk environment to evaluate technological innovations at the research and development level before technologies become militarized and integrated at the operational level.

    The autonomous UAV control demonstration will include a system manager in a UAV control ConOps scenario. System Manager is a model-based expert system of systems, which can plan, schedule and initiate ConOps processes to provide round the clock automation in the Flight Dynamics Operations Area (FDOA) on NASA’s Magnetospheric Multiscale (MMS) mission. This enables NASA to minimize human involvement in controlling satellite maneuvers along with optimizing data downloads.

    PULSEbox offers a high fidelity, real-time, RF threat scene generator that integrates SEG’s threat models with optimized hardware. The system will create advanced test ecosystems by providing real-world target simulated threat states and related radar representations in laboratory settings, leading to improved testing of interoperable elements before live-sea testing events of air-breathing and ballistic missile threats, the company said.

    “Both the autonomous UAV control and PULSEbox technologies align with the U.S. Navy’s requirements for more autonomous systems with limited human control requirements and more realistic training, simulation and modeling environments,” said Michael Anderson, Telephonics vice president and SEG general manager.

  • Komatsu debuts intelligent machine control excavator

    Komatsu debuts intelligent machine control excavator

    The PC210LCi-11 is designed to increase jobsite efficiency. (Photo: Komastu)

    Komatsu America Corp. has launched the PC210LCi-11 intelligent machine control hydraulic excavator.

    This second-generation PC210LCi leverages the proven track record and success of the pioneering PC210LCi-10, while adding machine-control joystick functionality.

    The technology offers up to a 63 percent improvement in excavating efficiency over a standard PC210LC-11 and traditional stake-plus-grade-checker methods, the company said.

    The extra efficiency can save time and money by  minimizing the need and expense of grading dozers and grade checkers. It also minimizes the costs associated with over-excavating, including extra materials, fuel and time. It saves time wasted waiting on grade checkers and over-excavation to finish jobs and potentially collect on-time or finish-early project bonuses.

    Key features of intelligent machine control technology include:

    • Full 3D GNSS Capabilities: Not limited like 2D only systems, the PC210LCi-11 features full 3D capabilities, allowing it to dig to grade everywhere on the jobsite a 3D GNSS dozer can.
    • Work Equipment Automation: GNSS technology tied into machine hydraulics to allow actual automation of work equipment functions — not just the indication/manual-only operation typical of aftermarket offerings.
    • Machine Control Function Enabled Joysticks: Frequently used machine control functions are now located on the operator’s control lever for increased convenience and comfort.
    • Stroke Sensing Hydraulic Cylinders: No delay position readout with our proven, robust technology, validated in thousands of machines worldwide.
    • Intelligent Guidance: Advanced features such as facing angle compass and minimum distance bucket control are delivered in a simple and intuitive manner, with a class-leading 12.1” touchscreen display.
    • Factory Integrated: Intelligent Machine Control technology factory installed, integrated into the base machine, and validated to the Komatsu quality standards.

    “The excavator is productive and precise enough to be a fixture on jobsites from basement and foundation pads to utility work,” said Sebastian Witkowski, product marketing manager for Komatsu America.

  • Hurricane Irma prep gets boost from Esri resource catalog

    Hurricane Irma prep gets boost from Esri resource catalog

    Esri has published a Hurricane Irma Resource Catalog in advance of the Category 4 hurricane cutting through the Caribbean islands on its path toward Florida.

    The catalog features read-to-use applications compiled by the Esri Disaster Response Program (EDRP). EDRP is an around-the-clock service that helps with monitoring events online, discovering useful content, augmenting software and obtaining assistance from Esri experts.

    To see the track of the hurricane, Esri provides its hurricane map.

    Resources include:

    • Hurricane Public Information Map (PIM)
    • Hurricane Impact Summary
    • Hurricane Force Wind Impact Summary
    • Storm Surge and Flooding
    • Storm Surge Inundation
    • Hurricane Evacuation Zones
    • Waze Alerts – Hurricane Irma
    • Florida 511 – Real-Time Traffic Information
    • Hurricane Irma Photo Story Map
    • Airport and Port Status
    • NOAA Real-Time Coastal Observations
    • Florida Division of Emergency Management Open Data
    Waze alerts light up Florida highways as people evacuate. (Image: Esri)
  • Taoglas launches ultra-wideband antennas for indoor positioning

    Taoglas launches ultra-wideband antennas for indoor positioning

    Taoglas has launched a range of small-form-factor ultra-wideband (UWB) antennas specifically designed to enable centimeter-level positioning and angle-of-arrival applications.

    The FXUWB10, UWC.01 and UWCCP.01 ultra-wideband antennas by Taoglas.

    Applications include asset tracking, follow-me drones, healthcare monitoring, smart home services and other applications that demand high-performance indoor localization capabilities, the company said.

    The antennas offer high efficiencies across a wide spectrum of frequency bands, from 3 GHz to 10 GHz.

    Indoor wireless positioning has long been hampered by technologies that were not designed for this purpose, such as Bluetooth, Wi-Fi and assisted GPS.

    Taoglas will be exhibiting in Booth 614 at Mobile World Congress Americas, Sept. 12-14, in San Francisco.

    Ultra-Wideband. UWB is a low-power digital wireless technology that offers significant increases in location precision and range while transmitting large amounts of digital data short distances over a wide spectrum of frequency bands. UWB’s low-power requirements offer increased battery life of sensors and tags, leading to reduction in overall operational costs.

    Taoglas’ range of UWB antennas, designed in Taoglas’ Munich, Germany, engineering center, features both state-of-the-art flexible embedded UWB antennas and UWB embedded SMT chip antennas. According to the company, the flexible FXUWB range of antennas were developed utilizing a “peel and stick” assembly process, attaching securely to non-metal surfaces via 3M adhesive with a flexible micro-coaxial cable mounting.

    The UWB chip antennas are designed to be surface mounted directly onto a printed circuit board (PCB). Both series of antennas help designers future-proof devices, keeping costs low while covering all common UWB commercial bands.

    “Today’s emerging applications require very precise indoor localization of assets, objects and people,” said Ronan Quinlan, co-CEO for Taoglas. “UWB can work as a type of ‘indoor GPS’ to help solve the precision dilemma for indoor applications, bringing much greater levels of precision than current technologies. We optimize complex antenna performance parameters such as the Group Delay, Polarization and Fidelity Factor. Taoglas’ first-to-market line of UWB antennas are designed to help our customers capitalize on this need for real-time precision localization.”

    Autonomous Antenna. One antenna that Taoglas co-developed exclusively with DecaWave is the UWCCP.01 circularly polarized chip antenna, a mass-market antenna specifically designed to enable a new generation of autonomous applications.

    The DecaWave DW1000 chip.

    The UWB antennas were designed for use with the DecaWave DW1000 chip and are also compatible with any other UWB sensor modules on the market, the company added. Since its launch in December 2013, more than 3.5 million units of the DW1000 have shipped across multiple industries.

    From real-time location of people and assets in factories, hospitals and mines, to automotive keyless entry systems, to drones, connected home and sports, the accurate location and secure communications capability of the DW1000 has already taken numerous applications to new heights.

    “Antennas play a key role in our customers’ applications. Performance is a given for customers but the capability to adapt to the constraints of the applications — size, shape, electronics environment — is equally important as end products get smaller and smaller,” said Ciaran Connell, CEO and co-founder, DecaWave. “DecaWave is really pleased to partner with Taoglas, as their expertise is not only in delivering high-performance, off-the-shelf antennas, but also to provide customization services that will be highly beneficial to our customers.”

  • The day GPS went away

    The day started like any other day. The land surveying crew loaded up their vehicle, equipment and marching orders to tackle the next project on the list.

    This field party is like most surveyors across the globe — they are equipped with the latest surveying technology including GPS base and receivers, robotic total station and a UAS for aerial photography. These tools are necessary to be competitive in today’s surveying arena as speed and productivity are paramount to the success of the project and the company.

    But on this day, any device with the ability to determine geographic location via satellite reception was rendered useless.

    Today became known as the day that GPS went away.

    How we  became dependent on GPS

    Let’s back up the story to the introduction of GPS and how our dependency on this technology came to be. With the invention of satellites culminating with the Russian effort to launch Sputnik, the United States became involved in a “race to space.” Our early efforts to use satellites were proven worthy with the successful ability to track submarines by reception of radio signals and trilateration.

    Further enhancements through research resulted in the development and creation of the NAVSTAR satellite in 1978. By 1993, 24 satellites were in orbit to make the GPS system fully functional (NASA.gov).

     

    Meanwhile, the Russians were committed to a satellite network for navigational purposes during the same time period. The first satellite, Kosmos-1413, was launched in 1982 with the full 24 satellite constellation becoming operational in 1995.

    Together, these systems (known as global network satellite systems or GNSS) allowed for location and navigation abilities never thought possible, and the surveying community began its adoption of the technology.

    Early survey adopters of GPS were usually large engineering firms, state departments of transportation (DOTs) and federal agencies that could afford the large financial commitment to the equipment (both GPS and computers), software and computing costs required to use the technology.

    The data-collection times were long, and the software analysis required enormous patience and extensive mathematical knowledge, but the results were beyond what the everyday surveyor had ever before accomplished.

    Significant distances could now be measured with the same or better accuracy than taping or using an electronic distance meter could have provided. The true revolution came when real-time kinematic (RTK) GPS was invented and was affordable to the everyday surveyor (GPS World, May 2016).

    S/A and A-S

    Most GPS users, especially operators of survey-grade receivers, are not aware of the early days of satellite navigation and the military’s use of selective availability, otherwise known as S/A (GPS World, Sept/Oct 1990). This methodology was implemented by the Department of Defense (DoD) on May 25, 1990 to limit accuracies for non-military GPS users.

    This procedure was created to allow erroneous timing at random occurrences throughout transmission of satellite radio signals. These variations in timing more than negatively tripled the normal precision of an autonomous GPS position calculation, all in the name of introducing uncertainty to potential enemy users.

    And if S/A wasn’t enough, the DoD also could implement another deterrent called anti-spoofing (A-S) and encrypt the precision or P-code of the satellite signal. The big factor here is that the general public (in our case, the surveying community) didn’t know if or when A-S was turned on. These factors were frustrating to the GPS user, so data collection and coordinate determination became a tedious operation.

    Early receiver use by surveyors relied on differential GPS data collection for high-accuracy location (<10 cm or better). This method consisted of placing one or more receivers on known positional points (usually on monuments published through the National Geodetic Survey) while simultaneously performing data collection on new points for positional establishment.

    Prior to S/A, the software utilized to analyze and reduce the data collection provided feedback on “bad” data, but there were usually environmental issues causing the problem (such as cycle slips and radio interference.) The software would highlight the suspect data for the reviewer to determine validity and acceptance.

    Because of the nature of differential GPS data collection, error checking remained the same once S/A was implemented. If the software calculated an incorrect coordinate at a known point, the same measurements to the new survey point were dismissed as a false reading.

    Surveyors were mostly left unfazed by S/A as real-time kinematic (RTK) and real-time network (RTN) follow a similar procedure utilizing a correction from a known terrestrial point. Even with the anti-spoofing activated, the surveying profession continued to use this high-tech location system that revolutionized long distance measurement. Things have been running along smoothly with steady improvement of receivers, data collectors, and data coverage until…

    The day it goes away

    …the unthinkable happens. Our national satellite system is no longer available.

    It doesn’t matter why GPS has gone away on this day. It could be for many different reasons: federal budgets; enemy interference such as geomagnetic disturbances (GMD) or electromagnetic pulse (EMP);
    conventional or nuclear war; interference from solar storms, asteroids, or comets; or the system just simply breaks.

    Artist’s rendering of a cross-section of the Earth’s magnetosphere. (IMAGE: NASA)

    Another thing for all users of GNSS to consider in these tumultuous times is how newer systems are integrating other countries’ satellite networks into their navigational observations.

    Our relationship with the Russian government can be on unsteady ground from time to time, so our use of their GLONASS signals must be reviewed for accuracy as well (See GPS World, August 2017).

    It won’t matter whether a spoofed satellite signal originates from a private Russian hacker or from their actual government; it will still lead to incorrect information and bad data. Imagine having to revise a plat because the GLONASS data was purposely corrupted!

    Obviously, the main reason they would allow transmittal of misinformation would be for military reasons, but I can only imagine their joy of messing with professional navigation and the recreational users in the U.S. These opportunities will also apply to the Chinese and Indian constellations, too.

    We’re not ready

    The bottom line is that we, the U.S., aren’t ready for it. Whatever may be the reason for the failure, we do not have a backup plan and have relied much too heavily on satellite navigation. Gone is our ability to navigate through our electronic devices, including smartphones, fitness trackers, in-car mapping and, yes, high-precision surveying equipment. These items have now become door stops and space wasters.

    This new conundrum doesn’t just stop with the surveyor and recreational GPS equipment. A significant amount of construction equipment relies on machine control, from bulldozers and road graders to high-rise cranes.

    This will also affect a large amount of agricultural equipment and processes. Those high-tech tractors with autosteer and computer-guided planters? Back to the drawing boards. So many things in our lives today are guided or controlled by navigational systems designed around GPS use, and the surveyor is squarely in this mix.

    What’s a surveyor to do?

    The first thought on the surveyor’s mind is now having to perform all surveying tasks with instruments that are not based on satellite navigation. Yes, the reason for this GPS shutdown isn’t widespread enough to affect cellphone signals and other radio communications, but it killed off the one navigation system more people rely on than any other.

    Because of this unfortunate shutdown, all GPS-based equipment is now worthless. This means your trusty RTN receiver with cellphone connection, your old base unit for those times when cellphone coverage is lacking, the fancy new UAV for taking orthophotography, and your cellphone or handheld GPS receiver for tracking down NGS monuments — all of them are done. Only your conventional equipment will complete the job.

    Is the surveying profession finished? How do we locate those remote section corners in the middle of nowhere?

    Don’t throw in the towel just yet. Surveyors have been measuring land using these types of instruments for centuries, with today’s versions being electronic and sophisticated. Robotic servos, mini computer-data collectors, efficient radio links and active tracking prisms have turned our forefathers’ simple transit into a sophisticated topographic or construction staking machine.

    Data collection is much easier than writing everything in a field book, and have graphical interfaces and remote connection capability to keep you in touch with the office from nearly anywhere. The reality, however, is that the surveyor will now have to use methods and equipment for traversing, data collections and all staking tasks that will greatly reduce our productivity and profitability.

    Experience could also end up being a big factor here as well. The average age of the professional land surveyor in the United States is 58 and climbing. This means most of these practitioners have been in the business well before GPS technology, so there is still the potential of surveying without the electronic birds in the sky.

    Surveyors can still hang their shingle and practice their craft, but we’ve now lost a big component of our world: geographical location. The key to the success of GPS was the ability to determine geographic location and subsequently convert that information into a data format compatible with one’s local system. From UTM coordinates to State Plane, the world became smaller with this technology.

    The surveyor can still determine latitude and longitude using manual surveying methods for specifically observing the sun and Polaris. The mathematics and procedures are complicated, but they still allow for determining a geographical location with high accuracy.

    We can also utilize the extensive geodetic monumentation networks established nationwide, all started around the formidable effort by the Coastal and Geodetic Survey. This key federal agency, later to become the National Geodetic Survey, laid the groundwork and set the monuments for the backbone of our national horizontal network system. This system has been augmented over the years by their own programs, as well as state and local authorities, to expand our coverage to all portions of the United States.

    By incorporating these monuments into a survey, a relationship to geographical datums is still easily obtained. While these methods of establishing geographical coordinates through use of conventional equipment sounds time consuming, without GPS and other satellite-based navigational aids, it will become much more cumbersome.

    So, what do we do next?

    Depending on which industry you are in or your necessary level of accuracy, several alternatives are being developed. For those in the shipping industry (including the trucking sector, which numbers more than 15 million vehicles), accuracy may only need to be nominal — for instance, 5 meters, give or take.

    Several systems are in development with the biggest priority on enhanced loran (short for “long range navigation”) or eLoran (also see GPS World April 2014 and GPS World Nov 2015). Several bills are currently being reviewed in the U.S. House and Senate for consideration of funding this technology.

    Differential eLoran operation concept (graphic courtesy Ursanav).

    Another government agency, the U.S.Defense Advanced Research Projects Agency (DARPA) has been exploring backup technologies for GPS for many years. Among the systems being considered are Adaptable Navigation Systems (ANS), Microtechnology for Positioning, Navigation, and Timing (Micro-PNT), Quantum-Assisted Sensing and Readout (QuASAR), Program in Ultrafast Laser Science and Engineering (PULSE) and Spatial, Temporal and Orientation Information in Contested Environments (STOIC) (love the government and their overuse of acronyms).

    These programs are still under development, but DARPA has been tasked with finding another system so our dependence on GPS will not cripple our defense in a time of war.

    Abraham Lincoln, the county surveyor — a statue at Lincoln’s New Salem State Historic Site, Illinois.

    Another alternative will be private satellite networks. With programs like SpaceX and Blue Origin, vehicles to carry new satellites into orbit are now a viable option. It will be possible for companies to create their own networks for private or commercial use.

    With the large number of construction, shipping and automobile sales, the day may come when the navigation system within each of these is proprietary. However, if we are faced with geomagnetic disturbances (GMD) or an electromagnetic pulse (EMP) as mentioned earlier, it won’t matter whose network it is — they will all be rendered useless.

    Until another viable option is created, the surveyor will be forced to take a step back in productivity and technology with conventional instruments. While not the most ideal thing, it will force the profession to retrain its entire workforce on procedures and methods that haven’t been regularly utilized for many years.

    For some, it will be like throwing away the computer for a typewriter or the remote control for the television set. For others, it will be an opportunity to truly “follow in the footsteps” of past surveyors. They will understand exactly how their predecessors went about “running the lines” and completing a true boundary survey.

    I, however, hope we don’t find ourselves in this situation, and that a suitable backup system or even a more advanced replacement for our antiquated GPS is invented soon.

    But if the day comes and our GPS goes away, I’m guessing that surveyors not having their favorite locating device will be the least of our society’s worries. It will truly be a day that will live in infamy.