In the July and August issues of the magazine, the “Out in Front” editorials held forth on the perfection or lack thereof in the GPS signal and service.
Now it’s your turn!
Give us your opinion at gpsworld.com/17augustpolland we’ll publish the results in the September issue. And you’ll gain entry to a random drawing for a $50 gift card.
The question is: How close to perfect is GPS performance?
And your choices are:
Absolutely perfect. 100 percent.
Nearly perfect. The space segment functions flawlessly. The only problems are with jamming and user equipment.
Almost nearly perfect. There have been a few hiccups in space, then there’s jamming, and user equipment weaknesses.
Not nearly close enough to perfect — but pretty good. The (admittedly rare) operator miscue, jamming, spoofing, and other exploitable user equipment weaknesses.
Fair, but a long way to go. All the above cited problems, plus lack of signal reception under canopy, urban canyons, indoors.
Not a passing grade. But it’s the best I have, so I grit my teeth and use it.
Pretty poor if you ask me. It just does not meet my requirements.
Other (please specify)
For background and two different views on the controversy engendered by a U.S. Air Force public release on this subject, see:
Three of six new Lockheed Martin-developed state-of-the-art receivers are now deployed to help the U.S. Air Force maintain the accuracy of GPS satellite signals.
In June, the first new Monitor Station Technology Improvement Capability (MSTIC) receiver became operational at Cape Canaveral Air Force Station, Florida. The upgrades continued at U.S. Air Force monitoring stations on the Kwajalein Atoll and Hawaii.
These critical upgrades of the GPS Monitoring Stations from early 1990s technology are part of an overall effort to modernize and maintain the current GPS ground control system, known as the Architecture Evolution Plan Operational Control Segment.
GPS monitoring stations are globally dispersed, fixed-position sites that monitor GPS satellite signals and help maintain their navigation and positioning accuracy for users around the world.
Under Lockheed Martin’s GPS Control Segment (GCS) Sustainment contract, the company used an agile development methodology to develop and deploy the first MSTIC receiver on schedule in under 36 months. The three remaining Air Force GPS Monitoring Stations will be upgraded with MSTIC receivers by the end of 2017.
“Taking advantage of current commercial technology trends has allowed us to provide the Air Force with a monitoring capability that can support the Air Force’s GPS mission for years to come,” said Vinny Sica, vice president and general manager of Mission Solutions for Lockheed Martin. “The MSTIC receiver addresses today’s obsolescence problem while providing the opportunity for the monitoring of modernized navigation signals in the future.”
The new MSTIC receiver’s software-defined radio (SDR) technology will replace the legacy monitor station receiver element (MSRE)’s hardware-based ASIC (application-specific integrated circuit) platform originally deployed almost two decades ago, Sica said.
MSTIC leverages commercial off-the-shelf hardware without the need for custom firmware. Standard interfaces and the inherent configurability of the architecture simplifies sustainment and enables MSTIC software to migrate to new hardware platforms as commercial vendors increase processing power, improve reliability and enhance cybersecurity, Sica said.
“MSTIC’s new SDR technology enables the remote application of mission specific software updates which will improve performance and enable reception of modernized GPS signals,” added Sica.
The GPS Directorate at the U.S. Air Force Space and Missiles Systems Center contracted the MSTIC upgrade. Air Force Space Command’s 2nd Space Operations Squadron (2SOPS), based at Schriever Air Force Base, Colorado, manages and operates the GPS constellation for both civil and military users.
Gen. David L. Goldfein, chief of staff of the Air Force, listens to 1st Lt. Mark Skinner, 2SOPS GPS mission commander, explain current 2SOPS activities during his visit to Schriever AFB Dec. 20, 2016. (U.S. Air Force photo/Christopher DeWitt)
Companies and organizations like Spirent Federal Systems share their products and insights in the exhibit hall. (Photo: ION)
The ION GNSS+ 2017 conference and industry exhibition covers all aspects of satellite navigation technology. It takes place Sept. 25–29 at the Oregon Convention Center in Portland.
The theme this year is “GNSS + Other Sensors in Today’s Marketplace.”
The conference will feature two tracks:
“Applications and Advances” focuses on safety of life, commercial and mass-market applications, and GNSS plans and policies.
The second track, “Research and Innovations,” will concentrate on autonomous systems, multi-sensor applications and advanced GNSS algorithms.
Short Courses taught by Internationally Recognized Leaders
This year, ION is introducing complimentary Short Courses to be taught by internationally recognized GNSS experts and educators throughout the day on Monday, Sept. 25.
Short Courses are designed to enhance the ION GNSS+ attendee experience while giving everyone an opportunity to learn from the rock stars in the field, according to ION’s Executive Director, Lisa Beaty.
Presented in a lecture-style learning environment, the Short Courses are designed for professionals at any level of their career, for engineers and academics as well as the non-engineer wanting to boost their knowledge base in a particular area (such as members of the sales team).
The Short Courses will taught by internationally recognized GNSS experts and educators. These instructors are masters in their field, the people who developed the technology and “wrote the textbooks.”
The Short Courses are complimentary to all registered ION GNSS+ 17 attendees.
Courses include:
GNSS 101: An Introduction
Fundamentals of GNSS Receiver Design
Precise Time and Time Interval (PTTI) Services from GPS and GNSS Systems
Image-Aided Navigation
Assisted GNSS (A-GNSS)
Resilient Position Navigation and Time
A Practical Introduction to GNSS/INS Integration
Nonlinear Estimation Techniques for Navigation Systems
Kalman Filter Applications to Integrated Navigation 1 and 2, James L. Farrell / Frank van Graas
Introduction to Multi-Constellation GNSS Signals, John Betz
Raw GNSS Measurements from Android Phones: Theory and Application, Wyatt Riley / Steve Malkos / Mohammed Khider
GNSS Error Characterization, Analysis and Mitigation, Chris Bartone
Plenary Session: Sept. 26, 6:30–8:30 p.m.
Featuring Stan Honey, yacht racing navigator, Emmy-winning developer of TV graphics, engineer in navigation and remote sensing.
Also featuring Carla Bailo, assistant vice president for Mobility Research and Business Development, The Ohio State University, speaking on smart mobility, smart cities and the importance of GIS in the Internet of Things.
Figure 1. Galileo constellation and occupation status of orbital slots (RAAN: right ascension of the ascending node, May 9, 2017). (Source: ESA)
What to Expect with the Current Constellation
This article demonstrates the benefits of Galileo integration for high-precision real-time kinematic (RTK) through representative case studies, considering baseline length, multipath impact and tree canopy.
The results confirm usability of the current Galileo constellation in high-precision RTK applications and show improved availability, accuracy, reliability and time-to-fix in difficult measuring environments.
Plus, Galileo-only RTK positions are compared with GPS-only and GLONASS-only solutions.
By Xiaoguang Luo, Jun Chen and Bernhard Richter, Leica Geosystems AG
Until now, based on simulated and observed data, the benefits of Galileo (FIGURE 1) for high-precision RTK have been investigated in single-base RTK and network RTK solutions. Building on the results of previous studies that frequently employed theoretic analysis and simulation, we present the benefits of Galileo for high-precision RTK based on real observations from the current Initial Operational Capability (IOC) satellite constellation. Using up-to-date real-time corrections including Galileo, we analyze the performance of network RTK under different measuring conditions with respect to availability, accuracy, reliability and time-to-fix.
To achieve the maximum inter-operability with other GNSS con-stellations, all the Galileo signals in the E1 and E5 band, i.e. E1, E5a, E5b and AltBOC (alternative binary offset carrier), are used for positioning in the latest proprietary firmware and receivers (see “Manufacturers” section for details).
The Galileo E1 signal is overlapped with the GPS L1 signal at a center frequency of 1575.420 MHz, whereas the Galileo E5a and GPS L5 signals are overlapped at 1176.450 MHz. As far as BeiDou is concerned, the E5b frequency of Galileo corresponds to the B2 frequency of BeiDou-2 at 1207.140 MHz.
The AltBOC signal is also supported in order to benefit from its superior performance in multipath suppression. The availability of more than two frequencies is beneficial for ionospheric modeling, which plays an important role in ambiguity resolution on the fly.
In addition, multi-frequency RTK provides more immunity to temporary interruption of GNSS signals caused by interference or by site-specific effects like multipath. When forming linear combinations, the incorporation of multi-frequency signals enhances flexibility and robustness, where the mathematical correlations introduced by including the same signal in different linear combinations of the same type need to be handled properly in RTK algorithms.
By enabling the tracking of Galileo satellites in the aforementioned firmware, the Galileo signals will be used in different RTK position types by default, including navigation position, phase-aided differential code position, extended RTK (xRTK) position and RTK fixed position. When compared to a standard RTK fix, an xRTK fix is provided at a slightly lower accuracy level, but with higher availability in difficult environments such as urban canyons and dense canopy.
In terms of RTK correction data formats, Galileo is included in the standardized RTCM v3 MSM format and in the proprietary 4G format. To use Galileo in network RTK, the real-time products provided by network correction services need to include Galileo as well. In the latest version of a proprietary GNSS network software, Galileo is used in network processing to provide RTK corrections via the individualized master-auxiliary (iMAX) method and the virtual reference station (VRS) method in the RTCM 3.2 MSM formats.
RTK PERFORMANCE CHARACTERISTICS
Multi-constellation and multi-frequency GNSS RTK is a complex real-time process, aiming to provide cm-level positioning accuracy with as few as possible data epochs for variable user kinematics and even in difficult measuring environments. Therefore, RTK performance characteristics need to be carefully selected to be able to evaluate the system as a whole and to address users’ concerns in their applications.
The following parameters are used in this article to assess the benefits of Galileo for high-precision RTK:
Satellite usage. Number of satellites used in RTK fixed solutions with an elevation cut-off angle of 10°;
Availability. Percentage of RTK fixed positions relative to all positions obtained during a time period;
Accuracy. Deviation of RTK fixed positions from ground truth with a higher degree of accuracy, where the ground truth can be determined by means of a total station or by post-processing long-term GNSS data;
Reliability. Percentage that the position error (with respect to ground truth) is less than 3 x coordinate quality (CQ) indicator;
Time to Fix. Time needed to regain an RTK fixed solution after losing ambiguity fix provided that GNSS signal tracking is not interrupted.
OPEN-SKY CASE STUDY
The open-sky case study was performed in the Heerbrugg testbed. Two receivers were connected to a single antenna via a four-way antenna splitter. One receiver received four-system iMAX corrections in the RTCM v3 MSM format over a short baseline of 2 km, whereas the other received RTK data of the same type over a long baseline of 116 km. By considering different baseline lengths, the open-sky experiment focused on the usability of the current Galileo constellation in GNSS RTK under normal conditions. Two days of 1-Hz GNSS data were investigated with respect to satellite usage and positioning accuracy.
Using different combinations of GNSS to analyze the short baseline data — GPS+GLO (GG), GPS+GLO+BDS (GGB) and GPS+GLO+GAL+BDS (GGGB) — the mean numbers of used satellites are 15, 17 and 20, respectively, where the elevation cut-off angle was set to 10°. On average, three Galileo satellites contribute to RTK fixed solutions.
For the four-system combination GGGB, Figure 2 shows the satellite usage for each individual system over the two-day period. It can be seen that for a short baseline of 2 km, a maximum number of four Galileo satellites can be used for positioning. In fact, during 80.3% of the whole test period, the number of Galileo satellites used in RTK fixed solutions is equal to or greater than the number of BeiDou satellites used.
Figure 2. Number of satellites used in RTK fixed positions with GGGB under open sky (iMAX, RTCM v3 MSM, baseline length: 2 km, GGGB: GPS+GLO+GAL+BDS, DOY: day of year).
Table 1 provides statistics on Galileo satellite usage in case of GGGB for different baseline lengths. As would be expected, the number of Galileo satellites used decreases with an increasing baseline length. In approximately 41% of the cases, three Galileo satellites are used in the short baseline test, whereas two Galileo satellites are used in the long baseline test.
Moreover, the probability that no Galileo satellites are involved in a four-system combined solution grows significantly from 1.9% to 15.0% as the baseline length increases from 2 km to 116 km. The probability that only one Galileo satellite is used under open sky is relatively small, amounting to around 0.5%. This is reasonable since no benefits for high-precision RTK are expected in this particular situation. Regarding the short baseline case, there is a 97.7% probability that at least two Galileo satellites are used for positioning, whereas this probability decreases to 84.4% in the long baseline case.
Table 1. Probability [%] that n Galileo satellites are used in RTK fixed positions with GGGB during the two-day period of the open-sky experiment (iMAX, RTCM v3 MSM, GGGB: GPS+GLO+GAL+BDS).In terms of positioning accuracy, Figure 3 compares the 3D errors from analyzing the long baseline data with different GNSS constellations. Regarding the entire two-day period illustrated in Figure 3a, the integration of BeiDou (GG vs. GGB) and Galileo (GGB vs. GGGB) results in higher position repeatability with more consistent errors. For a selected period of 12 hours, Figure 3b highlights the advantages of Galileo in reducing large 3D errors from 6–8 cm to 3–4 cm, where two or three Galileo satellites are used in case of GGGB.
Figure 3. 3D errors of RTK fixed positions under open sky (iMAX, RTCM v3 MSM, baseline length: 116 km, GG: GPS+GLO in green, GGB: GPS+GLO+BDS in blue, GGGB: GPS+GLO+GAL+BDS in red, DOY: day of year) (a) Entire two-day period, (b) Selected 12-hour period (28–40 h).
MULTIPATH CASE STUDY
In this case study, a GNSS smart antenna was set up in a location with strong multipath effects, where GNSS signals were obstructed and reflected by the surrounding buildings (Figure 4). This test setup simulates the use case that a user measures a point near a building with degraded GNSS signal reception, even at high elevation angels.
Figure 4. Test setup in a strong multipath environment in Heerbrugg (rover: GS16, antenna height: 1.8 m) (a) View from the south, (b) View from the north.
The default elevation cut-off angle of 10° was applied. The receiver received four-system VRS corrections in the RTCM v3 MSM format, where the distance to the physical reference station was approximately 200 m. Three hours of 1-Hz GNSS data were analyzed with respect to accuracy, reliability and time to fix.
Figure 5 illustrates the 3D errors from multi-GNSS RTK with and without Galileo (GGGB vs. GGB), along with the number of used satellites. Regarding the periods marked with dashed rectangles, the inclusion of two or three Galileo satellites (Figure 5b) leads to significant improvements in positioning accuracy at the few cm to dm level (Figure 5a). By comparing the empirical cumulative distribution function (CDF) of the 3D errors, the probability that 3D error is within 5 cm increases from 70% to 85% if Galileo is used, even with a maximum number of three satellites.
Figure 5. Impact of Galileo integration on RTK positioning accuracy under strong multipath (VRS, RTCM v3 MSM, GGB: GPS+GLO+BDS in blue, GGGB: GPS+GLO+GAL+BDS in red, DOY: day of year) (a) 3D errors of RTK fixed positions, (b) Number of used satellites (Galileo in green).
Tables 2 and 3 provide the root mean square (RMS) errors and reliability of RTK fixed positions from the multipath experiment, respectively. By using Galileo in high-precision RTK, the 3D RMS error is significantly reduced by 56.3% in this case study, from 0.080 m (GGB) to 0.035 m (GGGB). When compared to the horizontal components, the height RMS error shows a larger relative improvement of 58.7% due to Galileo integration. The reliability reflects the consistency between the actual position error with respect to ground truth and the CQ indicator estimated based on mathematical models in RTK algorithms. As shown in Table 3, the 3D reliability improves by 7.3%, from 88.2% (GGB) to 95.5% (GGGB), where the increases for the horizontal components and height are comparable.
Table 2. Root mean square errors [m] of RTK fixed positions under strong multipath (VRS, RTCM v3 MSM, GGB: GPS+GLO+BDS, GGGB: GPS+GLO+GAL+BDS).Table 3. Reliability [%] of RTK fixed positions under strong multipath (VRS, RTCM v3 MSM, GGB: GPS+GLO+BDS, GGGB: GPS+GLO+GAL+BDS).The time to fix (TTF) was determined by constantly re-initializing RTK once an ambiguity fix was gained. During the whole period of repeatedly resetting the RTK filter, the GNSS signals were tracked continuously without interruption. A total of 765 TTF values were obtained with GGB, whereas 1,128 TTF estimates were available with GGGB. The significantly larger number of the TTF samples from GGGB indicates higher availability of RTK fix if Galileo is used.
Figure 6 shows the statistical distribution of TTF with respect to Galileo integration. As can be seen in the empirical CDF in Figure 6a, it takes shorter time for GGGB to regain an ambiguity fix. As an example, GGGB allows ambiguity resolution within 5 s (10 s) with 46% (87%) probability, which is 29% (16%) higher than GGB. Regarding the boxplots of TTF in Figure 6b, GGGB shows a smaller median (by 25% from 8 s to 6 s) and a smaller interquartile range (IQR; by 50% from 4 s to 2 s) than GGB, where the IQR is the length of the box. This indicates that the integration of Galileo enables a faster ambiguity resolution with more consistent fixing performance.
Figure 6. Impact of Galileo integration on time to fix (TTF) statistics under strong multipath (VRS, RTCM v3 MSM) (a) Empirical cumulative distribution function (CDF) of TTF, (b) Boxplot of TTF with median and interquartile range (IQR).
CANOPY CASE STUDY
In this case study, a receiver was connected to an antenna under tree canopy (Figure 7), where GNSS signals are blocked, attenuated and reflected, leading to decreased number of observations, low data quality and degraded RTK performance.
Under these circumstances, the inclusion of Galileo satellites transmitting multi-frequency signals could be particularly beneficial for high-precision RTK. Using an elevation cut-off angle of 10°, the receiver received four-system iMAX corrections in the RTCM v3 MSM format, where the baseline length was 116 km. A long baseline was intentionally selected as an additional challenge for the RTK system. About seven hours of 1-Hz GNSS data were investigated regarding availability, accuracy and reliability.
Figure 7. Test setup under canopy in Heerbrugg (rover: GS10, antenna: AS10).
Figure 8 illustrates the impact of Galileo integration on RTK availability and accuracy under canopy, along with the number of used satellites. As can be seen in Figure 8a, the inclusion of Galileo improves the availability of RTK fixed positions by 12.2%, from 65.7% (GGB) to 77.9% (GGGB). Moreover, dm-level position errors are largely reduced, as shown in FigURE 8c. The improvements in availability and accuracy are achieved by using up to three Galileo satellites (Figure 8b). This demonstrates that the current Galileo constellation in the IOC phase brings considerable benefits to high-precision RTK under canopy conditions.
Figure 8. Impact of Galileo integration on RTK availability and accuracy under canopy (iMAX, RTCM v3 MSM, baseline length: 116 km, GGB: GPS+GLO+BDS in blue, GGGB: GPS+GLO+GAL+BDS in red, DOY: day of year) (a) Availability of RTK fixed positions over time, (b) Number of used satellites (Galileo in green), (c) 3D errors of RTK fixed positions.
Tables 4 and 5 provide the RMS errors and reliability of RTK fixed positions from the canopy experiment, respectively. The main factors degrading the RTK accuracy in this case study are not only the canopy environment, but also the long baseline length of 116 km. It can be seen in Table 4 that the integration of Galileo leads to a significant reduction of 3D RMS error by 23.7%, from 0.114 m (GGB) to 0.087 m (GGGB).
By comparing the 2D and 1D RMS errors, the benefits of Galileo for the height are more dominant than for the horizontal components, which was also observed in the multipath experiment (Table 2). In terms of reliability, only slight (below 2%) increases are visible in Table 5. 116km baseline length and heavy canopy are considered extreme conditions and beyond the standard conditions relevant for specifications. Considering reliability together with availability (Figure 8a), it is encouraging to see that both the RTK performance characteristics are improved in this case study.
Table 4. Root mean square errors [m] of RTK fixed positions under canopy (iMAX, RTCM v3 MSM, baseline length: 116 km, GGB: GPS+GLO+BDS, GGGB: GPS+GLO+GAL+BDS).Table 5. Reliability [%] of RTK fixed positions under canopy (iMAX, RTCM v3 MSM, baseline length: 116 km, GGB: GPS+GLO+BDS, GGGB: GPS+GLO+GAL+BDS).
GALILEO-ONLY RTK
To optimize the performance of multi-GNSS RTK positioning, the individual systems need to be fully understood and mastered. With a previous firmware release in August 2014, mass-market devices were able to perform GLONASS-only and BeiDou-only high-precision RTK. In 2014 tests, we compared the performance of GPS-only, GLONASS-only and BeiDou-only RTK at different accuracy levels. Considering that Galileo has reached the IOC phase, it is reasonable to assess the Galileo-only RTK performance with the latest firmware.
Due to the limited number of usable Galileo satellites, Galileo-only RTK positioning was carried out in the Heerbrugg open-sky testbed over a very short baseline of 1 m. In addition, the elevation cut-off angle was set to 0° in order to track as many Galileo satellites as possible simultaneously. Two receivers were connected to two choke-ring antennas with good low-elevation tracking ability. Single-base RTK positioning was performed with four-system corrections in the RTCM v3 MSM format. About one hour of 1-Hz GNSS data was analyzed with a special focus on positioning accuracy.
Figure 9 shows the 3D errors from GPS-only, GLONASS-only and Galileo-only RTK positioning, where the numbers of used satellites are 8–11, 7–9 and 5–6, respectively. During the test period, only three or four BeiDou satellites were tracked with poor geometry, making BeiDou-only RTK impossible. As the figure shows, the 3D errors from GPS-only and Galileo-only RTK are at a comparable level with similar RMS values, whereas the 3D RMS error from GLONASS-only RTK is almost twice as large as the GPS/Galileo-only case. Note that when compared to GPS-only RTK, almost half as many satellites are used in Galileo-only RTK.
Figure 9. 3D errors of RTK fixed positions from GPS-only, GLONASS-only and Galileo-only RTK under open sky (single-base RTK, baseline length: 1 m, RTCM v3 MSM, DOY: day of year, RMS: root mean square).
Figure 10 displays the statistical distribution of the 3D errors from GPS-only, GLONASS-only and Galileo-only RTK positioning. Regarding the empirical CDF in Figure 10a, GPS/Galileo-only RTK shows a clearly more favorable error distribution than the GLONASS-only case. Using only GPS or Galileo, the probability that 3D error is within 1 cm is above 80%, which is approximately 30% higher than using only GLONASS. For 3D errors ranging between 5 mm and 1.7 cm, Galileo-only RTK even provides a slightly higher cumulative probability than the GPS-only case. The 3D error boxplots in Figure 10b illustrate a similar pattern between GPS-only and Galileo-only RTK, which is superior to GLONASS-only RTK due to the significantly smaller median and IQR.
Figure 10. 3D error statistics from GPS-only, GLONASS-only and Galileo-only RTK under open sky (single-base RTK, baseline length: 1 m, RTCM v3 MSM). (a) Empirical cumulative distribution function (CDF) of 3D errors, (b) Boxplot of 3D errors (IQR: interquartile range).
CONCLUSIONS
With the declaration of Galileo Initial Services in December 2016, for the first time ever all GNSS users worldwide are able to use the positioning, navigation and timing information provided by Galileo’s global satellite constellation. Upon full system completion by 2020, Galileo will play an important role in high-precision GNSS applications for users around the world. This article showed representative case studies to understand the benefits of the current Galileo constellation for high-precision RTK. In addition to a multi-GNSS solution, the performance of Galileo-only RTK was presented. The main findings from the case studies can be summarized as follows:
In the open-sky test, with an elevation cut-off angle of 10°, on average three Galileo satellites can be used for high-precision multi-GNSS RTK. This leads to cm-level improvements in coordinate repeatability over a long baseline of 116 km.
In the multipath case study, the additional use of two or three Galileo satellites produces significant enhancements in positioning accuracy at the few cm to dm level, where the benefits for the height component are more significant. Moreover, the integration of Galileo increases the 3D reliability of RTK fixed positions by 7.3% and reduces the median time to fix by 2 s (25%).
In the canopy experiment, the inclusion of Galileo improves the availability of RTK fixed solutions by 12.2%. Furthermore, dm-level position errors are largely reduced.
When compared to GPS-only RTK, Galileo-only RTK provides a similar positioning accuracy over a 1-m baseline under open sky, where almost half as many satellites are used. The 3D RMS error from GLONASS-only RTK is approximately twice as large as the GPS/Galileo-only case.
The promising results achieved through Galileo integration already indicate the very important role of the European GNSS in high-precision, multi-frequency and multi-constellation RTK positioning. During the deployment of the Galileo system, more benefits can be expected in the near future.
ACKNOWLEDGMENTS
The staffs of Leica Geosystems AG (Heerbrugg/Switzerland), Christian Waese and Youssef Tawk, are gratefully acknowledged for support in setting up the variety of RTK network streams.
MANUFACTURERS
SmartWorx 6.16 of Leica Viva GNSS is the latest firmware cited and used in these high-precision RTK tests. Leica GNSS Spider 7.0.0 furnished the GNSS real-time corrections. The open-sky case study used two Leica Viva GS10 units connected to a Leica Viva AS10 antenna via a four-way antenna splitter. The multipath case study used a Leica Viva GS16 GNSS smart antenna. The canopy case study used a Leica Viva GS10 receiver and a Leica Viva AS10 antenna. The Galileo-only RTK test used two Leica Viva GS10 receivers and two Leica AR25 choke ring antennas.
Harris Corporation has delivered the third of 10 advanced navigation payloads to Lockheed Martin, which will increase accuracy, signal power and jamming resistance for U.S. Air Force GPS III satellites.
The navigation payload before integration into the second GPS III SV, which now is in environmental testing. (Photo: Harris)
The advanced navigation payloads feature a Mission Data Unit (MDU) with a unique 70-percent digital design that links atomic clocks, radiation-hardened computers and powerful transmitters — enabling signals three times more accurate than those on current GPS satellites.
The new payloads also boost satellite signal power, increase jamming resistance by eight times and help extend the satellite’s lifespan.
The payload is expected to be integrated into GPS III Space Vehicle 3 (GPS III SV03) this summer. In May, Harris’ second GPS III navigation payload was integrated into GPS III SV02.
The first navigation payload is integrated aboard GPS III SV01, which has now completed rigorous testing and is in storage awaiting its expected 2018 launch.
The MDU performs the primary mission of the GPS satellite, which is generation of the navigation signals and data that provide precise time information to users on a continuous basis. (Photo: Harris)
“We are now in full production and on target to deliver the fourth GPS III navigation payload to Lockheed Martin this fall,” said Bill Gattle, president, Harris Space and Intelligence Systems. “Our payloads help U.S. and allied soldiers complete their missions, enable billions of dollars in commerce and benefit the everyday lives of millions of people around the world.”
Harris has a long legacy of expertise in creating and sending GPS signals, extending back to the mid-’70s — providing navigation technology for every U.S. GPS satellite ever launched.
Harris is also developing a fully digital MDU for the U.S. Air Force’s GPS III Space Vehicles 11+ acquisition. This new MDU will be demonstrated in fall 2017 and provides even greater flexibility, affordability and accuracy versus existing GPS satellites.
Harris navigation payloads are already integrated in the second GPS III space vehicle, now in environmental testing, and the first GPS III satellite (pictured here), expected to launch in 2018. (Photo courtesy Lockheed Martin)
Dana Goward President, Resilient Navigation and Timing (RNT) Foundation
An apparent mass GPS spoofing attack in June involved more than 20 vessels in the Black Sea and suggests that Russia may be aggressively experimenting with signal disruption and spurious substitution.
“GPS equipment unable to obtain GPS signal intermittently since nearing coast of Novorossiysk, Russia. Now displays HDOP 0.8 accuracy within 100m, but given location is actually 25 nautical miles off…”
Subsequent dialog with the ship’s master and examination of various documents and screen grabs he furnished enabled navigation experts to conclude this was a fairly clear case of spoofing: sending false signals to cause a receiver to provide false information. Other vessels in the vicinity experienced the same problem.
The RNT Foundation has received numerous anecdotal reports of maritime problems with the automatic identification system (AIS), a tracking system used for collision avoidance on ships, and with GPS in Russian waters, though this is the first well-documented public account.
Russia has very advanced capabilities to disrupt GPS. More than 250,000 cell towers in Russia have been equipped with GPS jamming devices as a defense against attack by U.S. missiles. And there have been press reports of Russian GPS jamming in both Moscow and the Ukraine. In fact, Russia has boasted that its capabilities “make aircraft carriers useless.”
The U.S. director of National Intelligence issued a report on May 11 that states that Russia and other actors are focusing on improving their capability to jam U.S. satellite systems.
Assuming Russia is behind this, why would they do such a thing? Possibly to encourage use of GLONASS or their terrestrial loran system, Chayka, instead of GPS. Possibly for some security reason known only to them.
Whatever the reason, it reminds us of the vulnerability of GPS signals, and of the plethora of motives that “bad actors” — governmental or private criminal interests — may have to disrupt and deceive GNSS users.
And of the U.S. Coast Guard’s advice about GPS and all satnav: “Trust But Verify.”
Dana Goward is president of the Resilient Navigation and Timing Foundation. He is the proprietor at Maritime Governance LLC. In August 2013, he retired from the federal Senior Executive Service, having served as the maritime navigation authority for the United States. As director of Marine Transportation Systems for the U.S. Coast Guard, he led 12 different navigation-related business lines budgeted at more than $1.3 billion per year. He has represented the U.S. at IMO, IALA, the UN anti-piracy working group and other international forums. A licensed helicopter and fixed-wing pilot, he has also served as a navigator at sea and is a retired Coast Guard Captain.
Preliminary construction is underway on a new, $350 million Lockheed Martin facility that will produce next-generation satellites.
The new facility, located on the company’s Waterton Canyon campus near Denver, is the latest step in an ongoing transformation, infused with innovation to provide future missions at reduced cost and cycle time, the company said.
The new Gateway Center, slated for completion in 2020, includes a state-of-the-art high bay clean room capable of simultaneously building a spectrum of satellites from micro to macro.
Spacecraft now in production at the site include the Air Force’s GPS III satellites (in the GPS III Processing Facility), NASA’s InSight Mars lander, NOAA’s GOES-R Series weather satellites and commercial communications satellites.
The facility’s paperless, digitally-enabled production environment incorporates rapidly-reconfigurable production lines and advanced test capability.
It includes an expansive thermal vacuum chamber to simulate the harsh environment of space, an anechoic chamber for highly perceptive testing of sensors and communications systems and an advanced test operations and analysis center.
The Gateway Center will be certified to security standards required to support vital national security missions.
“This is our factory of the future: agile, efficient and packed with innovations,” said Rick Ambrose, executive vice president of Lockheed Martin Space Systems. “We’ll be able to build satellites that communicate with front-line troops, explore other planets and support unique missions.”
“You could fit the Space Shuttle in the high bay with room to spare,”Ambrose said. “That kind of size and versatility means we’ll be able to maximize economies of scale, and with all of our test chambers under one roof, we can streamline and speed production.”
Lockheed Martin expects the construction effort to employ a total of 1,500 contractors during the three-year construction phase. Lockheed Martin has added more than 750 jobs to its Colorado workforce since 2014, and has about 350 job openings in the Denver area alone.
Lockheed Martin’s planned satellite integration facility, the Gateway Center, is slated for completion in 2020. (Photo: Lockheed Martin.}
The building will accommodate that recent growth and new future projects. State and local officials in Colorado have helped strengthen the aerospace industry and foster an environment that helps aerospace companies thrive and grow.
“Aerospace is an engine of innovation and growth for America, and we’re investing in infrastructure and technology to help strengthen the nation’s leadership in military and commercial space and scientific exploration,” added Ambrose. “We’re transforming every aspect of our operations to help our customers stay ahead of a rapidly-changing landscape. The Gateway Center, coupled with advancements in 3D printing, virtual reality design and smart payloads, will deliver game-changing innovations while saving our customers time and money.”
Lockheed Martin’s Waterton Canyon campus has been a hub of space innovation since the 1950s, with more than 4,000 employees and a wide range of industry-leading design, manufacturing and test facilities on site.
Companies selected by Lockheed Martin for the project include Hensel Phelps as the general contractor, Matrix PDM Engineering and Dynavac for thermal vacuum chamber design and construction, and ETS-Lindgren for anechoic chamber design and construction.
A: Integration with GNSS and other sensors in most every military vehicle or weapon-control system will enable inertial sensor developers to focus on driving improvements in performance for the two fundamental parameters that a sensor-fusion INS filter cannot estimate: noise and in-run bias stability. Ultra-tightly coupled sensor fusion of GNSS with range-, speed- and video position-sensing, with tactical and navigation grade inertial sensors optimized for noise and in-run, will enable design of robust GPS chip-level solutions for high-dynamic, high-performance navigation for nearly any military environment or engagement.
Michael Whitehead, chief technology officer, Hemisphere GNSS
A: Previously used for military applications, inertial technology has become mainstream as performance-to-cost has improved with the emergence of low-cost microelectromechanical systems (MEMS). Precise point positioning (PPP) advancements have driven GNSS accuracies to 4 cm or better, but long PPP initialization times are problematic in challenging environments where reconvergence is often required. Tightly coupled integration of PPP and navigation-quality MEMS will overcome limitations of both technologies, yielding high accuracy with high availability, even in challenging environments.
Chris Wheeler, manager, telematics and connected sites, Trimble Navigation
A: The availability of multi-frequency GNSS receivers with inertial components on a small lightweight board can now deliver centimeter-accurate INS/GNSS solutions, so that OEMs and integrators can significantly improve reliability and robustness in harsh or GNSS-denied applications or for solutions such as UAVs. The advances provided by MEMS inertial components increase overall efficiency by reducing the number of ground control points while still meeting the needs for a low weight and power consumption solution.
Each Galileo satellite must go through a rigorous test campaign to assure its readiness for the violence of launch, the vacuum of space, and temperature extremes of Earth orbit, reported the European Space Agency.
Each one is despatched to a unique location in Europe to ensure its readiness before launch: a 3,000-square-meter cleanroom complex nestled in sandy dunes along the Dutch coast, filled with test equipment to simulate all aspects of spaceflight.
The test centre in Noordwijk — Europe’s largest satellite test site — is part of ESA’s main technical centre, but it is maintained and operated on a commercial basis on behalf of the Agency by a private company created for the purpose: European Test Services (ETS) B.V.
“Our company was founded 2000 as a joint venture between two of Europe’s leading satellite environmental test companies, Intespace in France and IABG in Germany,” said Pierre Destaing, ETS test programme support manager for Galileo. “That business setup is a source of flexibility: there are 30–35 people working here throughout the year, but if extra specialists are needed for a given campaign, we can call on our parent companies.”
ETS has been responsible for supporting many historic test campaigns – including space-certifying Europe’s 20-tonne ATV space truck and Envisat, the world’s largest civilian Earth-observing mission. But in terms of scale alone, its work with Galileo is the company’s greatest challenge.
ETS is about to complete its contracts with OHB System AG, covering the environmental test of 22 ‘Full Operational Capability’ Galileo satellites, preceded by the testing of the very first of the first-generation ‘In-Orbit Validation’ Galileo satellites on a previous, separate contract.
A Galileo FOC satellite is slid out of its transport container into the clean room at ESTEC. (Photo: ESA)
The pressure has been steady to ensure satellites are available in time to meet Galileo’s launch schedule.
“Traffic management is a big part of the job – it’s like a game of Tetris,” Pierre said. “We have a steady stream of Galileo satellites to accommodate, along with other missions such as the BepiColombo Mercury orbiter, Solar Orbiter, the Cheops exoplanet detector and currently the latest MetOp weather satellite, with a fixed set of test facilities. The biggest challenge is definitely ensuring that every project can have the access to the facility they need at the right time, which demands complicated logistics and security adherence.”
ETS has built up to a steady rhythm with the OHB System team, typically accommodating multiple satellites in storage on site, at the same time as others undergo further active testing.
“When each new satellite arrives, it is first unpacked within the carefully filtered and air conditioned Test Centre environment,” Pierre said.
Moving a Galileo Full Operational Capability satellite between test facilities at ESA’s Test Centre in Noordwijk, the Netherlands. (Photo: ESA)
The European Space Agency (ESA) and the U.S. National Aeronautics and Space Administration (NASA) are conducting a joint GPS/Galileo space receiver experiment onboard the International Space Station (ISS). This will be the first time that a combined GPS/Galileo receiver will operate in space.
The project aims to demonstrate the robustness of a combined GPS/Galileo waveform uploaded to NfASA hardware already operating in the challenging space environment: the Space Communications and Navigation (SCaN) software-defined radio testbed.
Testing activities include analysis of the GPS/Galileo signal and onboard position/velocity/time (PVT) performance; processing of code- and carrier-phase GPS/Galileo raw data for precise orbit determination (POD); and validating the added value of a space-borne dual-GNSS receiver compared to a single-system receiver under the same conditions.
This collaboration was initiated in 2014 and a Technical Understanding was signed in 2016.
Many new space applications may not be possible if constrained to using the limited signal availability associated with any single constellation of GNSS satellites.
This research therefore seeks to demonstrate the enhanced capabilities brought by the use of satellites from two or more GNSS constellations in the space domain. The net result will be more resilient space operations, greater mission flexibility, and enhanced PVT performance.
The project is currently in the testing and verification phase, and it is expected that the final implementation of the combined GPS/Galileo waveform on NASA’s SCaN Testbed on-board the ISS will be completed in September/October 2017, so that the initial operations of the first combined GPS/Galileo receiver in space can start in the October/November 2017 timeframe.
The researchers plan to present preliminary results at the UN International Committee on GNSS (ICG)-12 in Kyoto, Japan in December.
From ESA’s side, ESOC’s Navigation Support Office (NavSO) and ESTEC Experts for Radio Navigation Systems and Techniques (TEC-ESN) are involved in this project.
The overall project management from ESA’s side and POD aspects are covered by NavSO, and ESTEC’s Technical Directorate is in charge of the Galileo waveform development and implementation of the SW on the FPGA in cooperation with NASA. This activity is done with technical support from industry participants such as Qascom. Industry participation is a vital component as new markets for multi-GNSS receivers and complex space applications continue to emerge.
From NASA’s side, the project is sponsored by the Space Communications and Navigation (SCaN) Program within the Human Exploration and Operations Mission Directorate (HEOMD) at NASA Headquarters in Washington D.C. Integration and experimentation activities are being performed by the NASA Glenn Research Center.
NASA has initiated an international effort within the ICG to develop a fully interoperable multi-GNSS Space Service Volume (SSV), where a combination of constellation services will be available well above low-Earth orbit (LEO) to support newly emerging geostationary Earth orbit (GEO) and high-Earth orbit (HEO) missions — ranging from more precise station keeping to extend GEO belt capacity and maneuver recovery to enabling formation flyers and satellite servicing operations.
WERNER ENDERLE is head of Navigation Office, Ground Systems Engineering Department at the European Space Operations Centre of the European Space Agency.
JAMES J. MILLER is deputy director, Policy & Strategic Communications – Space Communications and Navigation in the Human Exploration and Operations Mission Directorate at NASA headquarters.
Anomalous GPS Signals from SVN49
By Fabio Dovis, Nicola Linty, Mattia Berardo, Calogero Cristodaro, Alex Minetto, Lam Nguyen Hong, Marco Pini, Gianluca Falco, Emanuela Falletti, Davide Margaria, Gianluca Marucco, Beatrice Motella, Mario Nicola and Micaela Troglia Gamba
Researchers at the Navigation Signal Analysis and Simulation (NavSAS) Group of the Politecnico di Torino detected in mid-May the presence of anomalous spikes in the L1 signal spectrum. The origin of the spikes was identified to be transmission of a non-standard code from a non-operational GPS satellite (GPS IIF-9, SVN49). Here we report on signal observations and address possible impacts on GNSS signal processing.
On May 17, 2017, during outdoor data collection, NavSAS researchers detected two spikes in the L1 spectrum, with sufficient power to be clearly visible on a display processing raw digital samples at the receiver’s intermediate frequency.
An initial check looked for a possible interfering source in the experimental set-up, since it was quite complex with multiple pieces of electronic equipment. The likelihood of this source was soon dispelled as the same kind of spectrum was visible on a spectrum analyzer (SA) connected to an active survey-grade GNSS antenna on the lab roof; results shown in FIGURE 1.
The spectrum is centered at 1575.42 MHz, with the SA set to a frequency span of 5 MHz. Connecting the SA to different survey-grade antennas on the roof, we found no remarkable differences. The spikes continued to appear on subsequent days, becoming clearly visible around 13:00 UTC and disappearing around 19:00 UTC.
Figure 1. L1 Spectrum of the received signal at 16:51 (Central European Summer Time; 14:51 UTC) on May 19, 2017, at the NavSAS Lab, Torino (located at 45°03’54.98767″ N, 7°39’32.28920″ E, 311.9667 meters).
Exclusion of Terrestrial Sources. The 24-hour repetition period of the phenomenon, along with the shape of the spectrum, could indicate the presence of a signal anomaly from a GNSS satellite. In a battery of tests, we probed the L1 spectrum in a wider area using assorted equipment.
For various reasons, we ended up focusing on a non-operational satellite: SVN49, launched March 24, 2009. We concluded that transmission of a non-standard code (NSC) from this satellite was the origin of the problem in the L1 spectrum.
Transmission of NSCs for testing purposes is foreseen in the GPS Interface Specification, IS-GPS-200. GPS satellites can switch off regular broadcasts of C/A code and P/Y code and transmit a non-standard C/A code and non-standard Y code.
Such operation is intended to protect users from receiving and utilizing erroneous satellite signals in case of unhealthy conditions on the spacecraft. Strictly speaking, this case cannot be formally considered as an “anomaly,” because the transmission of non-standard codes is documented in the IS-GPS-200.
Therefore, the transmission of an NSC can be considered a normal operation in itself, though it may reflect a problem with the transmitting satellite.
In this case the choice of the spreading sequence, which is likely a square wave, allowed the total power of the signal to be concentrated in just a few spectral components, thus originating continuous-wave-like in-band signals.
The distribution of the harmonics, the main components of which are at ±500 kHz, and the presence of the odd harmonics only, matches an earlier case in 2006 of a transmission of an NSC modulated as a binary-phase-shift-keying (BPSK) sequence with alternating logical 0s and 1s, transmitted at the C/A code chipping rate (Rc=1.023 megachips per second). The hypothesis of the BPSK with Rc=1.023 megachips per second spreading signal has been verified by simulation.
However, the NSC is designed to have negligible effect on tracking other healthy GPS satellite signals. Nonetheless, an NSC transmission can have a non-negligible impact in performance of user equipment.
When a GPS satellite is switched to NSC mode, a receiver immediately loses its capability to track that satellite signal. This is not the case with SVN49, as it is currently declared non-operational. However, due to the modified code sequence, a further effect is possible: the NSC introduces irregular components at a sustained level in the GPS signal spectrum.
According to Notice Advisory to Navstar Users (NANU) 2017001, SVN49 was broadcasting standard signals as PRN04 (though set unhealthy) since the beginning of the year; NANU 2017042 announced that PRN04 was to be re-allocated to SVN38 on May 18.
This switch matches the dates when we started to see the spikes, since, probably, SVN49 started that day to use the “square wave” for the spreading.
Implementing the square wave local code, it has been possible to successfully acquire and track the NSC.
The real-time software receiver N-Gene has been forced to acquire and track in real time the signal coming from SVN49. The receiver decoded the navigation message transmitted by SVN49, which exhibits a regular format, even if marked with an unhealthy flag.
Impact on Receiver Processing. Interference with harmonic components such as those generated by the use of a square wave could strongly impact a GNSS receiver in the acquisition and tracking blocks, because the interference power is dispersed over the whole search space by the correlation with the local code, compromising the acquisition accuracy and impacting other functional blocks.
The impact of interference spectral lines depends on their location within the frequency band. This is due to the almost periodic nature of the GNSS signals. The spectrum of a GNSS signal has components spaced at multiples of the inverse of the code period (for example, 1 kHz for GPS C/A code) with different power allocated to each component depending on the shape of the code spectrum.
The effect is larger in the case of matching of the interference spectral components with the ones of the GNSS signal. Furthermore, in this case, the strongest harmonics are close to the L1 carrier frequency and are not mitigated by the front-end filter since they fall within its narrow bandwidth.
The overall GNSS scenario has changed a lot recently. Galileo and BeiDou are also present, and Galileo signals, due to the different structure and code periods, have spectral lines spaced at 0.25 kHz. The frequency modulation of the interfering signal due to the variable Doppler shift is thus even more likely to hit some of the spectral components of these signals.
We are investigating further to assess the impact of the interfering signal from SVN49 on Galileo-based high accuracy applications.
U.S. Air Force Response
The 2nd Space Operations Squadron is performing maintenance on a presently non-operational satellite. SVN49 is broadcasting non-standard C/A and non-standard Y codes as described in IS-GPS-200. Space professionals continue to conduct safe and responsible command and control of the constellation to continue to provide accuracy that exceeds established system requirements.
As always, GPS users who experience issues should address them through the appropriate channels: military users should contact DSN 560-2541, commercial 719-567-2541 while civilian users should contact the U.S. Coast Guard Navigation Center at 703-313-5900.
Very Respectfully,
Nicholas J. Mercurio, Capt., USAF Director, 14th Air Force/JFCC SPACE Public Affairs
Possibly during the course of last month’s editorial here, “‘Nearly Perfect’ Not Nearly,” in which I called out the U.S. Air Force for lauding itself a bit much, I veered across the line separating vehemence from over-vehemence. Just possibly. Over-vehemence is a professional hazard of journalism. A gentle reader wrote in to suggest as much. He began, in his polite way, with “As always, I enjoyed your article and it made me think.” Then he offered a few of his thoughts for me in turn to consider.
First, he urged me to weigh all three GPS segments. The space and control segments operate almost flawlessly, he averred. Except, I can’t refrain from riposting, for the times that they don’t.
The user segment, we can all agree, is a different story. Most current GPS user equipment can be jammed and spoofed, sometimes very easily, and some have difficulty handling leap seconds and GPS week rollovers.
The U.S. Air Force and the GPS program office cannot fix the problem with user equipment. This is up to those who manufacture, purchase, install and maintain the user equipment.
Fair enough.
Let’s not even get into mapping and guidance algorithms and obsolete data that generate multitudinous stories in mass media about drivers led astray and into danger “by GPS.” Those are the fault, not of the user equipment per se, but of software conjoined to a receiver in a navigation device or smartphone.
My column in June’s GNSS Design & Test enewsletter covered the same ground and then tackled the potential costs of GPS disruption, citing a study done by Innovate U.K., the U.K. Space Agency and the Royal Institute of Navigation. This included a pie chart of potential economic losses in the U.K. that would stem from a prolonged GNSS disruption. I really should have correleated these with, or at least mentioned in the same breath, the reports done for the National Space Based-PNT Advisory Board by Irv Leveson, because there were several mismatches. In particular, the PNT Advisory Board study concluded that more than 50 percent of the value of GPS to the U.S. economy lies in high-precision uses — substantially higher than estimated in the U.K.
Regardless of statistics, we should think, my correspondent reminded me, about the performance needs of different uses. It’s not just whether you have PNT or you don’t. The degree to which you have it is the key: accuracy, coverage, 3D versus 2D positioning and other factors determine if a technology can perform to meet a given need. Aviation requires 3D positioning for some operations. Surveying and machine control require submeter accuracy. Road use requires meter accuracy now, and submeter in the future for autonomous driving. Almost 50 percent of the U.K. pie chart, and more than 50 percent of GPS value to the U.S., requires meter or better accuracy. Except for other satnav systems, what known technology can provide this kind of performance over an area the size of a nation, whether U.K. or U.S.?
Rohde & Schwarz and MediaTek have successfully completed the verification of location-based services (LBS) in the U-plane and C-plane for Assisted Beidou (A-BeiDou), China’s GNSS satellite positioning system.
The R&S TS-LBS test solution allows mobile manufacturers, chipset manufacturers, test houses and network operators to verify chipsets and mobile devices in order to obtain permission to operate them in a particular network.
The successful A-BeiDou verification of the MediaTek device under test (DUT) using the Rohde & Schwarz test system marks an important milestone in the GNSS evolution of positioning and navigation. According to Rohde & Schwarz, this was the first time that the setup could be used to validate and verify a device for A-BeiDou location-based services.
The R&S TS LBS from Rohde & Schwarz is a test system for testing GNSS and network-based LBS. It consists of an R&S CMW500 as the base station simulator and an R&S SMBV100A GNSS simulator. The R&S CMW500 provides assistance data to the DUT and the R&S SMBV100A simulates the BeiDou satellites. The R&S TS-LBS test system can be used to obtain GCF and PTCRB certification as well as network operator-specific certification for chipsets and mobile devices.
“We are delighted to collaborate with MediaTek and to contribute our test and measurement expertise to the development of A-BeiDou location based services,” said Alexander Pabst, vice president of Systems and Projects within the Rohde & Schwarz Test & Measurement Division. “Rohde & Schwarz already has a strong global footprint with testing solutions for A-GNSS, such as A-GPS or A-GLONASS, and for OTDOA/eCID. Thanks to our close cooperation with our partners, Rohde & Schwarz is committed to accompanying the evolution from existing to new satellite systems such as A-BeiDou with our innovative test and measurement solutions.”
“MediaTek is committed to developing and testing the latest mobile technologies and standards to drive the industry forward,” said TL Lee, general manager of the Wireless Communications Business Unit at MediaTek. “We have worked closely with Rohde & Schwarz to develop and validate the test solution for A-BeiDou LBS, verifying the A-BeiDou proof-of-concept trial system based on the R&S TS-LBS and MediaTek DUT. This represents an exciting step forward in the evolution of LBS technology, enabling the mobile ecosystem to verify chipsets and mobile devices on the new LBS technology.”
