Telit’s 300-Mbps LE940B6-NA LTE Cat 6 module has received AT&T certification for use on the carrier’s North American LTE wireless networks. The smart module is the first 300 Mbps Cat 6 automotive-grade solution certified by AT&T, Telit announced in a press release.
With advanced security features, the LE940B6 aligns with automakers’ vehicle roadmaps which include requirements for secure, high-speed mobile data that support next generation applications such as advanced diagnostics, infotainment and remote software updates.
“The automotive industry is continuously raising the bar on internet connection speeds to the car,” said Yossi Moscovitz, CEO of Telit Automotive Solutions. “Along with higher speeds, there are increasing requirements for security, quality and environmental performance which Telit has achieved with the LE940B6. With certification of the North American LTE-Advanced LE940B6-NA module variant, auto makers can immediately start delivering car models in the United States with these new modules.”
The LE940B6 powers the entire connected-car platform, supporting current needs while including advanced features that enable future integration of up-coming value-added, telematics and managed services.
The module can run in-vehicle applications inside a secure processing environment from the built-in 64-bit application processor, storage and memory. Automotive application programs can run entirely and securely on the module itself protected by advanced cyber-security capabilities.
Editor’s Note: This online preview presents brief highlights from the upcoming July cover story in GPS World, “Navigation from LEO: Current Capability and Future Promise.” The article is by David Lawrence, H. Stewart Cobb, Greg Gutt, and Michael O’Connor of Satelles, Tyler G. R. Reid and Todd F. Walter of Stanford University, and David Whelan.
Robust position, navigation, and timing services from low Earth orbit (LEO) are here today, providing augmentation to GPS where GPS isn’t available. The addition of navigation signals from LEO provides a number of benefits. The proximity of LEO satellites has the potential to provide much stronger signals than the distant GNSS core-constellations like GPS in medium-Earth orbit (MEO).
Today, the only LEO system with global coverage is the Iridium constellation used primarily for communications.
Figure 1 shows the 31-satellite GPS constellation in contrast with the 66-satellite Iridium network. The scale of the difference in distance (several Earth radii) is extraordinary. The result is that Iridium signals are 300 to 2400 times stronger than GNSS signals on the ground, making them attractive for use in position, navigation, and timing (PNT) applications where GNSS signals are obstructed.
Figure 1. The 66 satellite Iridium constellation in low Earth orbit and 31 satellite GPS constellation in medium Earth orbit.
LEO-based PNT is now mainstream, in the form of real-time signals that have been delivered over the Iridium satellite network since May 2016. This service is made possible by Satelles in partnership with Iridium Communications Inc. in a service called the Satellite Time and Location (STL), a non-GNSS solution for assured time and location that is highly resilient and physically secure. Consumers, businesses, and governments are already using these LEO-based signals in environments with high GNSS interference or occlusion.
The security features of these signals are also used to reliably validate GNSS position, navigation and time (PNT) solutions in real time to help mitigate potential spoofing. Furthermore, the fast LEO orbits of Iridium generate Doppler-frequency signatures significantly stronger than GPS, increasing the utility of the STL signal for positioning applications.
STL field tests demonstrate a positioning accuracy of 20 meters and timekeeping to within 1 microsecond, all in deep attenuation environments indoors. This adds substantial robustness in augmenting the GNSS core-constellations like GPS and also allows for a standalone backup in many applications.
Along with its strong signals compared to the GNSS core-constellations in MEO, Iridium’s global coverage makes it ideal for use in PNT applications where GNSS is obstructed. Figure 1 shows the scale of the difference in altitude with Iridium at 780 kilometers and GPS at 20,200 kilometers. This has substantial implications not only for signal strength but also for coverage.
Though Iridium has twice as many satellites as GPS, at the equator users can often only see one satellite whereas they can see ten from GPS. This was one of the fundamental trades considered in the design of the GPS constellation. The higher the altitude, the more each launch cost; the lower, the more satellites had to be built to provide coverage. To put this in perspective, global coverage for one satellite in view at all times requires fewer than ten satellites in MEO but requires closer to one hundred in LEO.
Future LEO Constellations
The hundreds of LEO satellites needed to match the coverage of GPS may be coming. In late 2014 and early 2015, the International Telecommunication Union (ITU) reported a half dozen filings for spectrum allocation for large constellations of LEO satellites.
In January 2015, OneWeb announced a partnership with Virgin and Qualcomm to produce a constellation of 648 LEO satellites to deliver broadband Internet globally. This represents the next order of magnitude, with tenfold more satellites than Iridium. Within days of this announcement, SpaceX, with support from Google, announced a similar ambition for a constellation of more than 4,000 LEO satellites.
In August 2015, Samsung expressed interest in a proposal for a LEO constellation of 4,600. Boeing joined the race in June 2016 announcing plans for a LEO constellation of nearly 3,000 satellites. These LEO constellations are being proposed to keep up with the rising demand for broadband, not to replace ground infrastructure.
LEO versus MEO
Low- and medium-Earth orbit each have their individual strengths and weaknesses in the context of navigation. Closer to Earth, LEO offers less spreading loss and improved signal strength on the ground. On the other hand, being closer to Earth means that satellites have much smaller footprints. The GPS footprint is threefold larger than Iridium, corresponding to nine times more area covered. Hence, to achieve the same coverage as GPS with Iridium’s altitude, the LEO constellation requires an order of magnitude more satellites.
Another major difference between LEO and MEO is speed. A GPS satellite completes one Earth revolution every 12 hours while an Iridium one does so in only 100 minutes. The shorter the orbital period, the faster the angular rate (also called mean motion) and the more quickly satellites pass overhead.
The swift motion whitens multipath (making it more random–like white noise) as reflections are no longer effectively static over short averaging times. Geometric diversity also leads to effective Doppler positioning and is also desirable for carrier-phase differential GNSS, allowing for much more rapid resolution of integer cycle ambiguities.
Iridium-Satelles Satellite Time and Location (STL)
The STL service has been in operation since May 2016. Many from industry and government are already using this service to achieve a more robust PNT solution. This service will only continue to improve with the Iridium NEXT satellites under deployment; the first ten satellites of this generation were successfully launched in January 2017.
STL is a non-GNSS solution for assured time and location that is highly resilient and physically secure. STL utilizes the Iridium constellation to transmit specially structured time and location broadcasts. Due to their high RF power and signal-coding gain, the STL broadcasts are able to penetrate into difficult attenuation environments, including deep indoors.
Like GNSS signals, these broadcasts are specifically designed to allow an STL receiver to obtain precise time and frequency measurements to derive its PNT solutions. STL is able to augment or serve as a backup to existing GNSS PNT solutions by providing secure measurements in the presence of high attenuation (deep indoors), active jamming, and/or malicious spoofing.
Unlike the MEO GNSS satellites, Iridium uses 48 spot beams to focus its transmissions on a relatively small geographic area. The complex overlapping spot beams of Iridium combined with randomized broadcasts give a unique mechanism to provide location-based authentication that is extremely difficult to spoof.
The July cover story in GPS World magazine will explore all the above topics in more technical detail, and go further into the areas of signal strength in challenging environments, indoor time-transfer capability, and a section on looking forward.
The PNT service using Iridium is perhaps a sign of things to come. On the horizon are constellations like OneWeb which promise the next order of magnitude with 648+ satellites, slated for the 2020s. This most recent scale gives rise to better satellite geometry than GPS today with the added benefits of LEO.
The STL signal using Iridium sets a precedent that could lead to unparalleled navigation services that are robust due to the improved signal strength and precise due to the huge number of LEO satellites coming, each moving quickly and giving the geometric diversity needed to enable fast carrier-phase differential GNSS.
The need for such a service is already present. This would be enabling for the safety-critical autonomous vehicles under development that must operate in challenging urban environments and to a diversity of other future technologies and applications as well.
Two further satellites have formally become part of Europe’s Galileo satnav system, broadcasting timing and navigation signals worldwide while also picking up distress calls across the planet, reported the European Space Agency.
Liftoff of Ariane flight VA233, carrying four Galileo satellites, on Nov. 17, 2016.
These are the 15th and 16th satellites to join the network, two of the four Galileos that were launched together by Ariane 5 on Nov. 17, 2016, and the first additions to the working constellation since the start of Galileo Initial Services on December 15.
The growing number of Galileo users around the world will draw immediate benefit from the enhanced service availability and accuracy brought by these extra satellites.
The launch into space and the maneuvers to reach their final orbits still left a lot of rigorous testing before the satellites could join the operational constellation.
Their navigation and search and rescue payloads had to be switched on, checked and the performance of the different Galileo signals assessed methodically in relation to the rest of the worldwide system.
Galileo L-band antenna at ESA’s Redu ground station.
This lengthy testing saw the satellites being run from the second Galileo Control Centre in Oberpfaffenhofen, Germany, while their signals were assessed from ESA’s Redu centre in Belgium, with its specialized antennas.
The tests measured the accuracy and stability of the satellites’ atomic clocks – essential for the timing precision to within a billionth of a second as the basis of satellite navigation – as well as assessing the quality of the navigation signals.
Oberpfaffenhofen and Redu were linked for the entire campaign, allowing the team to compare Galileo signals with satellite telemetry in near-real time.
Making the tests even more complicated, the satellites were visible for only three to nine hours a day from each site.
The satellites are now broadcasting working navigation signals and are ready to relay any Cospas–Sarsat distress calls to regional emergency services.
Now that these two satellites are part of the constellation, the remaining pair from the Ariane 5 launch is similarly being checked to prepare them for service.
Telit has introduced the LE940A9 smart module, an automotive-grade module designed to support LTE Advanced Category 9 (Cat 9) networks.
The series offers three multi-band, multi-mode variants — including voice-over-LTE (VoLTE) — and is optimized for automobile manufacturers to deploy next-generation connected-car technology in world markets.
The LE940A9 is the latest addition to Telit’s xE940 family of automotive-grade modules. According to Telit, it delivers 450 Mbps download and 50 Mbps upload speeds with extremely low latency and advanced security, enabling the next wave of automobile industry’s applications and services which also serve as a springboard for autonomous driving.
https://youtu.be/kXBlY_L3OjI
“Digital transformation is driving the evolution of the connected car with major improvements in driver safety, new revenue streams, and an immersive connected experience,” Telit said in a press release. “With government safety mandates around the globe, added advancements in the connected world, there is greater demand for more value-add services and feature-rich in-vehicle applications.
The xE940A9 40×40 mm LGA form factor nests with the 34x40mm Telit xE920 automotive module family, offering flexibility for the OEM or tier-one integrator.
“From commercial and consumer telematics services, to autonomous driving and driver assistance features, along with a host of other applications dependent on remote software updates, including infotainment; secure, wired broadband-like speed is now a requirement. The evolution to high-speed wireless connectivity is only possible if powered by LTE Advanced, with little to no lag time, for the applications to work.”
The LE940A9 powers the entire connected-car platform, supporting current needs while including advanced features that enable future integration of upcoming value-added, telematics and managed services.
The module can run in-vehicle applications inside a secure processing environment from the built-in application processor, storage and memory. Automotive application programs can run entirely and securely on the module itself, protected by advanced cyber-security capabilities.
“In addition to serving as a significant advancement for the connected car industry, the LE940A9 series is a powerful testament to Telit’s continued technology leadership enabling the future of the connected car worldwide,” said Yossi Moscovitz, CEO of Telit Automotive Solutions. “Not only does the LE940A9 enable unprecedented applications with the speed and low latency of Cat 9 of the multi-mode variants, it also simplifies integration and reduces costs that help accelerate the development of our OEM partners’ global roadmaps.”
Detection of anomalous harmonics in the L1 spectrum
Interfering signals are one of the most well-known nuisance for GNSS receivers. A number of terrestrial systems and devices can generate various types of interference, either intentionally or not, but one would not expect interfering signals to arrive from space. On May 17, researchers of the Navigation Signal Analysis and Simulation (NavSAS) Group at the Politecnico di Torino detected the presence of anomalous spikes in the L1 signal spectrum. The origin of the spikes was identified to be the transmission of non-standard codes from a non-operational GPS satellite (GPS IIF-9, SVN49). In this article, we report on some of the most significant signal observations we performed in an effort to identify and localize the source of the interference and we address the possible impact it could have on GNSS signal processing.
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
On the afternoon of May 17, 2017, during an outdoor data collection experiment, researchers of the NavSAS Group detected the presence of two spikes in the L1 spectrum, with sufficient power to be clearly visible on a display of the spectrum obtained by processing the raw digital samples at the receiver’s intermediate frequency. The initial check looked for a possible interfering source in the experimental set-up, since it was quite complex and included multiple GNSS receivers, PCs, a video camera and a couple of car batteries. But 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 mounted on the lab roof, as displayed 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 a different survey-grade antennas on the lab roof, we saw no remarkable differences.
The spikes also appeared on subsequent days, becoming clearly visible at about 13:00 UTC and disappearing at about 19:00 UTC, as illustrated in FIGURE 2. The main lobe of the GPS signal spectrum is visible, along with two spikes, at approximately ±0.5 MHz above and below the L1 carrier frequency. Weaker harmonics are also visible at ±1.5 MHz from the central frequency.
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).Figure 2. Spectrogram of the received signal. Power spectral density (PSD) is color coded.
Response from the U.S. Air Force about the anomaly
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 (Air Forces Strategic)/JFCC SPACE Public Affairs
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. However, we could not exclude the hypothesis of unintentional interference generated by a nearby terrestrial communication system, since the area is crowded with research labs belonging to the Instituto Superiore Mario Boella and the Department of Electronics and Telecommunications of Politecnico di Torino. Nevertheless, we probed the L1 spectrum in a wider area using a simple setup, consisting of a patch antenna and a narrow-band front end. We analyzed the spectrum at the output of the front-end’s analog-to-digital converter, plotting the results on a smartphone running our software receiver in real time.
FIGURE 3 shows the L1 spectrum observed several kilometers from the NavSAS Lab. The shape of the spectrum is different than that in Figure 1 because of the narrow-band filter of the front end, but again, the presence of the two spikes is clearly visible at ±0.5 MHz from the central frequency, approximately with the same power strength. In addition, during a dynamic data collection experiment, we recognized that the interfering signals disappeared when the western part of the sky was obscured by buildings, as demonstrated in Figure 3. This was further investigated (and confirmed) when we processed the collected set of data in the lab. At that time (May 19), the hypothesis of an interfering signal from space became more plausible.
Figure 3. L1 Spectrum of the received signal observed on the afternoon of May 19 in Torino, 6.7 kilometers away from the NavSAS Lab: (left) in open sky conditions, (right) with the western portion of the sky obscured by a nearby building.
Meanwhile, the presence of suspicious spikes was confirmed by colleagues at the European Commission Joint Research Centre located in Ispra, Italy, and also from researchers of the Finnish Geodetic Institute in Helsinki, Finland, and by the South African National Space Agency at the station of the South African National Antarctic Expedition IV. These multiple observations definitely excluded the possibility that the interference it could be coming from terrestrial sources or from within the receiving equipment.
Checking the satellites in view during the presence of the spikes in the spectrum (that is, from about 13:00 to about 19:00 UTC) and bearing in mind the periodicity of the event over consecutive days, we excluded the possibility that a Galileo satellite could be the source of interference. It is indeed known that, due to an orbital period of approximately 14 hours for observers on the ground, the constellation geometry repeats only every 10 days.
Figure 4. Visible operational GPS, Galileo and BeiDou satellites over Turin for the full time window between 13:00 and 19:00 UTC on May 20, 2017.
FIGURE 4 shows the visibility of operational satellites over the full time window of interest for the GPS, Galileo and BeiDou constellations.
Considering the duration of the satellites’ visibility, the search for the source of interference was restricted to SVN71 (PRN26), SVN45 (PRN21) and the C11 BeiDou satellite. However, considering the previous tests, the satellite should have been in the western portion of the sky with respect to our location, and the only operational satellite of this set is SVN71, which we initially identified as the possible source of the interfering signal.
GPS SVN71 (PRN 26) or SVN 49?
The frequency of the harmonics could be measured over time. The first peak at approximately 0.5 MHz above the central frequency was analyzed by post-processing a set of digital samples collected with an Universal Software Radio Peripheral, which was slaved to a 10-MHz rubidium standard and which converted the RF signal to baseband, sampling it at 5 MHz. The frequency was measured exploiting a Welch periodogram, based on a 102,400-point discrete Fourier transform, with rectangular windowing and no window overlaps.
FIGURE 5 (a) shows the trend of the measured frequency versus time, from 12:43 to 18:38 UTC, on May 21. The frequency profile reveals that it is not constant and has a trend similar to the typical Doppler frequency shift of a GPS satellite. FIGURE 5 (b) shows the derivative of the frequency, with a minimum around 16:22 UTC. At that time, we expected to have a null Doppler shift from GPS PRN26, whereas the frequency of the peak was equal to 510.449 kHz. This is the inverse of 1.959056 microseconds, which is close to the inverse of twice the chip length, 2/Rc = 1.955034 microseconds. This indicates that the interfering signal could be a square wave with the same rate as the C/A spreading code.
Figure 5(a). Measured frequency of the first upper harmonic versus time.Figure 5(b). Measured frequency of the first upper harmonic versus corresponding frequency rate.
FIGURE 6 shows the Doppler frequency of PRN26 (blue line), as estimated by the tracking loop of a GNSS software receiver, and compares the Doppler shift to the frequency of the first upper peak (orange line), measured on the spectrum. It is possible to note that the two curves almost overlap, with a significant difference at the beginning and at the end of the observation. Thus, although the frequency of the peak follows the Doppler trend of a GPS satellite, it does not exactly match the Doppler curve of PRN26. This result weakened the hypothesis indicating that PRN26 was the source of the interference.
Furthermore, since it was still possible to acquire and track the L1 C/A-code signal from PRN26, this satellite was unlikely to be the source of the interfering components. Thus, also motivated by the mismatch in the Doppler shift of PRN26 (as previously highlighted in Figure 6), we started to think that the source of the interference could be another satellite broadcasting a GPS-like signal.
The search then focused on potential sources of interference coming from a non-operational satellite. The non-operational GPS satellite SVN49, launched on March 24, 2009 (also known as NAVSTAR 63 with NORAD ID 34661), has an orbit similar to that of SVN71 (see FIGURE 7). The previous remarks, let us guess that the transmission of a non-standard code (NSC) from such a satellite was the origin of the problem in the L1 spectrum. Such a case, could be similar to what has been previously reported in by Zhu et al. [1,2] when discussing the effects of the transmission of an NSC on Nov. 28, 2006.
Figure 6. Doppler shift of GPS PRN26 estimated by a tracking loop (blue line) and comparison with the measured frequency of the first upper harmonic versus time (orange line).Figure 7. Skyplot illustrating the path of SVN71 (PRN26) and SVN49 over the time window of interest.
Transmission of NSCs for testing purposes is foreseen in the GPS Interface Specification, IS-GPS-200 [3]. GPS satellites can switch off regular broadcasts of the C/A code and the 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, even though it may reflect a problem with the transmitting satellite.
However, 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 the case recalled by Zhu et al. [1,2], 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 spectrum of this “square wave” with period used as a spreading signal is in fact know to be (1)
where δ is the Dirac-δ function. Zhu et al. [1,2] considered this specific case of a “non-standard code” to be especially remarkable, because it can affect the L1 spectrum, introducing multiple harmonic components similar to those previously illustrated in Figure 1 and Figure 3 (a).
Figure 8. Spectrum of the simulated NSC for different C/N0 values.
The hypothesis of the BPSK with Rc=1.023 megachips per second spreading signal has been verified by simulation. Figure 8. shows how the tested case of a received signal from SVN49 with a C/N0=55 dB-Hz best matches the measured spectrum when SVN49 is at its maximum elevation angle and the power of the received signal is the strongest.
However, it has to be remarked that according to Zhu et al. [1,2], the NSC is designed to have negligible effect on tracking other healthy GPS satellite signals. Nonetheless, their analyses showed that an NSC transmission (as occurred on Nov. 28, 2006) can have a non-negligible impact in the performance on user equipment. In detail, 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, an even worse effect is possible. In fact, the NSC introduces irregular components at a sustained level in the GPS signal spectrum.
As a final confirmation of the transmission of the NSC from SVN49, we have used the technique of averaging and summing over the code period as described by Mitelman [6]. Considering a time window during which the Doppler shift of the signal is negligible, we have extracted the spreading code, confirming the square wave hypothesis (see FIGURE 9).
Figure 9. Square wave code obtained by averaging and summing.
According to the Notice Advisory to Navstar Users (NANU) 2001701, SVN49 was broadcasting standard signals as PRN04 (although set unhealthy) since the beginning of the year, but NANU 2017042 announced that PRN04 was to be re-allocated to SVN38 starting from May 18. This switch actually matches the dates when we started to see the spikes in the spectrum, since, probably, the 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, as shown in FIGURE 10.
Figure 10. Acquisition and tracking of the NSC. Source: GPS World
Source: GPS World
The real-time software receiver N-Gene, documented by Molino et al. [5],has been forced to acquire and track in real time the signal coming from SVN49. FIGURE 11 shows a screenshot of the N-Gene graphical interface while processing this signal.
Figure 11. N-Gene software receiver processing the SVN49 signal.
The receiver was able to perform the decoding of the navigation message transmitted by SVN49, which exhibits a regular format, even if marked with an unhealthy flag (see FIGURE 12).
Figure 12. Decoded navigation message.
Impact on receiver signal processing
It is well known that the spectrum of GNSS signals is basically a line spectrum in the frequency domain, which is susceptible to interference (see, for example, the book edited by Davis [4]).
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 strongly depends on their location within the frequency band. This is due to the almost periodic nature of the GNSS signals. In fact, 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 case of matching of the interference spectral components with the ones of the GNSS signal. Furthermore, in the present 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.
As opposed to the case discussed by Zhu et al. [1,2] when GPS was virtually the only code-division-multiple-access system occupying the bandwidth around L1, the overall GNSS scenario has changed a lot recently. Galileo and BeiDou are also present, and the signals of the Galileo system, 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 then even more likely to hit some of the spectral components of these signals.
We are performing further investigations are being performed to assess the impact of the interfering signal from SVN49 on Galileo-based high accuracy applications.
Acknowledgments
The NavSAS Group thanks Dr. Matteo Paonni (EC Joint Research Centre) for the support given in the analysis of the L1 signal spectrum and Dr. Laura Ruotsalainen (Finnish Geospatial Institute) and Danielle Taljaard (South African National Space Agency), who performed the data collection in Antarctica.
Bios
Fabio Dovis, Nicola Linty, Mattia Berardo, Calogero Cristodaro, Alex Minetto and Lam Nguyen Hong are with the Navigation Signal Analysis and Simulation (NavSAS) Group, Politecnico di Torino, Torino, Italy.
Marco Pini, Gianluca Falco, Emanuela Falletti, Davide Margaria, Gianluca Marucco, Beatrice Motella, Mario Nicola and Micaela Troglia Gamba are with the Navigation Technologies Research Area of Istituto Superiore Mario Boella, Torino.
[2] “Satellite Anomaly and Interference Detection Using the GPS Anomalous Event Monitor” by Z. Zhu, S. Gunawardena, M. Uijt de Haag and F. van Graas in Proceedings of the 63rd Annual Meeting of The Institute of Navigation, Cambridge, Massachusetts, April 23–25, 2007, pp. 389–396.
[4] GNSS Interference Threats and Countermeasures by F. Dovis (ed.) published by Artech House, Norwood, Massachusetts, 2015.
[5] “N-Gene GNSS Software Receiver for Acquisition and Tracking Algorithms Validation” by A. Molino, M. Nicola, M. Pini and M. Fantino in Proceedings of EUSIPCO 2009, the 17th European Signal Processing Conference, Glasgow, Scotland, Aug. 24–28, 2009, pp. 2171-2175.
Tersus GNSS Inc. is now offering the INS-T-306, a GNSS-aided inertial navigation system. The INS-T-306 is the advanced module that combines GPS L1/L2, GLONASS, BDS navigation and a high-performance strap-down system. It is capable of determining position, velocity and absolute orientation (heading, pitch and roll) for any device on which it is mounted.
The launch of the INS-T-306 aims at facilitating motionless and dynamic applications that need high accuracy, such as vessels, ships, helicopters, unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs).
The INS-T-306 utilizes an advanced GNSS receiver, barometer, magnetometers, micro-electro-mechanical (MEMS) accelerometers and gyroscopes to provide accurate position, velocity, heading, pitch and roll of the device under measure.
Besides GPS L1/L2, GLONASS and BDS, the unit supports differential GPS and real-time kinematic (RTK). It is able to integrate into lidar (Velodyne, Riegl and Faro brands). The on-board sensor fusion filter, navigation and guidance algorithms, and calibration software inside all make INS-T-306 a commercially exportable GNSS-aided inertial navigation system.
Kongsberg Geospatial’s IRIS UAS situational awareness application now provides a certifiable option to monitor drones and airspace. Kongsberg Geospatial is an Ottawa-based developer of real-time geospatial visualization software.
The IRIS UAS Airspace Situational Awareness application meets the requirements of the DO-278A Assurance standard for air traffic management systems.
By anticipating the regulatory requirements for airspace visualization with Unmanned Traffic Management or UTM, the IRIS display will be a regulatory approved component increasing the safety of commercial drone flight operations — especially when operating beyond visual line-of-sight (BVLOS).
IRIS UAS program director Paige Cutland uses the IRIS UAS airspace situational awareness application to monitor the progress of a drone on a beyond line-of-sight (BVLOS) mission from a portable ground control station set up in a trailer.
Kongsberg Geospatial has been providing software design assurance to meet the certification requirements for real-time geospatial and spatial awareness technology to support air traffic management, air defense applications and unmanned systems for nearly three decades.
Their IRIS UAS situational awareness application had its genesis in supporting military UAV flight operations and was developed to help operators safely pilot UAVs in BVLOS operations. It was also used by regional airspace UTM managers to monitor the operations of multiple drones simultaneously.
The DO-278A standard (Guidelines for Communication, Navigation, Surveillance and Air Traffic Management [CNS/ATM] Systems Software Integrity Assurance) is the primary standard used by certification authorities such as FAA, EASA and Transport Canada to provide the assurance of software contained in non-airborne CNS/ATM systems. Unmanned systems manufacturers that build ground control stations for commercial drone systems, and airports and port authorities that create airspace control systems are anticipated to have to meet this standard when designing and building new systems.
By developing an airspace awareness application that satisfies this standard, Kongsberg Geospatial has provided a key component for unmanned systems manufacturers, airport operators and port authorities that wish to develop ground-based monitoring systems that are safe and certifiable for commercial operations.
“Unmanned Traffic Management and safe airspace operations will require certification of technology,” said Ranald McGillis, president of Kongsberg Geospatial. “We believe providing a certifiable airspace application will dramatically increase the safety of unmanned flight operations wherever it’s in use.”
NASA’s UAS Traffic Management System was tested May 25 at the Nevada UAS Test Site. (Credit: Drone America)
On May 25, the Federal Aviation Administration (FAA)-designated Nevada UAS Test Site and its NASA partners flew five different unmanned aerial vehicles (UAVs) to test NASA’s Unmanned Aircraft System Traffic Management (UTM).
The flights demonstrated multiple operational scenarios, including parachute-initiated emergency supply deliveries and aerial survey operations.
The UAVs were flown beyond the pilot’s visual line of sight using strategically placed visual observers and sophisticated command and control, communication and detect-and-avoid technologies.
The test is part of a three-week national campaign, which NASA is leading in close collaboration with the FAA and industry partners on a more complex version of its UTM technologies at six different UAS Test Sites around the nation.
The Technology Capability Level 2 (TCL2) National Campaign began May 9 with the Nevada UAS Test Site as the first of six UAS Test Site to begin UTM operations this year.
The partners not only demonstrated drone flight capability, but also tested UAS traffic mapping, sensor and radar technology, all of which were connected through a NASA UAS service supplier network to NASA Ames Research Laboratory.
Six FAA UAS Test sites and industry partners integrate their technologies with NASA’s UTM research platform and test the UTM concept in a range of conditions representative of those in the U.S. Airspace, explaind Tom Prevot, UTM project manager.
“For the Nevada NASA Team, we flew the longest multi-faceted NASA UTM flights to date in Nevada,” Prevot said. “The beyond-line-of-sight missions we completed over a distance of 13 miles north of Reno, Nevada, and the multiple aerial parachute package-delivery missions performed were a first in the National Airspace System under the NASA UTM.”
Current testing of the UTM TCL2 Test marks the second year in a row NASA has taken its UTM technologies on the road to further assess and refine their capabilities. During April 2016, NASA and its partners tested TCL1, which involved line-of-sight operations, and then began the first phase of TCL2 demonstrations in October 2016.
Two more phases, TCL3 and TCL4, each progressively more complex and involving flying drones with specific tasks over increasingly populated areas, are scheduled for 2018 and beyond.
The aerial parachute package-delivery missions performed were a first in the National Airspace System under the NASA UTM. (Credit: Drone America)
“Our Nevada NASA partners did an amazing job in extending the body of airspace management and sense-and-avoid knowledge under the UTM and across the UAS Industry,” said Chris Walach, director of the Nevada UAS Test Site. “The National Campaign data provided to NASA from our two-week operation will go a long way toward advancing the UTM for the FAA and the UAS Industry.”
“At AirMap, we consider UTM to be a critical ingredient for a thriving drone ecosystem,” said Steve Willer, business development manager for AirMap. “The TCL 2 trials demonstrate that technologies for geofencing, data exchange, and more can enable safe and sophisticated drone operations, even beyond line of sight. Along with NASA, the FAA, and NIAS we’re excited to show how UTM can chart a safe course for the drone ecosystem.”
“Drone America is a proud participant in a Nevada Institute for Autonomous Systems (NIAS) led NASA Unmanned Traffic Management (UTM) program at the Reno Stead Airport,” said Mike Richards, president and CEO of Drone America. “The safe integration of Unmanned Aerial Systems (UAS) into the National Airspace System (NAS) is critical to the future of this industry. Drone America is fortunate to call Nevada our home. Working in a state that is very supportive and business friendly makes a tremendous difference to our future sustainability. Our partnership with NIAS and NASA will not only contribute to successful testing, this partnership will pave the way for future generations to experience the true value of autonomous systems.”
“Carbon Autonomous Systems of Reno, in conjunction with their partner SmartPlanes of Skellefteå, Sweden, successfully took part in the planning, coordination, and flying in the most recent TCL2 NASA / NIAS UAS/UTM exercises conducted at the Reno Stead Airport UAS Test Range of the Nevada FAA UAS statewide test complex,” said John Hammond, chief pilot for Carbon Autonomous.
NIAS was also supported by Delair-Tech and SensoFusion who provided UAS and drone detection UAS technologies, which were also tested during this NASA UTM TCL 2 Test.
“We have been designing, manufacturing, and operating UAVs in the civilian airspace for almost 10 years in 100 countries,” said Benjamin Benharrosh, co-founder and head of Delair Tech North America. “This landmark agreement with NIAS, and the associated data collected for the UTM system designed by NASA at the Reno UAS Test Site will push our traffic management technology to a new level of precision and insight. We are thrilled to collaborate with NIAS on solutions that represent a new era for the commercial UAV market and a better presence of Delair-Tech in the U.S.”
“We’re excited to be shaping the future of air traffic management as an official partner of the NIAS by providing our counter-UAS solution, AIRFENCE, in the ongoing NASA UTM project. AIRFENCE is playing an active role in detecting, locating, and tracking UAS as part of the project, providing rich data to NASA as they develop their UTM system,” said Kaveh H. Mahdavi, Sensofusion VP of operations.
“NASA is one of Nevada’s most valuable partners. We appreciate the opportunity to support NASA’s UTM development. It is truly cutting-edge technology and will be instrumental in integrating UAS into the national airspace,” said Tom Wilczek, Aerospace & Defense Industry Representative for the Nevada Governor’s Office of Economic Development.
Europe’s Galileo satellite navigation system has undergone its first performance report since it started work at the end of last year, and it passed with flying colors, said the European Space Agency.
The European GNSS Agency, GSA, through its GNSS Service Centre, has published the first of its regular quarterly performance reports on Galileo. This European GNSS (Galileo) Initial Services Open Service report, now available online, covers the first three months of 2017 and documents the good performance of Galileo Initial Services to date.
The report shows the 11 satellites then operating in the Galileo constellation were able to provide healthy signals 97.33 percent of the time on a per satellite basis, with a ranging accuracy better than 1.07 m and disseminating global UTC time within its signal to within 30 billionths of a second on a 95 percentile monthly basis.
“Galileo Initial Services were declared by the European Commission on 15 December 2016,” said Joerg Hahn of ESA’s Galileo System Office.
“It was thanks to the tremendous effort of ESA’s Galileo team working closely together with colleagues from the commission and GSA that this milestone could be achieved: the key pillars for reaching are the currently deployed Galileo satellites in combination with the global Galileo ground segment infrastructure, defined and implemented by the ESA team with their respective industry partners.”
The Initial Service performance levels achieved by the system are monitored using two complementary monitoring platforms: the Time and Geodetic Validation Facility, an independent precision time-measuring system accurate to a billionth of a second — using an ensemble of atomic clocks located at ESA’s ESTEC technical centre in Noordwijk, the Netherlands — and the Galileo System Evaluation Equipment, GALSEE, based in Rome.
The steadily declining Signal in Space Ranging Error (SISE) of the Galileo constellation from 2014 to the present.
In the future, the independent monitoring of the services will be carried out by GSA’s Galileo Reference Centre, currently taking shape beside ESTEC in Noordwijk. The results for the first quarter of 2017 show the measured performances are generally far better than the minimum performance levels identified in the Service Definition Documents.
“Looking back over the ranging accuracy of the Galileo constellation from the time of the very first positioning fix in 2014 to the present, the overall performance trend for the Open Service is very positive,” Joerg said.
“It has reached values of less than 1 m in recent months, being already competitive with other satellite navigation systems.
“The high-quality ranging service enables user level positioning with a typical accuracy of around 3 m on the ground and 5 m in altitude during periods when four satellites are visible. With the limited infrastructure so far deployed, current horizontal position fixes can be achieved during more than 80 percent of the time with accuracies better than 10 meters.
“This user level performance is expected to improve with the launch of more satellites making the provided Galileo services more accurate, more available and more robust for end users.”
The Loran sites at Havre, Montana; George, Washington; and Fallon, Nevada, will continuously broadcast from 0900 (MST) June 20 through 1200 (MST) on June 30. The sites will operate on the 5990 rate but occasionally may operate at other rates.
Only the site at Fallon will operate as an eLoran site. The sites at Havre and George will operate as Loran-C sites synchronized to UTC.
For further information on eLoran, tune into the free webinar on June 15, “Alternative PNT Services.” One of the four presentations will be by Steve Bartlett, executive vice president of UrsaNav, who will provide a brief overview of eLoran technology and performance characteristics with a focus on timing in critical infrastructure applications. Other presentations will cover a new Satellite Time and Location service and indoor timing with a terrestrial beacon system.
UrsaNav is engaged in a Cooperative Research And Development Agreement with the U.S. Department of Homeland Security, the U.S. Coast Guard and Harris Corporation to research, evaluate and document eLoran technology as a candidate for providing position, navigation and timing (PNT) information. eLoran is being evaluated as a potential complementary system to GPS. UrsaNav believes that there is a potentially viable market, in both the public and private domain, for an alternative PNT service that is independent of GPS signal reception or which can be used in GPS-denied environments.
A number of geospatial intelligence companies are exhibiting at the GEOINT 2017 Symposium, which is taking place June 4-7 at the Henry B. Gonzalez Convention Center in San Antonio, Texas.
Hosted and produced by the United States Geospatial Intelligence Foundation (USGIF), the annual GEOINT Symposium is the nation’s largest gathering of industry, academia, and government to include defense, intelligence and homeland security communities as well as commercial, federal, civil, state and local geospatial intelligence stakeholders.
The event annually attracts more than 4,000 attendees from all over the world, with more than 250 exhibiting organizations and more than 50 hours of training sessions for attendees.
The theme for GEOINT 2017 is “Advancing Capabilities to Meet Emerging Threats.”
Companies planning to exhibit:
TerraGo will be demonstrating its R3 mobile app, customized for the missions of reconnaissance, response and recovery and built entirely using TerraGo Magic, a zero-code platform that enables customers to build apps tailored to their unique operations with web services, custom map products, imagery, forms and workflows.
Red Hen Systems will showcase its surveillance technology. The company’s Digital Mapping Reconnaissance Toolkit Exportable (DMRT-EX) and MediaMapper Mobile Android app have been used by law enforcement military and civilian members around the world for anti-narcotics operations, vegetation management and other surveillance missions.
Visit Booth 333 at GEOINT to see the company’s equipment in action.
Descartes Labs Inc., a cloud-based geospatial analytics company, will unveil its global-scale machine learning platform. The platform powers geographic and temporal analysis of remote-sensing data to identify objects, forecast change and deliver high-performance intelligence solutions.
GEOINT attendees can learn more about Descartes Labs at booth #1325 in the GEOINT Exhibit Hall. Descartes will also present a Lightning Talk at GEOINT Forward on Sunday, June 4, and a training workshop on Tuesday, June 6.
The Polaris TLS by Teledyne Optech
Teledyne Optech will showcase the advanced capabilities of the award-winning ALTM Galaxy T1000, now featuring a 1-MHz laser PRF, PulseTRAK and SwathTRAK technologies for a universal sensor that surpasses larger systems with consistent, ultra-dense data and measurement precision and accuracy.
In addition, visitors will see the new Polaris Terrestrial Laser Scanner (TLS) for ground-based survey applications. With an integrated high-resolution camera, inclinometers, compass, GPS receiver, and weather-proof housing, the Polaris can be deployed in many environments and orientations.
Visit Booth 1767, where sustaining USGIF Member Teledyne Optech will be joined by Teledyne DALSA, Teledyne Imaging Sensors, and Teledyne Brown Engineering to represent a broader range of Teledyne’s capabilities and solutions for GEOINT/ISR applications, including lidar, EO, IR and hyperspectral imaging.
Esri will be showcasing mission-focused enhancements using the ArcGIS platform for defense, intelligence and national security workflows.
ArcGIS provides high-performance 2D and 3D analysis for defense, intelligence, and national security. It is a complete and open platform for managing, analyzing, and sharing data and data products. ArcGIS leverages big data, web technologies, and integrated apps to make location-based data easy to use, more accessible, and collaborative.
“GEOINT and geographic information system [GIS] technologies have never been more important to the intelligence community,” said Ben Conklin, Esri head of industry, defense, and intelligence. “We are looking forward to the annual GEOINT Symposium, since it gives us a great opportunity to demonstrate the latest advances in GIS technology. The event also gives analysts access to tools that provide quick, responsive, and interactive experiences for increased productivity and support of decision-making and operations at every level.”
Esri will offer the following demonstrations at Booth 615:
Advancing The Science of Where
Reveal Deeper Insight through Analytics
Unlock Your Data with Apps
Open Platform for Intelligence
The Esri Presentation “Geospatial Intelligence Using a Web-Enabled GIS” takes place Tuesday, June 6, 2 p.m., 007C River Level.
East View Geospatial (EVG), a provider of content-rich cartographic products, continues to enhance the accuracy of automated feature identification using its newly developed training data sets in supervised machine learning applications. The early results pertained to automated recognition of building structures in an ongoing pilot project in Papua New Guinea (PNG).
“Our goal is to create a state-of-the-art process that produces the highest quality training data available for the users and developers of supervised machine learning technology,” said Rod Buhrsmith, business eevelopment at EVG. “In just a few months, we have made significant progress and expect to push the accuracy even higher.”
EVG will be available to discuss the PNG pilot in private meetings at GEOINT (contact Rod Buhrsmith at [email protected] or Mark Knapp at [email protected] or call 1-952-252-1205.)
José Ángel Ávila Rodríguez (left)) and Laurent Lestarquit holding a satellite model. (Credit: ESA)
The engineering team behind the signal technology underpinning Europe’s Galileo satellite navigation system has reached the final of this year’s European Inventor Award, run by the European Patent Office, reported the European Space Agency.
The team is led by Spanish engineer José Ángel Ávila Rodríguez — now part of ESA’s Galileo team — and his French colleague Laurent Lestarquit from France’s CNES space agency.
The team also includes German Günter Hein, formerly head of the department studying the evolution of EGNOS and Galileo for ESA, as well as Belgian Engineer Lionel Ries, now in ESA’s technical directorate, as well as French CNES engineer Jean-Luc Issler.
The engineers, who had previously worked together as members of the multinational Galileo Signal Task Force, came up with a pair of innovative signal modulation techniques to pack multiple Galileo signals together, simultaneously serving different sets of users while boosting signal performance and robustness. Both innovations have been adopted by Galileo and are in use today.
The first technique, called Alternative Binary Offset Carrier modulation — AltBOC — combines four signals into one large one, resulting in the widest bandwidth navigation signal ever transmitted. Two of these signals are sitting on the one carrier, namely E5a, while the other two are on E5b.
“AltBOC is a way of transmitting four components in a very wide bandwidth signal, using a single radio frequency chain on the satellite in an intelligent way, where originally two chains would have been needed to transmit in two separate frequency bands (E5a and E5b),” explains José Ángel, now ESA’s global navigation satellite system evolution signal and security principal engineer for Galileo.
“The result is a frequency-rich signal that fundamentally improves positioning performance and robustness.
“AltBOC is interoperable with GPS in E5a/L5 and allows receiver manufacturers to process it as one very large signal – extending over the whole E5a and E5b range – or as two separate signals, one at each frequency carrier (E5a or E5b).
“AltBOC serves open service users in general. Moreover, when used in its full performance mode (E5a+E5b), it also facilitates geodetic and precision scientific applications such as gradual tectonic motion, or the use of accurate positioning on Earth — including proposed ‘reflectometry’ missions to make altimetry measurements from satnav signals reflected from Earth’s surface.
“But the application of AltBOC could go beyond the current use by providing accurate positioning to satellites in space thanks to its unique bandwidth characteristics.”
