Qualcomm Incorporated announced Thursday that its subsidiary Qualcomm Global Trading Pte. Ltd. has completed the acquisition of CSR. CSR is known to the GPS/GNSS industry as the maker of the SiRFstar series of chips, which are used in many consumer devices.
Qualcomm started the acquisition process for CSR in October 2014. With this close of the acquisition, Cambridge Silicon Radio Limited, or CSR, is renamed Qualcomm Technologies International Ltd.
The acquisition, which was completed at an enterprise value of approximately $2.2 billion, complements Qualcomm Technologies, Inc.’s offerings by adding a compelling portfolio of new products, sales channels and a large number of customers in the areas of IoE and automotive — both key growth priorities for Qualcomm Technologies.
Cambridge Silicon Radio Limited is an indirect, wholly-owned subsidiary of CSR that operates, along with its affiliates, substantially all of CSR’s engineering, research and development functions, along with substantially all of the CSR products and services businesses. Cambridge Silicon Radio Limited will be renamed Qualcomm Technologies International, Ltd., which will become a subsidiary of Qualcomm Technologies.
“As we strive to connect billions more devices, automobiles and people within the Internet of Everything, we are enthusiastic about the growth that this combination will foster,” said Steve Mollenkopf, chief executive officer, Qualcomm Incorporated. “CSR’s complementary strengths in connectivity, audio technologies and systems-on-chips will help strengthen Qualcomm Technologies’ position in the IoE and automotive industries, and add to a broad and highly advanced portfolio.”
“We are pleased to join a recognized leader such as Qualcomm Technologies at an exciting time as customers race to satisfy the growing consumer desire for more and more seamlessly connected devices in their ‘smart’ homes, offices and cars,” said Joep van Beurden, chief executive officer, CSR. “Our employees have a strong history of pioneering new products and collaborating with customers to deliver critical technology requirements such as interoperability, low power and connectivity. Together with Qualcomm Technologies, we are better positioned to meet our customers’ needs today and into the future.”
While the accounting for the transaction is not yet finalized, Qualcomm estimates that on a Non-GAAP basis the acquisition will be modestly accretive to earnings per share in fiscal 2016 consistent with prior guidance. In addition, based on preliminary estimates, Qualcomm expects the transaction to be modestly dilutive to GAAP earnings for fiscal 2016 driven primarily by acquisition-related items.
Figure 1. Suomi NPP/VIIRS night-time light images for Iraq: (a) May 2014, (b) December 2014.
A new paper published in the academic journal International Journal of Remote Sensing analyzed city night lights in Northern Iraq during 2014, suggesting a major loss of electrical power supply within the Iraqi cities seized by ISIS.
The territory controlled by the Islamic State of Iraq and Syria (ISIS) has grown rapidly since the start of the Syrian Civil War, and in 2014 ISIS expanded its control into Northern Iraq. While there are many media reports on violence and geopolitical issues surrounding the takeover of these areas, the impact on everyday life, such as access to electricity for people living in ISIS-controlled regions, is less clear.
In the study, Xi Li and Deren Li (Wuhan University, China) and Rui Zhang and Chengquan Huang (University of Maryland) analyzed city lights as a proxy for the power supply in ISIS-controlled regions between May 2014 and December 2014. The city light data were acquired from the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor on the NASA/NOAA Suomi National Polar-orbiting Partnership (NPP) satellite.
The analysis indicates that most of the ISIS-controlled cities, including Mosul and Tikrit, experienced a decrease of more than 90 percent in city light after being seized by ISIS, while the loss of light in cities controlled by the Iraqi security forces (ISF) was very limited. However, the city lights in Ar Raqqa, Syria, ISIS’ de facto capital, did not show a decline after that region was seized by ISIS.
These comparisons suggest that the conflict in Northern Iraq has resulted in a major loss of electrical power supply within the Iraqi cities seized by ISIS, and that this loss is most likely due to lack of access to the Iraqi power grid, rather than a deliberate ISIS strategy of limiting night-time light.
The insurgency in Northern Iraq since 2014 has led to a severe humanitarian crisis, the study authors say. It is widely known that it is extremely dangerous to collect information from ISIS-controlled regions; therefore, the use of remotely sensed night-time light images such as these offer humanitarian agencies and NGOs a low-risk indicator of socioeconomic conditions in war-torn countries like Iraq.
The first Gen III F-35 Helmet Mounted Display System has been delivered. (Photo: Rockwell Collins)
Lockheed Martin and Rockwell Collins have delivered the first Gen III F-35 Helmet Mounted Display System (HMDS). The advanced technology for warfighters provides pilots with unprecedented levels of situational awareness and allows them to “look through” the airframe.
Company executives commemorated the delivery of the first HDMS on Aug. 11 with Sen. Joni Ernst in Cedar Rapids, Iowa. In addition to the HMDS, the Lockheed Martin F-35 Lightning II demonstrator was on site at the Cedar Rapids headquarters of Rockwell Collins for Sen. Ernst to get a first-hand experience of “flying” the military’s most advanced fighter jet following the delivery ceremony.
Rockwell Collins, through its joint venture, Rockwell Collins ESA Vision Systems LLC, is providing the most advanced technology for warfighters with the F-35 HMDS, which provides pilots with unprecedented levels of situational awareness and allows them to “look through” the airframe.
The Gen III helmet, which includes an improved night vision camera, improved liquid-crystal displays, automated alignment and software improvements is to be introduced to the fleet in low rate initial production Lot 7 in 2016. Rockwell Collins ESA Vision Systems LLC also developed the Gen II helmet that F-35 pilots currently use, which met the needs for the U.S. Marine Corps and will allow the service to declare Initial Operational Capability.
All the information that pilots need to complete their missions — through all weather, day or night — is projected on the helmet’s visor. Additionally, the F-35’s Distributed Aperture System (DAS), made by Northrop Grumman, streams real-time imagery from six infrared cameras mounted around the aircraft to the helmet, allowing pilots to “look through” the airframe.
“Today’s visit was an opportunity to place focus on Rockwell Collins, as manufacturing makes up such an important part of our economy here in Iowa,” said Senator Ernst. “Having served in the military for over 20 years, I appreciate the company’s efforts in support of our national defense, our armed forces and our veterans.”
“We’re pleased to be able to demonstrate the advanced capabilities of the F-35 Lightning II at Rockwell Collins today to Sen. Ernst and members of the Cedar Rapids community,” said Steve Callaghan, director, F-35 Program, Lockheed Martin Washington Operations. “The employees at Rockwell Collins are contributing to the F-35s flying today, and we’re pleased to have the opportunity to showcase the superior performance capabilities of this aircraft with them.”
Overall, Rockwell Collins has built and fit more than 200 helmets for F-35 pilots who are being trained for the program.
The Federal Aviation Administration (FAA) wants to send out a clear message that operating drones around airplanes and helicopters is dangerous and illegal. Pilot reports of unmanned aircraft have increased dramatically over the past year, from a total of 238 sightings in all of 2014, to more than 650 by Aug. 9 of this year. Unauthorized operators may be subject to stiff fines and criminal charges, including possible jail time.
Pilots of a variety of different types of aircraft — including many large, commercial air carriers — reported spotting 16 unmanned aircraft in June 2014, and 36 the following month. This year, 138 pilots reported seeing drones at altitudes of up to 10,000 feet during the month of June, and another 137 in July.
Meanwhile, firefighters battling wildfire blazes in the western part of the country have been forced to ground their operations on several occasions for safety reasons when they spotted one or more unmanned aircraft in their immediate vicinity.
The FAA says it will continue to work closely with industry partners through the “Know Before You Fly” campaign to educate unmanned aircraft users about where they can operate within the rules. The agency is also supporting the National Interagency Fire Center’s “If You Fly, We Can’t” efforts to help reduce interference with firefighting operations.
However, the FAA also is working closely with the law enforcement community to identify and investigate unauthorized unmanned aircraft operations. The FAA has levied civil penalties for a number of unauthorized flights in various parts of the country, and has dozens of open enforcement cases.
The FAA encourages the public to report unauthorized drone operations to local law enforcement and to help discourage this dangerous, illegal activity.
“While we wait for additional information regarding the missing Boeing 777, I wanted to examine if GIS could add plausibility that debris may have washed up this far west from the original search areas,” writes Anthony Calamito, solutions architect with Boundless. A piece of a wing known as a flaperon from a Boeing 777 was found on Reunion Island, thousands of miles from the plane’s flight path and official search area. No other Boeing 777 airplanes are missing. Flight MH370 vanished on March 8 last year with 239 passengers and crew.
Boundless says in the post that the georeferenced and digitized graphics illustrate how the debris could have washed on shore as the surface currents rotating around the Indian Ocean Gyre could have moved the debris in a general western direction.
According to Boundless, this is an example of how geospatial solutions can use existing data and intelligence to produce answers when none seem to be forthcoming, as it’s been during the search for MH370.
Phase One Industrial, a manufacturer and provider of medium-format aerial digital photography equipment and software solutions, is offering the iXU-R camera series. Available in 80 MP, 60 MP and 60 MP achromatic versions, the cameras feature dedicated interchangeable 40 mm, 50 mm and 70 mm Phase One Rodenstock lenses equipped with central leaf shutters that can be quickly changed in the field, offering flexibility in aerial applications.
The Phase One iXU-R systems have been designed to address the aerial data acquisition market’s needs for a small, lightweight camera with the high resolution of a medium format system, plus high-performance optics, flexibility to fit into small places and Phase One’s fastest 80 MP platform. For example, the iXU-R 180 is built around a large 80-megapixel sensor, with 10,328 pixels cross-track coverage yet it is compact enough to be easily integrated into a small gimbal or pod space or an oblique/nadir array. Or it can be used as a standalone photogrammetric camera with optional Forward Motion Compensation.
Cameras are easily integrated into new or existing setups with USB 3.0 connectivity for control and storage via the Phase One iX Capture application. All Phase One aerial cameras offer direct communication with GPS/IMU systems and the ability to directly write data to the image files.
“As the use of UAVs and small aircraft increases dramatically around the world, and every gram in a payload counts, Phase One Industrial is committed to offering small and lightweight cameras without sacrificing data accuracy, image quality and resolution,” said Dov Kalinski, general manager of Phase One Industrial.
Emirates Palace, courtesy of DigitalGlobe, taken on November 14, 2014, by WorldView-3 satellite at a resolution of 30 cm.
Proteus, a provider of satellite derived mapping and geospatial services, announces the official launch of its new professional satellite image procurement service. The service provides an approach to satellite imagery sales that is sensor agnostic, calling upon partnerships and agreements with the majority of satellite operators. Because of this, Proteus has the capability to support all imagery purchasing requirements.
The service was developed from customer feedback when conducting imagery purchases, which indicated that the experience and knowledgeable advice provided by Proteus removed the stress and complexity they had previously experienced when attempting to complete a purchase and navigate the end-user licenses themselves.
“These days there are many satellite imagery providers, all with a range of products, resolutions, licensing conditions and costings,” David Critchley, CEO of Proteus explained. “This can be overwhelming and time consuming for the end users. Our aim is to break down all the technical barriers and find the best coverage for your area of interest. We strive to determine the most suitable imagery at the most competitive pricing.”
Proteus has now developed relationships with all the main satellite imagery suppliers and provide their customers with a comprehensive, sensor agnostic and personable service.
Rohde & Schwarz designed its GNSS simulator for the R&S SMBV100A with a focus on production testing of GNSS receivers.
Rohde & Schwarz now offers a new, speed-optimized production tester — the R&S SMBV100A vector signal generator equipped with the R&S SMBV-P101 package.
During production testing of modules and receivers for satellite-based communications, the basic GNSS signal reception and the connection between the antenna and GNSS chipset need to be checked. The GNSS production tester simulates separate satellites for the GPS, GLONASS, BeiDou and Galileo navigation standards in the L1/E1 band specifically for these production tests.
The four satellite constellations can be activated individually, each with a high dynamic range of 34 dB. Level changes can be made on the fly without interrupting the signal, enabling users to simultaneously perform independent sensitivity tests for each navigation system. The 1 pps or 10 pps GNSS marker allows exact time synchronization between the tester and the DUT. Pure, level-stable CW signals can also be generated to calibrate the test setup or to simulate interferers.
The R&S SMBV-P101 option additionally offers test functions for efficient characterization of GNSS chipsets, Rohde & Schwarz said. As a result, a receiver’s ability to handle high-movement dynamics can be verified quickly and cost-effectively. To do this, users can access both predefined and user-defined Doppler profiles, from which the R&S SMBV100A automatically generates the appropriate satellite signal.
The R&S SMBV-P101 GNSS production tester package for the R&S SMBV100A is now available from Rohde & Schwarz.
Researchers at Qihoo 360, a Chinese Internet security firm, say they have found a way to make a GPS emulator that can falsify the location of smartphones and in-car navigation systems, reports Forbes. The system is inexpensive compared to expensive, sophisticated GPS emulators that can cost thousands of dollars.
Qihoo lead researcher Lin Huang is the first Chinese woman to present at the yearly hacker conference Defcon, held in Las Vegas on Aug. 6-9. Huang said her team used common software-defined radio (SDR) tools to create their module and software. They also used open-source software found on Github that had come from researchers at a Chinese university, along with their own code.
The SDR tools used include HackRF, described by Forbes as the $300 wireless Swiss army knife for hackers. The small board can move between radio frequencies, and read and transmit to a broad range of radio frequencies. On smartphones, the attack targets navigation signals delivered at the chipset level, on both Apple or Android smartphones.
Huang suggests that chipset manufacturers consider introducing new software that can better detect GPS spoofing.
One potential target of such spoofing is a drone., which could be commandeered by the spoofer and taken into restricted airspace. Alternatively, it’s possible to make drones believe they’re in a no-fly area.
The Qihoo team demonstrated such attacks using the free and open source GNU Radio, among other tools, to alter the GPS coordinates on a DJI Phantom 3. In a video at Forbes, filmed from a drone-mounted camera, the hackers force a UAV to crash land.
The researchers said the weaknesses could be fixed by DJI and other drone makers, but they would have to do so at the GPS chip level, meaning any drones already out there are unlikely to receive an update.
The Inertial+ by OxTS improves measurements from a GPS receiver.
OxTS has successfully integrated a Locata receiver with its Inertial+ to create the first Locata+INS device, according to both companies. The device is capable of achieving centimeter-level accuracy where GPS systems fail.
The Inertial+ series, first developed in 2008, was designed for users who had an external GNSS receiver already, but still wanted to gain the benefits of an inertial system. The company has been able to combine OxTS’ Kalman filter and expertise in GNSS/IMU integration with its existing systems, meaning the user doesn’t have to pay for survey-grade integrated receivers.
Over the years, a number of popular GNSS receivers have been integrated with the Inertial+ to keep up to date with the market and make sure customers with the latest models can take advantage of the benefits the Inertial+ brings, OxTS said. Now, the Inertial+ has expanded from GNSS receivers and become the first inertial navigation system to integrate a Locata receiver, combining the many benefits of both systems, the companies said.
Locata is an innovative positioning system designed to complement rather than replace GPS, by addressing the issues and shortfalls of GNSS. As always, the Inertial+ allows Locata users to take advantage of their existing technology while enjoying the extra layer of measurements an aided-inertial navigation system brings.
Locata enables positioning in environments where GPS is either marginal or unavailable. Instead of using signals from satellites, a network of ground-based Locata transmitters (known as a LocataNet) can be set up around any specified local area. The LocataNet transmits GPS-like signals that allow any Locata receiver in the network to accurately calculate its position and time. Unlike GPS, where signals are too weak to penetrate into buildings, Locata’s signals are very powerful — more than one million times more powerful than GPS.
Additionally, with a locally based system (rather than a global satellite system), a user gains the benefit of having total control over both the reliability and quality of positioning solutions within the LocataNet coverage area. Locata systems are being sold today in many markets where GPS is unusable or unreliable, such as inside warehouses, on dockyards, in open-pit mines, for UAVs in urban areas, and for military uses where GPS is being actively denied by an adversary.
By combining the technologies of an inertial navigation system and a local positioning system, users have access to an extremely reliable and robust navigation solution, the companies said. Locata positioning data is fused with the IMU data in the Inertial+ with OxTS’ custom Kalman filter, creating a full 3D navigation solution with precise position, orientation, heading, velocity and acceleration measurements.
SVN49 in space (artist’s rendering). The signal anomaly from SVN 49 alerted researchers to new possibilities in analysis and monitoring.
Chip Transition-Edge Based Signal Tracking for Ultra-Precise GNSS Monitoring Applications
By Sanjeev Gunawardena, John Raquet and Frank van Graas
Tracking GNSS signals using their underlying spreading sequence chip transition edges reveals positive versus negative chip asymmetries that are characteristic to each satellite. This asymmetry is due to various types of natural signal deformation that is known to occur within the satellite’s signal generation and transmission hardware. This novel concept of monitoring chip asymmetry can extend the state of the art in the areas of GNSS signal-quality monitoring and authentication. A technique to directly monitor chip asymmetry within a specially designed ChipShape GNSS receiver architecture employs separate code discriminators that align themselves to the chip rising-edge and falling-edge zero crossings.
The detailed study of naturally-present deformations in GNSS signals is a relatively new activity that was sparked by the GPS SVN49 anomaly and the associated research activities that followed. This research area has numerous applications that include:
Informing the design of sudden signal deformation detection and alerting algorithms for safety-of-life differential GNSS applications (such as aviation).
GNSS signal “fingerprinting” and authentication.
The detailed study of long-term degradation effects of GNSS satellite signal generation and transmission hardware.
Analysis of the impact to the first item in this list of swapping a satellite’s signal generation modules by its control segment.
Multipath detection, characterization, and mitigation are also closely tied to all research relating to GNSS signal deformation monitoring (SDM).
High-fidelity SDM can be performed using two methods:
observation of actual GNSS signals above the thermal noise floor using a high-gain dish antenna;
the combination of long coherent integration and multi-correlator processing.
Our previous research has revealed that these two methods are highly complementary for gaining full insight into the effects and causes of observed natural signal deformations.
Among the handful of multi-correlator processing techniques that can be applied for SDM, ChipShape processing allows the correlation function resolution to be finely adjustable while providing good numerical processing efficiency. This processing technique also allows chip-transition eye diagrams to be constructed in order to provide additional insight such as positive and negative chip width asymmetries.
One goal of our SDM research involves developing capabilities to observe GNSS signals with the highest levels of fidelity practically achievable in order to further the application areas described above. Key to this is developing techniques to track GNSS signals using a reference point that is both consistent and invariant (to the greatest extent possible) to nominal signal deformations and environmental effects such as multipath. Traditional multipath mitigating techniques such as narrow correlator and double-delta correlator are sub-optimal in this regard. This is because a significant portion of the signal around the chip transition point (that is, 10 percent and 20 percent for 0.1 chip correlator spacing, respectively) must be integrated to realize these discriminators and maintain robust tracking in moderate dynamics conditions. This integration tends to low-pass filter the desired observables.
Chip Transition Edge-Based Code Tracking
Figure 1 illustrates normalized C/A code chip rising edges for the GPS constellation of June 2014. These chip shapes were processed using a front-end with 24 MHz bandwidth. For visual comparison purposes, this and other related plots were obtained using 600 seconds of coherent integration.
Figure 1. Normalized ChipShape rising edges for the GPS SPS constellation of June 2014; each color represents a different GPS satellite.
The code tracking loop used to obtain this result employed an empirical normalized coherent rising-edge discriminator given by:
(1)
Where τ is relative code phase in chips, d is Early-Late correlator spacing,R’XYZ(i) is the differential correlation output for integer bin i obtained using ChipShape processing with masking sequence XYZ. bin(x) is a function that selects the closest ChipShape vector index that corresponds to relative code phase x. Each ChipShape processing bank is configured to span one chip early and one chip late with a resolution of N bins per chip, thus producing a ChipShape vector of 3N bins. α is a scale factor obtained through trial and error to yield robust tracking performance as observed by the code-minus-phase measurement. For the result shown in Figure 1, N=240 and d ≈ 0.017 chips.
The figure clearly shows that the rising-edge zero crossings vary by SV. This variation is due to nominal signal deformation present in each GPS-SPS signal.
Figure 2 illustrates the rising-edge zero crossings aligned to zero relative code phase. This alignment was performed by interpolating each R’NPN vector, precisely estimating code phase at the zero-crossing point, and shifting the curve appropriately.
Figure 2. Normalized ChipShape rising edges for the GPS SPS constellation of June 2014: Zero crossing compensated.
Figure 3 shows zero crossings for the falling edges after all rising edges were aligned to zero. The figure clearly illustrates subtle asymmetries between positive and negative chips which span a range of approximately ±1.5 meters. These asymmetries are not directly observable using typical GNSS receiver processing. However, they can lead to pseudorange biases through the resulting distortion that occurs to the traditional correlation function.
Figure 3. Normalized ChipShape falling edges for the GPS SPS Constellation of June 2014 when rising edges are aligned to zero.
In general, a family of code discriminators that precisely track chip rising-edge zero crossings can be defined by:
(2)
Where R’NPX is a linear combination of orthogonal ChipShape components that preserve the rising-edge transition, e.g.: R’NPX =R’NPN +R’NPP. R’FFX is a linear combination of orthogonal ChipShape components that preserve the non-transitioning (that is, flat) sections of chips, for example: R’FFX =R’PPP + R’PPN −R’NNP − R’NNN. a and b define an integration interval within the range −1 to +2 chips with respect to the chip transition edge. β is a bias compensation term. represents the real or imaginary component function for the coherent discriminator (depending on the modulation phase of the signal being tracked), or the magnitude function for a non-coherent discriminator implementation.
Similarly, a family of code discriminators that precisely track chip falling-edge zero crossings that occur one chip after the rising edges tracked by the discriminator of Equation 2 can be defined by:
(3)
Then, a two-step technique to precisely monitor chip asymmetry can be described as follows:
Setup two identical ChipShape processing channels to track a given PRN. Progressively tighten the code tracking loops to track the rising-edge zero crossings of the underlying signal using the discriminator of Equation 2.
After steady-state zero-crossing rising-edge tracking is achieved, switch the second channel’s code discriminator to that of Equation 3. This will cause the second channel to track the zero crossings of the falling edges that occur one chip later in the underlying signal’s spreading sequence. The discriminator’s linear range must be wide enough to pull-in the chip asymmetry shown in Figure 3.
When the second channel re-converges as a result of Step 2, the relative pseudorange displacement that occurs is equal to the chip asymmetry in meters. Hence, chip asymmetry can be monitored for the entire visible pass of a satellite. It is expected that positive and negative chip transitions are equally affected by channel distortions (that is, code and carrier multipath, ionosphere, troposphere, and the receiver antenna and front-end transfer function). Hence, the rising-edge-code-minus-falling-edge-code measure of chip asymmetry is expected to be invariant to most if not all channel distortions.
Estimating Compensation Parameters
As shown in Equations 2 and 3, due to natural signal deformation of many types, the rising and falling-edge zero-crossing discriminators are expected to be SV number, PRN code and elevation angle dependent. Hence, α and β must be estimated for a given correlator spacing d separately for all SV signals of the constellation. These values will also be specific to a given antenna and receiver front-end.
Figure 4 illustrates the procedure used to estimate the scale factor and bias terms starting with the empirical rising-edge tracking process described above.
Figure 4. Procedure for estimating scale factors and biases for rising-edge tracking early-late and double-delta code discriminators.
The following figures illustrate the edge tracking discriminator calibration process using R’NPN for a single SV.
Figure 5 illustrates the early-plus-late functions computed for various correlator spacings. As described previously, these functions typically do not cross through zero codephase due to natural signal deformation.
Figure 5. Uncorrected rising-edge early-late discriminator functions for various correlator spacings.
Figure 6 illustrates the rising-edge discriminator functions after bias compensation.
Figure 6. Rising-edge early-late discriminator functions for various correlator spacings after bias compensation.
Figure 7. Calibrated rising-edge early-late discriminator functions for various correlator spacings.
Figure 8 illustrates the multipath error envelopes for the rising edge-based coherent code discriminators. The performance of these discriminators is similar to the traditional Early-Late discriminators for the same correlator spacings. This result is consistent with the theoretical bounds for code multipath.
Figure 8. Multipath error envelopes for various rising edge-based coherent early-late code discriminator functions.
As shown in Figure 4, the edge-tracking discriminators described in Equations 2 and 3 that are based on Early-Late bin spacings can be combined to obtain edge-tracking double-delta discriminators. Double-delta discriminators provide significantly improved multipath performance.
In general, the edge-tracking double-delta discriminator for inner correlator spacing d is formed by the linear combination of two early-late edge-tracking discriminators, as follows:
(4)
Scale factor γ is estimated such that overall multipath error is minimized according to a given design criteria.
Figure 9 illustrates the double-delta rising-edge discriminator with inner spacing of 0.017 chips. This discriminator has a pull-in range of approximately ±0.01 C/A chips.
Figure 11 illustrates the multipath error envelope for the coherent rising-edge double-delta discriminator. Performance is consistent with a traditional second-derivative discriminator.
Figure 11. Multipath error envelope for coherent rising-edge double-delta code discriminator with inner spacing of ~0.017 C/A chips.
Figure 12 illustrates the performance of the various rising-edge tracking discriminators for a live-sky GPS-SPS signal (de-trended code-minus-carrier measurement). This figure clearly demonstrates robust code tracking and the multipath and noise mitigating benefit of ultra-narrow rising-edge discriminators.
Figure 12. Code tracking performance for live sky data of various rising edge-based coherent early-late code discriminator functions.
Conclusions
An empirical chip rising edge-based tracking technique was used to observe the underlying chip shapes of live sky GPS-SPS signals at high fidelity. These results reveal positive versus negative chip asymmetries that are characteristic to each satellite. The novel concept and technique of directly monitoring chip asymmetry has potential to extend the state of the art in the areas of GNSS signal quality monitoring and authentication.
Disclaimers. The views expressed in this paper are those of the authors and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the United States Government.
Acknowledgments. This research was supported by the Air Force Research Laboratory Sensors Directorate.
The authors thank Ohio University Avionics Engineering Center for making available a cluster of high-performance computers to process the 20 TB dataset for this research, and Kadi Merbouh of Ohio University for maintaining and overseeing operation of this equipment.
The ChipShape processing is an extension of the signal compression technique first published by Larry Weill and licensed by NovAtel for use in its Vision Correlator technology.
This article is based on a paper presented at ION Pacific PNT 2015 in Honolulu.
SANJEEV GUNAWARDENA is a research assistant professor with the Autonomy & Navigation Technology (ANT) Center at the Air Force Institute of Technology (AFIT). He earned a Ph.D. in electrical engineering from Ohio University.
JOHN RAQUET is a professor of electrical engineering and the Director of the ANT Center at AFIT. He has been involved in navigation-related research for more than 25 years.
FRANK VAN GRAAS is the Fritz J. and Dolores H. Russ professor of electrical engineering and principal investigator with the Avionics Engineering Center at Ohio University. He received the ION Johannes Kepler, Thurlow and Burka awards, and is a Fellow and past president of the ION.
Global Tracking Project Demystifies the Ocean’s Top Predators
Chris Fischer helps tag Katharine, a 14-foot 2-inch, 2,300-pound great white, on Sept. 17, 2012. Katherine cruises the East Coast of the United States. (Photo: OCEARCH)
By Tracy Cozzens Photos courtesy of OCEARCH / R. Snow
Where are sharks? What are their migratory patterns? And how close do they come to shore? Until recently, the life cycle of sharks has been a mystery. The nonprofit OCEARCH is tagging and tracking a variety of sharks, and sharing the data with scientists around the world.
OCEARCH’s Global Shark Tracker app.
Since 2007, OCEARCH has tagged a total of 200 sharks, including 80 great whites, 80 tiger sharks and a few smaller species. About 50 tags are actively sending data to a publicly available shark tracker, also accessible with an iOS and Android app. OCEARCH also has popular Twitter feeds and Facebook pages for its most famous sharks, and Mary Lee (@MaryLeeShark, 86,100 followers) and Katherine (@Shark_Katharine, 32,300 followers). The access has changed the conversation from fear of a shark interaction to curiosity about their movements and life cycles, explained OCEARCH Founder Chris Fischer.
Before the shark tracking project, “We lacked the critical data on our large apex predators’ life history. We didn’t understand where they were mating, where they were giving birth, and these large complicated migrations that they make,” Fischer said.
Pulling a great white shark from the water long enough to tag it was a daunting hurdle that OCEARCH overcame by bringing together professional mariners, ocean experts and the academic community to solve the problem. The answer is a hydraulic lift system designed for shark tagging installed on the M/V OCEARCH research vessel. Once a shark is on the line, it’s maneuvered into a custom hydrauic lift. The 75,000-pound-capacity platform is designed to safely lift mature sharks for access by a multi-disciplined research team, who rush to conduct about 12 studies within 15 minutes before setting the shark free. The shark is guided by hand in the water on and off the lift.
This hydraulic lift allows scientists to pull in and tag a live mature shark, in this case Mary Lee.
Once OCEARCH figured out how to capture and tag the sharks, the organization invited multiple institutions to share the data. “We decided to open source the data and give the tracking data away so that the world could track the sharks and be involved in the project at the same time as the Ph.D.s. And that’s where the Global Shark Tracker really came about: it was including the world in solving this puzzle in real time in this journey.”
The M/V OCEARCH now travels around the globe “to help the scientists who study our ocean’s giants explode their knowledge forward as fast as we can,” Fischer said. “So we have the critical data we need to keep these balance-keepers, these lions of the ocean, our large sharks with a bright future.”
Research expeditions are conducted worldwide aboard the M/V OCEARCH, which serves as both a mothership and at-sea laboratory.
The long-term goal is gaining a clear picture of the sharks’ needs, so that the oceans can be properly managed. “They’re the fundamental building block of the future of the ocean. If we don’t understand our apex predators, the top of the food chain, if we don’t understand how to manage them toward abundance, then we can’t manage the whole system toward abundance,” Fischer said.
More than 50 of the world’s leading institutions and more than 80 ocean scientists are involved collaborating and sharing data, a different paradigm from the classic way researchers work. “We realized quickly the old institutional way of researchers holding their data close to the vest and not sharing it with the world, trying to get ahead of one another to get papers published, wasn’t really effective for creating a movement and awareness around the future of the ocean at scale,” Fischer said.
Great White shark Katherine spotted by plane before being captured and tagged.
Information on where and when sharks swim and migrate can be leveraged for public safety, Fischer said. “Once we solve the puzzle of the migrations, the sharks then repeat the migrations to the same areas at the same times of the year. It allows people to get the rhythm of their lives and understand when they’re passing through their areas, and when they’re there and when they’re not.”
The sharks are tagged accelerometers, and with SPOT trackers from Wildlife Computers (short for Smart Position and Temperature Tag). Data from the accelerometers show that the animals regularly recover and start swimming strongly within 2–4 hours after release. Data from the Global Shark Tracker provides strong evidence that the animals tagged show long-term survival and long-distance migrations indicative of normal function and reproductive cycles, according to OCEARCH.
A SPOT tracker (top) and an accelerometer are attached to Mary Lee’s dorsal fin.
SPOT tags are designed to function in salt water. The tag is mounted on a shark’s dorsal fin and provides location data when a shark’s fin breaks the surface for at least 90 seconds. The five-year battery life of the trackers has helped scientists decipher the sharks’ three-year migratory loops. After that time, the sharks tend to shed the trackers. “We just borrow that access for five years, to solve the puzzle and collect the data,” Fischer said.
The data from OCEARCH has revealed that sharks come right to shore, into the breakwater, more often than most people thought. Also, their range is much bigger than expected, with some juvenile sharks discovered migrating all the way from Cape Cod to New Orleans.
