GPS World

Tag: FGI

  • FGI-GSRx software-defined GNSS receiver goes open source

    FGI-GSRx software-defined GNSS receiver goes open source

    NLS-FGI logo

    The open-source release of FGI-GSRx software receiver widens its user base and offers researchers, students and developers a chance to utilize the research platform for innovations.

    The GSRx software receiver, developed by the Finnish Geospatial Research Institute (FGI), is now being released as open source for use by the GNSS community.

    FGI-GSRx has been extensively used as a research platform for the last decade in different national and international research projects to develop, test and validate novel receiver processing algorithms for robust, resilient and precise positioning, navigation and timing (PNT).

    FGI-GSRx has been used to develop algorithms for detecting GNSS jamming and spoofing events in several past R&D projects. It is also used to develop mitigation algorithms to offer a resilient PNT solution to the user.

    The FGI-GSRx software receiver will be discussed in the next edition of the textbook GNSS Software Receivers by Borre, Fernández-Hernández, Lopez-Salcedo and Bhuiyan. The book will be published by Cambridge University Press in August.

    Uses of the software receiver

    The software receiver can be used in universities and other research institutes to provide graduate-level students and early-stage researchers with hands-on training in GNSS receiver development. It can also be used in the GNSS industry as a benchmark software-defined receiver implementation.

    The software receiver is already being used in the “GNSS Technologies” course offered widely in Finland at the University of Vaasa, Tampere University, Aalto University and the Finnish Institute of Technology.

    The open-source release of FGI-GSRx will enable any third-party developer, researcher or student to use the platform to develop, test and validate innovative algorithms. It offers a flexible interface and configuration files, so that researchers can further implement their own codes or algorithms at different receiver processing stages. This allows the user to go much deeper into the coding without addressing all the implementation details, explained Research Professor Zahidul Bhuiyan, FGI, National Land Survey of Finland.

    Meeting evolving industry needs

    The GNSS market has faced a transformation in the past two decades, with new features and signal properties being added to the modernized satellite navigation systems at an increasing pace. A software-defined receiver enables algorithm optimization and testing in this rapidly changing industry.

    The multi-constellation FGI-GSRx receiver has evolved to provide diversity and improved accuracy. When the FGI-GSRx was first developed, it was able to track the Galileo test satellites GIOVE A and GIOVE B. Since then, FGI researchers have been continuously developing new capabilities to the software receiver with the inclusion of Galileo in 2013, the Chinese satellite navigation system BeiDou in early 2014, the Indian regional satellite navigation System NavIC in late 2014, and the Russian satellite navigation system GLONASS in 2015.

  • ESA: Baltic ferry gathers data for self-aware sailing

    ESA: Baltic ferry gathers data for self-aware sailing

    News from European Space Agency (ESA)

    A day of ferry trips between Finland and Estonia became some of the best documented voyages in maritime history. Cameras, sensors, radio and satellite navigation receivers and even microphones recorded every instant of the crossings over the Baltic, gathering raw data for a new ESA-led project applying artificial intelligence (AI) to the situational awareness of shipping — as an important step to full autonomy.

    The Tallink shipping company’s new 212.2 meter-long Megastar passenger and car ferry was fitted with data-gathering devices for its sailings on the busy stretch of sea between Helsinki and Tallinn.

    The testing was overseen by a team from the Finnish Geospatial Research Institute (FGI) for an ESA project called Artificial Intelligence/Machine Learning Sensor Fusion for Autonomous Vessel Navigation, or Maritime AI-NAV.

    “Our aim is to show how AI can be applied to achieve autonomous situational awareness, so that a ship can reliably sense its own environment,” said FGI’s Sarang Thombre.

    Photo: European Space Agency
    Photo: European Space Agency

    “Such autonomous systems would initially be deployed in support of human crews, for enhanced safety and efficiency – with crewless ships a much longer-term goal.

    “The most experienced human ship captains will have the least trust in any single navigational device but will rather continuously cross reference between them. Similarly, our autonomous functionality will not be overly reliant on a single data source but combine and verify data from multiple sensors.

    “Having gathered many gigabytes of data during our initial August field campaign, then again in October with more days planned in December, we are applying the results to train and test our data-fusing algorithms. A follow-up seagoing test will then verify their performance in practice.”

    The Maritime AI-NAV team plans to employ a variety of sensor types, including satellite navigation receivers – also utilizing of Europe’s Galileo system — monocular and stereo cameras, standard radar, “laser radar” lidar and an array of microphones, along with “Automatic Identification System” radio signals. These AIS signals transmit position, size and routing information of all vessels above a certain class, as well as fixed infrastructure such as oil rigs or wind turbines.

    “Satellite navigation lets the ship know where it is in the sea, while the other sensors let it know what is around it, which is essential for identifying and avoiding any obstacles,” Thombre said. “The different data sources operate across a variety of ranges — so radar and AIS provide longer range detection out to the horizon, while cameras and lidars come into their own at shorter distances. Plus we had a trio of microphones aboard the Megastar, determining the angle of arrival of sound from other ships. The challenge now is to fully integrate all these sources using machine learning, to build up a holistic picture.”

    Maritime AI-NAV is supported through ESA’s Navigation Innovation and Support Programme, working with European industry and academia to develop innovative navigation technology.

    FGI is joined in the Maritime AI-NAV consortium by Aalto University’s Sensor Informatics and Medical Technology group and maritime IT startup Fleetrange.

  • 4th GPS civilian signal goes live

    4th GPS civilian signal goes live

    A new GPS civilian signal is now available for use. The new signal is stronger, more accurate, more resilient to interference events, and interoperable with European Galileo system.

    Researchers from the Finnish Geospatial Research Institute (FGI) recorded the new civilian signal transmitted by the first GPS III operational satellite.

    On Jan. 13 at 21:29 Finnish time, the first GPS III satellite (SVN74) was marked healthy after extensive operational testing in orbit. The satellite broadcasts PRN04 identification codes. It also transmits a new GPS civilian signal, known as L1C, different than the legacy L1 C/A signal used nowadays.

    10 times longer

    The two signals are transmitted at the same frequency, but L1C codes are 10 times longer than L1 C/A. This makes the signal more robust to interference when multiple satellites are tracked on the same frequency band.

    “Marking a satellite health means receivers can use this satellite in their positioning, navigation and timing applications,” said Octavian Andrei, senior research scientist at the Finnish Geospatial Research Institute (FGI). “L1C is the 4th GPS signal for the civilian use.” The Finnish Geospatial Research Institute is a part of the National Land Survey of Finland.

    The other three civilian signals of GPS are L2C, L5 and L1 C/A.

    For more on the L1C signal, also see First light: Broadcast of L1C by GPS III,

    Interoperable with the European GNSS signalL1C signal is transmitted on L1-band at 1575.42 MHz. It is meant to replace the legacy C/A signal in the future. L1C allows for the first time GPS compatibility and full interoperability with signals from other satellite systems, such as E1 signal from the European Galileo.

    The interoperability with Galileo is further enhanced by transmission of the inter-system timing biases; that is, the GPS-Galileo Time Offset. All these improvements will bring further benefits and developments to the GNSS market and civilian users in general.

    Ionosphere no problem with dual-frequency

    Andrei said the new signals means “Exciting times ahead for the civilian users and applications that demand precise satellite positioning and navigation. Most of the effects due to the ionosphere layers of the atmosphere are removed by combining signals from two frequency bands sufficiently apart from each other. This is the case with L1 and L2 or L1 and L5. All these civilian signals are stronger and more robust than ever before,” he explained.

    The satellite signals are affected by errors while travelling through the atmosphere. The main errors are due to the ionosphere, which is a dispersive medium and frequency dependent. The latter proves to be actually a significant benefit for the precise applications.

    The new signal (L1C, marked with blue) is 3-5 dBHz stronger and more robust than the legacy L1 C/A signal (marked with orange). (Image: Octavian Andrei)
    The new signal (L1C, marked with blue) is 3-5 dBHz stronger and more robust than the legacy L1 C/A signal (marked with orange). (Image: Octavian Andrei)

    More than 99 % of the ionosphere effect is removed by forming special linear combination of signals observed on two different frequencies. This is the main reason why high-precision is achieved with dual-frequency receivers.

    FinnRef network ready for new satellites and signals

    “Two GPS III satellites have been launched until now and two more are expected to be launched during 2020. With signals from four satellites, we will also be able to estimate L1C-only positions,” Andrei said.

    The first GPS III satellite SVN74, nicknamed Vespucci, was launched on Dec. 23, 2018. The second satellite SVN75, nicknamed Magellan, was launched on Aug.22, 2019. The third and the fourth satellite are planned to be launched in March and July during 2020. The first L1C testing signals were recorded at the FinnRef station in Metsähovi on April 5, 2019.

    FinnRef national network includes state-of-the-art multi-constellation tracking stations distributed around Finland. These stations are capable of tracking multiple satellite signals on multiple L-band frequencies from almost 120 GNSS satellites, including the European Union’s Galileo, US GPS, Russian GLONASS, and Chinese BeiDou constellation.

    Using new signals often requires updates to station equipment, usually meaning firmware updates on the receiver software. After the new firmware enabling L1C tracking is properly tested, the receivers will be updated and then whole FinnRef will start tracking GPS L1C.