Article

Can you trust your GNSS data?


published on 23 November 2022 534 -

This article was already published for the first time in April 2021

Introduction

Knowing where the ship is and where to sail next is the main task of navigating a ship and is commonly supported by using Global Navigation Satellite Systems (GNSS). But what happens if the GNSS gets intentionally disturbed? GNSS interference can lead to GNSS outages, causes major disruptions to the shipping industry impacting safe navigation, leading to delayed shipping routes, misunderstandings and even collisions.

In recent years, GNSS applications have become the target of intentional interference attacks.

Figure 1: Distorted course of a vessel
Figure 1: Distorted course of a vessel
Figure 1: Distorted course of a vessel
Figure 1: Distorted course of a vessel
The latest GPS outage that caught the shipping’s eye was in 2020, when it was reported that the People’s Republic of China observed several GNSS spoofing incidents in and around coastal areas and ports. Based on an analysis of AIS data, accomplished by the Centre for Advanced Defense Studies (C4ADS), hundreds of vessels were spoofed during a period of several months affecting vessels across Shanghai and vessels navigating the Huangpu River.

Also in 2019 the US Maritime Administration (US MARAD) informed the shipping industry that they received reports about GNSS  interference incidents in the Eastern and Central Mediterranean Sea, and Suez Canal resulting in the loss of GNSS Position, Navigation and Timing (PNT) information seriously affecting the vessel’s navigation and operations. Also ships operating in the Persian Gulf, Strait of Hormuz, and Gulf of Oman have been warned to encounter GNSS interference, bridge-to-bridge communication interference or other communications jammed. In 2019 more incidents occurred than the years before and the number is constantly rising [Source: “Understanding GPS spoofing in shipping: How to stay protected” by Safety for Sea, January 31, 2020

Dangerous portable devices can cause considerable economic but also material damage. GNSS interference, by means of jamming and spoofing can significantly influence the operation of GNSS. Jamming aims to prevent the receiver from estimating a position solution and thus conveys the impression of a loss of positioning. The aim of spoofing is to use specifically manipulated signals to force a receiver outputting wrong position and time information. Both can lead to degraded position accuracies or to a total failure of the positioning. In recent years, jammers have become available very cheaply and everybody can use them. In addition, instructions on how to perform spoofing appeared in the internet.
Figure 2: Distorted position of a vessel
Figure 2: Distorted position of a vessel
Figure 2: Distorted position of a vessel
Figure 2: Distorted position of a vessel
Thus, the question arises, what do against GNSS interference? Awareness is the key. Most GNSS users are unaware of the hazardous impacts GNSS interference can have on their application or operation. Thus, crews should be aware of such attacks and it is advised that cross-checks with other independent navigation techniques should be done. Detection of RFI is the first step towards mitigation. Only if GNSS interference attacks are fast and reliably detected it is possible to deploy countermeasures. The GNSS Interference Detection and Analysis System (GIDAS), offered by OHB Digital Solutions,enables a continuous 24/7 monitoring of the GNSS frequency bands within a defined region to automatically detect, classify and localize intentional interference by means of jamming and spoofing.
GIDAS
GIDAS, developed by OHB Digital Solutions, is a scalable real-time GNSS Interference Detection & Analysis System, using a network of monitoring stations for interference detection, classification and localization.

Figure 3: GIDAS approach
Figure 3: GIDAS approach
Figure 3: GIDAS approach
Figure 3: GIDAS approach

GIDAS considerably improves save and robust operation of GNSS receivers, terminals, and GNSSbased applications by offering the capabilities for reliable detecting, classifying and localizing GNSS jamming and spoofing attacks in real-time. GIDAS addresses private companies and public / governmental authorities, which are involved in

– regulate safety critical infrastructures and/or operations
– operate safety critical infrastructures and/or operations
– operate systems or services where global navigation satellite system (GNSS) is key to achieve a required high quality of service (QoS)

GIDAS offers the following main features:
– Real-time GNSS signal monitoring (detection, classification and localization)
– Reliable, configurable, flexible, scalable and joinable system
– Multi-signal band monitoring


  • GPS: L1, L2 and L5
  • Galileo: E1 and E5
  • GLONASS: G1 and G2
  • BeiDou: B1 and B2
  • SBAS and regional systems on L1 (e.g. EGNOS, QZSS)

– GNSS interference detection (jamming, spoofing including automatic alarm generation)
– Analysis and comparison of interference events in post-processing
– Classification of GNSS interference signals
– Easy adaptable to new upcoming signals and systems
– User definable as well as predefined (e.g. ICAO, RTCA) threshold masks
– Graphical user interface and network solution

Figure 4: GIDAS monitoring station / Figure 5: GIDAS hardware components
Figure 4: GIDAS monitoring station / Figure 5: GIDAS hardware components
Figure 4: GIDAS monitoring station / Figure 5: GIDAS hardware components
Figure 4: GIDAS monitoring station / Figure 5: GIDAS hardware components
GIDAS supports both, safety critical and mission critical GNSS applications. Depending on the users´ needs and requirements three different main target areas are foreseen:

  • Static (regional) GNSS interference monitoring for safety critical GNSS applications with high demanding interference monitoring requirements
  • Static (regional) GNSS interference monitoring for safety critical GNSS applications with less demanding requirements
  • GNSS interference monitoring for mission critical (dynamic) GNSS applications
  • Four example configurations of GIDAS are possible for individual requirements:

  • Single frequency wideband monitoring
  • Multi-frequency narrowband monitoring
  • Multi-frequency wideband monitoring
  • Multiple monitoring stations, either narrow- or wideband for localization

    Figure 6: Map of the campaign area near Hafen Wien in Vienna/Austria and close to the Lock Freudenau
    Figure 6: Map of the campaign area near Hafen Wien in Vienna/Austria and close to the Lock Freudenau
    Figure 6: Map of the campaign area near Hafen Wien in Vienna/Austria and close to the Lock Freudenau
    Figure 6: Map of the campaign area near Hafen Wien in Vienna/Austria and close to the Lock Freudenau
    Waterway monitoring campaign by OHB Digital Solutions

    In 2016 GIDAS was used within an interference measurements campaign at inland waterways. GIDAS was set-up near Hafen Wien in Vienna/Austria and close to the Lock Freudenau. Within a period of less than three hours, multiple GNSS interference events were
    successfully detected and classified. The detection was based on multiple algorithms allowing a fast and reliable detection in real-time.

    Figure 7: Power Spectral Density (PSD) showing interference events during the monitoring campaign
    Figure 7: Power Spectral Density (PSD) showing interference events during the monitoring campaign
    Figure 7: Power Spectral Density (PSD) showing interference events during the monitoring campaign
    Figure 7: Power Spectral Density (PSD) showing interference events during the monitoring campaign

    As visible within the Power Spectral Density (PSD) (Figure 7) the results clearly show multiple interference events during this period, since the received signal power was significantly above the expected one of GNSS signals.

    The PSD shows four different interference signals that were detected. At least three of them have been clearly classified as intentional jamming signals. The fourth signal type was classified as reoccurring disruption from an unintentional source, most likely from a satcom device.

    The results from this test campaign show that not only the large industrial ports are affected by intentional GNSS interference, but everyone is also affected: port operators and authorities, port industry, shipyards, captains, pilots.
    OHB Digital Solutions has gained significant expertise in GNSS interference detection, classification, localization and mitigation. Within several other similar activities performed throughout the last six years by OHB a dramatic increase of intentional interference events is visible. While in 2014 only one incident was detected per hour this value has increased by a factor of three within 2019.

    Conclusion
    GIDAS is addressing private companies as well as public and governmental authorities, which are involved in regulation or operation of safety critical infrastructures or operations, in addition to operators of systems or services where GNSS is key to achieve a required high quality of service for positioning and time synchronization.
    Even small interruptions of GNSS can cause severe damages. GIDAS helps you to make your GNSS application more robust and reliable.

    Also check the GIDAS video below

     

    GIDAS by OHB Digital Solutions. We are the Navigation experts

    Web:  https://www.ohb-digital.at/en/

    Email:  info@ohb-digital.at

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