最も耐障害性に優れたGNSS受信機：ノルウェーのJammerTestの結果

JammerTest 2023 - 2024 - picture taken by David Jensen @jensenmedia

                                                                                                                                        この記事は、简体中文でもご覧いただけます。

世界中で、PNT（測位、航法、計時）システムの耐障害性を向上させる必要性が高まっています。米国大統領は、PNTサービスを通じて国家の耐障害性を強化するため、大統領令に署名しました。地政学的な緊張により、GNSSが争奪される状況下の航法戦（NAVWAR）の分野における作戦に、より高いレベルのセキュリティが求められています。フィンランドなどの国々の企業は、悪意のある干渉源を検出するためにネットワークに接続できる受信機を探しています。基準ネットワーク、ドローンによる監視や配送、時間同期など、多くのGNS用途にとって、PNTの劣化や損失は悲惨な結果を招く可能性があります。そのため、このような極めて重要な用途で使用されるGNSS受信機には、厳しい環境でも着実に機能する最高レベルの耐障害性が求められます。

実際のGNSS干渉に対するAIM+のアンチジャミングとアンチスプーフィング機能

セプテントリオは、意図的および非意図的なGNSS電波妨害およびスプーフィング*に対して最高レベルの耐障害性を持つ受信機を提供します。実際の干渉条件下で受信機テクノロジーをテストすることは、アンチジャミングとアンチスプーフィングのアルゴリズムを検証し、継続的に改善するうえで極めて重要です。そのため、セプテントリオはノルウェー政府が主催する遠いアンドーヤ島での大規模なJammerTest 2023イベントに参加して、管理された環境下で実際の干渉試験を実施しました。セプテントリオはこのようなテストイベントに定期的に参加していますが、そのほとんどは機密扱いで、結果を公にすることはできません。JammerTestは、結果を共有することが推奨される、この種の最初の公開イベントの1つです。

ノルウェーでの5日間にわたる集中試験の結果、AIM+アンチジャミングおよびアンチスプーフィング技術は、実際の干渉条件下でも機能することが証明されました。試験の結果、実際の干渉下では、受信機技術が重要な役割を果たし、アンテナ技術がサポートの役割を果たすことが明らかになりました。様々なタイプのスプーフィング攻撃下で受信機をテストすることで、複数のアンチスプーフィング機構を併用することが最善のスプーフィング対策であることが示されました。

大手航空宇宙・防衛企業のSaabもJammerTestベントに参加し、要求の厳しい同社の航空交通管理システムで使用されているセプテントリオ受信機のの耐障害性を検証しました。

毎年何億人もの乗客が、気づいてはいないかもしれませんが目的地に安全に到着するためにSaabの航空交通管理システムを利用しています。これらのシステムのほとんどは、測位と時刻同期のためにGPS/GNSSを利用しています。このように大きなリスクを背負っているSaabは、セプテントリオの機器を使用して業界をリードするアンチスプーフィングおよびアンチジャミング機能を提供できることを誇りに思っています。Saabとセプテントリオの最近のJammerTestでのコラボレーションは、両社がいかに効果的な協力関係を築けるかを示すものでした。

Saab-logo
ロバート・ブラウン氏
Saab航空交通管理ポートフォリオ・営業・戦略部長

Results from JammerTest 2024

GPS-Jamming-test-Sepentrio-versus-competition-during-JammerTest-2024
Figure 1: Septentrio receiver (orange) is not jammed even by very powerful interference, while two competitor receivers (red, blue) show wrong positions.

この試験では「シガーライター」ジャマーが使用されました。これは最も一般的なタイプのジャマーの1つで、オンラインで簡単に購入できます。10～15dBmの電波を発し、GPS L1、L2信号を妨害します。その他の電波妨害試験では、GNSS信号の1000万倍もの電波を持つ、非常に強力なジャマーも使用されました。 

下図は、「シガレットライター」低電力ジャマーで行った携帯電話電波妨害試験の結果です。信号対雑音比の時系列図は、電波妨害が開始されると、追跡されたGNSS信号の品質が低下することを示しています。セプテントリオ受信機（上図）は信号を追尾し続け、測位を出力し続けますが、競合他社の「受信機は一定時間測位を失います。 

Spoof-proof GNSS receivers

The image below shows a meaconing test where Septentrio receiver performance is compared to a high-end competition receiver. Meaconing is a form of spoofing where GNSS signals are recorded and then retransmitted with a time delay. The spoofed receiver then “believes” it is at the location of the antenna that was used to record the GNSS signal. During the test, as the car traveled along a coastal road, the Septentrio receiver (orange line) maintained accurate positioning. In contrast, the competitor receiver (red line) was spoofed, reporting its location on a mountain - the site of the interference transmission antenna used in the JammerTest, as shown in this article's cover image. 

meaconing-septentrio-versus-competition-during-JammerTest-2024
Figure 2: Car test shows that a Septentrio receiver (orange) is resilient to GNSS spoofing of type meaconing, while competitor receiver is spoofed to the top of the hill.

Danger: Spoofed positions without a warning

GPS-spoofing-stats-Sepentrio-versus-competition-during-JammerTest-2024
Fig. 3 : The combination of high GNSS spoofing mitigation (green) & spoofing detection (red, flagged) demonstrates that Septentrio receivers are reliable during various types of spoofing attacks, as compared to 4 other RTK competitor receivers.

This graph shows a summary of performance of various receivers during spoofing testing throughout the 5-day event. The green sections represent the percentage of correct positions or successful spoofing mitigation. Grey indicates the percentage of time the receiver reported no position during spoofing, and red shows the percentage of time the receiver displayed spoofed positions.

The Septentrio receiver showed minimal spoofed positioning, even under sophisticated spoofing attacks, and consistently detected and flagged spoofing when it occurred, demonstrating situational awareness. In contrast, three competitor receivers failed to flag spoofing in many cases, displaying erroneous positions without warning the system of potential risks. 

GPS-time-spoofing-test-Sepentrio-versus-competition-during-JammerTest-2024
Fig. 4 : As GNSS time is spoofed, the Septentrio receiver keeps delivering correct timing information, while a competition receiver shows incorrect time.

Resilience of GNSS timing validated

The plot below shows results from a test where GNSS time was spoofed. The Septentrio receiver maintained accurate timing, while a competitor receiver was spoofed and displayed incorrect time. Applications such as telecom, power grids, and financial institutions depend on precise GNSS timing. Malicious spoofing can result in outages, with total costs reaching millions of dollars or euros. Investing in resilient GNSS technology is essential to protect mission-critical systems and the users who depend on them.
 

Multi-layered receiver protection pays off

During JammerTest 2024, Septentrio receivers with AIM+ technology demonstrated exceptional resilience to high-powered jammers and various types of spoofing. This performance reflects over 25 years of expertise in developing reliable GNSS positioning technology, incorporating multiple layers of protection:

  • Multi-frequency technology for signal diversity, ensuring fallback during jamming or spoofing
  • Cryptographic signal authentication (OSNMA) to verify genuine signals
  • Anomaly detection powered by continuously updated big data from years of field observations  

As seen on the news, GNSS spoofing is increasingly common due to readily available transmitter hardware and signal simulator software. Spoofing poses an even greater risk than jamming, as it can not only disrupt operations but also manipulate navigation systems, potentially resulting in planned collisions or theft. Securing your system at the receiver core is the most effective strategy to ensure resilient, reliable operation.

Learn more about AIM+ Anti-Spoofing technology or download our comprehensive GNSS Spoofing brochure. The video below is a summary of Septentrio’s results from JammerTest 2024. Feel free to share this video with those interested in resilient and reliable positioning. 

Tried, tested and true

Always accurate and available Positioning, Navigation and Time or Assured PNT is key to successful industrial or critical operations in challenging environments. By regularly participating in live events such as the JammerTest, Septentrio's anti-jamming and anti-spoofing technology is continuously being tested and improved to withstand the latest interference attacks. This technology has also been confirmed to be effective by users out in the field, who are using Septentrio receivers in places of malicious interference, such as near contested borders.  

Although an anti-jam antenna can play a role in hardening the system, the most effective approach to securing your system is to use a receiver with advanced anti-spoofing and anti-jamming (AJAS) protection. For spoofing this means including several layers of protection which shield the receiver from various types of attacks. Septentrio receivers come in various formats from rugged boxes to OEM boards and compact modules, like the low-weight, low-power mosaic-X5 module receiver, which is also easy to integrate and is compatible with popular autopilots like Pixhawk, ArduPilot and PX4 Autopilot. For more information about resilient GNSS receivers and technology please contact Septentrio. 

 

Septentrio GNSS receivers vs competition at JammerTest 2023
Figure 1 In real-time GNSS interference, the Septentrio receiver on the test car can provide accurate positioning, while the competitor receiver will lose positioning after a period of time.

AIM+ detects and mitigates GNSS jamming

The figure on the right shows that during jamming a Septentrio GNSS receiver in a car delivered accurate positioning along the whole route (orange track), while a high-end GNSS/INS competition receiver lost positioning two times (red track). 

GPS jammer device
Figure 2: During the jamming mobile car test a common "cigarette lighter"-type jammer was used. Image credit: Testnor.

During this test a “cigarette” jammer was used, which is one of the most common types of jammers and can easily be purchased online. It emits signals with power between 10-15 dBm and jams GPS L1, L2 signals. Other jamming tests included highly powerful jammers with signals 10 million times more powerful than GNSS signals.  

The plot below shows results of a mobile jamming test performed with the “cigarette” low-power jammer. The signal-to-noise time plot shows that when jamming is started the quality of the tracked GNSS signals decreases. A Septentrio receiver, shown at the top continues to track the signals and to output positioning, while a competition receiver loses positioning for a period of time. 

Signal quality plot
Figure 3: As GNSS signals start getting jammed, their quality decreases as seen in this signal-to-noise plot. The Septentrio receiver maintains tracking and positioning, while the competition receiver loses positioning for a period of time.

Over the 1-day period of intensive jamming tests, receivers with AIM+ demonstrated 99,5% positioning availability under various forms of jamming from simple continuous narrow-band interference to the most complex wide-band transmissions.

The magic is in the GNSS receiver

For mission-critical applications an anti-jam antenna can play a role in achieving maximum resilience against RF interference. During the JammerTest, 3 receivers were tested under heavy multi-frequency wideband jamming in combination with antennas of varying sophistication. The signal-to-noise time plots below show signal quality during this test. In the top plot, a receiver with a standard wideband helical antenna does not have AIM+ anti-jamming technology and so immediately loses tracking of satellite signals during jamming. A receiver with the same antenna, but with AIM+ continues to track signals and deliver positioning (middle plot). The bottom plot shows a receiver with AIM+ coupled with an anti-jam antenna. The drop in signal quality is slightly less than with a standard antenna and the receiver continues to track signals and to deliver positioning. 

 

Antenna-comparison-receiver-with-without-AIM+ septentrio
Figure 4: During heavy jamming Septentrio receiver with AIM+ mitigates interference and provides positioning (middle plot). With anti-jam antenna there is signal quality improvement and positioning (bottom plot). Without AIM+: no positioning (top plot)

関連パンフレット

Tests with various anti-jam antennas showed interference reduction of about 10 dB due to the antenna. While advanced anti-jam technology like AIM+ plays a key role in positioning availability under jamming, an antenna plays a supporting role and can improve the chances of getting positioning in cases where the jamming is still slightly stronger than the ability of the receiver to mitigate it. While anti-jam antennas can be effective for wide-band “white-noise” jamming they are less effective for other types of jamming.

Comprehensive anti-spoofing requires multiple layers of protection

Hackers employ various types of spoofing to hijack positioning, navigation or time, from simple asynchronous spoofing to sophisticated synchronous types which are almost identical to real GNSS signals. For the highest degree of anti-spoofing protection and situational awareness a receiver requires several layers of protection (find out more in our GPS Spoofing brochure).

AIM+ detects, flags and mitigates GNSS spoofing 

The plots below show positioning of several different receivers in a moving car during a GNSS spoofing attack.