SBG Systems response to GNSS Jamming and Spoofing

Accurate satellite-based positioning has become an inherent part of our life in the last decades with increasing accuracy, lower size, and price drop. However, while Global Navigation Satellite Systems (GNSS) deliver incredible performances, the nature of the technology makes it vulnerable to perturbations: it is comparable to the power emitted by a 60W light bulb located more than 20,000 km away from the surface of the earth. This means that the signal received on earth is very "weak," and it is therefore trivial to generate a signal from the surface that will be much stronger than the signal from the satellite.

This happens regularly, both unintentionally (local interferences and RF pollution) and intentionally (intentional interferences or fake signal).

Interferences and Jamming

Unintentional interferences are commonly generated by a variety of devices. Signals generated close to or within the GNSS spectrum may cause an issue. It is, for example, common for USB3.0 devices or some LIDAR sensors to create interferences in the GPS L1 band (1575.42 MHz +/-10 MHz), causing GNSS receivers to fail to provide an accurate position unless proper shielding is added. 

Some people or organizations may intentionally create interferences to prevent GNSS receivers from working in a specific area. This is called jamming, the voluntary interference of GNSS signals by transmitting powerful radio frequency signals that overwhelm the weaker GNSS signals. 

It is important to note that jamming is not limited to war actions. Many jamming situations are caused by low-cost GPS jammers that are, often illegally, used to prevent a car or a truck position tracking.

Spoofing

Spoofing, on the other hand, involves the creation of counterfeit GNSS signals that fool receivers into calculating false positions and providing inaccurate positioning information. 

While jamming is a relatively simple and inexpensive attack, spoofing requires much more advanced equipment and knowledge to be able to carefully mimic the GNSS signals. Note that spoofing is often combined with jamming: it allows the spoofing of only a subset of the GPS signals rather than all the signals at once, making it significantly easier.

To get an idea of which areas may be affected by jamming and spoofing, visit https://gpsjam.org . This website reports the location of potential jamming events, based on aircraft reported navigation accuracy.

SBG Systems response to Interferences, Jamming and Spoofing

Antenna is the first key 

When dealing with interference, jamming and spoofing, it’s important to consider the antenna as a key element. Since it’s the entry point for all signals, the antenna must play a role in mitigation actions: 

• Modern GNSS antennas include pre-filters that prevent signal distortion from adjacent frequencies interferences. This makes them suitable for nearby 4G or Wifi communications for example, while older antenna designs may have troubles in such conditions. 
• Placing a ground plane under the antenna will typically attenuates signals below the horizon, making it a cost-effective jamming mitigation measure. 
• Some antennas are designed for anti-jamming and offer a higher signal attenuation at low elevation (near and below the horizon) to optimize operation under challenging jamming conditions. 
• More advanced antenna designs (CRPA) can null the radiation pattern in some directions to avoid receiving signals from the suspected jammer’s location. 

Robust GNSS and INS Integration is the Second Key

Our GNSS aided Inertial Navigation Systems implement a three-step approach in the event of interference and/or spoofing:

• Mitigate: our products filter the GNSS signal to maintain a correct GNSS position / velocity for as long as possible.
• Alert: as soon as we detect a potential threat, we alert the integrator to take action (each integrator will react differently to a threat based on the mission profile).
• Circumvent: if a threat cannot be mitigated, we rely on pure inertial navigation to continue outputting position and attitude.

Technologies our Products Use to Mitigate and Alert

To mitigate and alert of jamming or spoofing attempts we rely on advanced algorithms to detect the event and filter the source:

• Multi-constellation and multi-frequency operations: all of our integrated receivers are multi band (either L1/L2 or L1/L2/L5) and support all constellations (GPS, GLONASS, Galileo, Beidou). This increases the resilience to attack which will have a harder time targeting all constellations and especially all frequency bands. 
• Interference mitigation: radio emitters such as a Software Defined Radio (SDR) or Personal Privacy Devices (PPD) can easily overpower the GNSS signals and cause a blackout. Our navigation systems incorporate interference mitigation technologies that attenuate the effects of jamming devices by applying a specific filtering as needed. 
• Sophisticated spoofing algorithms are also integrated to detect potential spoofing attempts. 
• Receiver Autonomous Integrity Monitoring (RAIM) algorithms are embedded to identify faulty GNSS signals that could be caused by intentional spoofing attempts (or by multipath). 

• Finally, inertial navigation system integration enable dead reckoning for a certain time during GNSS outages. Using aiding sensors like odometry can greatly extend the dead reckoning period. 

Message Authentication with OSNMA 

On top of these Radio Frequency analysis technologies, some of our products use Galileo’s Open Service Navigation Message Authentication (OSNMA) to authenticate the sender of the message as described below.

All the signals sent by Galileo satellites include a key that is authenticated using asymmetric cryptography techniques. At the receiver end, the public key is used to verify that the signature is valid and to confirm that the sender of the signal is the expected Galileo satellite. 

This makes it almost impossible to spoof Galileo signals. 

OSNMA is currently deployed in testing phase and is now enabled by default on some of the SBG Systems GNSS aided product range using High Performance INS Firmware 5.0 and above. 

New Flags added in our INS' firmware to Notify in case of Jamming or Spoofing attempt

Building on the above solutions, firmware 5.0 of our GNSS aided Inertial Navigation Systems (Ekinox, Apogee, Navsight, Quanta Plus, Quanta Extra) introduces specific flags to alert users of interference or spoofing events. These flags include:

• Interference flag: Indicates whether the signal is clean, polluted, and whether the interference can be mitigated.
• Spoofing flag: Detects attempts to spoof GNSS signals based on radio frequency monitoring.
• OSNMA flag: Indicates a spoofing attempt on the Galileo signal using OSNMA authentication for products with OSNMA enabled.

Using these 3 flags, an integrator or an end user can react to jamming or spoofing attempt and decide, based on the mission profile, on the best course of action. 

These flags, accessible through our APIS, can also be monitored through the web interface of our products.

Some of your questions remain unanswered? don't hesitate to contact us.