How much does the global economy rely on GNSS? If just the GPS constellation were suddenly unavailable, the economic loss could be as high as $45 billion per day, according to a 2019 RTI study. Since then, GNSS usage has skyrocketed, which means the potential economic impact is even greater.
The good news is that would take once-in-a-lifetime calamity — such as a war in space or a solar storm like the Carrington Event of 1859 — to disable an entire constellation for a day or longer. The bigger threat is something that occurs every day: GNSS jamming and spoofing.
Hackers, defense organizations, terrorists, and others are increasingly using jamming for a variety of civilian and military attacks such as preventing trans-Atlantic flights from ascending to the right altitude. Other attacks involve spoofing, which uses fake GNSS signals to fool the receiver aboard the plane, ship, or vehicle into believing it’s somewhere that it’s not.
But as attacks grow, so have the technologies that device OEMs and systems integrators can use to thwart jamming and spoofing. Here are the top ones to focus on.
Strength in Numbers
Each constellation has multiple signals, each operating at a different frequency. (For a rundown of all the current and forthcoming signals for each constellation, see “How to Navigate the L1, L2, L5, E5a, E5b, and G2 Alphabet Soup of GNSS Constellations and Signals.”)
This diversity can increase resilience because it’s highly unlikely that two or more constellations will be subject to simultaneous attacks. When a device’s receiver and antenna system support two constellations — such as Galileo and GPS — it has alternatives when the primary GNSS signals are jammed. Another option is to have an external GNSS receiver that supports the fallback constellation.
Spatial Filtering
Jamming attacks involve overpowering the GNSS receiver with strong RF signals in the same or adjacent frequency bands to the legitimate satellite signal. The first type is known as in-band jamming and is the most challenging to overcome.
One of the few mitigation technologies is Controlled Reception Pattern Antenna (CRPA) systems, which use multiple antenna elements to null out the interfering signals so the receiver can focus on the legitimate GNSS signals. The effectiveness of this spatial filtering depends partly on having enough antenna elements to counter each jamming signal. For instance, a CRPA system may have four, eight, or 16 antenna elements based on the anticipated scale of the attack.
A CRPA system also can be combined with a multi-constellation receiver to provide multiple layers of defense. This design enables the system to support all frequency bands simultaneously and perform independent beam nulling in each of those bands.
Cryptographic Authentication
If the device uses Galileo as its primary or fallback constellation, a powerful new option is Open Service Navigation Message Authentication (OSNMA). It combats spoofing by verifying that signals are coming from the Galileo system and have not been modified by a third party.
Launched in July 2025, OSNMA is free for use by a wide variety of civilian and other applications. But the device’s receiver must be designed to decode the geolocation information in the Navigation Message (I/NAV) broadcast on Galileo’s E1B signal component.
This decoding capability can’t be added to an existing receiver with a software or firmware update. (For more information, visit the OSNMA section of the EUSPA website.)
The GNSS antenna system plays a critical role in OSNMA by providing the receiver with a strong, reliable signal. This signal quality ensures that the receiver has a stable, uninterrupted data stream for collecting and verifying the authentication information.
When designing an OSNMA-ready device, focus on antennas with:
- Multi-band/multi-constellation support to provide access to the E1/B1C signals where OSNMA is broadcast.
- A low, stable axial ratio to ensure consistent signal reception regardless of orientation.
- Phase center stability to reduce positioning errors.
- High out-of-band rejection with filters for cellular (e.g., LTE Band 13) and other RFI that can disrupt the data stream.
- Robust LNA and Filtering to minimize noise and preserve the signal-to-noise ratio (C/N₀), ensuring the data bits are decoded correctly.
To learn more about mitigating jamming and spoofing, watch “Protected PNT: Antenna Design Strategies for GNSS Security.” This on-demand webinar provides a deeper dive into CRPA, OSNMA, custom GNSS antennas, multi-constellation designs, and other strategies.
