Accurate and resilient GNSS timing modules for critical infrastructure

Time synchronisation modules ensure continuous uptime for critical infrastructure such as data centres, telecom, financial institutions, satlink stations and more

Precise time synchronisation is the backbone of today’s connected world, keeping telecom networks, data centers, and financial systems running seamlessly. Without accurate timing, our digital infrastructure would quickly fall out of sync.

The Septentrio mosaic-T timing module delivers nanosecond-level precision for synchronization and is trusted by companies such as Meinberg, Viavi, and Saab. Built-in AIM+ technology protects against intentional and unintentional Global Navigation Satellite System (GNSS) jamming and spoofing, ensuring maximum system uptime even in challenging or hostile conditions. Regular participation in live jamming and spoofing events, such as the Jammertest in Norway, ensures Septentrio receivers remain at the forefront of resilience innovation. The next-generation mosaic-G5 T module continues this legacy, offering high precision and exceptional resilience in an ultra-compact form factor.

Rising threats to GNSS integrity: safeguarding critical timing systems

Incidents of GNSS interference are increasing worldwide. Airports in Eastern Europe have experienced GNSS disruptions that caused rerouting, delays, and potential safety hazards. But the impact extends far beyond aviation. When GNSS timing is compromised, the effects can cascade through telecom networks, power grids, and financial systems.

The UK’s Knowledge Transfer Network warned that organised criminals could spoof financial institutions’ clocks, manipulate trading timestamps, and then revert them to conceal fraudulent transactions.

These trends highlight that GNSS interference and spoofing pose systemic risks to critical infrastructure making robust and resilient timing references indispensable.

Industry-trusted timing: AIM+ technology powering global leaders

Driven by decades of expertise in GNSS timing and reinforced by AIM+ Advanced Interference Mitigation technology, Septentrio modules set the standard for precision and reliability—trusted by leading players in the timing industry.

VIAVI Solutions is another global leader providing Assured PNT solutions to safeguard critical operations for businesses, governments, and infrastructure providers. Their timing and frequency systems maintain nanosecond precision even under RF interference, leveraging Septentrio mosaic for assured accuracy.

Meinberg is a manufacturer of high-precision time and frequency synchronisation systems — including GNSS time servers—used in critical infrastructure, telecom, and industrial networks. Meinberg integrates Septentrio’s multi-constellation, multi-frequency GNSS module, mosaic-T, as the timing engine inside its high-resilience products. In combination with AtomiChron technology, Meinberg achieves unmatched spoofing resilience with authentication across all four major GNSS constellations.

Saab integrated Septentrio receivers in their Air Traffic Management system to synchronize their Multilateration and ADS-B surveillance. To validate GNSS resilience Saab also took these receivers to the Jammertest, find out more in this customer story.

Spoofing awareness and protection for critical infrastructure

GNSS spoofing is a cyberattack in which false satellite signals mislead a receiver into producing the wrong time. For timing receivers, this can disrupt entire networks. Because critical infrastructure depends on precise GNSS time, its static nature makes it particularly vulnerable to GNSS spoofing attacks.

Spoofing attacks can vary in type and sophistication. A cleverly set-up ‘pull-away’ attack gradually changes the time and can bypass built-in system-level software checks. Luckily sophisticated GNSS receivers have advanced technology, such as AIM+ to flag and prevent spoofing at the core signal-processing level, maintaining reliable time integrity.

Since the receiver is at the forefront of signal tracking and reception, interference detection and protection at the receiver core is essential to prevent GNSS spoofing from corrupting downstream systems. Septentrio’s approach combines multiple defensive that work in synergy to detect and mitigate GNSS spoofing.

• Multi-frequency, multi-constellation tracking maximises signal availability and redundancy.
• Advanced data analysis algorithms detect anomalies.
• Cryptography, including Galileo OSNMA, authenticates signals
• Trustworthy spoofing flag provides situational awareness so that the system can take preventative action.
• AIM+ technology protects against jamming. Spoofing often starts with jamming, which breaks the signal lock and forces the receiver to reacquire the signal with faulty timing information.
   

In addition to a fortified receiver, a system can be protected further by including anti-spoofing components such as continuity checks, a specialised antenna, and services to authenticate all GNSS constellations like Fugro AtomiChron.

Jammertest results prove timing resilience

At Jammertest 2025, Septentrio’s timing receivers underwent rigorous live spoofing trials. The results confirmed their exceptional resilience to spoofing attacks. During a spoofing test shown below the Septentrio receiver maintained accurate time while a competitor’s device was spoofed by three minutes. 

During this spoofing test the mosaic module continued to provide precise timing, while a competitor module was spoofed three minutes to the past.

In another test, spoofing shifted a competitor’s clock by two weeks — while Septentrio’s remained stable.

During this spoofing test Septentrio’s time remained correct, while a competitor module was spoofed by two weeks

For earlier test results, visit our Jammertest Insight article. Stay tuned for a full analysis of the 2025 event.

Defending against jamming with AIM+ advanced filtering

Jamming occurs when GPS frequencies are overpowered by other radio waves, degrading accuracy or cutting the signal entirely. In cities, GNSS signals can be unintentionally jammed by airport radars, radio hobbyists, or cars using illegal jammers. Intentional interference — where hackers exploit GNSS vulnerabilities — is even more dangerous.

Septentrio’s AIM+ Anti-Jamming technology employs sophisticated sampling and adaptive notch filters to suppress a wide range of interference — from narrowband continuous waves to complex wideband and pulsed transmissions. Test results show that a Septentrio module receiver operates much closer to a jammer than competing products, offering superior protection.

Receiver Type            Operating distance from a                                 Operat. dist. from chirp
                                 continuous wave jammer(m)                                     jammer (m)

mosaic module                                         90                                                                          90

Competitor receiver 1                              634                                                                       3998

Competitor receiver 2                              503                                                                       3623

Septentrio zero-delay anti-jam

While traditional GNSS anti-jam techniques do a good job in maintaining accurate positioning output during jamming, they tend to offset the time output.  The reason is that anti-jam filters often introduce delays that are reflected in the position of the time pulse generated by the receiver. Septentrio receivers only use special types of anti-jam filters that have the ‘zero-delay’ property, ensuring that the timing pulses remain stable and accurate even during jamming.

The figure below illustrates the effect of a jammer on the PPS (pulse per second) output of a GNSS receiver.  The upper part of the figure shows a spectrogram, where narrow and wide-band jammers are clearly visible as the thin and wide orange rectangles.  On the left side, traditional anti-jam maintains the PPS during jamming, but it is shifted away from its intended position. On the right side, Septentrio’s zero-delay anti-jam technology maintains unaltered PPS accuracy during the whole jamming period.

The upper part shows a spectrogram with narrow and wide band jamming. Of the left graph traditional anti-jam maintains PPS, but it is shifted. On the right side Septentrio zero-delay anti-jam technology maintains unaltered PPS accuracy

The future of GNSS timing with mosaic-G5 T

Building on decades of experience and the proven success of the mosaic-T module, Septentrio has introduced the ultra-compact GNSS timing module mosaic-G5 T. Measuring just 23 × 16mm and weighing only 2.2 grams, this receiver expands possibilities for system designers operating under strict size, weight, and power (SWaP) constraints. Its nanosecond precision, fortified by AIM+ Premium anti-jamming and anti-spoofing technology, ensures continuous and secure uptime. Featuring built-in cybersecurity functions, mosaic-G5 T is the ideal choice for data centres, telecom, satcom, and financial institutions seeking a high-quality, resilient timing source. The mosaic-go G5 T evaluation kit offers a fast and easy way to test or prototype with this new timing module. 

Mosaic-G5 T multi-frequency GNSS timing module has an optimisd SWaP as well as Premium interference resilience

Precision in every pulse: achieving nanosecond timing accuracy

GNSS satellites carry atomic clocks that transmit precise time signals to Earth, enabling receivers to generate synchronised timing pulses. However, factors such as atmospheric interference, satellite orbit and clock errors can degrade accuracy. GNSS correction services, such as HxGN SmartNet, provide real-time data to correct these errors, enabling receivers to achieve nanosecond-level precision.

Because of hardware constraints, the physical time pulses generated by the receiver often have a resolution which is coarser than then ideal accuracy achievable by a receiver, so the PPS accuracy is ultimately limited by this time resolution.  mosaic-G5 T features a PPS resolution of only 1.4ns, ensuring that the full timing accuracy is available at the PPS output. In the image below a competition receiver (pink) with a coarse hardware resolution is showing jitter on its PPS output, which means a reduced pulse accuracy for the end user. The mosaic-G5 T module (blue) has a finer hardware resolution resulting a higher PPS precision.

Reference PPS timing pulse (yellow), PPS from a receiver with a coarse hardware resolution (pink) and PPS from a mosaic G5-T module (blue)

Over the years Septentrio’s GNSS timing module technology has proven to be a benchmark in precision and resilience, delivering secure, interference-resistant synchronisation that keeps critical infrastructure worldwide operating reliably and in perfect time.

Find out more about Septentrio’s solutions for timing and synchronisation.

References

1. https://metro.co.uk/2012/02/21/gps-jammers-could-make-criminals-millions-on-the-stock-market-327410