When the satellites go quiet,
what still knows where it is?

How do you navigate and operate when GNSS is denied or spoofed?

By removing the single dependency. Assured position, navigation and timing combines inertial navigation, alternative signal sources, terrain or visual reference and disciplined local clocks, so that losing GNSS degrades accuracy gradually instead of removing the capability outright.

The design work is deciding how much drift each system can tolerate and for how long, then choosing the combination that meets it at acceptable cost and size. An inertial unit good for ten minutes and one good for ten hours are different programmes.

Spoofing is the harder case, because the receiver believes it has a fix. Detection depends on cross-checking — comparing GNSS against inertial, against a second independent source, and against physical plausibility — and on a system that is prepared to distrust its own position.

• Assured PNT architecture and source combination
• Inertial navigation and drift budgets
• Spoofing and jamming detection through cross-checking
• Timing resilience for communications and sensor fusion
• Trials, measurement and acceptance in a contested RF environment

Why does GNSS denial break more than navigation?

Because GNSS is also the timing source. Tactical radios, mesh networks, sensor fusion and encrypted links frequently depend on precise time rather than position, so a jamming event that a vehicle survives by dead reckoning can still take down the network and corrupt the fused picture.

This is the failure that surprises programmes, because timing dependency is usually buried inside a subsystem specification nobody read as a system-level risk. It is worth asking every vendor, in writing, what their equipment does when GNSS time is unavailable for an hour.

What is the difference between jamming and spoofing, practically?

Jamming denies the signal and the receiver knows it has lost fix. Spoofing replaces the signal and the receiver reports a confident, wrong position. Jamming is an availability problem; spoofing is an integrity problem, and integrity failures are far more dangerous because the system keeps operating on false data.

Operationally that means the response differs. Against jamming, you need a fallback. Against spoofing, you first need to know it is happening — which requires an independent source to disagree with.

How is assured PNT actually specified and tested?

With a written drift and holdover requirement, tested in a controlled RF environment rather than assumed from datasheets. The specification should state how long the platform must maintain a stated accuracy without GNSS, and the acceptance test should measure exactly that.

We work on these programmes with UAE government end users and with prime contractors including L3Harris, from requirement through delivery and acceptance.