Navigation · GNSS-denied USV
GNSS-denied navigation for unmanned surface vessels
Assured navigation for patrol and ISR USVs under jamming and spoofing. The Silentis navigation-integrity layer detects a spoofed fix, switches the autopilot to non-GNSS sources automatically, and fuses anti-jam GNSS, inertial and Doppler velocity log (DVL) data into one navigation solution. Configured per hull and quoted per boat, for 2–7 m USVs.
The problem
GNSS is the single point of failure
Jamming takes the fix away; spoofing is worse — it hands the autopilot a confident, wrong one. A small USV on a patrol or ISR task sits exactly where both happen: near the coast, near other ships, inside contested electromagnetic space.
Navies and defence innovation programmes are prioritising GNSS-denied navigation for unmanned surface vessels. The sensors exist; what is missing is the layer that decides which of them to trust, moment to moment, and tells the autopilot.
Our product
The navigation-integrity layer
The software that turns three sensors into one navigation solution the autopilot can trust. The antenna handles jamming; this layer handles spoofing.
Spoofing detection
An integrity monitor checks the GNSS fix against the inertial and DVL solution continuously, and flags the moment they disagree.
Automatic source switching
When the fix can't be trusted, the autopilot's navigation filter switches to the non-GNSS source set automatically, and back once GNSS is trustworthy again. No operator action needed.
GNSS, inertial and DVL, fused
Anti-jam GNSS, inertial and velocity-over-seabed data are fused into one position, velocity and heading solution, handed to the autopilot as its navigation source.
The sensors it fuses
Configured per hull, quoted per boat
Each configuration is chosen for the boat it goes on and the water it works in, at one of two grades.
Anti-jam antenna or CRPA
Rejects jammers from low elevations, where they usually come from: a filtered anti-jam antenna at the entry grade, a multi-element CRPA with null-steering at the higher grade.
Inertial unit
Carries position, heading and attitude through an outage. Its grade sets how fast the solution drifts once GNSS is gone, up to fibre-optic-gyro grade for long outages.
Doppler velocity log (DVL)
Measures velocity over the seabed acoustically, a non-GNSS speed reference that keeps dead reckoning honest for far longer than inertial alone.
Option: coastal position fix
Radar or camera matched to the shoreline, an independent position fix that bounds inertial and DVL drift on long outages. Adds to either grade.
| Grade | Built for | Sensor set |
|---|---|---|
| Entry | Littoral patrol and ISR: shallow and coastal water, shorter outages | Compact inertial unit, compact DVL, filtered anti-jam antenna |
| Higher grade | Long outages and open water | Fibre-optic-gyro inertial unit, flush-mount DVL, multi-element CRPA |
Limits, stated plainly
Where it works — and where it doesn't
- DVL bottom-lock needs the seabed within the sensor's range — shallow and coastal water. In deep water the DVL falls back to water-track, and drift depends on the grade of the inertial unit.
- The entry grade is built for littoral work. Long outages in open water call for the higher grade's fibre-optic-gyro inertial unit, the coastal position fix, or both.
- Spoofing detection isolates a bad fix; it does not restore GNSS. Through an outage, position quality is bounded by the inertial and DVL solution.
- Each configuration is set per hull and per mission — sensor mounting, lever arms and parameters are set for the boat it goes on.
Autopilot integration
Fits the autopilot you already run
The layer works with ArduPilot and other autopilots with a standard navigation interface. For ArduPilot Rover (boat mode) and ArduSub it comes with drivers, parameters and a documented configuration, on ArduPilot's supported External AHRS drivers. Other autopilots and navigation systems with a known interface take a standard navigation output.
Who it is for
Patrol and ISR boats that cannot stop when the fix does
USV builders and operators fielding 2–7 m boats for patrol, harbour and force protection, ISR and maritime security. You keep your hull and your autopilot; the integrity layer adds a navigation solution that holds when GNSS does not.
Briefing
Configure it for your boat
Tell us the hull, the mission and the water you work in, and we'll propose a grade and quote it for your boat.
Request a briefing