A second opinion on
every GNSS fix.
What it does
NavCore checks each GNSS fix against an inertial estimate, flags jamming and spoofing, picks a navigation mode, and writes each flag and mode change to a hash-chained log.
It is a navigation-integrity library inside QCOS, offered as a research preview. The logic is implemented; it has not been tested at sea, in the air or on track, and it holds no type approval.
50 m
GNSS vs inertial gate
10 dB
C/N0 drop that flags a jam
300 s
Holdover before denied
Thresholds set in the code, not measured performance.
sha256(event + previous_hash) · held in memoryExample: what the code returns when a jam is flagged.
Plain inputs in.
Every decision out.
The integrity logic takes GNSS and inertial samples as plain values, so it is not tied to one receiver. There is no receiver driver; connecting a specific receiver is pilot work.
What the Code Does Today
Each card says what is implemented and what we found when we replayed the logic on simulated voyages.
No detection rate, false-alarm rate or accuracy figure is published. None has been measured on real signals. The gaps below are OBSERVED by replaying NavCore's own logic on simulated inputs; real-signal results are TO-VALIDATE in a pilot.
Spoofing Flags
IMPLEMENTEDRaises a spoofing flag when the fix jumps more than 150 m between updates, the receiver clock bias jumps by more than 1,000 m, or the signals arrive suspiciously uniform and strong (spread under 2 dB, mean above 50 dB-Hz).
Inertial Cross-Check
IMPLEMENTEDCompares each GNSS fix with an inertial position and flags a disagreement above 50 m. Given an independent inertial position, it flagged a simulated 0.5 m/s drag-away once the offset reached 50 m.
Jamming Flags
IMPLEMENTEDFlags a C/N0 drop of more than 10 dB against a rolling baseline, an AGC rise above 20, or the satellite count falling below four.
Mode Switching
IMPLEMENTEDEach update picks a navigation mode: full GNSS, degraded GNSS, inertial-only, or holdover when a jam or spoof is flagged. After 300 s in holdover or inertial-only, the status drops to denied (alert while a threat is still flagged).
Hash-Chained Event Log
IMPLEMENTEDEach spoofing flag, jamming flag and mode change is appended to a SHA-256 hash chain. Verification flags an entry whose hashed fields were edited.
Integrity Status
IMPLEMENTEDEach update also carries a status (nominal, caution, holdover, alert or denied) and the list of active faults, so the operator sees why the mode changed.
The Problem: A Receiver Rarely Says It Is Wrong
GNSS jamming and spoofing are reported by ships and aircraft in several regions. The fix on screen can look normal while it is not.
Drag-Away
A spoofer can move the reported position a little at a time, so no single update looks wrong. Only an independent reference, such as inertial navigation, disagrees.
Silent Degradation
Jamming lowers signal strength and drops satellites. A receiver can keep reporting a position long after it should have stopped being trusted.
Little Record
After an incident, few systems can show what the receiver reported, what was flagged, and when the navigation source changed.
First Pilot Domain: Maritime
A pilot replays your own recorded GNSS and IMU data through NavCore and reports what it flags, when, and what it misses. No figure is promised before the data is in.
Maritime
Integrity checks for vessels that sail through interference
Threats
- GNSS jamming and spoofing reported in the Black Sea, the eastern Mediterranean and the Gulf
- Slow drag-away that no single update reveals
- Little record of what the receiver reported during an incident
What NavCore Runs
- Checks: position and clock jumps, C/N0 and AGC, satellite count, and the GNSS vs inertial cross-check
- Continuity: full GNSS, degraded, inertial-only or holdover, with a 300 s holdover limit
- Record: a SHA-256 hash-chained event log held in memory; persistent storage is pilot scope
What a Pilot Measures
- Which of your recorded jamming and spoofing events NavCore flags, and how late
- How many flags it raises on clean passages, including after GNSS outages
- How far the inertial estimate drifts on your IMU during holdover
- Whether the event log answers the questions your incident reviews ask
What NavCore is not: it does not optimise routes, fuel or weather routing, and it does not replace type-approved navigation equipment.
Not in NavCore Today
Listed so nobody buys it for something it does not do.
Capabilities
- No Galileo OSNMA authentication. The OSNMA code is research only.
- No protection levels and no satellite exclusion.
- No receiver drivers and no NMEA or AIS ingest. Connecting a receiver is pilot work.
- No hosted API. The integrity monitor runs as a library; it is not served over HTTP today.
- No published detection rate, false-alarm rate or accuracy figure, because none has been measured on real signals.
- No quantum-sensor integration. The code’s quantum mode is never selected.
Standards and Approvals
NavCore is not certified and holds no type approval. It has not been assessed against IEC 61108, IMO performance standards for navigation equipment, or any aviation or railway standard.
Any standards work would follow a pilot, not precede it.
Have recorded voyage data?
Send us a passage with known interference. We replay it through NavCore and show you every flag, every mode change and every miss.