GPS jamming and spoofing: what fleet operators need to know

Jamming and spoofing are not the same problem

Both attack the same weakness: GNSS signals arriving from roughly 20,000 km away are extremely weak by the time they reach a receiver, so even a low-power transmitter nearby can overwhelm them.

Jamming

A denial-of-service attack. Radio noise on the GNSS frequencies drowns out the satellites and the receiver loses lock. The device knows it has no fix, and typically reports a loss of position.

Spoofing

A deception attack. A transmitter broadcasts counterfeit satellite signals, and the receiver computes a position that is wrong but internally consistent. The device does not know anything is wrong, and neither does anything downstream.

Why this stopped being a military-only concern

GNSS interference has moved from a specialist concern to a mainstream operational risk. In March 2025, ICAO, the ITU and the IMO issued a joint statement expressing grave concern that jamming and spoofing had become an urgent threat to safety and to international commerce. In January 2026, thirteen European states and Iceland issued a joint warning about interference in Baltic and North Sea shipping lanes.

Reporting through early 2026 documented interference affecting well over a thousand vessels in the Gulf region within single 24-hour windows, with positions systematically displaced rather than merely lost — vessels appearing to transit over land, or clustering around inland points.

The relevance to a Singapore land fleet is indirect but real. The techniques and the equipment are now widely available, the effects propagate into any system that treats satellite position as authoritative, and operators with vessels or cross-border vehicles transiting affected corridors are already exposed.

What it looks like in fleet data

In telemetry, interference tends to show up as one of a small number of signatures:

• Position jump. A vehicle appears to move several kilometres between consecutive reports, at a speed no road vehicle achieves.
• Implausible speed. Reported speed inconsistent with the distance actually covered, or with the engine and odometer data from the same device.
• Satellite count collapse. A sudden drop in the number of satellites used, often with degraded dilution of precision, across several vehicles in the same area at the same time.
• Static drift. A parked vehicle wandering across the map while the ignition is off.
• Correlated anomalies. Several unrelated vehicles showing the same displacement at the same moment — the strongest single indicator that the cause is external rather than a faulty unit.

That last point is why detection works better at platform level than on the device. A single tracker cannot tell whether it is broken or being deceived. A platform watching a thousand devices can.

The cheap jammer problem

Most interference a Singapore fleet will actually encounter is not geopolitical. It is a personal privacy device — a cheap plug-in jammer bought online and put in the cigarette lighter socket by a driver who does not want to be tracked on a particular afternoon.

These devices are illegal to operate in most jurisdictions, including Singapore, and they do not discriminate: one in a cab will also affect vehicles alongside it in traffic and can interfere with nearby infrastructure.

From a management point of view the signature is distinctive — repeated, short, localised loss of fix on the same vehicle, often at the same time of day, with clean data either side. That is a pattern worth looking for, and it is usually invisible unless someone is looking.

How position integrity is checked

Integrity checking means treating each reported position as a claim to be tested rather than a fact to be stored. In practice, layered checks:

1. Kinematic plausibility. Is the implied speed and acceleration physically possible for this vehicle type?
2. Signal quality. Satellite count and dilution of precision compared against the device's own baseline.
3. Cross-sensor consistency. Does the position agree with ignition state, odometer and accelerometer?
4. Spatial correlation. Are other devices in the same area showing the same anomaly at the same time?
5. Flag, do not discard. The suspect record is retained and marked, not deleted. Deleting it destroys the evidence that something happened.

iTrack runs anomaly detection of this kind across the platform, covering position jump, speed implausibility and satellite-count checks, with flagged events surfaced rather than silently absorbed into your history.

What a fleet operator should ask a vendor

• Does the platform detect anomalous positions, or does it store whatever the device reports?
• When a signal is suppressed, do I get an alert, or just a gap in the report?
• Is a flagged position retained and marked, or discarded?
• Can you show me an example of a detected event from a real account?
• Does detection run per-device only, or across devices in the same area?

The last question is the most revealing. Cross-device correlation is the difference between noticing a broken tracker and noticing an attack.