Meaconing receives genuine navigation signals and retransmits them after a delay. A GNSS receiver that accepts the relayed signals can use the wrong arrival times and produce misleading position or time—even though the original satellite message content has not been rewritten. It is commonly treated as a form of spoofing. Unlike ordinary jamming, its significance is not limited to preventing reception.
For a system integrator, this explains why “signals tracked,” “message authentic” and “navigation trustworthy” answer different questions. Understanding the mechanism helps define which behavior a receiver or protection proposal needs to demonstrate.
GNSS measures arrival time as well as reading data
GNSS is not simply a radio service that sends a receiver its location. The receiver uses signal timing to form distance-related observations and combines observations from satellites to estimate its position and clock offset. ESA's GNSS Basic Observables explains pseudorange as signal travel time multiplied by the speed of light, including clock and propagation effects.
Relaying adds a path and delay that are not the direct satellite-to-receiver path. The timing observed by the receiving equipment can therefore be inconsistent with its actual location. NovAtel's explanation of meaconing describes retransmission of received signals and the effect of changed relative delays. This is the mechanism; it does not specify how a particular ResiNav configuration responds.
Not every added delay translates into the same position displacement. The receiver estimates its clock offset as well as position. In a simplified measurement model, a common added delay can be absorbed into that clock term, while changes in relative measurements can affect the position solution. The outcome also depends on which direct and relayed observations are accepted. “Delay × speed of light” describes an apparent-range contribution, not a universal formula for horizontal position error.
Compare the mechanisms, not just the map symptom
| Mechanism | What changes at reception | Why the distinction matters |
|---|---|---|
| Jamming or other RF interference | Unwanted RF energy degrades reception or processing of wanted signals | Loss of tracking is relevant, but a noise-interference test does not demonstrate rejection of relayed navigation signals |
| Synthesized spoofing | Fabricated GNSS-like signals can supply misleading measurements or data | The receiver must assess more than whether a signal can be tracked |
| Meaconing | Genuine received signals are relayed with altered arrival timing | Unchanged message content does not establish that the receiver observed the correct propagation path |
These are explanatory categories, not three mutually exclusive field-event labels. A real event may involve more than one mechanism. Septentrio's anti-spoofing overview describes meaconing and also notes that unintended leakage from a repeater or test setup can produce misleading navigation. An unexpected position is therefore an observation to investigate, not evidence identifying an attacker or a particular device.
Why authentic message content is only part of the answer
Navigation-message authentication checks the origin and integrity of specified data. It does not mean that every property of the received waveform, its path or the complete navigation solution has been authenticated.
That does not make authentication pointless. EUSPA's OSNMA description explains both authentication of Galileo navigation data and added signal unpredictability that makes replay more difficult. A receiver must implement the specified processing requirements. It would be equally misleading to say that authentication defeats every relay condition or that it offers no help against replay-related threats.
For the receiver selection, distinguish the service scope from the implementation and the evaluated condition. The existing OSNMA purchase guide covers supported data, provisioning and output-policy boundaries. Here the additional point is physical: authentic data and trustworthy arrival-time measurements are related, but different, parts of the navigation problem.
What useful detection evidence looks like
Different checks examine different evidence. Septentrio describes timing and signal-consistency checks alongside authentication and system-level comparisons. NovAtel's detection description describes using several detection metrics in its signal-processing chain. These are manufacturer-specific approaches; neither establishes a universal detector or a feature supplied by ResiNav.
A useful evaluation distinguishes three outcomes: the receiver detected a suspect condition; the navigation output remained within the agreed error requirement; and the consuming equipment handled the indication correctly. One does not automatically establish the others. A warning issued after a misleading output has already been consumed is different from an earlier warning, even if both test reports say “detected.”
Hypothetical review example: two demonstrations include a receiver displaying a position. The first reports a successful alarm during a specified noise-interference condition. The second documents a controlled relayed-signal scenario, a reference position and time, the receiver's outputs and a time-aligned alert record. The first supports its interference-alarm claim, but it does not answer the relay question. The second supplies relevant evidence for that question; the recorded error and alert timing still determine whether it meets the agreed requirement. Neither is a ResiNav result.
The receiver evaluation guide covers how to retain the configuration, baseline, output and recovery record. Use authorized controlled testing. This article explains the defensive evaluation question, not how to build or operate a signal-replay device.
Translate the threat description into the product discussion
If a brief says only “anti-jamming,” do not assume it includes a demonstrated response to misleading relayed signals. If the concern includes misleading position or time, state that anti-spoofing behavior is also part of the discussion and identify the condition to be evaluated. The distinction is about required behavior, not a ranking of antenna element counts or a claim that one technology solves every threat.
ResiNav supplies GNSS protection products under its own brand. Use the published product catalogue to compare anti-jamming and combined anti-jamming/anti-spoofing product records, then continue through the relevant model's enquiry path. A combined product description is a reason to discuss that scope; it is not, by itself, a documented meaconing test, authentication implementation or compatibility guarantee.
The key lesson is straightforward: preserving the satellite's message does not preserve the original signal journey. Compare evidence for the reception and navigation behavior you need, rather than accepting either a strong signal display or an authentication label as the whole answer.
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Turn available platform information into an engineering review.
Use the Technology centre to frame the discussion, review relevant application scenarios, then send the available platform and receiver details for confirmation.