The signal intelligence features derive intelligence from secondary analysis of ADS-B transponder data and aggregate public radio scanner infrastructure.
GPS jamming detection
The GPS Jamming layer detects active GPS interference zones by analyzing the NAC-P (Navigation Accuracy Category — Position) value broadcast by ADS-B-equipped aircraft.
What NAC-P measures
NAC-P is a 4-bit field in the ADS-B message that indicates the estimated position accuracy of the aircraft’s GPS receiver:
| NAC-P value | Estimated accuracy |
|---|
| 11 | < 3 meters (HPL) |
| 10 | < 10 meters |
| 9 | < 30 meters |
| 8 | < 0.05 NM (~93 m) |
| 7 | < 0.1 NM |
| 6 | < 0.3 NM |
| 5 | < 0.5 NM |
| 4 | < 1 NM |
| 3 | < 2 NM |
| 0–2 | > 2 NM or unknown |
Detection method
- Every ADS-B position report includes the aircraft’s current NAC-P value.
- Aircraft positions are aggregated into a geographic grid. Each grid cell accumulates the NAC-P reports from all aircraft that have flown through it.
- Grid cells where a statistically significant proportion of aircraft report degraded NAC-P are flagged as jamming zones.
- The frontend renders flagged cells as red overlay squares with a label showing GPS JAM XX% — the percentage of aircraft in that cell reporting degraded accuracy.
Interpretation
- A high severity % (e.g.,
GPS JAM 85%) indicates that most aircraft in that area are experiencing GPS degradation, consistent with active jamming or spoofing.
- Jamming zones frequently appear near active conflict areas, sensitive military installations, and certain border regions.
- Isolated low-severity cells may reflect individual aircraft GPS faults rather than environmental jamming.
GPS jamming detection is derived from civilian ADS-B traffic density. Areas with very low aircraft traffic may show inconclusive results due to insufficient sample size.
Update cadence
Jamming analysis runs as part of the fast-tier scheduler every 60 seconds, using the same ADS-B dataset as the aviation layers.
Radio Intercept Panel
The Radio Intercept Panel provides a scanner-style UI for monitoring communications. It is accessible from the right-side SIGINT panel.
Panel features
- KiwiSDR tuner — click any KiwiSDR receiver on the map to open an embedded live SDR tuner for that node
- OpenMHz trunked radio — automatically finds the nearest P25 trunked radio systems by distance from the current map center and streams recent audio bursts
- Broadcastify feeds — shows the current Broadcastify Top 50 scanner feeds with listener counts and direct stream playback
See the SDR radio layer documentation for full details on each radio source and its data pipeline.
Cross-reference active GPS jamming zones with KiwiSDR receiver locations. A KiwiSDR node inside a known jamming zone may exhibit degraded HF reception or unusual noise floor characteristics consistent with broadband interference.