Event confidence

High — dual signal, CEP <20km
Medium — CEP 20-100km
Low — complex environment

Actor (L2 estimate)

Houthi / Hudayda
Coalition naval
Iranian / Gulf of Aden
Unclassified
Zones shown as dashed borders

Display filters

Show zones
High confidence only
Validated attacks
Time range
Events
Dual-signal
Zones active 8
Data through
Free tier — data delayed 24h
Built by Harry Ellis  ·  Data: NASA PO.DAAC CYGNSS L2
GNSS Live

What is GNSS Live

GNSS Live monitors electromagnetic anomalies in the world's most strategically important maritime chokepoints using NASA's CYGNSS satellite constellation. When military radar, electronic warfare systems, or unusual vessel activity disturbs the RF environment over the ocean surface, CYGNSS detects it.

The platform provides passive civilian satellite intelligence derived entirely from publicly available NASA data — no classified sources, no proprietary sensors.

Validated results

Anomaly spikes have been independently validated against confirmed Houthi attack events across the October 2023 — October 2025 campaign period.

DateEventMatch
27 Nov 2023Missiles at USS MasonConfirmed
13 Dec 2023Ardmore Encounter attackConfirmed
15 Dec 2023Maersk suspends opsConfirmed
01 Jan 2024Iranian warship AlborzConfirmed
16 Jan 2024Post-Poseidon ArcherConfirmed
19 Feb 2026Houthi mobilisationConfirmed

Detection performance

TierLift vs baselineNear-attack rate
All events2.6x36.6%
Dual-signal only3.6x50.0%

Baseline rate: 13.8% (random chance)

Data source

CYGNSS Level 2 Science Data Record V3.2, sourced from NASA PO.DAAC under Creative Commons Zero licence. Each daily file contains all eight satellite observations merged into a single NetCDF file (~150MB). The Red Sea bounding box (lat 11-20°N, lon 41-45°E) yields approximately 5.3 valid observation hours per day.

Primary signal — NBRCS anomaly

The Normalised Bistatic Radar Cross Section (NBRCS) measures GPS signal reflectivity from the ocean surface. Elevated NBRCS relative to a 24-hour rolling baseline indicates unusual electromagnetic conditions — consistent with military radar, electronic warfare systems, or abnormal vessel traffic.

A rolling z-score is computed per hour against a 24-hour window. Events exceeding z > 1.5 are flagged as anomalies.

Dual-signal confirmation

Inspired by Gorman (GPS World, May 2026), a second detection channel uses cross-channel NBRCS variance — the standard deviation of NBRCS readings across the five DDM channels within each observation. When a jammer is active, channels disagree significantly, elevating this variance independently of the mean signal level.

Events where both channels fire simultaneously are flagged as dual-signal — the highest confidence detection tier with 3.6x lift over baseline.

Jammer localisation

For significant events, a parametric 1/r² inverse-distance model is fitted to the spatial distribution of anomalous observations. The source position is optimised using SciPy Nelder-Mead. Confidence is reported as CEP — circular error probable — estimated via 200-iteration bootstrap resampling.

L1 reactive download is triggered for events above z > 2.5, enabling four-method detection (noise floor, spatial grid, SNR hole, NBRCS drop) and sub-20km localisation accuracy.

Limitations

CYGNSS covers latitudes 38°N to 38°S. Coverage above 38°N (Ukraine, Baltic, Nordic) is not available from this data source. Localisation accuracy varies from <15km on clean single-source days to >100km on multi-source or low-observation days. All classifications are probabilistic estimates, not confirmed attributions.

Base URL

https://api.gnsslive.io/v1

All endpoints return JSON. Authenticate with your API key in the request header.

Authentication

# Include in every request X-API-Key: your_api_key_here

Endpoints

# Latest anomaly events per zone GET /anomalies ?zone=red_sea &confidence=dual # high | dual | all &limit=100 # Zone risk scores (current) GET /zones # Jammer location estimates GET /locations ?date=2024-01-16 &source=l1 # l1 | l2 # Validated attack events GET /events/validated

Example response — /anomalies

{ "timestamp": "2024-01-16T12:00:00Z", "zone": "red_sea", "snr_anomaly_score": 4.566, "cross_channel_anomaly": 2.134, "combined_anomaly": 3.891, "dual_signal": true, "confidence": "HIGH", "obs_count": 15, "est_lat": 19.09, "est_lon": 39.71, "cep_km": 32.0, "probable_source": "Coalition naval" }

Contact

For API access, enterprise data feeds, or custom zone coverage — contact harry@gnsslive.io

Access tiers

Free
£0 /month
  • Historical map — all zones
  • 24h data delay
  • Event validation overlay
  • Jammer location estimates
  • No API access
Beta — How to join
GNSS Live is currently in private beta. If you work in maritime intelligence, shipping operations, commodity trading, or defence research and want early access to the live API, get in touch directly. harry@harryellisdev.co.uk

Data policy

All derived intelligence is produced from NASA CYGNSS data (CC0 licence). Source data attribution required. No warranty on accuracy — all classifications are probabilistic estimates for situational awareness only.