RF and signal monitoring

The radio spectrum, mapped from orbit.

ADS-B aircraft tracking from space — LEO satellites receive 1090 MHz ADS-B transmissions to track aircraft over oceans and polar regions where ground radar cannot reach. Aireon, hosted on Iridium NEXT, is the only fully operational global system with published performance data.
Mode S extended squitter anomaly and spoofing detection from LEO — Space-based receivers collecting Mode S extended squitter messages from multiple orbital vantage points can cross-validate message authenticity using TDOA geometry, kinematic physics and ICAO address consistency, catching spoofed or manipulated ADS-B traffic that ground networks routinely miss.
ACARS aeronautical datalink monitoring from LEO — Space-based receivers can collect VHF ACARS, HFDL, and VDL Mode 2 traffic far beyond ground-station range, filling the oceanic gaps that radar and ATC simply cannot reach. This page explains the physics, the variants, the decode limits, and what the data is actually good for.
AIS dark vessel detection from orbit — Spaceborne AIS captures what vessels choose to broadcast; SAR captures what is actually there. The gap between those two layers is where dark vessels live.
AIS message spoofing and manipulation pattern analysis — Fabricated AIS messages, phantom vessels and MMSI cloning are detectable by cross-referencing spaceborne AIS reception with SAR imagery and RF geolocation. Temporal and geometric inconsistencies in message sequences expose manipulation that shore-based AIS alone cannot resolve.
Counter-UAS jammer and RF suppressor geolocation from orbit — Ground-deployed counter-UAS jammers broadcast across ISM bands that LEO RF-monitoring satellites can detect and geolocate. This page explains the physics, the methods, and the honest limits of doing that from orbit.
Cellular base station RF mapping in conflict and denied-access zones — Spaceborne RF sensors can detect, geolocate and track the operational status of GSM, LTE and 5G NR base stations without ground access, turning signal presence or absence into intelligence about infrastructure destruction, relocation or deliberate suppression.
DAB and DVB-T digital broadcast signal monitoring from orbit — Spaceborne RF receivers can detect, geolocate and fingerprint DAB and DVB-T transmitters by exploiting their OFDM pilot-tone structure, enabling regulators to verify compliance, resolve cross-border interference disputes and identify unlicensed transmitters without ground-based inspection.
Unmanned aerial vehicle RF control link detection from orbit — Spaceborne RF receivers can intercept UAS command-and-control and video downlink transmissions, but the physics is unforgiving. This page sets out what is genuinely detectable, under what conditions, and where the method runs out of road.
Aviation ELT distress signal detection from LEO — 406 MHz Emergency Locator Transmitters alert the Cospas-Sarsat constellation when aircraft crash or declare distress. LEO geometry, false-alarm rates and terrain masking all shape how quickly that alert becomes a rescue.
False-alert discrimination for 406 MHz distress beacons from LEO — More than 97% of 406 MHz EPIRB and PLB activations processed by Cospas-Sarsat are false alerts. Spaceborne RF receivers can cross-check signal fingerprints, registration records and positional context to help rescue coordination centres triage faster.
EPIRB and PLB signal detection from orbit — The Cospas-Sarsat system turns 406 MHz distress transmissions into geolocated alerts via LEO Doppler processing and MEO near-instantaneous relay. Understanding its geometry, latency and gaps is essential for any government operating search-and-rescue coordination.
Fishing vessel activity inference from RF fingerprinting — Passive RF detection from low Earth orbit can locate fishing vessels that have disabled or never carried AIS, by capturing navigation radar pulses, VHF traffic, and fish-finder emissions. Vessel-type inference from RF signatures alone is probabilistic, not definitive, and this page explains exactly where the confidence holds and where it does not.
GNSS jamming zone mapping from space — Deliberate GNSS jamming raises the L-band noise floor across wide areas. Spaceborne RF receivers can detect, geolocate and map those elevated noise zones in near-real-time, giving governments and operators a picture that no ground network alone can provide.
Ice sheet surface altimetry via GNSS reflectometry from LEO — Reflected GNSS signals collected by nadir-pointing LEO antennas reveal ice-sheet surface elevation and roughness. Vertical precision reaches tens of centimetres over flat ice but degrades sharply over crevassed or heavily sastrugi terrain.
Soil moisture retrieval from GNSS reflectometry — Reflected GPS and GLONASS signals carry a measurable imprint of surface dielectric constant, allowing near-surface volumetric soil moisture to be retrieved at basin scale from low Earth orbit, without an active radar transmitter.
Ocean surface wind speed retrieval via GNSS reflectometry — Reflected GPS and Galileo signals carry a measurable imprint of ocean roughness. GNSS-R turns that accidental return into wind speed and wave height at roughly 25 km resolution, globally, with no transmitter of your own.
GNSS spoofing event detection and attribution — GNSS spoofing displaces reported positions while leaving a physical trace detectable by SAR and multi-constellation signal analysis. This page covers detection methods, documented incidents, and honest limits.
HF skywave emitter monitoring from low Earth orbit — High-frequency transmissions bounce off the ionosphere, confounding ground-based direction-finding. Spaceborne receivers intercept the direct upward wave before refraction, enabling geolocation that ground networks cannot reliably achieve alone.
Illegal and unlicensed broadcast transmitter detection — Spaceborne wideband receivers can detect and geolocate HF, VHF, and FM broadcast transmitters operating outside licensed frequency, power, or geographic limits. This page explains the physics, the sensors, and the hard limits regulators need to understand before commissioning a campaign.
Uplink interference geolocation using TDOA and FDOA from GEO pairs — When a terrestrial emitter interferes with a GEO satellite uplink, time and frequency differences across two or more satellites can triangulate its position. This page explains the geometry, the error sources, and what commercial services can and cannot resolve.
Interference into radio astronomy protected bands from LEO — ITU-protected radio astronomy bands are being measurably degraded by LEO constellation emissions and terrestrial leakage. This reference covers how interference is characterised, quantified and attributed using ground observatory monitors and space-based RF sensors.
Ionospheric scintillation monitoring via GNSS from LEO — Plasma bubbles in the ionosphere cause GNSS signal amplitude and phase fluctuations that can ground aircraft, disrupt precision agriculture and mimic jamming. LEO radio-occultation constellations now map scintillation events globally, giving operators the evidence to tell space weather from hostile interference.
L-band mobile satellite service congestion and occupancy monitoring — Spaceborne RF scanners can measure power spectral density across the 1–2 GHz L-band from LEO, exposing congestion, unauthorised access and interference events in mobile satellite service allocations that ground-based monitoring consistently misses.
LORAN and Chayka navigation transmitter monitoring from orbit — LEO RF payloads can detect 90–110 kHz LF skywave emissions from LORAN-C and Chayka stations, revealing operational status, pulse-timing drift, and unexpected activations that ground-based monitoring networks miss.
Terrestrial LTE and GSM coverage mapping from LEO — Spaceborne SDR receivers detect LTE and GSM downlink emissions beyond their intended service areas, providing an independent audit of operator coverage claims and flagging unplanned cross-border signal spillage.
Shipborne radar activity monitoring from orbit — Passive detection of X-band and S-band navigation radar emissions from LEO satellites can confirm ship presence and operational status independently of AIS, exposing vessels that are dark by choice rather than by accident.
Military tactical datalink emission detection from orbit — Spaceborne wideband RF sensors can detect the presence and approximate location of military tactical datalink emissions such as Link 16 without decrypting them. This page covers what the open literature says about detection physics, geolocation accuracy, revisit limits, and why the application sits in legally and diplomatically sensitive territory.
RF activity signature monitoring near nuclear facilities — Space-based RF sensing can characterise emission patterns around nuclear sites, flagging state changes that optical and SAR imagery alone may miss. Ambiguity is real; multi-source corroboration is mandatory.
Offshore platform and subsea cable RF activity monitoring — Fixed offshore infrastructure emits predictable RF signatures. When those signatures change or disappear, spaceborne RF monitoring can catch it before a vessel inspection ever reaches the site.
Over-the-horizon radar waveform detection and classification from LEO — HF over-the-horizon radars broadcast distinctive chirp and FMCW signatures across thousands of kilometres of skywave path. LEO wideband receivers can detect, classify and schedule-track those emissions, within the real limits imposed by ionospheric geometry and networked emitter ambiguity.
P-band and UHF foliage-penetration emitter detection from orbit — Low-frequency emitters in dense forest are effectively invisible to ground direction-finding networks, yet their signals propagate upward with little canopy loss. Spaceborne RF receivers at LEO can intercept these emissions and geolocate sources using time-difference-of-arrival across clustered satellites.
Passive bistatic radar detection using LEO satellite signals of opportunity — Passive bistatic radar uses LEO satellite downlinks as uncooperative illuminators to detect aircraft, ships and ground targets without emitting a single watt. The technique is experimentally promising but operationally immature, and the signal-to-noise arithmetic is brutal.
ADS-B coverage gap characterisation over polar routes — Ground radar and VHF radio fade out above roughly 78°N. Space-based ADS-B receivers on Iridium NEXT and Spire LEMUR-2 satellites now quantify exactly where surveillance gaps remain, and by how much, informing ICAO performance-based requirements for polar route approval.
Push-to-talk VHF/UHF radio geolocation from space — Short-duration VHF/UHF push-to-talk radios are hard to fix from orbit precisely because they are brief and unpredictable. Multi-satellite TDOA/FDOA geometry can locate them, but only when the intercept probability problem is solved first.
Radar emitter geolocation from low Earth orbit — Passive RF-sensing satellites can fix the position of ground-based and shipborne radar transmitters without illuminating them, using time- and frequency-difference-of-arrival geometry across multi-satellite formations. Accuracy, revisit and ambiguity limits depend heavily on constellation geometry and emitter behaviour.
Railway signalling RF interference detection from LEO — LEO RF monitoring satellites can scan entire national rail corridors for GSM-R interference in hours, not weeks. Ground survey teams are fast at confirmation; they are slow at discovery.
Radio frequency interference mapping in SAR imagery — Ground-based transmitters in or near the C- and L-band SAR operating windows inject bright streaks and range-ambiguity artefacts into satellite radar imagery. Characterising that contamination reveals both where emitters sit and how to suppress them.
Satellite communications interference source location — Uplink interference, whether accidental cross-polarisation or deliberate jamming, can be geolocated by comparing the time and power differences of the same signal arriving at adjacent satellites. This page covers the physics, the published ITU procedures, and the practical limits of the method.
Satellite phone uplink geolocation from LEO intercept geometry — Passive intercept of L-band and S-band satellite phone uplinks from LEO platforms can geolocate a transmitting handset to within a few kilometres by exploiting the Doppler curve and time-difference geometry produced by a fast-moving receiver against a stationary emitter.
Correlation of AIS tracks with VHF voice radio activity from ships — Space-based VHF receivers can geolocate maritime voice transmissions to 5–15 km and compare that fix against AIS-declared positions. Where the two diverge, fraud is the most likely explanation.
VHF Data Exchange System (VDES) signal monitoring from orbit — VDES is the IMO-standardised successor to AIS, offering higher data rates and two-way satellite links in the 157–158 MHz band. Space-based receivers can already track adoption rates, coverage gaps, and protocol compliance, even though operational deployments remain sparse in the mid-2020s.
Ground-based space surveillance radar emission monitoring from orbit — High-power ground-based space surveillance radars emit signals detectable by RF receivers in LEO. Characterising their waveforms, frequencies, and duty cycles from orbit reveals operational tempo and mode changes, with significant caveats around classification and ambiguity.
VHF and UHF spectrum occupancy surveys from orbit — Wideband SDR payloads in LEO measure how densely VHF and UHF spectrum is occupied across entire regions in a single pass, revealing usage patterns no terrestrial monitor network can replicate at comparable scale.
Tactical military SATCOM uplink band occupancy monitoring — Space-based RF monitoring of the 292–317 MHz UHF MILSATCOM uplink band can characterise spectrum occupancy, flag unauthorised emitters and locate interference sources, without decoding a single protected message.
Shipborne radar type classification from spectral signatures — Space-based RF receivers can classify the type of radar fitted to a vessel by measuring pulse repetition frequency, bandwidth, and carrier frequency from LEO, providing an independent check on AIS-declared vessel type.
Meteorological wind profiler radar emission mapping from orbit — Ground-based wind profiler radars operating between 400 and 1300 MHz cause documented interference into adjacent mobile and satellite bands. Spaceborne RF sensors can map their locations, duty cycles and emission patterns without ground access.