NetSim Astra
Constellation visualization · Link budget · RF coverage
NetSim Astra is a web-based studio for satellite constellation visualization, link-budget analysis, and coverage prediction. Built on a CesiumJS 3D globe, it lets you design synthetic constellations, track live satellites from TLEs, and evaluate RF coverage with detailed link budgets, all from your browser.
Watch the overview
A short tour of RF planning and coverage analysis for satellite networks in NetSim Astra: constellations, link budgets, and coverage on the 3D globe.
▶
NetSim Astra overview: RF planning and coverage for satellite networks
What you can do with it
From constellation design to a per-point link budget, on an interactive 3D globe with CSV export.
3D globe visualization
Interactive CesiumJS globe with satellite orbits, ground markers, heatmap overlays, and footprint polygons, with playback for time-series results.
Link budget analysis
Full link budget: EIRP, free space path loss, antenna pattern gain, clutter, polarization, and ITU-R P.618 atmospheric losses.
Coverage prediction
Animated coverage heatmaps over a region at configurable grid resolution. Click any point for a full link-budget breakdown.
Point & footprint
Track received power at a fixed location over time, and map per-satellite coverage footprints from an Rx-power threshold.
Point analysis: satellite tracking and the ground link on the 3D globe.
Constellation sources
Four satellite sources, each compatible with the point, coverage, and footprint analyses.
Walker constellation
Generate Walker Delta or Star constellations with configurable planes, satellites per plane, altitude, and inclination for design studies.
Real satellites (TLE)
Track Starlink, OneWeb, GPS and more using live TLE data from CelesTrak or N2YO, with a configurable polling interval.
Single fixed satellite
Place a stationary satellite at any position for antenna-pattern testing and deterministic, single-timestep coverage analysis.
Geostationary orbits
Analyze GEO and inclined geosynchronous satellites by manual entry, presets (INSAT/GSAT), or live TLEs. GEO adds multibeam CINR.
The configuration form: choose a source, then set orbital and RF parameters.
Analysis modes
Pick a constellation source and an analysis type. Synthetic and live sources add a timeline; fixed and GEO sources compute a static snapshot.
| Mode | Source | Analysis | Output | Timeline |
|---|---|---|---|---|
| 1 | Synthetic Walker | Point analysis | RSSI plot + CSV | Scrub / replay |
| 2 | Synthetic Walker | Coverage prediction | Heatmap + CSV | Playback |
| 3 | Live TLEs | Point analysis | Real-time RSSI + CSV | Live |
| 4 | Live TLEs | Coverage prediction | Live heatmap + CSV | Live |
| 5 | Synthetic Walker | Satellite footprint | Footprint polygons + CSV | Playback |
| 6 | Live TLEs | Satellite footprint | Live footprint polygons + CSV | Live |
| Fixed | Fixed satellite | Any of the three | Snapshot + CSV | Static |
| Multibeam | GEO (manual) | Multibeam CINR | CINR heatmap + CSV | Static |
Multibeam CINR
For GEO satellites entered manually, evaluate multi-beam payloads with frequency reuse (FR1–FR4). CINR heatmaps reveal co-channel interference and signal quality across the service area.
Service-area boundaries
Per-satellite coverage polygons show instantaneous service areas from a configurable Rx-power threshold, in both synthetic playback and live modes.
Live footprint: per-satellite coverage polygons on the 3D globe.
Link budget and RF modelling
A full link budget from the satellite EIRP down to received power at the ground terminal, with configurable antennas, bands, and propagation.
Received power
- EIRP, receive gain, and antenna pattern gain at the off-axis angle
- Free space path loss, clutter, polarization, and additional losses
- Click any heatmap point for the full breakdown
RF parameters
- TX power, antenna gain, EIRP, RX gain, system margin
- Bands: L, S, X, Ku, K, Ka, Q/V
- Additional losses and polarization loss
Antenna pattern models
- Gaussian: simplified analytical model
- Bessel (3GPP TR 38.811): circular aperture
- ITU-R S.672-4: FSS reference pattern
- Phased array (URA): beam shaping for 5G NTN
ITU-R P.618 propagation
- Rain fade and gaseous absorption
- Cloud attenuation and tropospheric scintillation
- Link availability via exceedance conversion
Clutter loss
- Terrain attenuation from ESA WorldCover land classes
- From 0.5 dB over water to 8 dB in built-up areas
- Applied per ground point in coverage grids
Off-axis & elevation
- Antenna gain evaluated at the true off-axis angle
- Minimum elevation mask for visibility
- Slant range and geometry from satellite position
Link quality and dynamics
Beyond received power, assess whether a link will close, and how it moves with the satellite.
Carrier-to-noise
Carrier-to-noise density ratio (C/N₀, dB-Hz) and carrier-to-noise ratio (C/N, dB) from the receiver system noise temperature and channel bandwidth, to judge whether a link will close, not just its signal strength.
Figure of merit
Receiver figure of merit (G/T, dB/K) from receive gain and system noise temperature, to compare receiver and antenna configurations. A default 290 K is used when no temperature is specified.
Frequency shift
Doppler shift from the radial velocity between satellite and ground station. Positive when approaching, negative when receding; a 550 km LEO satellite reaches roughly ±40 kHz at Ku-band.
Under the hood
The geometry and orbital mechanics behind every position, angle, and loss.
Coordinate reference frames
Positions and angles are computed across Earth-Centered Earth-Fixed (ECEF), East-North-Up (ENU), and Local-Vertical-Local-Horizontal (LVLH) antenna frames.
SGP4 orbit propagation
Live satellites are propagated from their TLEs using the SGP4 model, then transformed to ground-relative geometry for elevation, slant range, and off-axis angle.
Time-stepped analysis
Synthetic scenarios step through a configurable simulation window; live scenarios poll in real time. Each step yields a full link budget per ground point.
Projects and reproducibility
Save a study, share it, and reproduce it exactly, even when live TLEs have moved on.
Save and load projects
Store a complete configuration, constellation, RF parameters, and analysis settings, as a JSON project, then reload it with every field repopulated.
TLE storage
Save live TLEs with their capture time and source alongside the project. Reload with the saved TLEs for identical positions, or fetch fresh ones for the current sky.
Record and replay
Record a live session and replay it later exactly as captured, with the same playback and scrubbing controls as synthetic runs.
Outputs and results
Interactive on the globe, and exportable for offline analysis.
Interactive 3D globe
- Heatmaps, footprint polygons, satellite markers, and ground links
- Click any heatmap point for satellite ID, Rx power, elevation, distance, gain, and losses
- Playback for synthetic modes: play/pause, restart, speed 1x–50x, timeline scrubbing
- Recording controls for live modes with elapsed and total time
CSV export
point_analysis.csv– received power time seriescoverage_grid.csv– per-point coverage resultssatellite_footprint.csv– footprint boundariesmultibeam_cinr.csv– CINR per beam- Link-quality fields included: C/N₀, C/N, G/T
Access report: the detailed link-budget metrics behind each pass.
Related product
Take it to packet-level simulation
Where NetSim Astra plans the constellation, link budget, and RF coverage, NetSim NTN simulates the protocol stack and traffic end-to-end. Use the two together to move from coverage design to measured throughput, latency, and error performance.
- Standards-based 5G NTN protocol simulation
- End-to-end, packet-level traffic and performance
- Throughput, latency, and error metrics per beam
Related and useful links
From coverage planning to packet-level simulation and enterprise network design.