How do I design a ground station receiver for a LEO satellite constellation like Starlink or OneWeb?
LEO Ground Station
The handover process: as one satellite sets below the useful elevation angle (typically 25-40°), the ground terminal must acquire the next rising satellite and transfer the data session. For seamless handover: make-before-break (connect to the new satellite before disconnecting from the old one). This requires either two antenna beams or pre-acquisition of the new satellite's signal. Handover intervals: every 2-8 minutes for a 550 km constellation. The network manages handover centrally, providing the terminal with timing, frequency, and beam pointing information for the next satellite.
| Parameter | GEO | MEO | LEO |
|---|---|---|---|
| Altitude | 35,786 km | 2,000-35,786 km | 200-2,000 km |
| Latency (one-way) | ~270 ms | 50-150 ms | 1-20 ms |
| Coverage per Sat | Full hemisphere | Regional | Local footprint |
| Handover | None | Periodic | Frequent |
| Path Loss (Ku-band) | ~206 dB | 190-206 dB | 170-190 dB |
- Performance verification: confirm specifications against the application requirements before finalizing the design
- Environmental factors: temperature range, humidity, and vibration affect long-term reliability and parameter drift
- Cost vs. performance: evaluate whether the application demands premium components or standard commercial grades
- Interface compatibility: verify impedance, connector type, and mechanical form factor match the system architecture
Frequently Asked Questions
Why phased array for user terminals?
Mechanical dishes cannot track LEO satellites fast enough (3°/s track rate) without expensive, heavy pedestals. Flat-panel phased arrays steer the beam electronically in microseconds, enabling: fast tracking, seamless handovers, and a form factor suitable for consumer installation (roof-mount flat panel). The Starlink Dishy uses a 0.5 m phased array with > 1,000 elements.
What about interference between constellations?
Multiple LEO constellations sharing the same frequency bands (Ku, Ka) must coordinate to avoid inter-system interference. ITU rules require coordination and may impose power flux density limits. Inline events (when two constellations' satellites align along the same path to a ground station) can cause significant interference. Frequency reuse planning and dynamic power control mitigate these issues.