Glossary
Definitions
8 definitions
L-band
The 1–2 GHz frequency band used by Inmarsat, Iridium, and GPS for mobile satellite services — valued for its near-omnidirectional reception (small antennas work in any orientation), resilience to rain fade, and global regulatory protection for safety communications like GMDSS and COSPAS-SARSAT distress beacons.
LEO (Low Earth Orbit)
Orbital region between 160 and 2,000 km altitude where most modern satellite constellations operate, offering low latency (15–70 ms) and strong signal strength.
Latency
The one-way propagation delay in a satellite communication link, determined primarily by the satellite's orbital altitude: approximately 240–270 ms for GEO, 70–150 ms for MEO, and 15–70 ms for LEO — a fundamental parameter for real-time applications.
Launch Cadence
The frequency at which a launch provider executes flights, typically measured in launches per year. SpaceX achieved 96 Falcon 9/Heavy launches in 2023 — the highest ever recorded by a single provider — enabling rapid constellation deployment and commercial payload turnaround.
Launch Vehicle
A rocket system designed to transport satellites from Earth's surface to orbit, ranging from small dedicated vehicles for single payloads (Rocket Lab Electron, 300 kg to LEO) to heavy-lift rockets (SpaceX Falcon Heavy, 64 t to LEO).
Launch Window
A defined period during which a rocket can be launched to reach a specific orbit, constrained by the alignment of Earth's rotation, the target orbit's geometry, range safety requirements, and weather conditions — ranging from an instantaneous window (ISS rendezvous) to a multi-hour window for simple LEO insertion.
Light Pollution / Dark Sky
The interference with astronomical observation caused by sunlight reflecting off LEO satellite constellations, creating bright streaks in long-exposure telescope images — a growing concern that has prompted ITU discussions, operator commitments to reduce satellite reflectivity, and the International Astronomical Union's CPS Centre for the Protection of the Dark and Quiet Sky.
Link Budget
A systematic accounting of all gains and losses along a satellite communication path — from transmitter EIRP through free-space path loss and rain fade to receiver G/T — used to verify that the received signal-to-noise ratio meets the demodulator's requirements.