Satellite Communication Glossary: G-L

G

G/T (Gain-to-Noise Temperature)

A figure of merit for receive systems, representing the antenna gain divided by the system noise temperature. Measured in dB/K.

GEO (Geostationary Earth Orbit)

An orbit at approximately 35,786 km altitude where satellites appear stationary relative to a point on Earth. Also called GSO (Geosynchronous Orbit).

Gateway

A large Earth station that connects the satellite network to the terrestrial network (internet, telephone, etc.).

H

HPA (High Power Amplifier)

An amplifier used at Earth stations to boost the transmit signal power. Types include SSPA and TWTA.

HTS (High Throughput Satellite)

Satellites that use frequency reuse through spot beams to achieve significantly higher capacity than traditional satellites.

I

IFL (Inter-Facility Link)

The cable connecting the indoor and outdoor units of a satellite terminal.

Interference

Unwanted RF signals that degrade the quality of the desired communication signal.

K

Ka-Band

The portion of the electromagnetic spectrum from 26.5 to 40 GHz. Satellite Ka-band typically uses 27.5-31 GHz (uplink) and 17.7-21.2 GHz (downlink).

Ku-Band

The portion of the electromagnetic spectrum from 12 to 18 GHz. Satellite Ku-band typically uses 14.0-14.5 GHz (uplink) and 11.7-12.2 GHz (downlink).

L

Latency

The time delay between transmitting and receiving a signal. GEO satellites have approximately 250-280ms one-way latency.

LEO (Low Earth Orbit)

Orbits at altitudes between approximately 300-2,000 km. LEO satellites have lower latency but require constellations for continuous coverage.

Link Budget

An accounting of all gains and losses in a satellite communication link, used to determine if the system will meet performance requirements.

LNB (Low Noise Block Downconverter)

The outdoor unit component that receives the satellite signal, amplifies it with low noise, and converts it to an intermediate frequency.

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