Gain - (1) A general term used to denote an increase in signal power in transmission from one point to another; usually expressed in decibels. (2) An increase or amplification. (3) A measure of amplification expressed in dB.

Gaussian Noise - Statistically random radio noise characterized by a wide frequency spectrum that is continuous and uniform over a specified frequency band.

Geostationary orbit - "Describes an orbit in which a satellite is always in the same position (appears stationary) with respect to the rotating Earth. The satellite travels around the Earth in the same direction, at an altitude of approximately 35,790 km (22,240 statute miles) because that produces an orbital period equal to the period of rotation of the Earth (actually 23 hours, 56 minutes, 04.09 seconds). A worldwide network of operational geostationary meteorological satellites provides visible and infrared images of Earth's surface and atmosphere."

Gimbal - A device with two mutually perpendicular and intersecting axes of rotation, thus giving free angular movement in two directions, on which an object may be mounted.

Greenwich Mean Time (GMT) - The mean solar time of the meridian of Greenwich, England, used as the prime basis of standard time throughout the world.