The Cable Center

This glossary of cable and telecommunications terms is intended to enhance your understanding of this dynamic industry. We are able to present this information with the generous help of CableLabs - consult their website for the most up-to-date information about cable technology.

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Gain
A measure of amplification expressed in dB. Gain of an amplifier is usually specified at the highest frequency of operation, for example, at Channel 13 of all-band equipment.

Gain Control
An adjustable control that changes the gain of an amplifier.

Gain Slope
A linear variation in gain from the lowest frequency to the highest frequency.

Gateway (GW)
A function or server that acts as a point of interconnection between two different networks. For example, a Public Switched Telephone Network (PSTN) gateway would interconnect a PacketCable-based network with the PSTN. A computing machine which is both connected to one or more networks and is capable of passing network information from one network to another.

Gate Controller (GC)
In a PacketCable 1.0 based network, the GC is responsible for authorizing the enhanced quality of service for the media stream.

Ghost
A shadowy or weak image in the received picture offset either to the left or right of the primary image, the result of transmission conditions which create secondary signals that are received earlier or later than the main or primary signal. A ghost displaced to the left of the primary image is designated as “leading” and one displaced to the right is designated as “following” (lagging). When the tonal variations of the ghost are the same as the primary image, it is designated as “positive” and when it is in reverse, it is designated as “negative.”

GigaHertz (GHz)
One billion cycles of electrical frequency per second.

Global System for Mobility (GSM)
A digital cellular service designed for world-wide implementation; uses a combination of TDMA and FDMA. Or Global System for Mobile Communications (GSM)—An international standard, developed in Europe, for digital mobile communications.

Global Title Translation (GTT)
Network routing functionality required to offer customers advanced features such as local number portability (LNP), toll-free, calling card, calling name delivery, and roaming support, as well as other advanced network services.

Government Channel
FCC rules require cable systems in the top 100 markets to set aside one channel for local government use, to be available without cost for the “developmental period.” That period runs for five years from the time that subscriber service began, or until five years after the completion of the basic trunk line.

Grandfathering
Exempting cable systems from the federal rules because 1) they were in existence or operation before the rules, or 2) substantial investments were made in the system construction before the rules. Grandfathering applies to signal carriage, access channels and the certification process.

Ground Communication Equipment
Satellite earth station electronic equipment.

Group Delay
The difference in transmission time between the highest and lowest of several frequencies through a device, circuit or system.

Guard Time
Minimum time allocated between bursts in the upstream referenced from the symbol center of the last symbol of a burst to the symbol center of the first symbol of the following burst. The guard time should be at least the duration of five symbols plus the maximum system timing error.