A/B Switch

A switch that selects one of two inputs (A or B) for routing to a common output while providing adequate isolating between the two signals.

A/D

Analog/Digital (Conversion).

ABC

Analog to Digital Conversion. Process of sampling and coding an analog quantity or signal or produce a digital representation.

Abrasion Resistance

Ability of a wire, cable or material to resist surface wear.

Absolute Zero

The coldest possible temperature at which all molecular motion ceases. It is expressed in degrees Kelvin as measured from absolute zero. Zero degrees Kelvin equals minus 273.16 °C or minus 459 °F.

Accelerated Aging

A test in which voltage, temperature, etc. are increased above normal operating values to obtain observable deterioration in a relatively short period of time. The plotted results give expected service life under normal conditions.

ACI

Adjacent - Channel Interference

Addressable cable system

A system which has yet to debut in India. In an addressable cable TV system, the cable operator installs an addressable set top box near the customer's TV set. Through this box, the cable operator can switch on/off channels that his subscriber is willing/unwilling to pay for. For the system to work, the cable TV operator has to install an encrypting system at his headend and send pay channels in an encrypted mode which will then be decrypted by the consumer's set top box and shown on his TV.

Adjacent Channel

An adjacent channel is immediately next to another channel in frequency. For example, NTSC channels 5 and 6 as well as 8 and 9 are adjacent. However, channels 4 and 5 or channels 6 and 7 and separated by signals used by non-TV media.

ADM

Adaptive Delta Modulation. Digital coding method employed by Dolby Labs' satellite TV audio system, to be used (via B-MAC) by Australia's HACBSS.

Admittance

The measure of the ease with which an alternating current flows in a circuit. The reciprocal of impedance.

Aerial Cable

A cable suspended in the air on poles or other overhead structure.

AFC (Automatic Frequency Control)

A circuit which locks an electronic component onto a chosen frequency.

AGC (Automatic Gain Control)

A circuit that uses feedback to maintain the output of an electronic component at a constant level.

Agile Receiver

A satellite receiver which can be turned to any desired channel.

Air Spaced Coaxial Cable

One in which air is the essential dielectric material. A spirally wound synthetic filament or spacer may be used to center the conductor.

AKM

Apogee-Kick Motor (also ABM, Apogee-Boost motor). Rocket motor fired at highest point of GTO, to circularise orbit and inject satellite into GEO.

Alignment

The process of fine tuning a dish or an electronic circuit to maximize its sensitivity and signal receiving capability.

Allay

A metal formed by combining two or more different metals to obtain describe properties.