Adaptive Equalization
Adaptive equalization is used at the receiver to cancel the distortion introduced by the propagation channel. Distortion usually takes the form of multiple, delayed copies of the transmitted signal arriving at the receiver. Other forms of distortion include co-channel interference caused by other transmission signals in the same frequency band. Since the characteristics of the distortion are unknown at the receiver and time-varying, the coefficients of the equalization filter need to be adapted (or adjusted) periodically over time.

ATSC
Advanced Television Systems Committee (see link below)

"Trained" Adaptive Equalization
Trained equalization methods rely on cooperation between the transmitter and receiver. The cooperation consists of the receiver periodically knowing what source sequence was sent by the transmitter. This periodic sequence is referred to as the training interval. The equalizer coefficients are adjusted during the training interval. Trained adaptive equalization fails to perform when the channel distortion changes between training intervals.

"Blind" Adaptive Equalization
Blind equalization methods adjust the equalizer coefficients using only the received data sequence. Unlike trained equalization methods, blind methods do not store or generate a replica of a training sequence at the receiver and operate without explicit cooperation from the transmitter. Most blind equalization methods attempt to match the statistics of the equalizer output with the statistics of the transmitted sequence.

Broadband
Broadband channels contain sufficient capacity to simultaneously carry voice, data and video.

COFDM
Coded Orthogonal Frequency Division Multiplexing is a modulation technique which codes information across multiple RF carriers. COFDM has been adopted by a number of countries as an alternative to a single-carrier transmission system such as the ATSC's 8-VSB standard.

FEC
Forward Error Correction periodically embeds additional data into the source sequence. This redundant data is used by the receiver to detect and correct errors at the demodulator output. This type of coding significantly reduces the bit error rate of the overall system and makes error-free transmissions practical.

LMDS
Local Multi-point Distribution Service

MAC
Media Access Control. In a network, that part of the protocol that governs access to the transmission medium independent of the physical characteristics of the medium.

MCNS/DOCSIS
Multi Media Cable Network System

MMDS
Multi-channel Multi-point Distribution Service

Multi-Mode Technology
Technology in which a single component can process multiple incompatible transmission standards without redundant circuitry.

NTSC
National Television Systems Committee. The NTSC committee defined the analog color television broadcast standard used today in North America.

QAM
Quadrature amplitude modulation. This modulation format encodes the source data into independent in-phase and quadrature carrier components. QAM modulation is two-dimensional in the sense that the resulting signal can be represented in the complex plane.

QPSK
A specific kind of QAM which uses a single level of amplitude modulation and contains four phases.

VDSL
Very High Data Rate Digital Subscriber Loop

VSB
Vestigial sideband modulation (also called VSB-AM (amplitude modulation)). This modulation format encodes data into the amplitude of a single carrier frequency. Portions of the one of the redundant AM sidebands are removed to form a vestigial sideband signal. VSB signals can be treated either as a one-dimensional AM signal or as a two-dimensional complex signal similar to the representation used for QAM.