QAM

(redirected from 256QAM)

QAM

QAM

In Q, or basic telecommunication code, it means, “What is the latest met (weather)?”

QAM

(1)

QAM

(2)
Quality Assurance Management.

QAM

(1) (Quality Assessment Measurement) A system used to measure and analyze voice transmission.

(2) (Quadrature Amplitude Modulation) A modulation technique that employs both phase modulation (PM) and amplitude modulation (AM). Widely used to transmit digital signals such as digital cable TV and cable Internet service, QAM is also used as the modulation technique in orthogonal frequency division multiplexing (see OFDM). The "quadrature" comes from the fact that the phase modulation states are 90 degrees apart from each other.

Analog QAM
Analog QAM uses two carriers 90 degrees out of phase with each other. Each carrier is modulated by an analog signal, and the resulting modulated waves are combined (see example below).

Digital QAM
In digital QAM, the number of modulation states determines how the digital signal is split up. For example, in 8QAM, each three bits of input alters the phase and amplitude of the carrier to derive eight unique modulation states (see example below). In 16QAM, 32QAM, 64QAM, 128QAM and 256QAM, four, five, six, seven and eight bits generate 16, 32, 64, 128 and 256 modulation states respectively. See modulation and binary values.

Analog QAM
Analog QAM modulates two carriers 90 degrees out of phase with each from two analog input streams. The modulated carriers are combined and transmitted.


Digital QAM (8QAM)
In 8QAM, three input bits generate eight modulation states using four phase angles on 90 degree boundaries and two amplitudes (4 phases X 2 amplitudes = 8 states). Digital modulation greater than 8QAM is difficult to visualize.


Quadrature PSK (QPSK)
QPSK is like 4QAM without amplitude modulation. QPSK uses four phase angles to represent each two bits of input; however, the amplitude remains constant.
References in periodicals archive ?
Technologies such as 256QAM encoding and carrier aggregation are essential for delivering high-quality LTE experiences to subscribers in Greece and other markets around the world, Our demonstration with Cosmote both builds upon and showcases Ericsson s technology leadership in these critical areas, and we are pleased to work with Cosmote in delivering these capabilities to the Greek market.
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Xilinx 256QAM millimeter wave modem IP integrated on the BEEcube BEE7 baseband platform provides complete "out of the box" solution for wideband backhaul prototyping
Data is differentiated from 4QAM to 256QAM depending on transmission volume.
In addition, it will present 256QAM (quadrature amplitude modulation), part of the latest 3GPP Release 12 issued in December 2014 for LTE-Advanced devices.
The hub connects directly to the cable plant and uses a portion of the wireless unlicensed band to provide high-speed broadband connectivity to the transceiver, supporting up to 256QAM downstream and up to 64QAM upstream modulation -- speeds that are higher than DSL and rival T1 service.
Complementing Carrier Aggregation, the company is launching MIMO4x4 doubling peak data rates and demonstrating 256QAM (quadrature amplitude modulation), offering a further 30% boost.
Our latest solutions featuring state-of-the-art 256QAM modulation and GPS-based fixed-frame performed better than all the competitive options being reviewed by the customer, said Rod Cronin, Redline s director of product management.
11n protocol with wider instantaneous bandwidth up to 160MHz, more MIMO channels, and higher density modulation up to 256QAM.