QAM


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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, 256QAM, 512QAM and 1024QAM, from four to 10 bits generate from 16 to 1,024 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 ?
For the demonstration, held in Zurich, Switzerland, 256 QAM was introduced using software from the recently announced Ericsson Networks Software 16A, which will become commercially available later in 2015.
Heynen adds: "We're expecting CMTS and edge QAM revenue to grow more than 20% in 2013.
The MAX5880/MAX5882 delivers up to 32 times more broadband cable capacity per RF port compared to a conventional analog upconverter, and saves up to 93% in power dissipation per QAM (quadrature amplitude modulation) channel.
The enhanced product enables cable operators to measure a wide variety of indicators across all QAM carriers, including pre- and post-Forward Error Correction (FEC) Error Vector Magnitude (EVM) and Bit Error Rate (BER), as well as Modulation Error Ratio (MER).
In addition, the product offers high QAM density and low power consumption, making it suitable for narrowcast applications.
Fee-based advisors (those registered with QAM as IARs) have access to additional tools and programs to help them provide solutions to clients.
When coupled with the ARRIS D5 Universal Edge QAM, the solution presents cost-efficient and easy-to-deploy Modular and Integrated CMTS solutions (M-CMTS & I-CMTS).
The discussions then continue by contriving sophisticated iterative coded modulation systems, such as TCM, TTCM, BICM, BICM-ID designed for turbo-detected QAM-based space-time coded OFDM and CDMA systems operating over wireless channels In summary, this volume amalgamates a comprehensive textbook with a deep research monograph on the topic of QAM, ensuring it has a wide-ranging appeal for both senior undergraduate and postgraduate students as well as practicing engineers and researchers.
The number of output channels can be set independently for each RF port, ranging from 1 QAM per port to 8 QAMs per port to offer the operator a 'deploy now' and 'wire once' migration to higher QAM channels counts per service group.
Aurora Networks combined its premier node expertise with the multiplexing and QAM modulation technology it acquired from GoBackTV in May 2011 to create a game-changing approach.
Shah will oversee public market investments for QAM including global equities, equity related instruments, fixed income and related investments.
The LxS-16016 wideband edge QAM from CommScope, Inc.