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McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


In Q, or basic telecommunication code, it means, “What is the latest met (weather)?”
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved




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

(2) (Quantum Abstract Machine) An interface from Rigetti Computing for running programs in a hybrid classical/quantum computer environment. See QVM and quantum computing.

(3) (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.
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References in periodicals archive ?
where, MOD denotes the selected modulation format (it will be replaced by BPSK, QPSK, 8QAM or 16QAM) and [C.sub.EON-MOD] is the corresponding slot capacity.
Caption: Figure 5: The computational complexity of the proposed detectors with [N.sub.T] = 8, [N.sub.R] = 4, and 16QAM modulation.
In figure 7, it is observed that the PAPR of the OFDM signal is about 10.9 dB corresponding CCDF of [10.sup.-3] without SPS-SLM for 256 subcarriers and 16QAM modulation Scheme.
Figure 7: Transmission performance of 16QAM based 116-wavelengths after a16-km transmission.
Figure 5 displays the CCDF comparisons for PAPR of the OFDMA, the LFDMA, the SLM based LFDMA, the PTS based LFDMA uplink systems with V = 4, for M = 64 and N = 256 with 16QAM modulation.
Figure 5 shows the PCC based on BPSK, QPSK, 8PSK, and 16QAM modulation signals at different SNR.
This bitwise computation achieves acceptable accuracy for single-input single-output (SISO) and 2x2 MIMO channels with BPSK, QPSK, 16QAM, and 64QAM [4].
And, 16QAM encodes four bits of information as combinations of four phases and four amplitudes: DP-16QAM encodes eight bits of information per symbol.
Powered by Ciena's WaveLogic 3 Extreme chipset, the solution provides software programmable modulation to enable both 100G encryption with QPSK modulation and 200G encryption with 16QAM modulation an industry first.
Huawei's exclusive 400G OTN network employs leading oDSP and dual-carrier 16QAM coding technologies, maximising the transmission capacity over fibers.