# QAM

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## QAM

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

## QAM

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

(1)

## QAM

(2)
Quality Assurance Management.

## QAM

(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 ?
A QAM communication system can easily be represented and understood by a constellation diagram (Shashidharan et al., 2015).
In the rest of strata, only odd subcarriers are loaded with M-QAM symbols while even subcarriers are loaded with zero QAM symbols.
[N.sub.MF], [K.sub.R] is a real-valued scalar, [S.sub.k] are the transmitted QAM symbols in (2), [f.sub.Rx] is relative received carrier frequency offset, and NB is communication channel background noise [22].
La union de estos bloques de programacion mostrados en la Figura 2 y Figura 3 (transmision y recepcion respectivamente) conforman un transceptor QAM, es decir, el sistema desarrollado combina transmisor y receptor en un solo codigo [16].
Amal Al-Kuwari, one of the parents who attended the event, praised QAM's role in shaping the children's future: "This is the third year for my children at QAM.
where M is the number of subchannels; [d.sub.m,n] is the real or imaginary part of the QAM data carried on the mth subchannel in the nth FBMC symbol; [f.sub.0] is the spacing between neighboring subchannels in a frequency domain; [[tau].sub.0] is the time offset between FBMC symbols; and [g.sub.m,n](t) is the filter of the mth subchannel in the nth FBMC symbol.
However, for Quadrature Amplitude Modulation (QAM), SNR estimation has been done mostly using method of moments for AWGN and fading channels [13-16].
Iftikhar Ahmad Khan, PML-N district president, Mehmoodul Hassan of JI chief, Rangaiz of PTI district coordinator, , Javid Inqilabi, PPP district president, Muhammad Ali Dagaiwal of Pakhtunkhwa Ulasi Tehrik Muhammad Jalil, general secretary of Abaseen Union of Journalists, Muhammad Sagheer, general secretary of Swabi Bar, Aziz Minerwal of Qam Qalam, Prof Yaseem Ibal, Prof Farmanuddin and various other leaders also spoke on the occasion.
TVI also chose ARRIS Global Services to converge its current QAM services into EQAM utilising the APEX3000.
By reverting to lower-order modulation schemes of 128 QAM, 64 QAM, 32 QAM, 16 QAM or 8 QAM, the link can support a reliable connection, even in heavy rainfall.
The QAM president demanded of the PPP government not to put hurdles in the way of Karachi crackdown against criminal elements or else it should brace itself to face protest, strike and siege of Sindh Assembly.

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