# QAM

(redirected from QAM64)

(communications)

## 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) (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 ?
At OFC 2018, Keysight will demonstrate test solutions for 100G, 400G, 600G, and 1-Tb/s transmission--that includes both coherent signal forms such as QAM64 and noncoherent signal forms such as PAM4.
The outstanding RF performance of SiGe technology such as deliverable output power of up to 18 dBm of PA, extreme low noise figure of 6 dB of LNA and excellent VCO phase noise better than -85dBc/Hz at 100kHz offset allows a system designer to implement high modulation schemes up to QAM64 with a sample rate of 500 Msamples/sec and QAM32 with 1Gsamples/sec at a 10 -6 BER (Bit Error Rate).
We congratulate ZTE on the system's outstanding performance in QAM64 testing and we believe our work with them will help CSLNWM to stay way ahead of the competition and deliver its 2.
In this paper we have considered the following digital signals: ASK2, ASK4, ASK8, PSK2, PSK4, PSK8, QAM16, QAM32, QAM64, Star-QAM8, and V32.

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