# QAM

(redirected from 16QAM)
Also found in: Acronyms.

(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 ?
Figure 7: Transmission performance of 16QAM based 116-wavelengths after a16-km transmission.
The arbitrary waveform generation capabilities of the AWG70000 Series make it possible to create multilevel signals such as 16QAM or 64QAM, add impairments to a signal, or create waveforms that are pre-compensated for the real-world effects of the test system.
The pilot carriers are always BPSK modulated and the data carriers are BPSK, QPSK, 16QAM, or 64QAM.
Grad A includes only QPSK modulation, grad B includes both QPSK and 16QAM.
To further verify the designed system's performance, we also conduct the simulations to get the BER performances of other baseband modulations, such as BPSK, 16QAM and 64QAM.
With Huawei-developed core technologies, the 400G ultra high-speed solution of OSN 9800 support multiple modulation formats such as 16QAM, 8QAM, and QPSK to flexibly adapt to different bandwidth and distance requirements.
Using an advanced digital signal processor (DSP) combined with Ekinops' enhanced T-Chip (Transport-on-a-Chip) technology to support both DP-QPSK and 16QAM modulation formats on a single line card, Ekinops is able to deliver a low-cost, programmable 400G solution.
Para determinar el throughput promedio acumulado de cada algoritmo, se utilizo como estandar la modulacion 16QAM.
DVB-T includes three modulation options (QPSK, 16QAM, 64QAM) and the option of hierarchical modes allowing carrying streams with different priorities corresponding to different degrees of robustness.
NEC's strength in ultra-long-haul transmission technologies is supported by its achievements providing the world's first transmission of Optical-OFDM over 10,000km and the world's first trans-pacific transmission of 16QAM signals.
Figures (11) and (12) are the BER and MSE curves of the LS method, the Lee method and the proposed method in case of 16QAM with pilot spacing 15 respectively.

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