Quadrature Amplitude Modulation


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quadrature amplitude modulation

[¦kwäd·rə·chər ‚am·plə‚tüd ‚mäj·ə′lā·shən]
(communications)
Abbreviated QAM.
Quadrature modulation in which the two carrier components are amplitude-modulated.
A digital modulation technique in which digital information is encoded in bit sequences of specified length and these bit sequences are represented by discrete amplitude levels of an analog carrier, by a phase shift of the analog carrier from the phase that represented the previous bit sequence by a multiple of 90°, or by both.

Quadrature Amplitude Modulation

(QAM) A method for encoding digital data in an analog signal in which each combination of phase and amplitude represents one of sixteen four bit patterns. This is required for fax transmission at 9600 bits per second.
References in periodicals archive ?
The joint research will enable ultra-high-speed 400Gbps-class optical transmissions through the use of dual-polarization quadrature phase shift keying (DP-QPSK) (*3), which is currently in use for 100Gbps transmissions, together with dual-polarization 16 quadrature amplitude modulation (DP-16QAM) (*4), which takes advantage of an even greater number of quadrature carriers.
Increases the amount of time during which the new 256 Quadrature Amplitude Modulation (QAM) encoding scheme can be utilized by up to 280 percent and extends its benefits to outdoor macro environments.
The joint research will enable ultra-high-speed 400Gbps-class optical transmissions through the use of dual-polarization quadrature phase shift keying (DP-QPSK)(3), which is currently in use for 100Gbps transmissions, together with dual-polarization 16 quadrature amplitude modulation (DP-16QAM)(4), which takes advantage of an even greater number of quadrature carriers.
World's First Commercial Implementation of 2048 Quadrature Amplitude Modulation
These condensed channels are a result of flexible grid utilization and are combined with advanced modulation techniques including dual-polarization quadrature phase shift keying (DP-QPSK) and dual-polarization 16-ary quadrature amplitude modulation (DP-16QAM) to greatly increase network utilization without requiring any physical adjustments to the MAX network infrastructure.
The 210C, using Selectable Quadrature Amplitude Modulation, allows data rates up to 54 Kbps in the narrow band channels.
These new systems use multi-level modulation techniques such as 16 bit Quadrature Amplitude Modulation (QAM) and quadrature phase shift keying (QPSK) to improve the special efficiency of the network.
These include space-time block and trellis codes, as well as other Multiple-Input Multiple-Output (MIMO) schemes and near-instantaneously Adaptive Quadrature Amplitude Modulation (AQAM).
The combined use of Electrical Orthogonal Frequency Division Multiplexing (eOFDM) and frequency-domain Hybrid Quadrature Amplitude Modulation (QAM) technologies substantially improve spectrum efficiency to 10 bit/s/Hz.
0 measurement and certification capabilities, including analysis of live spectrum, modulation error rate (MER) and quadrature amplitude modulation (QAM).
This demonstration illustrates how cable operators can deliver IP-based video to either TVs or PCs leveraging their quadrature amplitude modulation (QAM) and CMTS equipment.