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 ?
NEC will implement 2048 Quadrature Amplitude Modulation (2048QAM) within its iPASOLINK product family in the second half of 2012.
Examples of digital modulation include quadrature phase shift keying (QPSK), frequency shift keying (FSK), minimum shift keying (MSK) and quadrature amplitude modulation (QAM).
The 210C, using Selectable Quadrature Amplitude Modulation, allows data rates up to 54 Kbps in the narrow band channels.
Modulation schemes such as multilevel linear quadrature amplitude modulation (QAM) increase spectral efficiency yet their operating envelopes fluctuate, making this approach much more sensitive to the inherent nonlinear component of power amplifier behavior - the major source of nonlinear distortion in microwave transmitters.
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).
Other technological breakthroughs in small cell air interface that enabled higher 4G data rates include 256 Quadrature Amplitude Modulation, 3-component-carrier aggregation and Distributed Multiple Input Multiple Output.
Complex modulation formats such as binary phase-shift keying, quadrature phase-shift keying and 64 quadrature amplitude modulation required for testing RF digital communications systems may be accomplished by driving the I/Q inputs with analog signals.
The SRU2 features multiple modulation schemes from quadrature phase shift keying (QPSK) to 4096 quadrature amplitude modulation (QAM), and its maximum RF bandwidth for one single channel can support up to 112MHz.
When dealing with quadrature modulation schemes, it is useful to think of an M-level quadrature amplitude modulation (QAM) signal as two half-data-rate amplitude shift-keying signals that occupy the same bandwidth but with an orthogonal phase relationship.
This latest technology milestone was delivered by Ericsson Networks Software 16B for LTE and the Qualcomm Snapdragon X12 LTE modem from Qualcomm Technologies, which supports 4x4 Spatial Multiplexing combined with 256 Quadrature Amplitude Modulation (QAM).
When properly configured, the signal generators can generate many waveforms, including frequency- (FSK), amplitude- and phase-shift keying, and quadrature amplitude modulation (QAM).
Making use of LTE-Advanced tri-band carrier aggregation and 256 quadrature amplitude modulation in partnership with Ericsson and Qualcomm, the carrier gained pace of around 500 Mbps on the 4G network.