# Modulation order

﻿
Modulation order

The modulation order of a digital communication scheme is determined by the number of the different symbols that can be transmitted using it.

Modulation order can only be defined for digital modulations. The simplest forms of digital modulation are of second order because they can transmit only two symbols (usually denoted as "0" and "1" or as "-1" and "1"). They are called binary shift keying (BSK).

Modulations which have an order of 4 and above usually are termed as higher-order modulations. Examples of these are quadrature phase shift keying (QPSK) and its generalisation as m-ary quadrature amplitude modulation (m-QAM).

Because existing computers and automation systems are based on binary logic most of the modulations have an order which is a power of two: 2, 4, 8, 16, etc. In principle, however, the order of a modulation can be any integer greater than one.

When the order of a digital modulation approaches infinity its properties approach those of the respective analog modulation. Thus the analogue modulations can be viewed as extreme cases of higher-order digital modulations for which the order is equal to infinity.

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Modulation — For musical change of key, see Modulation (music). For other uses, see Modulation (disambiguation). Passband modulation v · d · e …   Wikipedia

• Order — Contents 1 Ordinality 2 Philosophy 3 Science 4 Mathe …   Wikipedia

• modulation — /moj euh lay sheuhn, mod yeuh /, n. 1. the act of modulating. 2. the state of being modulated. 3. Music. transition from one key to another. 4. Gram. a. the use of a particular distribution of stress or pitch in a construction, as the use of… …   Universalium

• Modulation transfer function (infrared imaging) — The Modulation Transfer Function (MTF) is used to approximate the position of best focus of an infrared imaging system. In an imaging system, best focus is typically achieved when the MTF is between 0.4 and 0.6; most often at 0.5 (50% cutoff… …   Wikipedia

• Higher-order modulation — is a type of digital modulation usually with an order of 4 or higher. Examples: quadrature phase shift keying (QPSK), m ary quadrature amplitude modulation (m QAM), etc.ee also* phase shift keying * modulation order …   Wikipedia

• Delta-sigma modulation — Delta sigma (ΔΣ; or sigma delta, ΣΔ) modulation is a method for encoding high resolution or analog signals into lower resolution digital signals. The conversion is done using error feedback, where the difference between the two signals is… …   Wikipedia

• Quadrature amplitude modulation — (QAM) (Pronounced IPA|kwa:m) is a modulation scheme which conveys data by changing ( modulating ) the amplitude of two carrier waves. These two waves, usually sinusoids, are out of phase with each other by 90° and are thus called quadrature… …   Wikipedia

• Pulse-width modulation — (PWM) of a signal or power source involves the modulation of its duty cycle, to either convey information over a communications channel or control the amount of power sent to a load. PrinciplePulse width modulation uses a square wave whose pulse… …   Wikipedia

• Pulse-density modulation — Pulse density modulation, or PDM, is a form of modulation used to represent an analog signal in the digital domain. In a PDM signal, specific amplitude values are not encoded into pulses as they would be in PCM. Instead it is the relative density …   Wikipedia

• Single-sideband modulation — (SSB) is a refinement of amplitude modulation that more efficiently uses electrical power and bandwidth. It is closely related to vestigial sideband modulation (VSB) (see below).Amplitude modulation produces a modulated output signal that has… …   Wikipedia