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phase modulation

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phase modulation

[′fāz ‚mäj·ə‚lā·shən]
(communications)
Modulation in which the linearly increasing angle of a sine wave has added to it a phase angle that is proportional to the instantaneous value of the modulating signal (message to be communicated). Abbreviated PM.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

phase modulation

A method of modulating a sine-wave carrier, so its phase is changed by an amount proportional to the instantaneous value of the modulating voltage.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

phase modulation

Varying the angle of a wave in a carrier in order to transmit analog or digital data. For digital signals, phase modulation (PM) is widely used in conjunction with amplitude modulation (AM). For example, quadrature amplitude modulation (QAM) uses both phase and amplitude modulation to create different binary states for transmission (see QAM). See modulation and carrier.


Vary the Angle
In PM modulation, the angle of the carrier wave is varied by the incoming signal. In this example, the modulating wave implies an analog signal.







Digital Phase Shift Keying (PSK)
For digital signals, phase shift keying (PSK) uses two phases for 0 and 1 as in this example. See DPSK.
Copyright © 1981-2025 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Phase Modulation

 

a method of modulating oscillations in which the transmitted signal controls the phase of a high-frequency carrier. The characteristics of phase modulation are similar to those of frequency modulation. If the modulating signal is sinusoidal, the spectra and wave forms of phase-modulated and frequency-modulated signals coincide. Differences between the two methods become apparent if the modulating signal has a more complex wave form.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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References in periodicals archive
Aulin, "Multiuser serially concatenated continuous phase modulation,' in International Symposium on Turbo Codes, pp.
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The amplitude and phase modulations caused by damage defects and contamination particles can result in downstream intensification, which can damage certain optical components in the systems [1-5].
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Incidence at grazing angle forces the response of the grating to be ultra-wide band and phase tunable with the use of LC making it suitable for phase modulation. A grazing incidence angle, though, can considerably complicate the geometry of the grating.
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Section 2 presents the FIR-embedded [DELTA][summation] phase modulation and clarifies the proposed FIR-compensated low-noise architecture.
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The three nonlinearity effects that is cross gain modulation (XGM), cross phase modulation (XPM), and four wave mixing (FWM) make it possible to use it as nonlinear medium for gates.
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These movements are caused by the respiration as well as heartbeat and can be tracked by analyzing the phase modulation of the backscattered signal.
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As long as the total phase modulation is much less than a radian, the spectrum corresponding to each modulating frequency [f.sub.m] will consist of a pair of sidebands offset from the carrier by [+ or -][f.sub.m] and with amplitude [beta]/2 relative to the carrier.
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Its 18 chapters cover the Newton, Fizeau, Haidinger, Twyman-Green, common-path, lateral shear, radial shear, rotational shear, reversal shear, multiple-beam, and multiple-pass interferometers; the Foucault, wire, phase modulation, Ronchi, Hartmann, Hartmann-Shack tests; star tests; testing of aspheric wavefronts and surfaces; Zernike polynomial and wavefront fitting; phase shifting interferometry; surface profilers, multiple wavelength, and white light interferometry; optical metrology of diffuse surfaces; angle, prisms, curvature, and focal length measurements; and mathematical representation of an optical surface and its characteristics.
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This architecture assumes that the baseband modulation is available and can be represented as orthogonal amplitude and phase modulation functions.
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The location of spread-spectrum emitters using the precision emitter-location techniques as described in previous "EW 101" columns is very difficult, because communications signals use continuous modulations (such as AM, FM, and phase modulation) and, therefore, require significant correlation times that are much greater than hop times.
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