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Topic: Phase modulation


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In the News (Mon 17 Jun 19)

  
  What is phase modulation? - a definition from Whatis.com - see also: PM
Phase modulation (PM) is a method of impressing data onto an alternating-current (AC) waveform by varying the instantaneous phase of the wave.
Each phase angle (that is, each shift from one phase state to another) represents a specific digital input data state.
Phase modulation is similar in practice to frequency modulation (FM).
whatis.techtarget.com /gDefinition/0,294236,sid9_gci213998,00.html   (443 words)

  
 The PHASITRON Web Page
In a phase modulation transmitter, as the modulating frequency is increased, the phase modulation stays the same but the frequency modulation increases.
In a frequency modulation transmitter, as the modulating frequency is increased, the amount of frequency modulation stays the same, but the phase modulation decreases.
Since most phase modulators produce small amounts of phase modulation, the problem of obtaining huge amounts of phase modulation was solved by using frequency multipliers, which not only multiply the carrier frequency, but also any phase or frequency modulation.
www.w9gr.com /phasitron.html   (2740 words)

  
  MODULATION
The process of phase modulation consists of varying the phase of the carrier linearly in proportion to the modulating signal such that maximum phase shift occurs during positive and negative peaks of the modulating signal.
The instantaneous phase angle in a frequency modulated wave varies directly as the integral of the modulating signal.
If the modulating signal f(t) is integrated before using it to phase modulate a carrier, the result is an FM wave, similarly, if the modulating signal is differentiated before allowing it to frequency modulate a carrier, the result is a PM wave.
www.sem.mosaic-service.com /electron2/phase.htm   (0 words)

  
  Method and apparatus for creating phase modulation in edge-sensitive signals invention
Whether it is to create a phase modulation inside a phase-locked loop for wide-bandwidth clock recovery or to cause phase modulation in a test stimulus, high-performance phase modulators with sufficient phase variation range, very high speed of modulation (modulation bandwidth) capable of operation for multi-gigabit per second data rate applications are needed.
This type of modulation is not the same as phase modulation except during sinusoidal modulation where the integral of a sine wave is a cosine wave which has a similar amplitude response.
The signal is paralleled to implement high performance phase modulation on both rising and falling edges as one flip-flop is used to toggle based on the direct input signal and another flip flop is used to toggle on an inverted copy of the direct input signal.
www.freshpatents.com /Method-and-apparatus-for-creating-phase-modulation-in-edge-sensitive-signals-dt20061026ptan20060238396.php   (2128 words)

  
  Amateur Radio application of Frequency Modulation
Frequency Modulation (FM) is a system where the amplitude of a carrier wave is held constant while the frequency is varied in sympathy with the voltage of the modulating signal.
Phase Modulation (PM) is a similar system where the phase of the carrier wave is varied in sympathy with the voltage of the modulating signal, and as in frequency modulation, the amplitude of a carrier is held constant.
Now Phase and Frequency are related, an incremental frequency shift of the carrier wave frequency causes a continuing change in phase (wrt the original carrier), the rate of change of phase is proportional to the frequency shift.
www.vk1od.net /FM/FM.htm   (3127 words)

  
  Phase modulation: Definition and Links by Encyclopedian.com
...Phase modulation Phase modulation Phase modulation (PM) is the encoding of...variation of its phase in accordance with an input signal.
Phase modulation (PM) is the encoding of information into a carrier wave by variation of its phase in accordance with an input signal.
Note that phase modulation can be regarded as a special case of frequency modulation where the carrier frequency modulation is the time derivative of the PM modulating signal.
www.encyclopedian.com /ph/Phase-modulation.html   (301 words)

  
 Phase modulation
In phase modulation the phase of the carrier is caused to shift at the rate of the af modulating signal.
Phase modulation is also similar to frequency modulation in the number of sidebands that exist within the modulated wave and the spacing between sidebands.
In frequency modulation, we saw that as the frequency of the modulating signal increased (assuming the deviation remained constant) the number of significant sideband pairs decreased.
www.tpub.com /neets/book12/49e.htm   (1001 words)

  
 Nikon MicroscopyU: Modulation Transfer Function
Modulation is typically less in the image than in the specimen and there is often a slight phase displacement of the image relative to the specimen.
The modulation transfer function is also related to the point spread function, which is the image of a point source of light (commonly referred to as the Airy disk) from the specimen projected by the microscope objective onto the intermediate image plane.
Radial modulation transfer targets are ideal for high-resolution measurements using photographic film or analog sensors, but the horizontal and vertical pixelated nature of CCD detectors benefits from analysis utilizing targets that are geometrically consistent with the pixel rows and columns of the imaging device.
www.microscopyu.com /articles/optics/mtfintro.html   (4055 words)

  
 Amplitude and periodic phase modulation transmission system - Patent 4217467
The phase of the carrier signal also conveys information of the unipolar signals, so that the combination of the phase discrimination of the received carrier signal and the envelope detection permits the original signal to be reconstructed if the amplitude waveform is substantially distorted over the transmission path.
The modulator 5 also receives the train of unipolar signals from the source 1 as a modulation signal, and the phase modulated carrier is amplitude modulated by the unipolar signal.
The amplitude modulation in the modulator 5 takes place by a timing adjustment such that the points at which the phase of the phase modulated carrier changes are in coincidence with the points at which the amplitude of the unipolar signal changes.
www.freepatentsonline.com /4217467.html   (5138 words)

  
 Anderson Electronics, Inc. - Tutorial (Phase Noise)
The modulation is caused by a combination of the noise figures of the crystal and the transistors used in the circuit.
Phase noise is measured in the frequency domain and is measured by beating two oscillators of like design in a double balanced mixer in quadrature.
Phase noise performance is degraded by frequency multiplication at the rate of 20 log (N) whereas N being the multiplication factor.
www.aextal.com /tutorial-phase-noise.htm   (305 words)

  
 Part16: Modulation   (Site not responding. Last check: )
By moving to two bits per phase change, the number of changes per second is still the same (baud rate), but the number of bits per second is doubled.
Modulation is the mechanism that a modem uses to convert digital signals to analogue signals for sending across a telephone connection.
The three different type of modulation are amplitude, frequency and phase, although phase amplitude modulation is a combined technique of different phase and relative signal levels that offers the greatest speed of the methods discussed above.
goforit.unk.edu /datacomm/dc_016.htm   (674 words)

  
 Modulation Information
Modulation is the process of varying a carrier signal in order to use that signal to convey information.
The three key parameters of a sinusoid are its amplitude, its phase and its frequency, all of which can be modified in accordance with an information signal to obtain the modulated signal.
A device that performs modulation is known as a modulator and a device that performs the inverse operation of demodulation is known as a demodulator.
www.bookrags.com /wiki/Modulation   (720 words)

  
 Modulation at AllExperts
A device that performs modulation is known as a modulator and a device that performs the inverse operation of demodulation is known as a demodulator.
These are the general steps used by the modulator to transmit data:# Accept incoming digital data;# Group the data into symbols;# Use these symbols to set or change the phase, frequency or amplitude of the reference signal appropriately;# Pass the modulated signal on for further processing, such as filtering and channel-coding, before transmission.
At the receiver, the demodulator# Is passed the de-filtered and de-channel-coded signal;# Determines its phase, frequency or amplitude;# Maps the phase, frequency or amplitude to its corresponding symbol;# Translates the symbol into its individual bits;# Passes the resultant bit stream on for further processing such as removal of any error-correcting codes.
en.allexperts.com /e/m/mo/modulation.htm   (854 words)

  
 KVR: Phase Modulation, Frequency Modulation, and Pitch shifting.   (Site not responding. Last check: )
Frequency modulation by a waveform G(x) is equivalent to phase modulation by the integral of G(x), or, alternately, PM by a waveform F(x) is equivalent to FM by the derivative (slope) of F(x).
Frequency modulation by a square wave is equivalent to phase modulation by a triangle wave.
Frequency modulation by a sawtooth is equivalent to phase modulation by a parabola.
www.kvraudio.com /forum/viewtopic.php?p=2198143   (1177 words)

  
 Modulation   (Site not responding. Last check: )
Modulation is the process where a Radio Frequency or Light Wave's amplitude, frequency, or phase is changed in order to transmit intelligence.
In Pulse Amplitude Modulation, a pulse is generated with an amplitude corresponding to that of the modulating waveform.
Also known as Pulse Time Modulation, PPM is a scheme where the pulses of equal amplitude are generated at a rate controlled by the modulating signal's amplitude.
telecom.tbi.net /mod1.html   (797 words)

  
 Apple - Logic Pro - Modulation Effects   (Site not responding. Last check: )
The innovative Anti Pitch button ensures that the pitch of the modulated signal remains constant, and Constant Mod guarantees a constant modulation depth — regardless of the LFO frequencies.
The concept of mixable LFOs, taken from the Modulation Delay, is extended by level-dependent frequency modulation of LFO 1.
The modulation phase between the different voices is controllable, or random if desired, and you can change the stereo base, allowing the resulting output to match the needs of the mix.
www.apple.com /logic/modulationeffects.html   (652 words)

  
 Overview of Phase Modulation Technology
Phase modulation allows the achievement of higher sensitivity for the characterization of thin film thickness and optical constants when compared with conventional ellipsometers.
The output head comprises a photoelastic modulator and an analyzing polarizer that resolves the polarization state of the reflected beam.
Both polarizers are held fixed during the measurement while the photoelastic modulator is used to induce a modulated phase shift of the reflected beam.
www.jobinyvon.com /usadivisions/TFilms/phasemod.htm   (310 words)

  
 RA Fisher Associates/ Publications
Feldman, I. Bigio, and E. Bergmann, Proceedings of 1979 CLEA Conference, Washington, D. "Optical Phase Conjugation," R. Fisher and B.
"Intracavity Technique for High-Reflectivity Phase Conjugation in Germanium and Inverted CO," with R. Fisher, I. Bigio, and E. Bergmann, Proceedings of 1979 CLEO Conference, Wash.
"Phase Conjugation and Image-Retaining Reflection of KrF Laser Radiation at 2486 Angstroms," I. Bigio, B. Feldman, R.
www.rafisher.com /pub.htm   (1486 words)

  
 Definition of phase modulation - Merriam-Webster Online Dictionary
: modulation of the phase of a radio carrier wave by voice or other signal
Learn more about "phase modulation" and related topics at Britannica.com
See a map of "phase modulation" in the Visual Thesaurus
www.m-w.com /cgi-bin/dictionary?book=Dictionary&va=phase+modulation   (51 words)

  
 phase modulation - OneLook Dictionary Search
phase modulation : The American Heritage® Dictionary of the English Language [home, info]
PHASE MODULATION : Space and Electronic Warfare Lexicon [home, info]
noun: modulation of the phase of the carrier wave
www.onelook.com /?w=phase+modulation&ls=a   (176 words)

  
 phase modulation- Developer Zone - National Instruments
To properly develop a backdrop for phase modulation, you should first understand modulation and its carrier.
is signal modulated, it produces a carrier that is periodically changing in phase.
Whereas this phase modulation is accomplished when the value of the phase angle is changed as a direct function of the modulating signal, frequency modulation will be accomplished only when the value of the phase angle is changed with the derivative of the modulating signal.
zone.ni.com /devzone/cda/tut/p/id/1320   (750 words)

  
 Model Group: Phase Modulators   (Site not responding. Last check: )
Model 4001 Resonant Modulator to 250 MHz - Their resonant tank circuit maximizes the power transfer from the driver to the crystal, maximizing the voltage across the crystal and lowering drive voltages.
Model 4003 Resonant Modulator to 250 MHz - Their resonant tank circuit maximizes the power transfer from the driver to the crystal, maximizing the voltage across the crystal and lowering drive voltages.
With low insertion losses and efficient phase modulation with extremely low unwanted amplitude modulation, this new line of phase modulators is ideal for a wide variety of demanding applications.
www.newfocus.com /product/modelgroup.cfm?productlineid=1&modelgroupid=1126   (1234 words)

  
 Phase modulation
Phase-shift keying refers to the simple case of phase modulation by a simple signal with a discrete number of states, such as in morse code or radioteletype applications.
For example, with only two states, the technique is Binary Phase Shift Keying (BPSK).
With four states, it's known as Quadrature Phase Shift Keying (QPSK), with eight states, it's known as 8-PSK, 16 states is 16-PSK, and so on.
www.xasa.com /wiki/en/wikipedia/p/ph/phase_modulation.html   (163 words)

  
 Programmable Phase Optics
Thus combining an amplitude modulator with a tuneable phase filter would result in a high performance phase-only SLM in which the spatial light modulation and phase shift are effectively decoupled.
Reconfigurable spatial phase modulation of a light field is required in a number of areas in optics, including phase modulation for holographic multiplexing, storage and encoding, phase-only encryption and decryption and the testing of focus in optical apparatus.
In the case of a fixed phase distribution, a major advantage of the use of amplitude masks to define the required phase pattern is the relative simplicity with which they can be manufactured when compared to phase-only elements.
www.ppo.dk /Research-RPC.html   (739 words)

  
 Phase modulation and FM
The amplitudes are functions of the index of modulation, and don't depend on the frequencies.
Phase modulation can thus be seen simply as a form of ring modulated waveshaping.
One well-trodden path is to effect phase modulation on the phase modulation spectrum itself.
www.crca.ucsd.edu /~msp/techniques/latest/book-html/node87.html   (301 words)

  
 What is modulation? - a definition from Whatis.com
Modulation can be applied to direct current (mainly by turning it on and off), to alternating current, and to optical signals.
Phase modulation (PM), in which the natural flow of the alternating current waveform is delayed temporarily
Optical signals are modulated by applying an electromagnetic current to vary the intensity of a laser beam.
searchnetworking.techtarget.com /sDefinition/0,,sid7_gci212586,00.html   (726 words)

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