نتایج جستجو برای: frequency modulation

تعداد نتایج: 614681  

Journal: :Applied optics 2003
Stéphane Schilt Luc Thévenaz Philippe Robert

A theoretical model of wavelength modulation spectroscopy that uses a laser diode on a Lorentzian absorption line is presented. This theory describes the general case of a current-modulated semiconductor laser, for which a combined intensity and frequency modulation with an arbitrary phase shift occurs. On the basis of this model, the effect of several modulation parameters on the detected sign...

2006
Shahram Mohammad Nejad Kiazand Fasihi

This paper presents a technique to improve the performance of laser phase-shift range finders. The phase measurement is performed by using a new method to extract the phase-shift data from the peak of received and transmitted intermediate frequency signal amplitudes. The pulse width modulation is used to minimize the noise effect and enhance the signal amplitude measurement. The advantages of p...

2009
Stefan Wabnitz Nail Akhmediev

Please cite this article in press as: S. Wabnitz, N We show that inducing modulation instability with a weak modulation whose frequency is such that its second harmonic falls within the band of instability may lead to asynchronous Fermi–Pasta–Ulam recurrence and efficient transfer of power from the pump into the second harmonic of the modulation, resulting in a periodic modulation at the second...

2015
Jessica J. M. Monaghan Stefan Bleeck David McAlpine

Sensitivity to interaural time differences (ITDs) conveyed in the temporal fine structure of low-frequency tones and the modulated envelopes of high-frequency sounds are considered comparable, particularly for envelopes shaped to transmit similar fidelity of temporal information normally present for low-frequency sounds. Nevertheless, discrimination performance for envelope modulation rates abo...

Journal: :The Journal of the Acoustical Society of America 2004
Hongbin Chen Fan-Gang Zeng

Frequency modulation (FM) detection was investigated in acoustic and electric hearing to characterize cochlear-implant subjects' ability to detect dynamic frequency changes and to assess the relative contributions of temporal and spectral cues to frequency processing. Difference limens were measured for frequency upward sweeps, downward sweeps, and sinusoidal FM as a function of standard freque...

2012
Nabil A. Ahmed

This paper presents a novel three-phase utility frequency to high frequency soft switching power conversion circuit with dual mode pulse width modulation and pulse density modulation for high power induction heating applications as melting of steel and non ferrous metals, annealing of metals, surface hardening of steel and cast iron work pieces and hot water producers, steamers and super heated...

Journal: :TBC 2002
Saso Tomazic

This paper demonstrates that no ultra narrow band modulation method, which includes VMSK and VPSK, can have substantially greater efficiency than conventional methods, such as QAM, in transmission in the same frequency band. Keywords– VMSK, VPSK, Ultra Narow Band Modulation, QAM

2010
Subhransu Sekhar Dash

In this paper, various novel pulse width modulation techniques are proposed, which can minimize the total harmonic distortion and enhances the output voltages from five level inverter to multilevel topologies. Multilevel inverters are important for power electronics applications such as flexible ac transmission systems, renewable energy sources, uninterruptible power supplies and active power f...

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