Journal articles on the topic 'Modulation'
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Bean, Bruce P. "Modulating Modulation." Journal of General Physiology 115, no. 3 (February 14, 2000): 273–76. http://dx.doi.org/10.1085/jgp.115.3.273.
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Bin Zhang, Bin Zhang, Shiyu Liu Shiyu Liu, Xianzhu Tang Xianzhu Tang, and and Jian'gang Lu and Jian'gang Lu. "Adaptive modulation system for liquid crystal phase modulator." Chinese Optics Letters 14, no. 9 (2016): 090604–90607. http://dx.doi.org/10.3788/col201614.090604.
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Campo-Valera, María, and Ivan Felis. "Underwater Acoustic Communication for The Marine Environment’s Monitoring." Proceedings 42, no. 1 (November 14, 2019): 51. http://dx.doi.org/10.3390/ecsa-6-06642.
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Within the possibilities of non-linear acoustics, the parametric effect offers a range of acoustic applications that are currently being exploited in different areas. In underwater acoustics, environmental monitoring and security are one of the applications that can benefit from these technologies, allowing the transmission of information in a directivity controlled and efficient manner. An essential aspect for the optimal functioning of these technologies is the choice of the modulation that best suits the needs of communication. In the present work, different modulation techniques are explained, through their non-linear propagation, that allows generating the signals to be propagated. Among the modulations presented in this work, we have Amplitude Modulation (AM), Continuous Phase Frequency Shift Keying (CPFSK), and Linear Frequency Modulation (LFM) modulations normally used in communications. These modulations are performed with a modulating signal (sine and sine-sweeps type) whose non-linear demodulation determines the shape of the 1 and 0 bits, through the transmission of a bit string. With all this, comparisons are made between each technique, to obtain a more precise detection and discrimination of the bits.
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Tanyi, Gregory Beti, Miao Sun, Christina Lim, and Ranjith Rajasekharan Unnithan. "Design of an On-Chip Plasmonic Modulator Based on Hybrid Orthogonal Junctions Using Vanadium Dioxide." Nanomaterials 11, no. 10 (September 26, 2021): 2507. http://dx.doi.org/10.3390/nano11102507.
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We present the design of a plasmonic modulator based on hybrid orthogonal silver junctions using vanadium dioxide as the modulating material on a silicon-on-insulator. The modulator has an ultra-compact footprint of 1.8 μm × 1 μm with a 100 nm × 100 nm modulating section based on the hybrid orthogonal geometry. The modulator takes advantage of the large change in the refractive index of vanadium dioxide during its phase transition to achieve a high modulation depth of 46.89 dB/μm. The simulated device has potential applications in the development of next generation high frequency photonic modulators for optical communications which require nanometer scale footprints, large modulation depth and small insertion losses.
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Stenson, Trevor H., and Mark S. Peppler. "Osmolarity affects Bvg-mediated virulence regulation by Bordetella pertussis." Canadian Journal of Microbiology 53, no. 9 (September 2007): 1053–61. http://dx.doi.org/10.1139/w07-071.
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Bordetella pertussis dramatically alters its phenotype by sensing its environment via the BvgAS regulatory system. Increased concentrations of specific chemicals are used in vitro to induce modulation of the bacterium from the Bvg+virulent phenotype to a fully Bvg–phenotype. Varied expression of sets of Bvg-regulated molecules depends on the modulating capacity of the environment. We examined the effect of a number of chemicals on the modulating capacity of B. pertussis growth media, both alone and in combination with known modulators. It was demonstrated that under certain conditions the Bvg-intermediate protein, BipA, is coexpressed with the Bvg–antigen, VraA. This demonstrates that the patterns of molecules expressed in the different phenotypes of B. pertussis are more fluid than has previously been demonstrated. The in vitro modulator, sulfate, was found to be a relatively inefficient modulator of our Tohama I-derived B. pertussis strain. However, addition of nicotinic acid, MgCl2, or sucrose in combination with relatively low sulfate concentrations resulted in effective modulation. This suggests that multiple signals may affect modulation through the BvgAS system or possibly through other regulatory networks. In addition, the cooperative modulating effect of sucrose implicates osmolarity as an environmental stimulus that affects phenotypic modulation.
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Yang, D., J. C. Canit, and E. Gaignebet. "Photoelastic modulator: polarization modulation and phase modulation." Journal of Optics 26, no. 4 (July 1995): 151–59. http://dx.doi.org/10.1088/0150-536x/26/4/002.
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Shetty, Mamtha. "Design of BPSK Modulator Using VHDL." INTERNATIONAL JOURNAL OF COMPUTERS & TECHNOLOGY 13, no. 12 (October 23, 2014): 5247–52. http://dx.doi.org/10.24297/ijct.v13i12.5276.
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Binary Phase Shift Keying represents the simulation results of binary digital modulation schemes. Here for BASK and BPSK modulation techniques use FPGA algorithm. If multiplier block is used for multiplication bit stream with carrier signal, used time will rises. In addition using multiplier block obtained simulation results were analyzed and compared to other simulation results. Source consumptions of FPGA-based BASK modulation technique and BPSK modulation technique were compared. Also, for different modulation algorithm, source consumptions of BASK and BPSK modulation technique were analyzed using VHDL. Designed modulators using VHSIC (Very High Speed Integrated Circuit) Hardware Description Language (VHDL) was realized on high speed FPGA (Field Program Programmable Gate Array). Because for used modulation technique data rate transfer is fairly important in wireless communication systems. The highest speed data rate transfer can be realized using fiber optic cables. In addition, BER (Bit Error Rate) of BASK and BPSK modulator was compared using MATLAB simulation program. Binary data rate is same for BPSK and BASK. BPSK and BASK modulations were designed on FPGA using VHDL hardware description language.
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Chandra, Dikky, Fauzi Aditia Rahmat, Siska Aulia, Firdaus -, and Andre Febrian Kasmar. "Effect of Modulation on Throughput of 4G LTE Network Frequency 1800 MHz." International Journal of Advanced Science Computing and Engineering 5, no. 1 (April 10, 2023): 44–53. http://dx.doi.org/10.62527/ijasce.5.1.121.
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In the development of 4G LTE technology, network speed (Throughput) in several regions has increased or decreased. Network speed (Throughput) certainly cannot be separated from Modulation. In modulation there are several kinds of modulation schemes, be it QPSK modulation, 16 QAM modulation, and 64 QAM modulation. The modulation scheme is instrumental in increasing throughput. Based on several previous studies, they only check the Throughput parameters without doing a more in-depth analysis of the modulation scheme which also plays a very important role in network speed (Throughput). For this reason, it is necessary to carry out an analysis related to the effect of modulation on the throughput value. To find out the effect of modulation on throughput, it is necessary to take data in the field, the method used is the Drive Test method. Based on the results of the Drive Test, QPSK modulation has a Throughput value of 5.247.4 Kbps, modulation of 16 QAM has a Throughput value of 27.293.9 Kbps and modulation of 64 QAM has a Throughput value of 65.275.1 Kbps. Based on the data in the field and in terms of calculations, the modulation that most affects the throughput value is the modulation of 64 QAM. Modulating 64 QAM having 64 symbols where each symbol consists of 6 bits will make the data rate at throughput higher. This also applies to the use of modulation of 16 QAM (16 symbols with 4 bits) and QPSK (4 symbols with 2 bits).
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Zheng, Ningxuan, Wenliang Liu, Jizhou Wu, Yuqing Li, Vladimir Sovkov, and Jie Ma. "Parametric Excitation of Ultracold Sodium Atoms in an Optical Dipole Trap." Photonics 9, no. 7 (June 22, 2022): 442. http://dx.doi.org/10.3390/photonics9070442.
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Parametric modulation is an effective tool to measure the trap frequency and investigate the atom dynamics in an optical dipole trap or lattices. Herein, we report on experimental research of parametric resonances in an optical dipole trap. By modulating the trapping potential, we have measured the atomic loss dependence on the frequency of the parametric modulations. The resonance loss spectra and the evolution of atom populations at the resonant frequency have been demonstrated and compared under three modulation waveforms (sine, triangle and square waves). A phenomenological theoretical simulation has been performed and shown good accordance with the observed resonance loss spectra and the evolution of atom populations. The theoretical analysis can be easily extended to a complex waveform modulation and reproduce enough of the experiments.
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Ozaki, Kouta, Keita Kikuchi, Guangtao Zhu, Kohei Noda, Yuguo Yao, Yuangang Lu, Rajan Jha, Heeyoung Lee, and Yosuke Mizuno. "Noise mechanism clarification in external-modulation Brillouin optical correlation-domain reflectometry with double-sideband modulator." Japanese Journal of Applied Physics 63, no. 7 (July 1, 2024): 070904. http://dx.doi.org/10.35848/1347-4065/ad5f6c.
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Abstract Brillouin optical correlation-domain reflectometry (BOCDR) allows for relatively high spatial resolution and random accessibility with single-end light injection into the sensing fiber. Typically, BOCDR relies on directly modulating the laser diode’s driving current, which facilitates sinusoidal frequency modulation for distributed sensing but also introduces unintended power modulation that can degrade performance. To address these power variations, external-modulation BOCDR using a double-sideband modulator has been developed. However, this method generates substantial noise, overpowering the Brillouin signal and impeding accurate strain and temperature measurements. This study clarifies the previously unexplained noise mechanisms and suggests system design optimizations to mitigate their impact.
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Hörpel, Stephen Gareth, and Uwe Firzlaff. "Processing of fast amplitude modulations in bat auditory cortex matches communication call-specific sound features." Journal of Neurophysiology 121, no. 4 (April 1, 2019): 1501–12. http://dx.doi.org/10.1152/jn.00748.2018.
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Bats use a large repertoire of calls for social communication. In the bat Phyllostomus discolor, social communication calls are often characterized by sinusoidal amplitude and frequency modulations with modulation frequencies in the range of 100–130 Hz. However, peaks in mammalian auditory cortical modulation transfer functions are typically limited to modulation frequencies below 100 Hz. We investigated the coding of sinusoidally amplitude modulated sounds in auditory cortical neurons in P. discolor by constructing rate and temporal modulation transfer functions. Neuronal responses to playbacks of various communication calls were additionally recorded and compared with the neurons’ responses to sinusoidally amplitude-modulated sounds. Cortical neurons in the posterior dorsal field of the auditory cortex were tuned to unusually high modulation frequencies: rate modulation transfer functions often peaked around 130 Hz (median: 87 Hz), and the median of the highest modulation frequency that evoked significant phase-locking was also 130 Hz. Both values are much higher than reported from the auditory cortex of other mammals, with more than 51% of the units preferring modulation frequencies exceeding 100 Hz. Conspicuously, the fast modulations preferred by the neurons match the fast amplitude and frequency modulations of prosocial, and mostly of aggressive, communication calls in P. discolor. We suggest that the preference for fast amplitude modulations in the P. discolor dorsal auditory cortex serves to reliably encode the fast modulations seen in their communication calls. NEW & NOTEWORTHY Neural processing of temporal sound features is crucial for the analysis of communication calls. In bats, these calls are often characterized by fast temporal envelope modulations. Because auditory cortex neurons typically encode only low modulation frequencies, it is unclear how species-specific vocalizations are cortically processed. We show that auditory cortex neurons in the bat Phyllostomus discolor encode fast temporal envelope modulations. This property improves response specificity to communication calls and thus might support species-specific communication.
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Chao Liu, Chao Liu, Di Wang Di Wang, Lixiao Yao Lixiao Yao, Lei Li Lei Li, and Qionghua Wang Qionghua Wang. "Optical attenuator based on phase modulation of a spatial light modulator." Chinese Optics Letters 13, no. 8 (2015): 082301–82304. http://dx.doi.org/10.3788/col201513.082301.
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Wen, Ya-Chien, and Chen-Gia Tsai. "The effect of harmonization on cortical magnetic responses evoked by music of rapidly changing tonalities." Psychology of Music 45, no. 1 (July 7, 2016): 22–35. http://dx.doi.org/10.1177/0305735616639386.
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The act of shifting from one key to another is termed tonal modulation, which has been used to articulate emotion expressions and formal structures in Western music. The present study recorded cortical activity to examine how the auditory-evoked magnetic fields are affected by harmonizing music of rapidly changing tonalities. Participants were asked to covertly sing the pitch names of well-learned modulating melodies along with the harmonized or unharmonized melodies. In our musical stimuli, three flats were added to the key signature for every four beats. Such a rapid modulation is achieved by a chromatic inflection of the submediant tone between the third and fourth beats. Tonal modulations with such chromatic progressions are termed chromatic modulations. A major finding was that the amplitude of N1m (neuromagnetic response at approximately 110 ms after the onset of a stimulus) was significantly reduced by harmonization only when a modulation occurred. We also observed that harmonization enhanced the P2m (neuromagnetic response at approximately 200 ms after the onset of a stimulus) amplitude. The results provide evidence of the impacts of harmonization on attention efforts and pitch categorization.
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Latychevskaia, Tatiana. "Wavefront Modulation and Beam Shaping into Arbitrary Three-Dimensional Intensity Distributions." Photonics 8, no. 6 (May 23, 2021): 179. http://dx.doi.org/10.3390/photonics8060179.
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In this study the methods of three-dimensional (3D) wavefront intensity modulation by employing contrast-inverted holography, previously introduced as Gabor inverted holography, are further investigated. The present study provides the recipes for creating 3D wavefront intensity modulations using phase-only and amplitude-only modulators and compares the results. The 3D wavefront modulation using spherical waves is also demonstrated, and the miniaturization of 3D intensity beams is discussed; it is shown that both the resolution and the size of the created 3D structures are ultimately given by the wavelength of the employed radiation. The manuscript also addresses the quality of the formed 3D intensity curves and determines the parameters that provide the best smooth appearance of the 3D curves. The presented methods of 3D intensity wavefront modulation can be realized for all kinds of waves: light, X-ray, electron, etc, provided the modulator can be manufactured for the corresponding wavelength. The methods of 3D intensity wavefront modulation can be applied in various techniques: lithography, micro-robotics, particle trapping, etc.
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Raman, Rachna, and W. Jay Dowling. "Perception of Modulations in South Indian Classical (Carnātic) Music by Student and Teacher Musicians." Music Perception 34, no. 4 (April 1, 2017): 424–37. http://dx.doi.org/10.1525/mp.2017.34.4.424.
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Modulation, a shift in mode (rĀgam), is important in South Indian classical (Carnātic) music. Here we investigate the sensitivity of Carnātic and Western listeners to such shifts. Carnātic music has two kinds of shifts: rāgamālikā (retaining tonal center, resembling a shift from C major to C minor in Western music) and grahabēdham (shifting tonal center, resembling a shift from C major to A minor). Listeners heard modulating pieces of music and indicated the point of modulation, and were measured for accuracy and latency. Indians were more accurate than Westerners with both types of modulation but Westerners were faster with grahabēdhams. Cues could explain performance differences between nationalities: Indians were more familiar with rāgamālikā-type modulations whereas Westerners’ culture made them more familiar with grahabēdham-type modulations. Increased caution toward the less familiar grahabēdhams for Indians could explain their slower response time compared to rāgamālikās. With grahabēdhams, hit rates for both groups were comparably high, but Westerners’ lower level of accuracy was due to higher false-alarm rates to lures that were superficially similar to actual modulations. This indicated their dependence on surface-level cues in the absence of familiarity and culture-specific information. Music training helped teachers in both groups make fewer errors when compared to students. Older listeners’ performance was comparable to that of younger listeners.
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Arias, Ricardo, Hernán Mediote, and Hernán Tacca. "Flash FPGA-Based Numerical Pulse-Width Modulator." Advances in Power Electronics 2011 (April 4, 2011): 1–6. http://dx.doi.org/10.1155/2011/215376.
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A pulse-width modulator to drive three-phase AC motors is described. It performs a numerical modulation technique, also known as optimum or calculated modulation, but, in order to reduce hardware resources, a hybrid approach merging that calculated modulation with proportional modulation is proposed. The modulator is tested in a flash-based field programmable gate array (FPGA) implementation.
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Huang, Ling, Lijuan Wang, Wangming Shen, Mengsha Li, Shiyu Wang, Xiaotong Wang, Leslie G. Ungerleider, and Xilin Zhang. "A source for awareness-dependent figure–ground segregation in human prefrontal cortex." Proceedings of the National Academy of Sciences 117, no. 48 (November 16, 2020): 30836–47. http://dx.doi.org/10.1073/pnas.1922832117.
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Figure–ground modulation, i.e., the enhancement of neuronal responses evoked by the figure relative to the background, has three complementary components: edge modulation (boundary detection), center modulation (region filling), and background modulation (background suppression). However, the neuronal mechanisms mediating these three modulations and how they depend on awareness remain unclear. For each modulation, we compared both the cueing effect produced in a Posner paradigm and fMRI blood oxygen-level dependent (BOLD) signal in primary visual cortex (V1) evoked by visible relative to invisible orientation-defined figures. We found that edge modulation was independent of awareness, whereas both center and background modulations were strongly modulated by awareness, with greater modulations in the visible than the invisible condition. Effective-connectivity analysis further showed that the awareness-dependent region-filling and background-suppression processes in V1 were not derived through intracortical interactions within V1, but rather by feedback from the frontal eye field (FEF) and dorsolateral prefrontal cortex (DLPFC), respectively. These results indicate a source for an awareness-dependent figure–ground segregation in human prefrontal cortex.
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Moyer, Jason T., John A. Wolf, and Leif H. Finkel. "Effects of Dopaminergic Modulation on the Integrative Properties of the Ventral Striatal Medium Spiny Neuron." Journal of Neurophysiology 98, no. 6 (December 2007): 3731–48. http://dx.doi.org/10.1152/jn.00335.2007.
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Dopaminergic modulation produces a variety of functional changes in the principal cell of the striatum, the medium spiny neuron (MSN). Using a 189-compartment computational model of a ventral striatal MSN, we simulated whole cell D1- and D2-receptor–mediated modulation of both intrinsic (sodium, calcium, and potassium) and synaptic currents (AMPA and NMDA). Dopamine (DA) modulations in the model were based on a review of published experiments in both ventral and dorsal striatum. To objectively assess the net effects of DA modulation, we combined reported individual channel modulations into either D1- or D2-receptor modulation conditions and studied them separately. Contrary to previous suggestions, we found that D1 modulation had no effect on MSN nonlinearity and could not induce bistability. In agreement with previous suggestions, we found that dopaminergic modulation leads to changes in input filtering and neuronal excitability. Importantly, the changes in neuronal excitability agree with the classical model of basal ganglia function. We also found that DA modulation can alter the integration time window of the MSN. Interestingly, the effects of DA modulation of synaptic properties opposed the effects of DA modulation of intrinsic properties, with the synaptic modulations generally dominating the net effect. We interpret this lack of synergy to suggest that the regulation of whole cell integrative properties is not the primary functional purpose of DA. We suggest that D1 modulation might instead primarily regulate calcium influx to dendritic spines through NMDA and L-type calcium channels, by both direct and indirect mechanisms.
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Karpman, V. I., and A. G. Shagalov. "Influence of dispersion on the modulational instability of a whistler wave." Journal of Plasma Physics 41, no. 2 (April 1989): 289–300. http://dx.doi.org/10.1017/s0022377800013878.
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The modulational instability of a whistler wave propagating along an external magnetic field is investigated, taking into account the dispersion of the low-frequency modulations. The dispersive effects are significant if the modulation frequencies Ω are comparable to or greater than the ion cyclotron frequency ωci. It is shown that in this case there are four unstable branches: the long-wave modulational instability and three others with much larger growth rates. At Ω≪ωci the latter correspond to fast magnetic sound, Alfvén and slow magnetic sound branches.
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M, Adarsha, S. Malathi, and Santosh Kumar. "Analysis of System Capacity and Spectral Efficiency of Fixed-Grid Network." International journal of Computer Networks & Communications 15, no. 5 (September 28, 2023): 93–111. http://dx.doi.org/10.5121/ijcnc.2023.15506.
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In this article, the performance of a fixed grid network is examined for various modulation formats to estimate the system's capacity and spectral efficiency. The optical In-phase Quadrature Modulator (IQM) structure is used to build a fixed grid network modulation, and the homodyne detection approach is used for the receiver. Data multiplexing is accomplished using the Polarization Division Multiplexed (PDM) technology. 100 Gbps, 150 Gbps, and 200 Gbps data rates are transmitted under these circumstances utilizing various modulation formats. Various pre-processing and signal recovery steps are explained by using modern digital signal processing systems. The achieved spectrum efficiencies for PM-QPSK, PM-8 QAM, and PM-16 QAM, respectively, were 2, 3, and 4 (bits/s)/Hz. Different modulation like PM-QPSK, PM-8-QAM, and PM-16-QAM each has system capacities of 8-9, 12-13.5, and 16-18 Tbps and it reaches transmission distances of 3000, 1300, and 700 kilometers with acceptable Bit Error Rate (BER≤ 2× 10-3 ) respectively. Peak optical power for received signal detection and full width at half maximum is noted for the different modulations under a fixed grind network.
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Dold, J. W., and D. H. Peregrine. "WATER-WAVE MODULATION." Coastal Engineering Proceedings 1, no. 20 (January 29, 1986): 13. http://dx.doi.org/10.9753/icce.v20.13.
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Accurate numerical computations of wave trains with small modulations that grow are described. The range of wave steepness and modulation lengths that give breaking waves are determined. The number of wave crests is reduced for a time at greatest modulation but frequency downshifting is not observed. Near-breaking wave-group structure is always similar, with energy concentrated into one or two wavelengths.
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WEI, MING-DAR, and CHIH-CHANG HSU. "RESHAPING MODULATION PROFILE TO DECREASE AND INCREASE THE THRESHOLD FOR CHAOTIC BEHAVIOR IN A PUMP-MODULATION Nd:YVO4 LASER." International Journal of Bifurcation and Chaos 22, no. 08 (August 2012): 1250185. http://dx.doi.org/10.1142/s0218127412501854.
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This study investigates the changes of the threshold of chaotic behavior in a pump-modulation Nd:YVO4 laser created by varying the shape of the modulation profile. The threshold for chaotic behavior can be increased and decreased when the modulation profiles are reshaped by triangular wave and Jacobi elliptic sine functions, respectively. Experimental results show that sinusoidal-wave, square-wave, and triangular-wave modulations have different chaotic thresholds, agreeing with numerical results. In addition to the dynamic parameters of modulation frequency and modulation depth, the shape of modulation is an important parameter for controlling the nonlinear dynamics in pump-modulation lasers.
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Proshchenok, E. V., and A. Yu Rodionov. "Modern types of signal manipulation analysis of wireless communication systems." Herald of the Siberian State University of Telecommunications and Informatics 16, no. 4 (January 4, 2023): 43–58. http://dx.doi.org/10.55648/1998-6920-2022-16-4-43-58.
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This paper presents an overview of modern types of signal manipulation such as hierarchical quadrature amplitude modulation (HQAM), circular quadrature amplitude modulation (CQAM) and parametric quadrature amplitude modulation (θ-QAM). Then follows the modeling of the above-mentioned types of modulations and quadrature amplitude modulation (QAM) using the MATLAB programming language. To compare the four selected types of modulation two types of modulation order are used: 16 and 64. To evaluate the effectiveness of using one or another type of modulation a communication channel was modeled to which additive white Gaussian noise (AWGN), Doppler frequency distortion and inaccurate frame synchronization were added.
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Zhao, Chenyu, Dayong Wang, Shufeng Lin, Jie Zhao, Yunxin Wang, and Lu Rong. "Design Optimization of Silicon-Based Optically Excited Terahertz Wave Modulation." Photonics 11, no. 3 (February 24, 2024): 202. http://dx.doi.org/10.3390/photonics11030202.
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The modulation of a terahertz (THz) wave on amplitude, phase and polarization is important for the application of THz technology, especially in the field of imaging, and is one of the current research hotspots. Silicon-based, optically excited THz modulator is a wavefront modulation technique with a simple, compact and reconfigurable optical path. It can realize the dynamic modulation of THz wavefronts by only changing the projected two-dimensional pattern, but it still suffers from the problems of lower modulation efficiency and slower modulation rates. In this article, the Drude model in combination with the multiple thin layers structure model and Fresnel matrix method is used to compare the modulation efficiencies of three modulation modes and more factors. The method is more accurate than the popular proposed method, especially when the thickness of the excited photoconductive layers reaches a few hundred microns. In comparing the three modes, namely transmission, ordinary reflection and total internal reflection, it is found the total internal reflection modulation mode has the best modulation efficiency. Further, under this mode, the effects of three factors, including the lifetime of photo-excited carriers, the wavelength of pump light and the frequency of THz wave, on the performance of THz modulator are analyzed. The simulation results show that the realization of total internal reflection using silicon prisms is a simple and effective method to improve the modulation efficiency of a silicon-based optically excited THz modulator, which provides references for the design of a photo-induced THz modulator.
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Feng, Song, and Bin Xue. "Micro-Nano Electro-Optic Modulator Structure Based on the Si/SiGe/Si Material." Journal of Nanoelectronics and Optoelectronics 15, no. 6 (June 1, 2020): 693–99. http://dx.doi.org/10.1166/jno.2020.2796.
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The modulation power consumption and the modulation efficiency are the key parameters of the electro-optic modulator, which directly affect the electro-optic modulator's photoelectric properties. Improving the performance of the electro-optic modulator, a micro-nano electro-optic modulator structure based on the Si/SiGe/Si material is proposed in this paper, which has low power consumption and high efficiency. After the plasma dispersion effects and the thermo-optic effects are analyzed, we can know that the performance of the electro-optic modulator could be affected by the carrier concentration and the temperature of modulator. Silicon Germanium (SiGe) material is attached to the common Silicon (Si) electro-optic modulator, and a large injection ratio is obtained from the Si/SiGe/Si double hetero-junction. With the modulation region's carrier concentration rise, and the working voltage and the power consumption of modulator all are reduced. The jugged active region structure is attached to the common Si electro-optic modulator, and the probability of inelastic collision among carriers is decreased, so the temperature rise of modulator can be reduced. The thermal-optic effects are weakened, and the modulation efficiency is increased. The simulation results show that the working voltage of the jugged SiGe modulator is less than that of the Silicon modulator at the same refractive index differences, and the jugged SiGe modulator has lower modulation power consumption; the jugged SiGe modulator's effective refractive index differences are more than the Silicon modulator's effective refractive index differences at the same working voltage, and the jugged SiGe modulator has higher modulation efficiency. Therefore, this jugged SiGe modulator is a micro-nano electro-optic modulator with lower power consumption and higher efficiency.
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Hayrapetyan, Yegisabet Hakob, and Stepan Karen Petrosyan. "Construction Features of The High-Precision Laser Rangefinder Light Modulator." Journal of Architectural and Engineering Research 1, no. 1 (June 25, 2021): 26–31. http://dx.doi.org/10.54338/27382656-2021.1-5.
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The issues related to the development of a light modulator operating on the electro-optical effect of laser rangefinders by the modulation method are considered. To reduce the modulation power, it is proposed to lower the modulation frequency to 750-800 MHz, while simultaneously increasing the modulation quality to Q = 1000. The study of the phase determination error of a high-precision laser rangefinder depending on temperature showed that it is rational to construct the light modulator by radial installation of the KDP electro-optical crystal, with separated modulation and demodulation channels, while on combined resonators.
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Sakamoto, Hirokazu, Takeji Takui, and Koichi Itoh. "General description of multiple-modulation effects and sideband production in magnetic resonance." Canadian Journal of Chemistry 66, no. 12 (December 1, 1988): 3077–82. http://dx.doi.org/10.1139/v88-476.
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A theory is presented for the sideband structure produced by a general multiple-modulation scheme with arbitrary combination of p-tuple field modulation, q-tuple frequency modulation, and r-tuple amplitude modulation for integral p, q, and r. A general formula describing the multiple-modulation effects is analytically derived using a density matrix formalism under the assumption of negligible saturation; an equivalent result is obtained from the phenomenological Bloch equation. The general formula reveals that field and frequency modulations are equivalent for the sideband production, even in the presence of amplitude modulation. Two particular cases, viz., r-tuple amplitude modulation and double field modulation are dealt with to show the validity and applicability of the general formula.
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Fogerty, Daniel, Jayne B. Ahlstrom, William J. Bologna, and Judy R. Dubno. "Glimpsing Speech in the Presence of Nonsimultaneous Amplitude Modulations From a Competing Talker: Effect of Modulation Rate, Age, and Hearing Loss." Journal of Speech, Language, and Hearing Research 59, no. 5 (October 2016): 1198–207. http://dx.doi.org/10.1044/2016_jslhr-h-15-0259.
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Purpose This study investigated how listeners process acoustic cues preserved during sentences interrupted by nonsimultaneous noise that was amplitude modulated by a competing talker. Method Younger adults with normal hearing and older adults with normal or impaired hearing listened to sentences with consonants or vowels replaced with noise amplitude modulated by a competing talker. Sentences were spectrally shaped according to individual audiograms or to the mean audiogram from the listeners with hearing impairment for a younger spectrally shaped control group. The modulation spectrum of the noise was low-pass filtered at different modulation cutoff frequencies. The effect of noise level was also examined. Results Performance declined when nonsimultaneous masker modulation included faster rates and was maximized when masker modulation matched the preserved primary speech modulation. Vowels resulted in better performance compared with consonants at slower modulation cutoff rates, likely due to suprasegmental features. Poorer overall performance was observed with increased age or hearing loss, and for listeners who received spectrally shaped speech. Conclusions Nonsimultaneous amplitude modulations from a competing talker significantly interacted with the preserved speech segment, and additional listener factors were observed for age and hearing loss. Importantly, listeners may obtain benefit from nonsimultaneous competing modulations when they match the preserved modulations of the sentence.
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Hadj Ali, Bakir. "Performance Comparison Between Direct and External Modulation Using RZ and NRZ Coding." ELEKTRIKA- Journal of Electrical Engineering 19, no. 1 (April 24, 2020): 1–8. http://dx.doi.org/10.11113/elektrika.v19n1.144.
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Such as in any optical communication system, the light modulation is considered a main key to determine the performance (or the maximum) of the data rate that can be transmitted and over what the long distance can be applied. So, a choice of the modulation type in any optical link is more important and should base on measuring of the BER and the Q factor parameters. In that issue, we propose a comparative study as contribution between the principle or the schemes of the direct modulation (DM) and the external modulation (EM) respectively, which the chirp frequency modeling is described for the two modulations. However, the main issues addressed also in the simulation analysis when the amount of the chirp (in GHz) introduced for the two modulations applied is discussed, and also the Q factor introduced using different power values and, in different data rate for the two modulations studied is presented where we can determine from these results of the Q factor the effect of the power and the limit of applying the direct modulation and the external modulation in terms of the maximum of the data rate that can be transmitted. Moreover, we provide a numerical results of the Q factor and the BER for the two modulations (DM and EM) using RZ and NRZ format codes at different distance transmission, and in different data rate through these results we can conclude in which code (RZ and NRZ) the DM and the EM performed better.
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Graetsch, Heribert A., Chandra Shekhar Pandey, Jürgen Schreuer, Manfred Burianek, and Manfred Mühlberg. "Incommensurate modulation of calcium barium niobate (CBN28 and Ce:CBN28)." Acta Crystallographica Section B Structural Science 68, no. 2 (February 25, 2012): 101–6. http://dx.doi.org/10.1107/s0108768111054863.
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The incommensurately modulated crystal structures of Ca0.28Ba0.72Nb2O6 (CBN28) and Ce0.02Ca0.25Ba0.72Nb2O6 (Ce:CBN28) were refined in the supercentred setting X4bm(AA0,−AA0) of the 3 + 2-dimensional superspace group P4bm(aa½,−aa½). Both compounds are isostructural with a tetragonal tungsten bronze-type structure. The modulation of CBN28 consists of a wavy distribution of Ba and Ca atoms as well as vacancies on the incompletely occupied Me2 site with 15-fold oxygen coordination. The occupational modulation is coupled with a modulation of the atomic displacement parameters and a very weak modulation of the positional parameters of Me2. The surrounding O atoms show strong displacive modulations with amplitudes up to ca 0.2 Å owing to the cooperative tilting of the rigid NbO6 octahedra. The Me1 site with 12-fold coordination and Nb atoms are hardly affected by the modulations. Only first-order satellites were observed and the modulations are described by first-order harmonics. In Ce:CBN28 cerium appears to be located on both the Me2 and Me1 sites. Wavevectors and structural modulations are only weakly modified upon substitutional incorporation of 0.02 cerium per formula unit of calcium.
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Muñoz-Ramírez, Mauricio, Hugo Valderrama-Blavi, Marco Rivera, and Carlos Restrepo. "An Approach to Natural Sampling Using a Digital Sampling Technique for SPWM Multilevel Inverter Modulation." Energies 12, no. 15 (July 30, 2019): 2925. http://dx.doi.org/10.3390/en12152925.
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This paper introduces an approach that applies a digital sampling technique for a sinusoidal pulse width modulation (SPWM) multilevel inverter modulation that reduces the total harmonic contents in the output voltage compared to that of classical regular sampling techniques. This new modulation emulates with a high degree of fidelity a natural sampling pulse width modulation (PWM). The theoretical analysis of this new digital technique compared with natural sampling has been validated by simulations and through experiments with a built prototype that performed five–level inverter modulations with vertically displaced carriers in phase disposition. Both simulation and experimental results generate a SPWM output voltage with higher fidelity than classic regular sampling techniques, allowing a reduction of the filtering demands on the inverter output, which in turn can decrease the converter size and its manufacturing costs. As the presented technique is digital, the resulting modulation is more robust against switching noise, jitter, and other system perturbations and the modulation parameters can be changed easily, even in an automated way. For this reason, the modulation introduced here can be a useful tool to perform spectral analysis for different multilevel modulations and systems.
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Koelsch, Stefan, Thomas Gunter, Erich Schröger, and Angela D. Friederici. "Processing Tonal Modulations: An ERP Study." Journal of Cognitive Neuroscience 15, no. 8 (November 1, 2003): 1149–59. http://dx.doi.org/10.1162/089892903322598111.
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A common stylistic element of Western tonal music is the change of key within a musical sequence (known as modulation in musical terms). The aim of the present study was to investigate neural correlates of the cognitive processing of modulations with event-related brain potentials. Participants listened to sequences of chords that were infrequently modulating. Modulating chords elicited distinct effects in the event-related brain potentials: an early right anterior negativity reflecting the processing of a violation of musical regularities and a late frontal negativity taken to reflect processes of harmonic integration. Additionally, modulations elicited a tonic negative potential suggested to reflect cognitive processes characteristic for the processing of tonal modulations, namely, the restructuring of the “hierarchy of harmonic stability” (which specifies musical expectations), presumably entailing working memory operations. Participants were “nonmusicians”; results thus support the hypothesis that nonmusicians have a sophisticated (implicit) knowledge about musical regularities.
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Li, Liang, Alexander Wölfel, Andreas Schönleber, Swastik Mondal, Antoine M. M. Schreurs, Loes M. J. Kroon-Batenburg, and Sander van Smaalen. "Modulated anharmonic ADPs are intrinsic to aperiodic crystals: a case study on incommensurate Rb2ZnCl4." Acta Crystallographica Section B Structural Science 67, no. 3 (May 14, 2011): 205–17. http://dx.doi.org/10.1107/s0108768111013814.
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A combination of structure refinements, analysis of the superspace MEM density and interpretation of difference-Fourier maps has been used to characterize the incommensurate modulation of rubidium tetrachlorozincate, Rb2ZnCl4, at a temperature of T = 196 K, close to the lock-in transition at T lock-in = 192 K. The modulation is found to consist of a combination of displacement modulation functions, modulated atomic displacement parameters (ADPs) and modulated third-order anharmonic ADPs. Up to fifth-order Fourier coefficients could be refined against diffraction data containing up to fifth-order satellite reflections. The center-of-charge of the atomic basins of the MEM density and the displacive modulation functions of the structure model provide equivalent descriptions of the displacive modulation. Modulations of the ADPs and anharmonic ADPs are visible in the MEM density, but extracting quantitative information about these modulations appears to be difficult. In the structure refinements the modulation parameters of the ADPs form a dependent set, and ad hoc restrictions had to be introduced in the refinements. It is suggested that modulated harmonic ADPs and modulated third-order anharmonic ADPs form an intrinsic part, however small, of incommensurately modulated structures in general. Refinements of alternate models with and without parameters for modulated ADPs lead to significant differences between the parameters of the displacement modulation in these two types of models, thus showing the modulation of ADPs to be important for a correct description of the displacive modulation. The resulting functions do not provide evidence for an interpretation of the modulation by a soliton model.
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Cai, Ming, Shulong Wang, Zhihong Liu, Yindi Wang, Tao Han, and Hongxia Liu. "Graphene Electro-Optical Switch Modulator by Adjusting Propagation Length Based on Hybrid Plasmonic Waveguide in Infrared Band." Sensors 20, no. 10 (May 18, 2020): 2864. http://dx.doi.org/10.3390/s20102864.
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A modulator is the core of many optoelectronic applications such as communication and sensing. However, a traditional modulator can hardly reach high modulation depth. In order to achieve the higher modulation depth, a graphene electro-optical switch modulator is proposed by adjusting propagation length in the near infrared band. The switch modulator is designed based on a hybrid plasmonic waveguide structure, which is comprised of an SiO2 substrate, graphene–Si–graphene heterostructure, Ag nanowire and SiO2 cladding. The propagation length of the hybrid plasmonic waveguide varies from 0.14 μm to 20.43 μm by the voltage tunability of graphene in 1550 nm incident light. A modulator with a length of 3 μm is designed based on the hybrid waveguide and it achieves about 100% modulation depth. The lower energy loss (~1.71 fJ/bit) and larger 3 dB bandwidth (~83.91 GHz) are attractive for its application in a photoelectric integration field. In addition, the excellent robustness (error of modulation effects lower than 8.84%) is practical in the fabrication process. Most importantly, by using the method of adjusting propagation length, other types of graphene modulators can also achieve about 100% modulation depth.
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Yijun Qi, Yijun Qi, Chenliang Chang Chenliang Chang, and and Jun Xia and Jun Xia. "Accurate complex modulation by the iterative spatial cross-modulation method." Chinese Optics Letters 15, no. 2 (2017): 020901–20905. http://dx.doi.org/10.3788/col201715.020901.
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Ma, Z. T., Z. X. Geng, Z. Y. Fan, J. Liu, and H. D. Chen. "Modulators for Terahertz Communication: The Current State of the Art." Research 2019 (May 29, 2019): 1–22. http://dx.doi.org/10.34133/2019/6482975.
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With the increase of communication frequency, terahertz (THz) communication technology has been an important research field; particularly the terahertz modulator is becoming one of the core devices in THz communication system. The modulation performance of a THz communication system depends on the characterization of THz modulator. THz modulators based on different principles and materials have been studied and developed. However, they are still on the way to practical application due to low modulation speed, narrow bandwidth, and insufficient modulation depth. Therefore, we review the research progress of THz modulator in recent years and evaluate devices critically and comprehensively. We focus on the working principles such as electric, optical, optoelectrical, thermal, magnetic, programmable metamaterials and nonlinear modulation methods for THz wave with semiconductors, metamaterials, and 2D materials (such as graphene, molybdenum disulfide, and tungsten disulfide). Furthermore, we propose a guiding rule to select appropriate materials and modulation methods for specific applications in THz communication.
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Krebs, Bjarne, Nicholas A. Lesica, and Benedikt Grothe. "The Representation of Amplitude Modulations in the Mammalian Auditory Midbrain." Journal of Neurophysiology 100, no. 3 (September 2008): 1602–9. http://dx.doi.org/10.1152/jn.90374.2008.
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Temporal modulations in stimulus amplitude are essential for recognizing and categorizing behaviorally relevant acoustic signals such as speech. Despite this behavioral importance, it remains unclear how amplitude modulations (AMs) are represented in the responses of neurons at higher levels of the auditory system. Studies using stimuli with sinusoidal amplitude modulations (SAMs) have shown that the responses of many neurons are strongly tuned to modulation frequency, leading to the hypothesis that AMs are represented by their periodicity in the auditory midbrain. However, AMs in general are defined not only by their modulation frequency, but also by a number of other parameters (duration, duty cycle, etc.), which covary with modulation frequency in SAM stimuli. Thus the relationship between modulation frequency and neural responses as characterized with SAM stimuli alone is ambiguous. In this study, we characterize the representation of AMs in the gerbil inferior colliculus by analyzing neural responses to a series of pulse trains in which duration and interpulse interval are systematically varied to quantify the importance of duration, interpulse interval, duty cycle, and modulation frequency independently. We find that, although modulation frequency is indeed an important parameter for some neurons, the responses of many neurons are also strongly influenced by other AM parameters, typically duration and duty cycle. These results suggest that AMs are represented in the auditory midbrain not only by their periodicity, but by a complex combination of several important parameters.
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Sławiński, W., R. Przeniosło, I. Sosnowska, and V. Petříček. "Helical screw type magnetic structure of the multiferroic CaMn7O12 with low Cu-doping." Acta Crystallographica Section B Structural Science 68, no. 3 (May 4, 2012): 240–49. http://dx.doi.org/10.1107/s0108768112008038.
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The modulated crystal structure and modulated magnetic ordering of the multiferroic CaCu x Mn7−x O12 is studied by analysing neutron and synchrotron-radiation (SR) powder diffraction data with a model based on the magnetic superspace group R31′(00γ)ts. Both atomic position modulations and magnetic modulations are described with the modulation vector (0, 0, q). The magnetic ordering is a screw-type circular helix where the magnetic moments are perpendicular to the c direction. The temperature dependence of the modulation vector length and the ordered magnetic moments of Mn3+ and Mn4+ ions is given between T = 50 K and the Néel temperature T N ≃ 90 K. The atomic position modulation length L p and the magnetic modulation length L m fulfil the relation L m = 2L p at all temperatures between 50 K and T N.
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Horii, Yoshiyuki. "Frequency Modulation Characteristics of Sustained // Sung in Vocal Vibrato." Journal of Speech, Language, and Hearing Research 32, no. 4 (December 1989): 829–36. http://dx.doi.org/10.1044/jshr.3204.829.
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Frequency modulation characteristics of sustained vowel phonations in vocal vibrato were investigated. Eight male singers produced sustained // in vibrato at low-, middle-, and high-pitch levels with comfortable loudness. The recorded voice samples were digitized and analyzed by a program yielding a plot of fundamental frequencies (F 0 ) of individual fundamental cycles. Modulation frequency, extent, rates of F 0 increase and decrease, and modulation jitter and modulation shimmer were measured for individual modulation cycles. Central tendency and variability of these measures, intercorrelations among these measures, and temporal patterns of frequency modulations were investigated. Results indicated (1) significant effects of pitch levels on modulation frequency, (2) more regularity in modulation frequency than extent, (3) predominantly linear temporal patterns of frequency modulation, and (4) faster F 0 increase than decrease. Implications of these findings for the nature of underlying mechanisms of frequency control in vocal vibrato are discussed.
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Chen, Lei, Junhua Huang, Gui-Shi Liu, Feifan Huang, Huajian Zheng, Yaofei Chen, Yunhan Luo, and Zhe Chen. "Photon coupling-induced spectrum envelope modulation in the coupled resonators from Vernier effect to harmonic Vernier effect." Nanophotonics 11, no. 5 (January 26, 2022): 957–66. http://dx.doi.org/10.1515/nanoph-2021-0596.
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Abstract The Vernier effect and harmonic Vernier effect have attracted ever-increasing interest due to their freely tailored spectrum envelope in tunable laser, modulator, and precision sensing. Most explorations have mainly focused on configuring two isolated optical resonators, namely the reference and tunable resonator. However, this configuration requires a stable reference resonator to guarantee robust readout, posing a significant challenge in applications. Here, we discover the coupled-resonators configuration enabling a reference-free envelope modulation to address this problem. Specifically, all parameters of one resonator theoretically span a hypersurface. When the resonator couples to another one, photon coupling merit an escaped solution from the hypersurface, resulting in an envelope modulation independent of reference. We have first experimentally verified this mechanism in a coupled air resonator and polydimethylsiloxane resonator by inserting a semi-transparent 2-mercaptobenzimidazole-modified silver nanowire network. In addition, this novel mechanism provides a new degree of freedom in the reciprocal space, suggesting alternative multiplexing to combine more envelope modulations simultaneously. This study facilitates the fundamental research in envelope multiplexing. More importantly, the combination of silver nanowire network and flexible microcavity experimentally progress the spectral envelope modulation in optoelectronic integration inside resonators.
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Su, Lin Bo, Jian Hua Chen, and Ying Peng Hu. "The Study of Coded CPM Schemes." Applied Mechanics and Materials 198-199 (September 2012): 1408–12. http://dx.doi.org/10.4028/www.scientific.net/amm.198-199.1408.
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Continuous Phase Modulation (CPM) schemes belong to a class of constant-envelope digital modulation schemes, the constant-envelope nature of the CPM signals makes them robust for the nonlinear and fading channels, and very useful for the satellite and/or the mobile radio channels. Comparing to PSK modulation, CPM modulation can not only provide spectral economy, but also exhibit a “coding gain”. CPM can be decomposed into a Continuous Phase Encoder (CPE) followed by a Memoryless Modulator (MM), this allows many new coded modulation schemes of combination of convolutional encoder and CPM modulator to be possible, such as serially-concatenated CPM (SC-CPM), SC-CPM with Convolutional Codes over Rings, pragmatic CPM (P-CPM), Concatenation of convolutional endocder and extended CE（CCEC）, etc. Some simulations show that these new CPM schemes can offer superior performance.
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Feng, Li Shuang, Bo Hao Yin, Zhen Zhou, Jia Wei Sui, and Chen Long Li. "Design and Simulation of a Polarization-Independent Active Metamaterial Terahertz Modulator." Applied Mechanics and Materials 455 (November 2013): 167–72. http://dx.doi.org/10.4028/www.scientific.net/amm.455.167.
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The design and simulation of a polarization-independent active metamaterial terahertz modulator is presented in this work. The device incorporates an array of gold triple SRRs on an n-doped gallium arsenide layer to create an active metamaterial terahertz modulator with a high modulation depth, a high modulation speed and an especial polarization-independent performance for use in terahertz communication, imaging and sense.We established the theoretical model and simulatedthe key performances of the device with Ansoft HFSS.The results showed that the device exhibits a polarization-insensitivebehavior with a maximum amplitude modulation depth of 71% and a modulation rate of3.2Mbps at the resonance frequency of0.86 THz.
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Li, Baolong, Xiaomei Xue, Qiong Wu, Yang Liu, Guilu Wu, and Zhengquan Li. "Multiuser Transmit Precoding Design for Dimming Compatible Visible Light Communications." Applied Sciences 9, no. 6 (March 18, 2019): 1147. http://dx.doi.org/10.3390/app9061147.
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In multiuser visible light communication (VLC) systems, many transmit precoding (TPC) techniques have been investigated to suppress multiuser interference. However, these conventional works restrict their modulation to the special case of zero mean, which inherently limits their application to some popular modulations associated with the non-zero mean in VLC, such as pulse position modulation (PPM). Since the modulation with non-zero mean leads to more intricate optical power constraints and design objective functions than the case of zero mean, the TPC design that can support a general modulation is still an open problem. In the paper, we conceive of a general solution of the TPC scheme combined with dimming control for multiuser VLC systems, which is capable of mitigating multiuser interference, while at the same time, achieving the desired dimming level. The proposed scheme is applicable to a wide range of modulations in VLC, such as pulse amplitude modulation (PAM), PPM, and so on. Simulation results demonstrate that the proposed scheme outperforms the traditional pseudo-inverse-based zero-forcing TPC in terms of bit error rate (BER).
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Zhou, Zhi Yuan, Qing Xin Meng, Hao Tian, and Zhong Xiang Zhou. "Optimization for Amplitude Modulator of THz Wave Based on Polymer Waveguide." Applied Mechanics and Materials 378 (August 2013): 322–26. http://dx.doi.org/10.4028/www.scientific.net/amm.378.322.
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The Terahertz modulator based on polymer electro-optic modulation is designed by Macher-Zehnder structure. The ridge waveguide is used to realize TM00 mode transmission, and the Y-branch with double circular arch type is to decrease the loss of transmission in modulator. The transmission of THz is analyzed by the beam propagate method (BPM). The structure parameters of the M-Z modulator, such as the size of ridge waveguide, the type of Y-branch and the optical offset structure for phase, are optimized to realize THz amplitude modulation. The depth of modulation is 83.8% when the applied field is 31.5V.
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Belousov, Igor’ V., Veniamin F. Samoseiko, and Alexander V. Saushev. "OPTIMAL PULSE WIDTH MODULATION IN THE ELECTRIC DRIVE CONTROL SYSTEM." Vestnik Gosudarstvennogo universiteta morskogo i rechnogo flota imeni admirala S. O. Makarova 14, no. 3 (September 2, 2022): 463–71. http://dx.doi.org/10.21821/2309-5180-2022-14-3-463-471.
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The process of pulse width modulation (PWM) in the converter - electric motor system is considered. It is noted that the main task of pulse-width modulation of the voltage generated by the electron-key converter in the converter - electric motor system is to reduce current pulsations during the modulation period. It is proved that the dynamic process of changing the current in an electric machine on the PWM period can be approximated by an R, L-filter. It is established that the most important task of PWM is to minimize the current modulation error in the electric motor. The analysis of possible criteria for assessing the quality of the modulation process in electric drive control systems is carried out. It is shown that as an optimality criterion for assessing the quality of modulation in a converter - electric motor system, it is advisable to use an integral quadratic criterion of relative error, called local current dispersion, as well as the average value of local current dispersion over the period of the modulating function, called integral current dispersion. The process of single-phase modulation on a single-phase load is considered. Analytical estimates of the load current dispersion for this process are obtained. A condition, under which the current dispersion takes a minimum value, is recorded. The efficiency of pulse-width modulation optimization by the criterion of current dispersion is investigated. The average dispersion of currents in the load with a centrally symmetric arrangement of pulses on the modulation interval is taken as the base value of the dispersion. An expression that allows us to evaluate the efficiency of optimizing the current dispersion, taking into account the increment of the center of the modulation interval, is obtained. The dependence illustrating the efficiency of optimization by the criterion of pulse displacement relative to the center of the PWM interval on the relative frequency of modulation at different amplitudes of the modulating voltage is constructed. An expression is obtained for estimating the average value of the local current dispersion over the half-period of the modulating function.
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Zhang, Hao Chi, Tie Jun Cui, Yu Luo, Jingjing Zhang, Jie Xu, Pei Hang He, and Le Peng Zhang. "Active digital spoof plasmonics." National Science Review 7, no. 2 (October 4, 2019): 261–69. http://dx.doi.org/10.1093/nsr/nwz148.
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Abstract Digital coding and digital modulation are the foundation of modern information science. The combination of digital technology with metamaterials provides a powerful scheme for spatial and temporal controls of electromagnetic waves. Such a technique, however, has thus far been limited to the control of free-space light. Its application to plasmonics to shape subwavelength fields still remains elusive. Here, we report the design and experimental realization of a tunable conformal plasmonic metasurface, which is capable of digitally coding and modulating designer surface plasmons at the deep-subwavelength scale. Based on dynamical switching between two discrete dispersion states in a controlled manner, we achieve digital modulations of both amplitude and phase of surface waves with nearly 100% modulation depth on a single device. Our study not only introduces a new approach for active dispersion engineering, but also constitutes an important step towards the realization of subwavelength integrated plasmonic circuits.
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Mase, Hajime, and Yuichi Iwagaki. "WAVE GROUP PROPERTY OF WIND WAVES FROM MODULATIONAL INSTABILITY." Coastal Engineering Proceedings 1, no. 20 (January 29, 1986): 43. http://dx.doi.org/10.9753/icce.v20.43.
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This paper discusses wave grouping of wind waves from the physical viewpoint of wave modulational instability. Amplitude modulation periods obtained from the smoothed instantaneous wave energy history (SIWEH) of the observed data are compared with the predicted values by the modulational instability theory using the Zakharov equation for a finite constant water depth derived by Stiassnie and Shemer(1984). The modulation period normalized by the typical wave period corresponds to the length of total run. It is shown that the amplitude modulation periods of the observed data agree satisfactorily with the predicted values. Thus we conclude that the modulational instability is a hydrodynamical cause of grouping of high waves.
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Chakraborty, Meenakshi, and Taraprasad Chattopadhyay. "Total Harmonic Modulation Distortion of an Injection-Locked Fabry-Perot Laser Diode Directly Modulated by a Multi-harmonic RF Signal." International Journal of Engineering & Technology 7, no. 4.5 (September 22, 2018): 309. http://dx.doi.org/10.14419/ijet.v7i4.5.20095.
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This paper describes effects of low-level light injection into a directly modulated Fabry-Perot laser diode on the external total harmonic modulation distortion when the external fundamental modulating signal is multi-harmonic contaminated. Necessary theory of the injected FPLD has been developed and an expression for total harmonic distortion of the modulating signal has been derived considering low-level light injection. The total harmonic modulation distortion has been experimentally measured for the RF modulation source and for the injection-locked slave FPLD output after photodetection.
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Henry, Kenneth S. "Behavioral and neurophysiological signatures of the modulation filterbank in an animal model." Journal of the Acoustical Society of America 153, no. 3_supplement (March 1, 2023): A335. http://dx.doi.org/10.1121/10.0019059.
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Fluctuations in the temporal envelope of sound, called amplitude modulation (AM), are an important information-bearing feature of many complex communication signals including speech. Human listeners show diminished sensitivity to AM signals in the presence of competing modulations of similar frequency, known as modulation masking. Modulation masking is not explainable by classic power-spectrum models, but instead suggests a “modulation filterbank” processing strategy that separates concurrent sounds (e.g., AM signals from noise) that have different modulation frequencies. The modulation filterbank is an exciting theoretical development because in addition to explaining modulation masking, the model predicts differences in speech perception across noise environments with different envelope statistics. However, the physiological underpinnings of the modulation filterbank remain uncertain due to limited nonhuman animal models. New behavioral and neurophysiological studies of the modulation filterbank are presented in budgerigars, a parakeet species with human-like behavioral sensitivity to many simple and complex sounds. Behavioral modulation-masking results show compelling evidence of the modulation filterbank in this animal model. Neural recordings from the inferior colliculus (midbrain level) further suggest that rate-based AM sensitivity can explain behavioral modulation-masking results. This new animal model of the modulation filterbank can be used to explore hearing mechanisms in real-world noisy listening environments.
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Dvornikov, Sergey, Sergey Dvornikov, and Kirill Zheglov. "Noise Immunity of Single-Sideband Modulation Signals with a Controlled Carrier Level." Informatics and Automation 22, no. 2 (March 17, 2023): 261–88. http://dx.doi.org/10.15622/ia.22.2.2.
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Single-sideband modulation is actively used in the organization of communication through the ionospheric channel in the decameter range of radio waves. This is due to the fact that transmissions with single-sideband modulation make it possible to minimize the frequency band while maintaining the information transfer rate and at the same time increase the noise immunity of reception in relation to transmissions with amplitude and frequency analog modulation. At the same time, the widespread use of quadrature synthesis technologies has opened up new possibilities for the formation of transmissions with single-sideband modulation without the direct use of filtering procedures. An analysis of the implementation features of the method of quadrature synthesis of signals with single-sideband modulation showed that the introduction of an additional parameter into its procedures will allow you to control the residual level of the carrier wave, and thereby control the noise immunity of the reception. The opened opportunities made it possible to develop a method and a device for generating a single-sideband modulation signal with an adjustable level of the carrier wave that implements it. The technologies of quadrature synthesis of signals of amplitude modulation and single-sideband modulation with the suppressed carrier are considered both at the level of analytical modeling and using a standard quadrature modulator. The necessity of transition to the analytical form of representation of the modulating signal is substantiated. The role and place of the Hilbert converter in the formation of signals with single-sideband modulation are shown. Known technologies for generating single-sideband modulation signals with a stored pilot signal are considered. The possibility of controlling the value of the stored pilot signal at the level of quadrature synthesis procedures is substantiated. An analytical model and, based on it, a structural diagram have been developed that allow one to generate single-sideband modulation signals with an adjustable pilot signal level. The results of analytical modeling are demonstrated. The value of the provided energy gain as a result of regulation by the residual level of the carrier wave is calculated. Approaches to assessing the noise immunity of transmissions with single-sideband modulation are analyzed. An approach is proposed for calculating the bit error probability of SSB transmissions manipulated by discrete oscillations based on the results of energy redistribution between the carrier oscillation and the sideband, determined by the residual pilot signal level. Conclusions and proposals for the practical implementation of the results obtained are formulated.