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Artigos de revistas sobre o tema "Radio frequency modulation"

Autor: Grafiati

Publicado: 4 de junho de 2021

Última modificação: 6 de setembro de 2023

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1

Yang, Kai, Zhanshan Sun, Ruiqi Mao, Yi Lin, Yi Liu, Qiang An e Yunqi Fu. "Wideband Rydberg atom-based receiver for amplitude modulation radio frequency communication". Chinese Optics Letters 20, n.º 8 (2022): 081203. http://dx.doi.org/10.3788/col202220.081203.

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2

Cho, Chihyun, Hyunji Koo, Jae-Yong Kwon, Joo-Gwang Lee e Tae-Weon Kang. "Measurement of Analog Modulation Index with a Calibrated Radio Frequency Attenuator". Journal of Electromagnetic Engineering and Science 21, n.º 2 (30 de abril de 2021): 87–94. http://dx.doi.org/10.26866/jees.2021.21.2.87.

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This paper presents a method for the accurate and traceable measurement of the analog modulation index. A calibrated step attenuator was used as the main apparatus because it has a higher dynamic range and lower uncertainty than a spectrum analyzer or an oscilloscope. In amplitude modulation (AM), the modulation index is obtained from the amplitude difference between the carrier and the first sideband, as in the conventional method. The resolution and calibration uncertainties of the step attenuator were propagated to the measurement uncertainty of the modulation index. The uncertainty produced by the impedance mismatch and repeatability was also included. For frequency modulation (FM) and phase modulation (PM), the modulation index, β, was estimated (with the step attenuator) from the spectrum of each sideband through the nonlinear fitting of the Bessel function. Thus, the uncertainty of the fitting process was added to the uncertainty of the measurement. The three modulations, AM, FM, and PM, exhibited an expanded uncertainty (approximately 95% confidence level, k = 2) of 0.372% for 50% nominal depth of the AM, 88.8 Hz for the peak frequency deviation of 10 kHz, and 0.88 mrad for a 0.1 radian modulation index, respectively.

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3

Bello, N., e F. O. Edeko. "Design of a Robust Orthogonal Frequency Division Multiplexing (OFDM) Transceiver for a Cognitive Radio Testbed". March 2022 6, n.º 1 (março de 2022): 13–27. http://dx.doi.org/10.36263/nijest.2022.01.0301.

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Primarily, a Cognitive Radio (CR) resolves the problem of spectrum scarcity and underutilization. However, it should also attain a good throughput and Quality of Service (QoS) as its objectives. These requirements are solely dependent on the modulation used. Though single carrier modulations such as Gaussian Minimum Shift Keying (GMSK) are highly spectral efficient, they are not robust to frequency selective fading. An implementation of multicarrier modulation supports high spectral efficiency and resistance to multipath fading. Therefore, in this paper, there is a comprehensive how-to-guide of the design of Orthogonal Frequency Division Multiplexing (OFDM) in cognitive radio using GNU Radio (GR) 3.8 that interfaces with Universal Software Radio Peripheral (USRP) B210s for video transmission. The implementation achieved allows for the choice of any modulation schemes out of four commonly used ones for communication of the payloads thus offering dynamism for use in a cognitive radio system. The effective implementation of the proposed methods in this paper is verified by the successful transmission and reception of a 4 minute 37 seconds MP4 video across the different choices of modulation schemes. It was observed that the error performance of the payloads degraded with higher constellation points however, the throughput was increased. Hence, the trade-off between error probability and throughput in the cognitive radio is based on the radio-scene metrics about the signal-to-noise ratio (SNR) of the available channels.

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4

Volkov, A. A., V. A. Kuzyukov e M. S. Morozov. "MODEM OPTIONS FOR DIGITAL RADIO COMMUNICATION SYSTEMS". World of Transport and Transportation 15, n.º 6 (28 de dezembro de 2017): 48–56. http://dx.doi.org/10.30932/1992-3252-2017-15-6-4.

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[For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version)].ABSTRACT New versions of the modulator and demodulator (modem) for the digital railway radio communication system GSM-R have been developed, which increase the noise immunity twofold. To realize «cos» and «sin» blocks, a phase modulator is used, two coherent quadrature demodulators are connected to its output in parallel. It is shown that «cos» block generates the signal cos [msinφ(t)], which is transferred to the operating frequency of the transmitter by means of subsequent blocks representing the structure of the one-side amplitude modulation driver, forming the final phase-modulated signal. It is proposed to detect an FM signal not from the modulation envelope, as it is done customary, but coherently, which excludes the quadrature component of the interference. Keywords: railway, radio communication, digital signal, Gaussian filter, modulation, coherent FM signal detector, noise immunity, frequency efficiency.

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5

Han, Huangpu, Fan Yang, Chenghao Liu, Zhengfang Wang, Yunpeng Jiang, Guangyue Chai, Shuangchen Ruan e Bingxi Xiang. "High-Performance Electro-Optical Mach–Zehnder Modulators in a Silicon Nitride–Lithium Niobate Thin-Film Hybrid Platform". Photonics 9, n.º 7 (19 de julho de 2022): 500. http://dx.doi.org/10.3390/photonics9070500.

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We analyzed a Mach–Zehnder electro-optical modulator based on a silicon nitride strip–loaded waveguide on 0.5 μm thick x-cut lithium niobate thin film. The optical and radio frequency parameters for two different modulator structures (Type I: packaged with 2 μm thick SiO2 and Type II: unpackaged) were simulated, calculated, and optimized. The Optical parameters included the single-mode conditions, effective indices, the separation distance between the electrode edge and the Si3N4-strip-loaded edge, optical power distribution, bending loss, optical field distribution, and half-wave voltage. The radio frequency parameters included the characteristic impedance, attenuation constant, radio frequency effective index, and −3 dB modulation bandwidth. According to the numerical simulation and theoretical analysis, the half-wave voltage product and the −3 dB modulation bandwidth were, respectively, 2.85 V·cm and 0.4 THz for Type I modulator, and 2.33 V·cm and 1.26 THz for Type II modulator, with a device length of 3 mm.

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6

Shantha Selva Kumari, R., e K. Seyatha. "Performance evaluation of hybrid modulation techniques for high speed radio over fiber communication system". International Journal of Modern Physics C 30, n.º 09 (setembro de 2019): 1950070. http://dx.doi.org/10.1142/s0129183119500700.

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In Radio over Fiber (RoF) technology, the optical network capacity is integrated with the wireless network. The main objective of this work is to enhance the performance behavior of optical fiber communication system in terms of BER, Received Power and Q-Factor. The proposed combined modulation technologies, such as Pulse Amplitude Frequency Modulation (PAFM), Differential Phase Shift Keying Amplitude Modulation (DPSKA), Offset Quadrature Phase Shift Keying Amplitude Modulation (OQPSKA), Quadrature Amplitude Frequency Modulation (QAFM), Frequency Phase Modulation (FPM) and Pulse Amplitude Phase Modulation (PAPM), are used to meet this objective. The input data are used for modulating the electrical carrier signal with a frequency of 250 and 255[Formula: see text]GHz. This hybrid modulation technique obtained the minimum BER of about [Formula: see text] in FPM technique. The maximum Q-Factor of 33 is obtained in QAFM technique. The obtained maximum received power is 0.79[Formula: see text]mW in OQPSKA technique.

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7

Luo, Junshan, Hao Wang, Fanggang Wang e Shilian Wang. "Secure Spatial Modulation via Radio Frequency Mirrors". IEEE Transactions on Vehicular Technology 69, n.º 8 (agosto de 2020): 9168–73. http://dx.doi.org/10.1109/tvt.2020.2999917.

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8

Bulyuk, A. N. "Radio-frequency electrooptic modulation in optical fibers". Soviet Journal of Quantum Electronics 22, n.º 10 (31 de outubro de 1992): 948–50. http://dx.doi.org/10.1070/qe1992v022n10abeh003638.

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9

Bai, Jiang Ling, Li Bin Zhong, Wen Hai Xu e Jian Lin. "Research on Optical Signal Carrier Transmission Technology". Advanced Materials Research 1022 (agosto de 2014): 193–96. http://dx.doi.org/10.4028/www.scientific.net/amr.1022.193.

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This paper studies the single-sideband RF signals in the optical carrier side than the problem. RF signals modulated optical carrier OSSB + C modulation index is usually small, leading edge modulated carrier radio frequency signal generated by the optical carrier ratio is not ideal. A design scheme based on three-arm and four-arm MZM MZM optimized optical carrier single sideband radio frequency signal containing the edge ratio. By adjusting the DC bias voltage of the modulator can control the carrier side than the light signal. For any modulation index, are able to make the optical carrier single sideband radio frequency signal containing edges than the optimal value of 0 dB, improving the performance of the system. The simulation also verify their feasibility.

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10

Xiang Jingfeng, 项静峰, 王利国 Wang Liguo, 任伟 Ren Wei, 李唐 Li Tang, 吕德胜 Lü Desheng e 刘亮 Liu Liang. "Frequency Noise Suppression of Single-Frequency Laser with Radio-Frequency Modulation". Chinese Journal of Lasers 44, n.º 5 (2017): 0501009. http://dx.doi.org/10.3788/cjl201744.0501009.

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11

Chen, Shichuan, Kunfeng Qiu, Shilian Zheng, Qi Xuan e Xiaoniu Yang. "Radio–Image Transformer: Bridging Radio Modulation Classification and ImageNet Classification". Electronics 9, n.º 10 (9 de outubro de 2020): 1646. http://dx.doi.org/10.3390/electronics9101646.

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Radio modulation classification is widely used in the field of wireless communication. In this paper, in order to realize radio modulation classification with the help of the existing ImageNet classification models, we propose a radio–image transformer which extracts the instantaneous amplitude, instantaneous phase and instantaneous frequency from the received radio complex baseband signals, then converts the signals into images by the proposed signal rearrangement method or convolution mapping method. We finally use the existing ImageNet classification network models to classify the modulation type of the signal. The experimental results show that the proposed signal rearrangement method and convolution mapping method are superior to the methods using constellation diagrams and time–frequency images, which shows their performance advantages. In addition, by comparing the results of the seven ImageNet classification network models, it can be seen that, except for the relatively poor performance of the architecture MNASNet1_0, the modulation classification performance obtained by the other six network architectures is similar, indicating that the proposed methods do not have high requirements for the architecture of the selected ImageNet classification network models. Moreover, the experimental results show that our method has good classification performance for signal datasets with different sampling rates, Orthogonal Frequency Division Multiplexing (OFDM) signals and real measured signals.

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12

Paramonov, A. A., V. M. Nguyen e M. T. Nguyen. "Multi-task neural network for solving the problem of recognizing the type of QAM and PSK modulation under parametric a priori uncertainty". Russian Technological Journal 11, n.º 4 (1 de agosto de 2023): 49–58. http://dx.doi.org/10.32362/2500-316x-2023-11-4-49-58.

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Objectives. Automatic modulation recognition of unknown signals is an important task for various fields oftechnology such as radio control, radio monitoring, and identification of interference and sources of radio emission. The paper aims to develop a method for recognizing the types of signal modulation under conditions of parametric a priori uncertainty, including the uncertainty of carrier frequency- and initial signal phase values. An additional task consists in estimating the offset values of the carrier frequency or signal phase at the initial stage of the recognition process.Methods. A multi-task learning with artificial neural network and the theory of cumulants of random variables are used.Results. For signals with a carrier frequency and initial phase shift, cumulant approaches for QAM-8, APSK-16, QAM-64, and PSK-8 modulations are calculated. A multi-task learning with artificial neural network using cumulant features and a data standardization algorithm is presented. The results of the experiment show that using multi-task learning with an artificial neural network provides high accuracy of recognizing QAM-8 and APSK-16, QAM-64 and PSK-8 modulations with small mismatches of the carrier frequency or initial phase. The accuracy of determining the offset values from the carrier frequency or the initial phase for QAM-8, APSK-16, QAM-64, and PSK-8 modulation is high.Conclusions. The multi-task learning with neural network using high-order signal cumulants makes it possible not only to recognize modulation types with high accuracy under conditions of a priori uncertainty of signal parameters, but also to determine the offset values of carrier frequency or initial signal phase from expected values.

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13

CANSIZ, Mustafa. "Radio Frequency Energy Harvesting with Frequency Shift Keying Modulation Technique". DÜMF Mühendislik Dergisi 10, n.º 2 (20 de junho de 2019): 531–36. http://dx.doi.org/10.24012/dumf.561336.

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14

Shum, Chi Man, e Edward A. Whittaker. "Determination of radio-frequency phase in harmonic frequency modulation spectroscopy". Applied Optics 30, n.º 27 (20 de setembro de 1991): 3799. http://dx.doi.org/10.1364/ao.30.003799.

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15

Zhang, Ruixue, Yiming Gong, Matthew W. Day, Dong Sun e Steven T. Cundiff. "Radio frequency polarization modulation based on an optical frequency comb". Review of Scientific Instruments 91, n.º 8 (1 de agosto de 2020): 083111. http://dx.doi.org/10.1063/5.0016256.

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16

Yu, Longqiang, Rong Wang, Lin Lu, Yong Zhu, Chuanxin Wu, Baofu Zhang e Peizhang Wang. "Stable radio frequency dissemination by simple hybrid frequency modulation scheme". Optics Letters 39, n.º 18 (3 de setembro de 2014): 5255. http://dx.doi.org/10.1364/ol.39.005255.

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17

Razmi, Shirin, e Naser Parhizgar. "Adaptive resources assignment in OFDM-based cognitive radio systems". International Journal of Electrical and Computer Engineering (IJECE) 9, n.º 3 (1 de junho de 2019): 1935. http://dx.doi.org/10.11591/ijece.v9i3.pp1935-1943.

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Spectrum efficiency of orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR) systems can be improved by adaptive resources allocation. In resources allocation, transmission resources such as modulation level and transmission power are adaptively assigned based on channel variations. The goal of this paper is maximize the total transmission rate of secondary user (SU). Hence, we investigate adaptive power and modulation allocation to achieve this purpose. For power allocation, we investigate optimal and conventional methods and then introduce a novel suboptimal algorithm to calculate the transmission power of each subcarrier. In addition, for adaptive modulation, we consider two kinds of modulations including multi-quadrature amplitude modulation (MQAM) and multi-phase-shift keying (MPSK). Also, simulation results are indicated the performance of our algorithm.

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18

Huang, Qingchuan, e Tetsuya Kawanishi. "Precise RF Phase Measurement by Optical Sideband Generation Using Mach–Zehnder Modulators". Photonics 10, n.º 3 (17 de março de 2023): 324. http://dx.doi.org/10.3390/photonics10030324.

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A novel radio frequency (RF) phase measurement method that uses optical modulation was proposed. The mathematical model of Mach–Zehnder modulator (MZM) characterization was reviewed. By measuring the output sideband power of the optical modulator, the phase difference of the electric signals fed to the modulator was experimentally measured, and picosecond-level accuracies were achieved. This technique is expected to be useful for radio-over-fiber-based antenna array systems.

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19

Waters, C. L., T. K. Yeoman, M. D. Sciffer, P. Ponomarenko e D. M. Wright. "Modulation of radio frequency signals by ULF waves". Annales Geophysicae 25, n.º 5 (4 de junho de 2007): 1113–24. http://dx.doi.org/10.5194/angeo-25-1113-2007.

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Abstract. The ionospheric plasma is continually perturbed by ultra-low frequency (ULF; 1–100 mHz) plasma waves that are incident from the magnetosphere. In this paper we present a combined experimental and modeling study of the variation in radio frequency of signals propagating in the ionosphere due to the interaction of ULF wave energy with the ionospheric plasma. Modeling the interaction shows that the magnitude of the ULF wave electric field, e, and the geomagnetic field, B0, giving an e×B0 drift, is the dominant mechanism for changing the radio frequency. We also show how data from high frequency (HF) Doppler sounders can be combined with HF radar data to provide details of the spatial structure of ULF wave energy in the ionosphere. Due to spatial averaging effects, the spatial structure of ULF waves measured in the ionosphere may be quite different to that obtained using ground based magnetometer arrays. The ULF wave spatial structure is shown to be a critical parameter that determines how ULF wave effects alter the frequency of HF signals propagating through the ionosphere.

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20

Luong, Kevin Q. T., Wei Gu, Foad Fereidoony, Lap Yeung, Zhi Yao e Yuanxun Ethan Wang. "Radio Frequency Precession Modulation-Based Magnetic Field Sensors". IEEE Access 10 (2022): 3756–65. http://dx.doi.org/10.1109/access.2021.3140142.

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21

Piccardo, Marco, Michele Tamagnone, Benedikt Schwarz, Paul Chevalier, Noah A. Rubin, Yongrui Wang, Christine A. Wang et al. "Radio frequency transmitter based on a laser frequency comb". Proceedings of the National Academy of Sciences 116, n.º 19 (24 de abril de 2019): 9181–85. http://dx.doi.org/10.1073/pnas.1903534116.

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Since the days of Hertz, radio transmitters have evolved from rudimentary circuits emitting around 50 MHz to modern ubiquitous Wi-Fi devices operating at gigahertz radio bands. As wireless data traffic continues to increase, there is a need for new communication technologies capable of high-frequency operation for high-speed data transfer. Here, we give a proof of concept of a compact radio frequency transmitter based on a semiconductor laser frequency comb. In this laser, the beating among the coherent modes oscillating inside the cavity generates a radio frequency current, which couples to the electrodes of the device. We show that redesigning the top contact of the laser allows one to exploit the internal oscillatory current to drive a dipole antenna, which radiates into free space. In addition, direct modulation of the laser current permits encoding a signal in the radiated radio frequency carrier. Working in the opposite direction, the antenna can receive an external radio frequency signal, couple it to the active region, and injection lock the laser. These results pave the way for applications and functionality in optical frequency combs, such as wireless radio communication and wireless synchronization to a reference source.

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22

Sobacchi, Emanuele, Yuri Lyubarsky, Andrei M. Beloborodov e Lorenzo Sironi. "Filamentation of fast radio bursts in magnetar winds". Monthly Notices of the Royal Astronomical Society 511, n.º 4 (29 de janeiro de 2022): 4766–73. http://dx.doi.org/10.1093/mnras/stac251.

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ABSTRACT Magnetars are the most promising progenitors of fast radio bursts (FRBs). Strong radio waves propagating through the magnetar wind are subject to non-linear effects, including modulation/filamentation instabilities. We derive the dispersion relation for modulations of strong waves propagating in magnetically dominated pair plasmas focusing on dimensionless strength parameters a0 ≲ 1, and discuss implications for FRBs. As an effect of the instability, the FRB-radiation intensity develops sheets perpendicular to the direction of the wind magnetic field. When the FRB front expands outside the radius where the instability ends, the radiation sheets are scattered due to diffraction. The FRB-scattering time-scale depends on the properties of the magnetar wind. In a cold wind, the typical scattering time-scale is τsc ∼ $\mu$s–ms at the frequency $\nu \sim 1\, {\rm GHz}$. The scattering time-scale increases at low frequencies, with the scaling τsc ∝ ν−2. The frequency-dependent broadening of the brightest pulse of FRB 181112 is consistent with this scaling. From the scattering time-scale of the pulse, one can estimate that the wind Lorentz factor is larger than a few tens. In a warm wind, the scattering time-scale can approach $\tau _{\rm sc}\sim \, {\rm ns}$. Then scattering produces a frequency modulation of the observed intensity with a large bandwidth, $\Delta \nu \sim 1/\tau _{\rm sc}\gtrsim 100\, {\rm MHz}$. Broad-band frequency modulations observed in FRBs could be due to scattering in a warm magnetar wind.

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23

Hussaini, A. S., I. T. E. Elfergani, J. Rodriguez e R. A. Abd-Alhameed. "Efficient multi-stage load modulation radio frequency power amplifier for green radio frequency front end". IET Science, Measurement & Technology 6, n.º 3 (2012): 117. http://dx.doi.org/10.1049/iet-smt.2011.0127.

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24

Kim, Boram, e Kazuo Nakazato. "Dual Data Pulse Width Modulator for Radio Frequency Identification Biosensor Signal Modulation". Japanese Journal of Applied Physics 52, n.º 4S (1 de abril de 2013): 04CE12. http://dx.doi.org/10.7567/jjap.52.04ce12.

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25

Yonghao Zhu, Yonghao Zhu, Hua Li Hua Li, Wenjian Wan Wenjian Wan, Li Gu Li Gu, Tao Zhou Tao Zhou, Stefano Barbieri Stefano Barbieri e and Juncheng Cao and Juncheng Cao. "Beat note analysis and spectral modulation of terahertz quantum cascade lasers with radio frequency injection". Chinese Optics Letters 15, n.º 1 (2017): 011404–11408. http://dx.doi.org/10.3788/col201715.011404.

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26

Carreira, Robson Ribeiro, Joaquim José Barroso de Castro, José Edimar Barbosa Oliveira, André Paim Gonçalves e Alessandro Roberto dos Santos. "Photonic-assisted microwave frequency measurement towards cognitive radio". Revista Brasileira de Aplicações de Vácuo 39, n.º 3 (28 de dezembro de 2020): 211–17. http://dx.doi.org/10.17563/rbav.v39i3.1185.

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Cognitive radio frequency (RF) systems can be seen through an OODA (observe, orient, decide and act) loop, and electronic warfare (EW) can be used in some of these stages, namely the observe and the act. Instantaneous microwave frequency measurement (IFM) systems can contribute to cognitive RF technology taking the real world to the data world. In an OODA loop, IFM can be arranged as in the observe stage. Here we have proposed an IFM device that allows the adjustment of the directional couplers coupling coefficients, optical fiber lengths, modulation index and modulation formats, which makes the system tunable. The analytical model result shows good agreement with the simulation, achieving frequency differences of 130 MHz and 210 MHz for the lowest and the highest amplitude comparison function values, respectively.

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Sobacchi, Emanuele, Yuri Lyubarsky, Andrei M. Beloborodov e Lorenzo Sironi. "Self-modulation of fast radio bursts". Monthly Notices of the Royal Astronomical Society 500, n.º 1 (20 de outubro de 2020): 272–81. http://dx.doi.org/10.1093/mnras/staa3248.

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ABSTRACT Fast radio bursts (FRBs) are extreme astrophysical phenomena entering the realm of non-linear optics, a field developed in laser physics. A classical non-linear effect is self-modulation. We examine the propagation of FRBs through the circumburst environment using the idealized setup of a monochromatic linearly polarized GHz wave propagating through a uniform plasma slab of density N at distance R from the source. We find that self-modulation occurs if the slab is located within a critical radius Rcrit ∼ 1017(N/102 cm−3)(L/1042 erg s−1) cm, where L is the isotropic equivalent of the FRB luminosity. Self-modulation breaks the burst into pancakes transverse to the radial direction. When R ≲ Rcrit, the transverse size of the pancakes is smaller than the Fresnel scale. The pancakes are strongly diffracted as the burst exits the slab, and interference between the pancakes produces a frequency modulation of the observed intensity with a sub-GHz bandwidth. When R ∼ Rcrit, the transverse size of the pancakes becomes comparable with the Fresnel scale, and the effect of diffraction is weaker. The observed intensity is modulated on a time-scale of 10 µm, which corresponds to the radial width of the pancakes. Our results suggest that self-modulation may cause the temporal and frequency structure observed in FRBs.

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Dal Cin, Sandro, Florian Pilat, Aleš Konečný, Nikola Opačak, Gottfried Strasser e Benedikt Schwarz. "Coherent control of transverse modes in semiconductor laser frequency combs via radio-frequency injection". Applied Physics Letters 121, n.º 7 (15 de agosto de 2022): 071106. http://dx.doi.org/10.1063/5.0098474.

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Increasing the output power of semiconductor laser frequency combs, while maintaining a single-lobe far-field characteristic is of great interest for mid-infrared sensing applications. Broadening of the ridge waveguide represents the most common approach for power scaling, however, the excitement of higher-order transverse modes often limits general applicability. Here, we demonstrate that the coherent control of the longitudinal laser modes enables control over the transverse modes of a quantum cascade laser. Modulating the laser in a frequency range 60 ± 3 MHz above the free-running laser beatnote and applying modulation powers above 25 dBm provides reliable fundamental transverse mode operation, observable as single-lobe, Gaussian-like characteristic in the recorded far-field. Furthermore, coherent comb operation for both fundamental and higher-order transverse mode states is demonstrated.

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HULA, IHOR, e OLEKSIY POLIKAROVSKYKH. "STUDY NEUR NETWORKS FOR SOFTWARE DEFINED RADIO CONTROL". Herald of Khmelnytskyi National University 303, n.º 6 (dezembro de 2021): 31–36. http://dx.doi.org/10.31891/2307-5732-2021-303-6-31-36.

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The scientific article is devoted to the issues of SDR system control. Software Defined Radio is a system designed for software control of information transmission processes in a radio communication channel. Recognition of digital modulation types is used, which automatically classifies the type of digital modulation of the received signal. The following issues are covered in the article: the analysis of existing approaches in the task of automatic recognition of types of digital modulation is carried out; the analysis and classification of informative features in the task of automatic recognition is carried out the following types of digital modulation: 2-PSK, 4-PSK, 8-PSK, 2-FSK, 8-QAM, 16-QAM, 64-QAM and OFDM. This article uses a neural network approach based on cumulative characteristics. To solve these problems, the methods of calculation and selection of informative cumulative features described in the developed model of the system of automatic recognition of digital modulation types by means of a neural network on cumulative features at a known value of carrier frequency are described. A model of the system of automatic recognition of digital modulation types at a known value is constructed carrier frequency. An algorithm for automatic recognition of digital modulation types has been developed using a multilayer neural network. The influence of noise in the communication channel on the probability of recognizing the types of digital modulation at a known value of the carrier frequency is investigated. It was found that regardless of the type of noise in the communication channel, the law of error distribution in IQ data becomes close to normal. This fact is one important argument for the use of cumulative features in the task of automatic recognition of types of digital modulation. Therefore, the task of automatic recognition of digital modulation types is quite relevant. Further research may be aimed at expanding the range of high-order cumulative features used, due to which it is possible to increase the probability of correct recognition of types of digital modulation, and solving the recognition problem at an unknown value of the frequency and initial phase of the carrier signal.

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Kareem, Marwa M., Sameer A. S. Lafta, Hadi Fakhir Hashim, Raed Khalid Al-Azzawi e Adnan Hussein Ali. "Analyzing the BER and optical fiber length performances in OFDM RoF links". Indonesian Journal of Electrical Engineering and Computer Science 23, n.º 3 (1 de setembro de 2021): 1501. http://dx.doi.org/10.11591/ijeecs.v23.i3.pp1501-1509.

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Radio over fiber (RoF) can be assessed as a system of most convenient combination of optical fiber and radio signals. The technique of orthogonal frequency division multiplexing (OFDM) considers as a data distribution over a huge number of carriers having spaced from each other with specific frequencies at overlap bands. Hence incorporates OFDM with the optical fiber, OFDM-RoF system can be increased the modulation RF access capacity besides high-speed data transmission, it considers a broadband communication trend of the current and future applications specifically for 5G mobile. The optical network scenarios of various RF can be model with optisystem software, and OFDM in addition to use a section of the orthogonal multiplex frequency of 16-quadrature amplitude modulation (QAM) RF modulating signal. In the optical domain, Mach-Zehnder modulator (MZM) optical modulators are used to carry out different results with different fiber lengths. An OFDM-RoF wireless communication system considers as advanced data rate transmission achievement by minimum delays. The essential goal of this paper is for identifying the minimum bit error rate (BER) for the 16-QAM modulation with varying fiber length. The OFDM-RoF system can be able for realizing a fiber length 100 km with a restricted decreasing in the received power so that the constellation noise is became greater despite of applying electrical amplification and optical amplification.

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Kador, Lothar, Tatiana Latychevskaia, Alois Renn e Urs P. Wild. "Radio-frequency Stark effect modulation of single-molecule lines". Journal of Luminescence 86, n.º 3-4 (abril de 2000): 189–94. http://dx.doi.org/10.1016/s0022-2313(00)00162-9.

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Esepkina, N. A., A. P. Lavrov e S. V. Dmitriev. "Acoustooptical processor for radio signals with discrete frequency modulation". Technical Physics Letters 23, n.º 1 (janeiro de 1997): 54–56. http://dx.doi.org/10.1134/1.1261616.

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Cho, Herman, Susanne Pfenninger, Jörg Forrer e Arthur Schweiger. "Radio-frequency-driven electron-spin-echo-envelope-modulation spectroscopy". Chemical Physics Letters 180, n.º 3 (maio de 1991): 198–206. http://dx.doi.org/10.1016/0009-2614(91)87140-7.

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Quyen, Nguyen Xuan. "On the Study of a Quadrature DCSK Modulation Scheme for Cognitive Radio". International Journal of Bifurcation and Chaos 27, n.º 09 (agosto de 2017): 1750135. http://dx.doi.org/10.1142/s0218127417501358.

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The past decade has witnessed a boom of wireless communications which necessitate an increasing improvement of data rate, error-rate performance, bandwidth efficiency, and information security. In this work, we propose a quadrature (IQ) differential chaos-shift keying (DCSK) modulation scheme for the application in cognitive radio (CR), named CR-IQ-DCSK, which offers the above improvement. Chaotic signal is generated in frequency domain and then converted into time domain via an inverse Fourier transform. The real and imaginary components of the frequency-based chaotic signal are simultaneously used in in-phase and quadrature branches of an IQ modulator, where each branch conveys two bits by means of a DCSK-based modulation. Schemes and operating principle of the modulator and demodulator are proposed and described. Analytical BER performance for the proposed schemes over a typical multipath Rayleigh fading channel is derived and verified by numerical simulations. Results show that the proposed scheme outperforms DCSK, CDSK and performs better with the increment of the number of channel paths.

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Ujang, Febrizal, Teguh Firmansyah, Purnomo S. Priambodo e Gunawan Wibisono. "Irregular Shifting of RF Driving Signal Phase to Overcome Dispersion Power Fading". Photonics 6, n.º 4 (12 de outubro de 2019): 104. http://dx.doi.org/10.3390/photonics6040104.

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The main problem with the radio-over-fiber (RoF) link is the decrease in the recovered radio frequency (RF) power due to the chromatic dispersion of the fiber known as dispersion power fading. One of the methods for dealing with dispersion power fading is to use the optical single sideband (OSSB) modulation scheme. The OSSB modulation scheme can be generated by biasing the dual-drive Mach–Zehnder modulator (DD-MZM) to the quadrature bias point (QBP) and shifting the RF drive signal phase (θ) by 90°, which is called the regular θ. However, the OSSB modulation scheme only overcomes dispersion power fading well at the modulation index (m) < 0.2. This paper proposes an irregular θ method to overcome dispersion power fading at all m. There are two irregular θ for every m used. The irregular θ managed to handle dispersion power fading better than OSSB modulation scheme did at every m. Specifically, the irregular θ could handle the dispersion power fading well at m ≤ 1. In sum, the irregular θ could overcome the dispersion power fading at any RF frequency and optical wavelength without having to re-adjust the transmitter.

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Yang, Wei Dong, Li Li e Kai Peng. "Realization of Low Frequency Wakeup in Tire Encoded Radio Frequency Identification System". Applied Mechanics and Materials 556-562 (maio de 2014): 2895–98. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.2895.

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In car tires coded identification system, radio frequency technology plays a vital role, the key to radio frequency signals transmitted process is waveform modulation. The key of adjusting the waveform is how to match its resistor and capacitor easily. In the paper their resistance and capacitance values are optimized by using the simulation software (Protues) to simulate the transmitted waveform, and based on matching results the optimized physical models are produced. The actual test results agree well with the simulation results. The method of simulation tests can save the resources effectively, and shorten the development time.

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Han, Cheng Hao, Ye Ren e Bing Shang. "Wireless Identification System Based on Radio Frequency Technique". Advanced Materials Research 433-440 (janeiro de 2012): 6760–63. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.6760.

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Using radio frequency technique, the reader machine will load call signal into 70MHz radio frequency, and send to response machine wirelessly. The call signal will be sent to the control of response machine by circuit coupling, demodulation, voltage comparator. The control will analyze and identify the call signal, send the stored 4-bit binary code back to the reader machine by transmitting modulation circuit, and display the detail of response machine.

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Unchenko, I. V., e A. A. Emelyanov. "Specific Features of Designing Microwave Photonic Receiving and Transmitting Channels of Onboard Systems for Communication, Radar and Radio Monitoring". Journal of the Russian Universities. Radioelectronics 26, n.º 1 (7 de março de 2023): 58–67. http://dx.doi.org/10.32603/1993-8985-2023-26-1-58-67.

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Introduction. Designers of modern on-board systems for communication, radar, and radio monitoring face the problem of improving their qualitative characteristics, including the operating frequency, instantaneous bandwidth, receiver sensitivity, and electromagnetic compatibility. In addition, the dimensions, weight, and power of such systems, as well their cost, should be minimized. However, the current semiconductor microwave electronics has reached its limits in terms of frequency and dynamic characteristics. A possible solution consists in the implementation of microwave photonic transmission lines in the design of on-board systems for communication, radar, and radio monitoring on the basis of modulation of laser radiation by means of electro-absorption.Aim. To study the transfer characteristics and noise figure of a microwave photonic transmission line realized based on the modulation of laser radiation by means of electro-absorption. To compare the results of theoretical calculations and experimental investigations.Materials and methods. The research methodology involved external modulation using an electro-absorption modulator (EAM), mathematical representation of the transmission coefficient, as well as comparison of the theoretical and practical results.Results. Theoretical values of the transmission coefficient and noise figure for a microwave photonic transmission line based on the external modulation method using an EAM were obtained. Experimental values of the transmission coefficient and noise figure for a microwave photonic line in the frequency range from 100 MHz to 16 GHz were presented. The obtained data were compared with those of the nearest mass-produced products of foreign production and those presented in domestic publications on microwave photonic signal transmission lines.Conclusion. The use of an EAM, whose main advantage consists in the possibility of integration with a laser emitter, allowed the authors to design and manufacture a small-sized industrial prototype of a radio-photonic transceiver, capable of transmitting a radio signal over tens of kilometers in the frequency range from 100 MHz to 12 GHz with a transmission coefficient of at least −3 dB and a noise figure no more than 36 dB at the upper operating frequency. At the same time, the closest analogue manufactured by Emcore with similar dimensions has a transmission coefficient of −30 dB and uses direct modulation of laser radiation as a transmission method, which significantly reduces the transmission range of the microwave signal.

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Wei, Zifei. "Research on STM32-Based Signal Conditioning System Measurement System". Highlights in Science, Engineering and Technology 42 (7 de abril de 2023): 9–17. http://dx.doi.org/10.54097/hset.v42i.7050.

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The measurement of the signal modulation system is a vital part of channel transmission signal technology, which has a very important position in the signal communication quality assurance system. With the development of radio communications in modern radio technology, the research of AM and FM signal modulation measurement methods has become an important element in this field of research. This research is a signal modulation system using an STM32F407 microcontroller as the control core. The hardware of the system is mainly composed of a coherent demodulation circuit system and a comparator judgment circuit system, and the coherent demodulation circuit system is divided into AM demodulation circuit system and an FM demodulation circuit system. The frequency of the input signal was measured by a comparator, and the frequency change was used to initially determine the signal type. In which the modulating signal of AM signal was obtained by DDS generating separate orthogonal sine and cosine signals with the input signal through a series of operations, while the FM signal was operated with the sine signal. Finally, the amplitude and frequency information of the FM signal was obtained through the comparator, and finally reduced to the modulating signal of the FM signal. Output demodulated signal, its signal waveform without obvious distortion apparent phenomenon. Promotes the prospect of using the calibration of AM and FM signal generators in the field of communication.

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Chen, Chien-Sheng, Chyuan-Der Lu, Ho-Nien Shou e Le-Wei Lin. "Baseband Transceiver Design of a High Definition Radio FM System Using Joint Theoretical Analysis and FPGA Implementation". International Journal of Antennas and Propagation 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/580479.

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Advances in wireless communications have enabled various technologies for wireless digital communication. In the field of digital radio broadcasting, several specifications have been proposed, such as Eureka-147 and digital radio mondiale (DRM). These systems require a new spectrum assignment, which incurs heavy cost due to the depletion of the available spectrum. Therefore, the in-band on-channel (IBOC) system has been developed to work in the same band with the conventional analog radio and to provide digital broadcasting services. This paper discusses the function and algorithm of the high definition (HD) radio frequency modulation (FM) digital radio broadcasting system. Content includes data format allocation, constellation mapping, orthogonal frequency division multiplexing (OFDM) modulation of the transmitter, timing synchronization, OFDM demodulation, integer and fraction carrier frequency (integer carrier frequency offset (ICFO) and fractional CFO (FCFO)) estimation, and channel estimation of the receiver. When we implement this system to the field programmable gate array (FPGA) based on a hardware platform, both theoretical and practical aspects have been considered to accommodate the available hardware resources.

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Zakharchenko, Vladimir, e Alexander Khoperskov. "Scheme features of radio pulse gating for radar measurements". ITM Web of Conferences 30 (2019): 11011. http://dx.doi.org/10.1051/itmconf/20193011011.

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The model of a radio pulse stroboscopic converter consisting of a mixer and a narrowband filter tuned to the difference frequency of the carrier signals is considered. We demonstrate that the measurement of the phase structure of the input signals can be made at low frequency by amplitude methods by changing the phase both in the channel of the gating radio pulses and in the low frequency channel. The radio-pulse gating scheme goes into a phase-sensitive mode when the system clock frequency is synchronized with the second harmonic of the difference frequency, however, in this case, a parasitic phase modulation occurs in the converted signal, which does not depend on the transformation coefficient of the spectrum and is determined only by the duty cycle of the input signal. To eliminate parasitic modulation, which distorts the envelope of the output signal of the converter in a phase-sensitive mode, it is proposed to use an auto-shift circuit with a falling “slow” sawtooth voltage when generating gating radio pulses.

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Liu, Bing, e Xinhong Hao. "Research on Anti-Frequency Sweeping Jamming Method for Frequency Modulation Continuous Wave Radio Fuze Based on Wavelet Packet Transform Features". Applied Sciences 12, n.º 17 (30 de agosto de 2022): 8713. http://dx.doi.org/10.3390/app12178713.

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Frequency modulation continuous wave (FMCW) radio fuze is widely used in military equipment, due to its excellent range and anti-jamming ability. However, the widespread use of radio fuze jammers on modern battlefields poses a serious threat to fuzes. In this study, a classification method of targeting and sweeping frequency jamming signals of FMCW radio fuze based on wavelet packet transform features is proposed, which improves the anti-jamming ability of fuze. The wavelet packet transform of the output signal of the radio fuze detector is used to form a feature vector, which is fed into a support vector machine for targeting and jamming signal classification. The experimental results of the measured data show that the proposed method can achieve a high accuracy rate of classification and identification of FMCW radio fuze targets and frequency sweeping jamming signals. The highest recognition accuracy reached is 98.81% ± 0.0037. The lowest false alarm probability is 0.57% ± 0.0043, which indicates its potential application values in the near future.

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Avdeev, Vladimir B., S. I. Babusenko, V. Yu Gorovoi, A. I. Katrusha, N. I. Kozachek, S. N. Panychev, D. V. Senkevich e A. A. Chaplygin. "An Active Nonlinear Radio-Range Station with Frequency and Pulse Modulation for Measuring Distances to Radio-Frequency Sources". Telecommunications and Radio Engineering 65, n.º 9 (2006): 847–56. http://dx.doi.org/10.1615/telecomradeng.v65.i9.80.

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Lin, Wei-Lun. "Orthogonal Time/Frequency Multiplexed Modulation Families for Software Defined Radio". Recent Advances in Communications and Networking Technology 5, n.º 1 (29 de dezembro de 2016): 43–48. http://dx.doi.org/10.2174/2215081105666160726165552.

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CANSIZ, Mustafa. "Radio Frequency Energy Harvesting with Phase Shift Keying Modulation Technique". DÜMF Mühendislik Dergisi 11, n.º 1 (27 de março de 2020): 105–11. http://dx.doi.org/10.24012/dumf.639282.

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Bykov, Yu N. "Noise Immunity of a Radio-Control System with Frequency Modulation". Telecommunications and Radio Engineering 66, n.º 8 (2007): 729–39. http://dx.doi.org/10.1615/telecomradeng.v66.i8.30.

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Jachura, Michał, Jan Szczepanek, Wojciech Wasilewski e Michał Karpiński. "Measurement of radio-frequency temporal phase modulation using spectral interferometry". Journal of Modern Optics 65, n.º 3 (17 de outubro de 2017): 262–67. http://dx.doi.org/10.1080/09500340.2017.1387676.

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Fulda, P., D. Voss, C. Mueller, L. F. Ortega, G. Ciani, G. Mueller e D. B. Tanner. "Alignment sensing for optical cavities using radio-frequency jitter modulation". Applied Optics 56, n.º 13 (1 de maio de 2017): 3879. http://dx.doi.org/10.1364/ao.56.003879.

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Tiwari, V., K. Makita, M. Arino, M. Morita, T. Crozes, E. Bellet-Amalric, S. Kuroda, H. Boukari e L. Besombes. "Radio-frequency stress-induced modulation of CdTe/ZnTe quantum dots". Journal of Applied Physics 127, n.º 23 (21 de junho de 2020): 234303. http://dx.doi.org/10.1063/5.0011124.

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Ciobanu, A. A., D. D. Brown, P. J. Veitch e D. J. Ottaway. "Mode matching error signals using radio-frequency beam shape modulation". Applied Optics 59, n.º 31 (28 de outubro de 2020): 9884. http://dx.doi.org/10.1364/ao.404646.

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