Zeitschriftenartikel: „Radio frequency signal transmission“

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Bai, Jiang Ling, Li Bin Zhong, Wen Hai Xu, and Jian Lin. "Research on Optical Signal Carrier Transmission Technology." Advanced Materials Research 1022 (August 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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Randy, B. Renil, M. Hariharan, and R. Arasa Kumar. "Secured Wireless Power Transmission Using Radio Frequency Signal." International Journal of Information Sciences and Techniques 4, no. 3 (2014): 115–22. http://dx.doi.org/10.5121/ijist.2014.4315.

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Logarasu, R., and Dr R. Dhanasekaran. "VLC signal reconstruction with wavel transform in turbulence environment." International Journal of Engineering & Technology 7, no. 2.20 (2018): 178. http://dx.doi.org/10.14419/ijet.v7i2.20.12803.

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Communication involves exchange of data between sender and receiver. The data exchange complexity reduce with wireless data transmission. Conventionally radio signals use for wireless data transmission. The radio frequency limited band width and requirement of new hardware installation make LIFI an optimal solution for wireless data transmission. Since the existing LEDs can be used for data transmission. Recent trends in LiFi have made it possible to transmit data at THz frequency. However, the LiFi signals easily degrade due to surrounding environment noise. In this paper, we propose to reconstruct and eliminate noise in LiFi signal. Wave coefficient block apply for noise level estimation and filter banks use to reconstruct original message signal.

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Mendakulov, Zh K., S. Morosi, A. Martinelli, and K. Zh Isabaev. "Investigation of the possibility of reducing errors in determining the coordinates of objects indoors by multi-frequency method." Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, no. 1 (2021): 137–44. http://dx.doi.org/10.33271/nvngu/2021-1/137.

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Purpose. To investigate the influence of LOS/NLOS conditions on the radio signal propagation and the possibility of interference mitigation by using multi-frequency method of transmitting and receiving for positioning tasks in enclosed spaces. To check the difference in measurement accuracy when receiving a signal at one frequency from receiving a signal at four frequencies by combining the measurement results of individual frequencies into one reading. To check the influence of various obstacles on the signal passing. Methodology. Design at the laboratory of UHF generator and BLE beacons with the ability to set broadcast frequencies and adjust transmission power. Application of a multi-frequency transmission and reception method. Findings. The possibility of increasing the accuracy of positioning of objects in closed rooms, including mine workings, through the use of multi-frequency radio signals is investigated. It is shown that the influence of re-reflections of radio signals from the walls of structures, from obstacles of various origins, and the associated interference, can be reduced by using averaged values of attenuation at different frequencies. The use of radio emitters with many frequencies as beacons can provide new possibilities in solving the problem of positioning objects in closed rooms. Originality. The work proposes a method for combining measurement results of individual frequencies into one reading, which will reduce interference. Multi-frequency transmission method and multi-frequency reception method are proposed to reduce the influence of interference caused at one frequency on the overall signal level. Practical value. The experimental results obtained can be used at deploying positioning systems in closed rooms, including mine workings.

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Bukhala, Z. A., M. T. Glinkowski, J. K. Nelson, and V. J. Forte. "Radio frequency signal transmission on medium voltage power distribution lines." IEEE Transactions on Power Delivery 14, no. 1 (1999): 46–51. http://dx.doi.org/10.1109/61.736679.

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Wolff, A. M., D. M. Akos, and S. Lo. "Potential radio frequency interference with the GPS L5 band for radio occultation measurements." Atmospheric Measurement Techniques Discussions 7, no. 5 (2014): 4529–50. http://dx.doi.org/10.5194/amtd-7-4529-2014.

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Abstract. New Radio Occultation (RO) receivers are planned to utilize the newly implemented Global Positioning System (GPS) L5 signal centered at 1176.45 MHz. Since there are currently no operational GPS L5 receivers used for space-based RO applications, the interference environment is unclear. Distance Measuring Equipment (DME) and Tactical Air Navigation (TACAN) stations share the same frequency band as the GPS L5 signal. DME/TACAN signals have been identified to be a means of interference for any GPS L5 receiver. This study focuses on implementing a Systems Tools Kit (STK) simulation to gain insight into the power received by a RO satellite in Low Earth Orbit (LEO) from a DME/TACAN transmission. In order to confirm the validity of utilizing STK for communication purposes, a theoretical scenario was recreated as a simulation and the results were confirmed. Once the method was validated, STK was used to output a received power level aboard a RO satellite from a DME/TACAN station as well as a tool to predict the number of interfering DME/TACAN stations at any point in time. Taking a conservative approach, the signal power received was much greater than the typical power level received by a RO satellite from a GPS satellite transmission. This relatively high received power along with a high number of interfering DME/TACAN stations as an RO satellite passes over North America or Western Europe indicate that DME/TACAN interference may conflict with RO receivers.

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Yan, Hou. "Theoretical Model of Signal Transmission Based on Digital Radio Receiver." Open Electrical & Electronic Engineering Journal 8, no. 1 (2014): 705–8. http://dx.doi.org/10.2174/1874129001408010705.

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Radio receiver, as an extensively feasible modern technology, has been widely applied in all fields of military and civil. It is mainly to demodulate all kinds of required signals with strong interference and noise. Based on intermediate frequency (IF) software radio receiver test platform, the data transmission approach combining direct memory access (DMA) and multichannel buffered serial port (McBSP) was studied and the parallel operation of data transmission and data processing was realized. The method proposed for signal transmission and processing shows strong universality and can be used in other relevant fields.

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Korchynskyi, V. V., V. I. Kildishev, A. M. Berdnikov, and K. O. Smazhenko. "INCREASE OF STEALTH TRANSMISSION BASED ON TIMER SIGNALS AND LINEAR FREQUENCY MODULATION." Proceedings of the O.S. Popov ОNAT 1, no. 1 (2020): 53–58. http://dx.doi.org/10.33243/2518-7139-2020-1-1-53-58.

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Recently, much attention has been paid to the research of the properties and methods of forming complex noise-like signals to increase the noise immunity of radio communication systems operating in the conditions of electronic conflict. Using such signals, the tasks are resolved to improve the noise immunity and the main indicators of transmission stealth (energy, structural and information). For the task of the synthesis noise-like signals using timer signal designs in combination with the method of spreading the spectrum based on linear frequency modulation is proposed. The advisability of using timer signals is justified by their properties, which increase the noise immunity and stealth transmission. In contrast to positional codes, timer signals have more complex structure for construct signal construction. The initial parameters for constructing timer signals allow the formation of various sets of signal constructions. Such variational possibilities of constructing timer signals substantially increase the potential structural stealth of the transmission. Also based on timer signals, noise immunity coding is implemented without additional test elements. In the article A method for synthesizing noise-like signals based on linear frequency modulation and timer signal designs is proposed.

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Ohtsuki, Tatsuya, Takamitsu Aiba, and Motoharu Matsuura. "Simultaneous Radio-Frequency and Baseband Signal Transmission Over a Multimode Fiber." IEEE Photonics Journal 11, no. 6 (2019): 1–12. http://dx.doi.org/10.1109/jphot.2019.2957066.

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Gelozhe, Yuri, Pavel Klimenko, and Aleksander Maksimov. "Formation the radio signal for the system of space-time signal processing." ITM Web of Conferences 30 (2019): 03011. http://dx.doi.org/10.1051/itmconf/20193003011.

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The work is devoted to digital information transmission systems using space-time signal processing. The formation of radio signals whose carrier frequencies are determined by the frequency-time matrices is considered. The signal shaper is based on a PLL system with a programmable frequency divider. The analysis of the processes in the phase automatic system under the influence of large destabilizing factors and frequency switching of the generated oscillations is carried out. It is theoretically and experimentally shown that in the above-mentioned conditions the automatic system may lose stability. The algorithm for controlling the PLL has been developed, which ensures the stability of processes under large disturbances. Experimental studies have been carried out that have shown the efficiency of the improved system.

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Paramonov, A. A., and Van Zung Hoang. "Joint use of frequency-time division and antinoise coding in radio communication systems with FHSS." Russian Technological Journal 9, no. 4 (2021): 77–84. http://dx.doi.org/10.32362/2500-316x-2021-9-4-77-84.

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In the context of continuous improvement of radio prospecting and active radio jamming technics along with introduction of automated active countermeasures systems (ACS), the frequency-hopping spread spectrum (FHSS) radio communication systems (RCS) are widely used in order to improve reliability and noise immunity of data transmission. The noise immunity of the RCS affected by unintentional or deliberate interference can be significantly perfected by the combined use of frequency-time division and antinoise coding. This paper explores the case when the interference created by an ACS system with a limited transmitter power covers a part of the RCS frequency range. The receiver gets input mix of the wanted signal, the receiver noise, and probably a deliberate interference also considered as a noise. The article analyzes the noise immunity of signals reception with FHSS in the low-speed radio systems with joint use of frequency-time division of information subsymbols and noise combating codes when the deliberate interference destructively impacts a part of the RCS working band. Dependence of the bit error probability on the signal-to-noise ratio is calculated for the joint use of frequency division of information subsymbols and noise combating codes. It is shown that due to effective use of the frequency-energy resource of a radio line, considering the use of correction codes, a quite high noise immunity of RCS under the influence of deliberate interference can be assured. The indicated dependences of the error probability on the signal-to-noise ratio confirm that the reliability of data transmission can be significantly increased by the proper combination of signal spectrum spreading, applying of correction codes, and frequency division of subsymbols followed by their weight processing.

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Okorochkov, Alexander, and Nadezda Dmitrienko. "Influence of the radio signals frequency band on their spatial selection in communication channels." E3S Web of Conferences 279 (2021): 02002. http://dx.doi.org/10.1051/e3sconf/202127902002.

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This article deals with the dependence of the signal-to-noise ratio (S/N) on the frequency band of a radio channel when transmitting three different radio signals over it based on a mathematical model. Signals are transmitted on a single carrier frequency, in one direction and occupy the entire channel frequency band, which varied from 0 to 30 GHz. A threeelement sparse antenna array (SAA) is used for signal transmission. Each signal is emitted by all three SAA elements with certain phase shifts. In the reception area, such a structure of the total field is formed, at which the maxima of all transmitted signals are spatially spaced. This allows each signal to be received on a separate antenna. Studies have shown that the S/N ratio for different signals depends differently on the channel bandwidth. For a signal emitted by all SAA antennas in phase, the S/N ratio is practically independent of the bandwidth and is about 70 dB. For the two remaining phased signals the S/N ratio varies equally over the entire range of the channel frequency band values and is characterized by a sharp drop from 62 to 8 dB.

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Afanasiev, Nikolay, and Stanislav Chudaev. "DIAGNOSTICS OF THE STOCHASTIC IONOSPHERIC CHANNEL IN THE DECAMETER BAND OF RADIO WAVES." Solar-Terrestrial Physics 6, no. 4 (2020): 66–73. http://dx.doi.org/10.12737/stp-64202010.

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We propose a method for direct diagnostics of a stochastic ionospheric radio channel. This method can recalculate probe signal characteristics into transmitted signal characteristics. We derive analytical equations of second-order statistical moments for trajectory characteristics of the main and probe signals propagating in a three-dimensional randomly inhomogeneous ionosphere. We take into account boundary conditions at signal transmission and reception points. As a model of random irregularities of permittivity of the ionosphere, we utilize the concept of a changing space-time correlation ellipsoid, which is self-consistent with spatial changes in the average ionosphere. Time fluctuations of random irregularities are taken into account by the hypothesis of frozen transfer. We use analytical relationships to calculate the expected statistical characteristics of decameter signals along oblique probing paths of the ionosphere. An operational numerical algorithmization of the formulas derived is proposed. We report results of numerical experiments to determine the expected phase variances, group delay, and Doppler frequency shift of the main signal on a given single-hop path, based on measurements of these characteristics of a probe signal on a secondary path. We demonstrate the efficiency of the proposed method for diagnosing statistical trajectory characteristics of a decameter signal along single-hop paths under conditions when ground points of transmission and reception of the main and probe signals are outside the vicinity of focusing points of the wave field.

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Xuan, Wenjing. "Analysis of Signal Transmission Performance of Radio Frequency Cable under Multiple Factors." Advances in Modelling and Analysis B 60, no. 2 (2017): 391–402. http://dx.doi.org/10.18280/ama_b.600209.

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Kim, Sun Jun, Byeongho Park, Seung Hyo Noh, et al. "Carrier scattering in quasi-free standing graphene on hexagonal boron nitride." Nanoscale 9, no. 41 (2017): 15934–44. http://dx.doi.org/10.1039/c7nr04571a.

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Zhou, Hui, Yunlong Shen, Ming Chen, Jun Cheng, and Yuting Zeng. "A ROF Access Network for Simultaneous Generation and Transmission Multiband Signals Based on Frequency Octupling and FWM Techniques." Advances in Condensed Matter Physics 2018 (September 2, 2018): 1–9. http://dx.doi.org/10.1155/2018/9409583.

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We report a radio-over-fiber (ROF) access network with multiple high-repetive frequency mm-wave signals generation utilizing a dual-parallel Mach-Zehnder modulator (DP-MZM) and an semiconductor optical amplifier (SOA) for multiple base stations (BSs). In the scheme, at the central station (CS), signal and pump with frequency interval of 8fRF are generated by properly adjusting the parameters of the DP-MZM. After FWM in a SOA, new converted optical signals are obtained. Two tones of the optical signals are selected by using tunable optical filter (TOF), which are then sent into a photodiode (PD) to generate multiple mm-wave signals with different frequencies (8fRF, 16fRF, and 24fRF) for different BSs. Based on the proposed scheme, the mm-wave signals with frequencies of 20, 40, and 60 GHz carrying 2.5 Gb/s signal by a 2.5GHz RF signal have been generated by numerical simulation. Simulation results show that the proposed ROF system architecture with multiple-frequency millimeter-wave signals generation serving multiple BSs can work well. This scheme can raise the capacity of ROF system, reduce the requirement of the repetitive frequency of the driven RF signal, and support multiple mm-wave wireless access for BSs.

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FABO, Peter, Pavol NEJEDLÍK, Michal KUBA, Milan ONDERKA, and Dušan PODHORSKÝ. "Applicability of the ultra-high radio frequency band (UHF) for hydrometeor detection by phase difference method." Contributions to Geophysics and Geodesy 51, no. 2 (2021): 109–27. http://dx.doi.org/10.31577/congeo.2021.51.2.1.

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Hydrometeors (rain, fog and ice crystals) affect the transmission of electromagnetic signals. Previous research showed that alterations in the signal (amplitude and phase) are affected by the composition of the atmosphere, e.g. the presence of hydrometeors. The majority of hydrometeorological detecting methods are based on the attenuation of electromagnetic signals as they penetrate the atmosphere. Novel methods based on monitoring of parameters of the signal appeared in recent time. This article presents the first results from our investigation of how hydrometeors affect the phase differences in signals transmitted by BTS stations. Cell phone operators transmit electromagnetic signals in the 1 GHz frequency band. This paper describes a novel concept of how phase differences between two signals arriving at two different antennas can be used to detect hydrometeors. Although the described concept is assumed to be independent from the signal strength, the analysed signal must be detectable. The primary advantage of the proposed passive method is that the signal is almost ubiquitous and does not require demodulation. In densely populated areas, the network of BTS stations reaches a spatial density of 1 station per 1 km2 which gives excellent opportunity to use the signal for detection purposes.

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Mohamed, Norliza, Sevia Mahdaliza Idrus, Azura Hamzah, et al. "All optical Millimeter-wave signal generation and transmission for radio over fiber (RoF) link." Indonesian Journal of Electrical Engineering and Computer Science 15, no. 3 (2019): 1428. http://dx.doi.org/10.11591/ijeecs.v15.i3.pp1428-1435.

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Fiber-based wireless system has become a promising solution as a cost- effective communication and it offers high capacity network with millimeter- wave (mm-wave) signal transmission. The system significantly offers superior possible bandwidths for both fiber and free-space applications. Hence, with the increased capacity as well as wireless mobile network applications particularly at mm-wave signal, radio over fiber (RoF) technology is the utmost option. Nevertheless, when high frequency signal transmission is involved, power fading or dispersion effect limits the performance of RoF link. Therefore, this work proposed a RoF system by integrating remote optical local oscillator (LO) with frequency up-conversion at the base station (BS). All optical mm-wave signals are generated and transmitted for the RoF link. The effects of the changes of fiber loop length, optical power of the continuous wave (CW) optical laser carrier and responsivity value of the p-i-n photodiode (PD) mainly at 40 GHz are investigated and the power fading effects are discussed.

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Buhaiov, M. V., B. V. Molodetsky, I. O. Mykhailiuk, and V. V. Hordiichuk. "METHOD OF SIGNAL PARAMETERS ESTIMATION OF RADIOSTATIONS WITH FAST FREQUENCY HOPPING SPREAD SPECTRUM." Проблеми створення, випробування, застосування та експлуатації складних інформаційних систем, no. 17 (December 30, 2019): 14–26. http://dx.doi.org/10.46972/2076-1546.2019.17.02.

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Modern special-purpose radios utilize ultra-short burst mode with frequency hopping spread spectrum. Such digital radios operate, as a rule, in the fast frequency hopping spread spectrum mode and use a considerable number of frequency channels with frequency separation between adjacent channels, which is significantly less than the spectrum width of the frequency element. The main modulation in such radios is frequency manipulation. The identification of signals with fast frequency hopping spread spectrum and frequency manipulation is performed by estimating the speed of frequency tuning, the speed of information transmission, the number of frequency channels and the step of the frequency grid and comparing the obtained values with the corresponding characteristics of known radio stations with fast frequency hopping spread spectrum. The time limits and the duration of the frequency elements are calculated by the envelope of the received signal. For this purpose, a suitable method has been developed, which consists in filtering the envelope by means of a moving average window for suppression of the noise component and threshold processing. The threshold value is selected by the given probability of its exceeding by noise sample. The proposed approach to determining the time limits of frequency elements does not require any a priori signal information. To determine the frequencies of the frequency elements periodogram estimates are used. An exponential extrapolation of the discrete power spectrum was used to increase the frequency resolution at a fixed window length of the fast Fourier transform. It is shown that in order to uniquely determine the step of the frequency grid and the diversity of frequency manipulation frequencies, it is necessary to analyze the number of frequency elements not less than the number of frequency channels. By analyzing the histogram of the differences of sorted frequency vector of the frequency elements, determine the frequency grid, frequency diversity and the multiplicity of frequency manipulation. An approximate estimate of the number of frequency channels is calculated as the ratio of the magnitude of the frequency vector of the frequency elements to the step of the frequency grid. As a rule, symbol transmission at frequency manipulation is carried out at orthogonal frequencies, so it can be roughly assumed that the symbolic speed is equal to the frequency diversity of the frequency manipulation. The baud rate can be set only after signal demodulation and bit stream analysis, which can determine the frame structure and the number of service and information bits. The proposed method provides the estimation of the values of the parameters necessary for the identification of radio stations of signal parameters with a relative error not exceeding 0.3%, with values of signal to noise ratio not lower than 5 dB.

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Chen, Xiaogang. "Photonic Generation and Transmission of 20-Tupling Millimeter-Wave Without Optical Filter." Journal of Nanoelectronics and Optoelectronics 16, no. 4 (2021): 565–68. http://dx.doi.org/10.1166/jno.2021.2978.

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Without the optical filter, a novel approach is designed for frequency 20-tupling photonic millimeter-wave generation based on four nested Mach-zehnder modulators (MZMs). Theoretical derivations and simulation verifications are demonstrated for the millimeter-wave frequency multiplication scheme. Optical sideband suppression ratio (OSSR) of 33 dB and radio frequency sideband suppression ratio (RFSSR) of 28 dB is achieved, respectively. Further, a 1.25 Gb/s data transmission performances are evaluated, the data signal could be transmitted 40 Km with the proposed scheme at BER = 10−9. The obtained results can assist with the design of high frequency radio over fiber (RoF) system.

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Frank, T., A. Klein, E. Costa, and E. Schulz. "Robustness of IFDMA as Air Interface Candidate for Future High Rate Mobile Radio Systems." Advances in Radio Science 3 (May 12, 2005): 265–70. http://dx.doi.org/10.5194/ars-3-265-2005.

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Abstract. The Interleaved Frequency Division Multiple Access (IFDMA) scheme is a candidate for next generation mobile radio systems. IFDMA is based on compression, repetition and subsequent user dependent frequency shift of a modulated signal. As in OFDMA, multiple access is enabled by the assignment of overlapping but mutually orthogonal subcarriers to each user. It provides various advantages such as low peak to average power ratio, orthogonality of the signals of different users even for transmission over a time dispersive channel and low complexity. However, IFDMA is sensitive to frequency offsets. In this paper, a derivation of IFDMA based on a generalised OFDMA signal model with specific precoding and specific subcarrier allocation is presented. Moreover, simulation results showing the robustness properties of IFDMA against frequency errors are given.

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Amiri, I. S., S. E. Alavi, and H. Ahmad. "Radio Frequency Signal Generation and Wireless Transmission Using PANDA and Add/Drop Systems." Journal of Computational and Theoretical Nanoscience 12, no. 8 (2015): 1770–74. http://dx.doi.org/10.1166/jctn.2015.3956.

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Zhang, Anxu, Yitang Dai, Feifei Yin, et al. "Phase stabilized downlink transmission for wideband radio frequency signal via optical fiber link." Optics Express 22, no. 18 (2014): 21560. http://dx.doi.org/10.1364/oe.22.021560.

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Yang, Yong, Yu Liang Li, and Jing Li. "Radio Channel Research in Coal Mine Laneways." Advanced Materials Research 605-607 (December 2012): 2222–26. http://dx.doi.org/10.4028/www.scientific.net/amr.605-607.2222.

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The transmission mode of wireless waves in coal mine tunnel is different from the mode in free space.The multipath propagation of wireless wave is severe in tunnel.As a result,the characteristics study of multipath propagation is very important to the design of wireless communication system in coal mine tunnel.After analyzing the multipath propagation attenuation in tunnel,the statistics of single frequency signal,narrowband signal and broadband signal are obtained.This is the foundation for the application of resisting multipath decline techniques.

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Aris, Azuan, Yanuar Z. Arief, Lau Kwan Yiew, and Nor Asiah Muhamad. "Development of Remote Operation System on Residential AC Power Supply Using Radio Frequency." Applied Mechanics and Materials 818 (January 2016): 179–83. http://dx.doi.org/10.4028/www.scientific.net/amm.818.179.

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This paper deals with the development of a remote operation system for residential AC power supply using medium radio frequency transmission. Application of this system is to disconnect and reconnect the electricity supply which is operated by power utility company. Radio frequency (RF) remote control consists of a transmitter and receiver, which is the main module of the developed system. The transmitter will send a control signal through the module equipment transmitting antenna and the signal will be received by the antenna radio frequency transceiver module. Then, the recipient will control the electrical signals through the contactor as an interface with all electrical equipment. The operation of this system is at a fixed frequency of 315 MHz and distance control of electrical equipment is up to 10m at open space and subject to any restriction, antenna and supply of power. The results of this system are successfully demonstrated in the prototype of the remote control system for residential AC power supply. Some modifications have been proposed to improve the function of remote control system.

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Abdorahimi, Danial, and Ali M. Sadeghioon. "Comparison of Radio Frequency Path Loss Models in Soil for Wireless Underground Sensor Networks." Journal of Sensor and Actuator Networks 8, no. 2 (2019): 35. http://dx.doi.org/10.3390/jsan8020035.

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A wireless Underground Sensor Network (WUSN) is a group of sensors that collectively communicate through the underground medium. Radio Frequency (RF) signal transmission of the sensors through the ground is the most challenging aspects of a WUSN due to the high attenuation of the electromagnetic (EM) signal in the soil. Signals are often required to travel through soils with a high density or water content and generally through a non-isotropic and non-homogenous soil mixture with different boundaries, both of which can attenuate the signal sharply. The variability of the these conditions and complexity of the behaviour of signal attenuation with respect to these parameters makes accurate estimation of EM signal attenuation in soil challenging. Two main EM signal attenuation models exist to estimate attenuation (modified-Friis and Complex Refractive Index Model-Fresnel (CRIM-Fresnel). These were reviewed and a methodology was developed in order to measure the attenuation of the EM signals in the laboratory. Results from the laboratory measurements were compared with the estimation values calculated from the attenuation models. These comparisons showed a large difference between the estimated values by the models. In addition, analysis of the comparison tests showed that the CRIM-Fresnel model provides a better estimation of attenuation in samples with lower permittivity values while the modified-Friis model had a higher accuracy in samples with higher clay/water content which have higher permittivity values.

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Lim, Huey Sia, Nayan Nafarizal, Mohd Zainizan Sahdan, et al. "Transmission of Microwave Signal through Metal-Oxide Thin Film of Energy Saving Glass Using Different Shape of Frequency Selective Structure." Advanced Materials Research 925 (April 2014): 630–34. http://dx.doi.org/10.4028/www.scientific.net/amr.925.630.

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Metal oxide thin films are widely used for energy saving glass coating. This coating has the ability of blocking the infrared signal while being transparent to other visible part of the spectrum. However, there is one critical disadvantage of this metal oxide coating which it attenuates useful radio frequency and microwave signal such as GSM mobile signal, personal communication, GPS signal through them. These important microwave signals are fall within the range of 800 MHz to 2200 MHz. Frequency selective structure has been applied to solve the attenuation of microwave signal. With the adding of frequency selective structure, it can bring huge improvement of the transmission loss through it. Computer simulation using CST software is used to investigate the transmission loss through the metal oxide coated glass. The frequency selective structure will be etched out from the metallic oxide coated on the glass. Results showed that different shape of the structure will have different peak transmission loss through the glass. When cross dipole and circle shape been simulated using CST software, it can clearly see that the transmission lost and peak frequency had changed drastically. Then, triangle and pentagon shape also have different transmission through it. In addition, conductivity and electrical properties of coated metal oxide thin film is also very important. The transmission through the different ohmic sheet resistance of metal oxide thin film was also investigated. The sheet resistance value was obtained from the reported experimental results. Simulated results showed that full width half maximum, maximum transmission loss and peak frequency loss was very much dependent on the metal oxide sheet resistance. Therefore, the control of the thickness and oxygen content in metal oxide thin film are very much important to optimize the transmission loss through it for energy saving glass applications.

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Afanasiev, Nikolay, and Stanislav Chudaev. "DIAGNOSTICS OF THE STOCHASTIC IONOSPHERIC CHANNEL IN THE DECAMETER BAND OF RADIO WAVES." Solnechno-Zemnaya Fizika 6, no. 4 (2020): 77–85. http://dx.doi.org/10.12737/szf-64202010.

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We propose a method for direct diagnostics of a stochastic ionospheric radio channel. This method can recalculate probe signal characteristics into transmitted signal characteristics. We derive analytical equations of second-order statistical moments for trajectory characteristics of the main and probe signals propagating in a three-dimensional randomly inhomogeneous ionosphere. We take into account boundary conditions at signal transmission and reception points. As a model of random irregularities of permittivity of the ionosphere, we utilize the concept of a changing space-time correlation ellipsoid, which is self-consistent with spatial changes in the average ionosphere. Time fluctuations of random irregularities are taken into account by the hypothesis of frozen transfer. We use analytical relationships to calculate the expected statistical characteristics of decameter signals along oblique probing paths of the ionosphere. An operational numerical algorithmization of the formulas derived is proposed. We report results of numerical experiments to determine the expected phase variances, group delay, and Doppler frequency shift of the main signal on a given single-hop path, based on measurements of these characteristics of a probe signal on a secondary path. We demonstrate the efficiency of the proposed method for diagnosing statistical trajectory characteristics of a decameter signal along single-hop paths under conditions when ground points of transmission and reception of the main and probe signals are outside the vicinity of focusing points of the wave field.

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Wang, Chun Wu, Chun Ling Liu, and Zheng Kun Qin. "Design of Wireless Monitoring Environment System Based on AVR SCM." Advanced Materials Research 744 (August 2013): 532–35. http://dx.doi.org/10.4028/www.scientific.net/amr.744.532.

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The system had achieved a wireless data communication function using AVR SCM as a control center and basing on radio frequency identification technology. The transmitting terminal of system produces a high frequency signal through capacitance connecting three point type oscillator. And the encoded signal will be transmitted after high-frequency carrier modulated. While after the receiving terminal receive the signal through antenna, and the signal after a series processes including amplification, detection, rectification, voltage comparison will be processed by SCM. The system includes temperature humidity sensor, clock generator chip, photosensitive element, could detect the surrounding environment signal and wireless transmit. The paper elaborates the soft and the hardware realizing specific course of the wireless transmission system. It has an important meaning for the wireless transmission technique.

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Лавлинский, Валерий, V. Lavlinskiy, Юрий Громов, et al. "SIMULATOR ERROR STREAM IN THE DATA CHANNEL WHEN DIGITAL SIGNALS WITH A QUADRATURE PHASE SHIFT KEYING." Modeling of systems and processes 12, no. 3 (2019): 65–71. http://dx.doi.org/10.12737/2219-0767-2019-12-3-65-71.

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A variant of constructing an error flow simulator in a sequence of data transmitted over the radio channel using a signal with quadrature phase manipulation is proposed. The developed simulator takes into account the features of the implemented in practice coherent reception of signals with multi-position phase manipulation in the transmission of data in a digital communication channel. The adequacy of the results obtained by its use is confirmed in the process of modeling data transmission in a limited frequency resource channel. The expediency of using the proposed error flow simulator is due to the possibility of correlating the error flow parameters with the technical characteristics of the data transmission system and the intensity of interference in the radio channel.

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Shaddad, R. Q., A. B. Mohammad, S. A. Al-Gailani, and A. M. Al-Hetar. "Optical Frequency Upconversion Technique for Transmission of Wireless MIMO-Type Signals over Optical Fiber." Scientific World Journal 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/170471.

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The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3external optical modulator. The wireless MIMO signals are then modulated by LiNbO3optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength.

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Gajewski, Sławomir. "Design of OFDM-Based Radio Communication Systems for Coast-to-Sea and Coast-to-Air Propagation Environments." Polish Maritime Research 23, no. 1 (2016): 12–19. http://dx.doi.org/10.1515/pomr-2016-0002.

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Abstract In the paper the study of radio communication system design process for systems based on OFDM transmission is considered. The signal propagation model for 1.4 GHz frequency band is discussed, and the study of signal propagation characteristics, important from the point of view of OFDM system design, is presented. The methodology of OFDM interface design is proposed and some characteristics of the OFDM-based radio communication system are analysed.

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Науменко, Виктория Владимировна, Галина Анатольевна Проскура, Александр Владимирович Тоцкий та Валерий Борисович Шаронов. "ИСПОЛЬЗОВАНИЕ РАЗВЕТВЛЕННОГО БИСПЕКТРАЛЬНО-ОРГАНИЗОВАННОГО КОДА В НЕСТАЦИОНАРНЫХ КАНАЛАХ СВЯЗИ С ЗАМИРАНИЯМИ". RADIOELECTRONIC AND COMPUTER SYSTEMS, № 1 (23 березня 2019): 44–57. http://dx.doi.org/10.32620/reks.2019.1.05.

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One of the main problems in modern wireless telecommunication systems and networks is the transmission and reception of signals in a multipath environment. Due to the nonideal impulse response of the communication channel, the frequency selective fading of the transmitted signal occurs. Diffraction and interference effects create a complex non-stationary structure of the electromagnetic field, which varies greatly in space and time. The method of branched BIS is organized - redundant coding, which allows you to receive and recognize a signal in a digital communication system in the presence of additive Gaussian noise, multipath propagation of radio waves, fading, random signal delays, as well as random changes in Doppler frequency shift. The advantages of the bispectral signal processing method include the ability to identify and evaluate the phase relationships of the spectral components in the observation, high noise immunity with respect to additive Gaussian noise and invariance to random signal time delays. The proposed method is based on solving the problem of multi-alternative detection and distinguishing of known triple signals against the background of interference according to test statistics – estimating the amplitude bispectrum by comparing the corresponding peak values of bi-amplitudes at the output of the matched bispectral filter. Since the bi-amplitude serves as a measure of the contribution of the frequency-phase dependences specified in a polyharmonic signal, the reception rule is to choose a triplet as the solution of a bispectrically organized signal, whose frequency dependencies are most similar to the frequency dependencies in the adopted oscillation. The aim of the work is to substantiate the advantages of using a branched bispectrically-organized code in digital radio communication systems in conditions of fading and multipath propagation of radio waves in comparison with the known redundant code. The results of computer statistical modeling of communication systems with the proposed coding method and the known one show a lower probability of symbol error for branched bispectrically-organized redundant coding under conditions of multipath radio propagation channels within the considered Rice and Rayleigh fade models. Computer simulations performed to show that the proposed method of branched bispectrically-organized redundant coding improves noise immunity in the propagation of radio waves in a channel with additive white Gaussian noise and also in a multipath radio link with fast and slow fading compared to the known frequency-redundant system-prototype.

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Shi, Hong Mei. "The Design and Implementation of Spread Spectrum Communication System." Advanced Materials Research 933 (May 2014): 693–97. http://dx.doi.org/10.4028/www.scientific.net/amr.933.693.

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The main research content of this article is to design a direct sequence spread spectrum communication system based on software radio technology. In this paper, design of spread spectrum receiver system directly to intermediate frequency sampling signal processing, after internal processing directly output transmission baseband signal information.

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Mahrer, Kenneth D., and David F. List. "Radio frequency electromagnetic tunnel detection and delineation at the Otay Mesa site." GEOPHYSICS 60, no. 2 (1995): 413–22. http://dx.doi.org/10.1190/1.1443778.

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Using three radio frequency electromagnetic field procedures: surface‐to‐surface, borehole‐to‐surface, and borehole‐to‐borehole, we detected and delineated a horizontal, 2 1/2 × 5-ft (3/4 × 1 1/2-m), and 45-ft (14-m) deep tunnel crossing the US‐Mexico border near Otay Mesa east of San Diego, CA. We used continuous monochromatic signals to delineate the tunnel by (1) locating and identifying signature variations in signal transmissivity from the tunnel void in the local rock (sandstone) and (2) inducing and mapping the (secondary) radiation from electrical cabling within and running the length of the tunnel. In the surface‐to‐surface study we evaluated both a single magnetic dipole and a dipole gradiometer receiver and both a magnetic dipole and a grounded long‐wire transmitter operating between 22 kHz to approximately 300 kHz to isolate the induced radiation. We found that both sources operating at approximately 100 kHz gave the best transmitter‐cable coupling, and the nulling effect of the gradiometer was necessary to eliminate the primary field. In the surface‐to‐borehole study we placed a dipole receiver in boreholes and a dipole transmitter on the surface and operated at approximately 100 kHz. Horizontal traverses of the transmitter found peaks in the signal amplitude when the transmitter was directly above the tunnel. Vertical traverses of the receiver found (secondary) radiation peaks in the signal amplitude at depths corresponding to the tunnel depth. In the borehole‐to‐borehole studies, using zero‐offset (i.e., transmitter and receiver at the same depth) traverses and 1 MHz and 15 MHz signals, we found peaks in the signal amplitude at depths corresponding to direct ray transmission through the tunnel.

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Davies, D. Kenneth. "Wavelength-multiplexed analog fiber optic link for wideband radio- frequency local oscillator signal transmission." Optical Engineering 31, no. 11 (1992): 2323. http://dx.doi.org/10.1117/12.59947.

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Hu, Guoqiang. "Study on the Signal Transmission Characteristics of 2.4GHz Wireless Network in Dorms." International Journal of Online Engineering (iJOE) 12, no. 10 (2016): 58. http://dx.doi.org/10.3991/ijoe.v12i10.6208.

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In accordance with the deployment requirements of WLAN node in college student dorms and its features of application environment, this paper studies the relevance among factors like radio-frequency signal transmission characteristics, communication distance, AP height and transmission path, etc., with a case study of AP radio frequency 2.4GHz. Experiments show that the attenuation of wireless network signal in student dorms conforms to Keenan-Motley model. When AP is fixed, the signal strength received by laptop generally reduces with the increase of communication distance, yet just opposite with packet loss rate. When deploying AP, 1.25-1.75 height is ideal, and one-side coverage of 3 dorm rooms optimal. Based on the above researches, a relational model of AP height, communication distance and received signal strength is established. In it, model parameter and AP height display a cubic polynomial relationship, and attenuation coefficient and AP height show a quadratic polynomial relationship. Experiment results demonstrate that this model can satisfactorily predict the received signal strength of different AP heights and communication distances, providing technical support for wireless network deployment in student dorms.

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Shyshatskyi, A., O. Cherniak, A. Lyashenko, et al. "DEVELOPMENT OF THEORETICAL PROVISIONS OF TRANSMISSION OF DISCRETE MESSAGES OF MILITARY RADIOCOMMUNICATION SYSTEMS." Системи управління, навігації та зв’язку. Збірник наукових праць 2, no. 60 (2020): 180–83. http://dx.doi.org/10.26906/sunz.2020.2.180.

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Modern military radio systems operate in the complex conditions of the electronic environment, due to the limited frequency range, the influence of deliberate interference and signal fading. One of the ways to improve the effectiveness of military radio communication systems is to develop indicators (methods, techniques) for evaluating the effectiveness of military radio communication systems. The analysis found that known approaches to evaluating the performance of military radio communications systems are based on the use of bit error probability in a channel, which is a rather rough indicator of channel estimation. This necessitates the development of theoretical provisions for the transmission of discrete messages to military radio systems. In order to improve the known theoretical provisions for the transmission of discrete messages of military radio communication systems, the authors of the article developed indicators for assessing the quality of functioning of military radio communication systems that operate in complex conditions of electronic conditions. In the course of the study, the authors of the research substantiated two indicators of link quality in the fading channel: the probability of correctly receiving a message of finite duration and the likelihood of a link of finite duration without breaks. The first metric is the overall metric (communication) quality of the communication, and the second metric is the quality of the channel in the session of the final duration. During the research, the authors used the basic principles of communication theory, theories of insecurity, the theory of transmission of discrete messages, etc. The proposed results can be used to evaluate the status of radio channels when they are exposed to a variety of origins and signal fading. The practical significance of these results is that they can be used to upgrade existing radios or to develop new ones by developing appropriate software

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Wang, Juan, Yi Hai Wang, An Hua Wang, and Chang Pu Wang. "Simulation Research of the Underground Coal Mine Wireless Signal Transmission Characteristics." Applied Mechanics and Materials 568-570 (June 2014): 1321–25. http://dx.doi.org/10.4028/www.scientific.net/amm.568-570.1321.

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According to the special communication environment of the underground coal mine and the characteristic of high frequency electromagnetic wave approximation light propagation, this research adopts ray tracing method to simulate and analyze the characteristics of radio wave propagation in the underground roadway. The study not only is the theoretical basis for the development of wireless communication system in the underground, but also will provide an effective guarantee for safe production and modernization superintendence of coal mine.

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Valério de Souza, Pedro Thiago, Vinícius Samuel Valério de Souza, and Luiz Felipe de Queiroz Silveira. "Design of Wavelet-Encoded Symbol Constellations for Cyclostationary Spectrum Sensing." Wireless Communications and Mobile Computing 2020 (January 21, 2020): 1–9. http://dx.doi.org/10.1155/2020/9863785.

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In mobile communication systems, the signals propagate through multipath over time-varying channels, which are subject to distortion caused by fading and Doppler shifts. In order to minimize such distortions, coding techniques and transmission diversity can be employed, e.g., wavelet coding. In this work, the wavelet coding is investigated in scenarios of cognitive radio systems with dynamic spectrum access. Cognitive radio systems with dynamic spectrum access should be able to sense unoccupied frequency bands for opportunistic transmissions, as well as detect the presence of primary users when they occupy their licensed spectrum. Therefore, an essential element for the accurate operation of cognitive radio systems encoded by wavelet coding is the ability to sense the signals encoded by this technique. It is effectively demonstrated that the possibility of sensing such signals is associated with a suitable design of the signal constellation used in the modulation of the coded symbols. The constellation design of these is performed via genetic algorithms using a multiobjective optimization approach. The developed system is evaluated according to the robustness to time-varying flat fading through a bit error probability (BER) versus Eb/N0 analysis. The spectral sensing ability is also addressed employing the cyclostationary analysis. The results denote the feasibility of using wavelet coding in radio scenarios with dynamic spectrum access, with good performance in terms of BER and signal detection rates.

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Liu Anliang, 刘安良, 殷洪玺 Yin Hongxi, 吴宾 Wu Bin, and 刘畅 Liu Chang. "Phase-Shift Characteristics of Radio Frequency Signals for Radio over Fiber Transmission Systems." Acta Optica Sinica 38, no. 5 (2018): 0506003. http://dx.doi.org/10.3788/aos201838.0506003.

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42

Wolff, A. M., D. M. Akos, and S. Lo. "Potential radio frequency interference with the GPS L5 band for radio occultation measurements." Atmospheric Measurement Techniques 7, no. 11 (2014): 3801–11. http://dx.doi.org/10.5194/amt-7-3801-2014.

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Abstract. Future radio occultation (RO) receivers are planned to utilize the newly implemented Global Positioning System (GPS) L5 band centered at 1176.45 MHz. Since there are currently no operational GPS L5 receivers used for space-based RO applications, the interference environment is unclear. Distance measuring equipment (DME) and tactical air navigation (TACAN) stations share the same frequency band as GPS L5. The signals from these stations have been identified as possible sources of interference for any GPS L5 receiver, including those used in RO applications. This study utilizes Systems Tools Kit (STK) simulations to gain insight into the power received by a RO satellite in low Earth orbit (LEO) from a DME–TACAN transmission as well as the amount of interfering stations. In order to confirm the validity of utilizing STK for communication purposes, a theoretical scenario was recreated as a simulation and the results were confirmed. Once the method was validated, STK was used to output a received power level aboard a RO satellite from a DME–TACAN station as well as a tool to detail the number of interfering DME–TACAN stations witnessed by a space-based RO receiver over time. The results indicated a large number of DME–TACAN stations transmitting at similar orientations as a receiving RO satellite, thereby leading to the possibility of signal degradation in an unclear interference environment.

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Bian, Hong Ning, Yong Ming Li, Lan Lei Wei, and Zhao Liu. "A Design of Underwater Acoustic Signal Acquisition Module." Applied Mechanics and Materials 433-435 (October 2013): 441–44. http://dx.doi.org/10.4028/www.scientific.net/amm.433-435.441.

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This paper introduced a underwater acoustic signal acquisition module which used preamplifier, filter plate and the digital circuit board collect original data for 20 Hz to 1K Hz frequency data through acoustic vector hydrophone .It could send the collected data to the PC on the coast through wireless data transmission radio station and store the collected original data d into the SD card as well.

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Liu, Lingxiao, Tian Lu, Mingxue Gong, and Wuyu Zhang. "Study on the strength loss of Multi-hop HF Radio Propagation." MATEC Web of Conferences 175 (2018): 03012. http://dx.doi.org/10.1051/matecconf/201817503012.

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The reflections of high frequency (HF) radio waves between ionosphere and earth’s surface make long-distance information transmission possible. In this paper, the propagation process of radio signals was analyzed and the ionosphere was simplified. Considering the strength loss of signals that occurs in the travelling process and at the reflection points, two pairs of differential equations and integral equations were established to simulate the strength variations of HF radio waves and noises. A different equation of SNR was also developed, which utilized the failure threshold of signal-noise-ratio (SNR) as a criterion to evaluate the effectiveness of signals. Meanwhile, the pace of SNR attenuation was simulated when reflections happens on calm ocean, turbulent ocean, smooth terrain and rugged terrain.

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Qiu, Zi Xue, Zhi Xin Chen, Jiang Yuan, You Wei Wang, Jie Yang, and Yun Lei Yu. "Design of Sensor-Tag Using Radio Frequency Power to Energize and its Research on Structural Health Monitoring." Applied Mechanics and Materials 330 (June 2013): 373–79. http://dx.doi.org/10.4028/www.scientific.net/amm.330.373.

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A new method of structural health monitoring based on sensor-tags using radio frequency power to energize node wirelessly is proposed. A modular RFID sensor-tag, which has the function of signal conditioning, energy harvesting, and wireless transmission, is designed for some sensing elements commonly used in structural health monitoring, such as resistance strain gauges, piezoelectric ceramic and shape memory alloy (SMA). Sensor-tags receive energy which is the feedback of reader antenna coupling and provide power for sensor nodes. It overcomes defects of wireless sensor network (WSN) powered by battery, such as weak capabilities of processing, storage and communication. Stretching, bending and impact tests show that the system can achieve reliable signal acquisition and wireless transmission, the wireless communication distance between tag and reader is up to 128 meters, bit error rate of signal transmission 2 %.

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Bello, Hilal, Zeng Xiaoping, Rosdiadee Nordin, and Jian Xin. "Advances and Opportunities in Passive Wake-Up Radios with Wireless Energy Harvesting for the Internet of Things Applications." Sensors 19, no. 14 (2019): 3078. http://dx.doi.org/10.3390/s19143078.

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Wake-up radio is a promising approach to mitigate the problem of idle listening, which incurs additional power consumption for the Internet of Things (IoT) wireless transmission. Radio frequency (RF) energy harvesting technique allows the wake-up radio to remain in a deep sleep and only become active after receiving an external RF signal to ‘wake-up’ the radio, thus eliminating necessary hardware and signal processing to perform idle listening, resulting in higher energy efficiency. This review paper focuses on cross-layer; physical and media access control (PHY and MAC) approaches on passive wake-up radio based on the previous works from the literature. First, an explanation of the circuit design and system architecture of the passive wake-up radios is presented. Afterward, the previous works on RF energy harvesting techniques and the existing passive wake-up radio hardware architectures available in the literature are surveyed and classified. An evaluation of the various MAC protocols utilized for the novel passive wake-up radio technologies is presented. Finally, the paper highlights the potential research opportunities and practical challenges related to the practical implementation of wake-up technology for future IoT applications.

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Xu, Tianhua, Cenqin Jin, Shuqing Zhang, et al. "Phase Noise Cancellation in Coherent Communication Systems Using a Radio Frequency Pilot Tone." Applied Sciences 9, no. 21 (2019): 4717. http://dx.doi.org/10.3390/app9214717.

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Long-haul optical fiber communication employing digital signal processing (DSP)-based dispersion compensation can be distorted by the phenomenon of equalization-enhanced phase noise (EEPN), due to the reciprocities between the dispersion compensation unit and the local oscillator (LO) laser phase noise (LPN). The impact of EEPN scales increases with the increase of the fiber dispersion, laser linewidths, symbol rates, signal bandwidths, and the order of modulation formats. In this work, the phase noise cancellation (PNC) employing a radio frequency (RF) pilot tone in coherent optical transmission systems has been investigated. A 28-Gsym/s QPSK optical transmission system with a significant EEPN has been implemented, where the carrier phase recovery (CPR) was realized using the one-tap normalized least-mean-square (NLMS) estimation and the differential phase detection (DPD), respectively. It is shown that the RF pilot tone can entirely eliminate the LPN and efficiently suppress the EEPN when it is applied prior to the CPR.

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Zhou, Lin, Fahd Ahmed Khan, Tharmalingam Ratnarajah, and Constantinos B. Papadias. "Achieving Arbitrary Signals Transmission Using a Single Radio Frequency Chain." IEEE Transactions on Communications 63, no. 12 (2015): 4865–78. http://dx.doi.org/10.1109/tcomm.2015.2493140.

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Zhang, Zhen, Yibing Li, Chao Wang, Meiyu Wang, Ya Tu, and Jin Wang. "An Ensemble Learning Method for Wireless Multimedia Device Identification." Security and Communication Networks 2018 (October 15, 2018): 1–9. http://dx.doi.org/10.1155/2018/5264526.

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In the last decade, wireless multimedia device is widely used in many fields, which leads to efficiency improvement, reliability, security, and economic benefits in our daily life. However, with the rapid development of new technologies, the wireless multimedia data transmission security is confronted with a series of new threats and challenges. In physical layer, Radio Frequency Fingerprinting (RFF) is a unique characteristic of IoT devices themselves, which can difficultly be tampered. The wireless multimedia device identification via Radio Frequency Fingerprinting (RFF) extracted from radio signals is a physical-layer method for data transmission security. Just as people’s unique fingerprinting, different Internet of Things (IoT) devices exhibit different RFF which can be used for identification and authentication. In this paper, a wireless multimedia device identification system based on Ensemble Learning is proposed. The key technologies such as signal detection, RFF extraction, and classification model are discussed. According to the theoretical modeling and experiment validation, the reliability and the differentiability of the RFFs are evaluated and the classification results are shown under the real wireless multimedia device environments.

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Li, Tai Hao, and He Pan. "Study of the Wireless Sensor Networks Radio Frequency Signal Loss Based on Different Planting Density Corn Environment." Applied Mechanics and Materials 427-429 (September 2013): 2771–73. http://dx.doi.org/10.4028/www.scientific.net/amm.427-429.2771.

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In order to rationally arranged cornfield wireless sensor network nodes, fields of corn are studied in the loss of signal of 2.4GHZ wireless sensor radio frequency signal, and selecting 3 levels of planting density carries out the field random test with the transmission distance and antenna height as influencing factors, environmental impact factors and antenna height exist linear relationship, establishing the mathematical model.

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