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Magnetic communication systems are typically used when the medium contains matter, or when short-range communication is of interest. Previous works have disregarded impediments to transmission performance due to skin and proximity effects and radiation resistance, although such effects may be significant. This paper addresses these effects and prop...
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... 2 2 Fig. 2 shows a schematic representation and an equivalent circuit of the MI sensor. The circuit is excited just by the induced voltage v emf . The passive elements are the coil self- inductance L, the wire inductance L w , the AC loss (ohmic) resistance R AC , and the self-capacitance C. The core losses (due to eddy currents and hysteresis), ...
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Citations
... If the transmission rate is too fast, it is easy to affect the communication performance. erefore, in order to study the relationship between transmission rate and bit error rate, the relationship between transmission rate and signal-to-noise ratio is established by taking the signalto-noise ratio as a bridge, so as to evaluate the link bit error performance [27]. e data to be transmitted is sent to the fountain code encoder to code the transmitted data, then the pilot sequence is added according to the specified data frame structure, and the information is grouped. ...
Ground-to-air data link communication has the advantages of fast transmission rate, strong anti-interference ability, and large data communication volume and has been widely used in the field of civil aviation. This article mainly studies the measures to improve the real-time performance of the airborne data link communication system. The design of the hardware platform of the jamming environment simulator needs to comprehensively consider the implementation complexity of the jamming environment model and the real-time simulation method adopted by the UAV data link system. This paper uses the multicore and multithread in the Linux operating system to simulate the functions of the original data link communication system and uses the TFT screen to display the data communication process in the multicore and multithread design scheme. When evaluating and scoring the evaluation indicators, it must be carried out in accordance with certain standards. However, most of the indicators cannot be directly assessed quantitatively only through certain specific values. This article mainly uses the AHP method to analyze the weight of indicators. In the simulation, user information is generated by a random code generator and then distributed to each branch through serial-to-parallel conversion (S/P), and the spreading process is completed by long-code spreading on each branch, respectively, by BPSK. It is modulated on different carriers to form a transmission signal; the signal passes through a Gaussian white noise channel, and a certain frequency offset noise is added at the same time to reach the receiving end; the receiving end uses correlated demodulation, and after despreading, the error rate is counted. The data shows that under different distances, the frame loss rate of the data link is different. The frame loss rate in the 500 m range is about 1%, and the frame loss rate in the 2 km range is about 2.3%. The results show that the real-time performance of the data link communication system in this paper has been greatly improved.
1. Introduction
With the popularization and application of information theory, data link technology has evolved from traditional combat support to main combat weapons and has been proved in many wars since the 1990s. Compared with traditional wireless communication, there are many scenarios in which a wireless communication base station is used [1]. It can not only realize real-time communication in closed buildings such as rooms and parking lots but also realize real-time communication in the streets with high-rise buildings. This is of great significance for the development of wireless communication base stations.
UAV downlink data link not only solves the problems of long time [2], low timeliness, and instability of traditional relay communication but also ensures the accuracy and integrity of the received information to the greatest extent due to its mobility and flexibility and further improves the processing capacity of the whole system for docking and receiving information. Whether the communication can be carried out at high speed, timely, correctly, and safely is the key factor affecting the success of the task. Therefore, the simulation research of UAV airborne communication system has great military practical significance [3].
For wireless communication in an open space, it is bound to be subject to various interferences from the open space. Long et al. reexamined the channel characteristics of indoor visible light communication systems. His purpose is to evaluate channel frequency selectivity, in other words, to evaluate the importance of intersymbol interference (ISI) at the receiver and the need for channel equalization to restore the transmitted data. He focused on the effect of indoor channels by assuming that there is no bandwidth limitation on light-emitting diodes and considering a simple intensity modulation technique (not including discrete multitone modulation). First, he simulated the channel impulse response (CIR) using an iterative site-based method. Then, he studied the conventional indicators used to evaluate channel frequency selectivity, namely, root mean square delay spread and channel frequency response. Although his algorithm is necessary, it lacks accuracy [4]. Rahmani Hosseinabadi et al. proposed an efficient partial transmission sequence technology based on genetic algorithm and peak optimization algorithm (gapoa) to reduce the peak-to-average power ratio (PAPR) in the visible light communication system based on orthogonal frequency division multiplexing (vlc-ofdm). By analyzing the advantages and disadvantages of the mountain climbing algorithm [5], he proposed a kind of Poa with excellent local searchability, which can further process the signal whose PAPR still exceeds the threshold after being processed by genetic algorithm (GA). He evaluated the PAPR performance and bit error rate (BER) performance, compared them with ga-pts and genetic-based PTS, and compared them with gh-pts and sflahc-pts [6]. Although his research performance is better, the factors considered are not comprehensive [7]. Thakur P believes that, recently, due to the explosive growth of application requirements for bandwidth, the demand for the radio spectrum of the next-generation communication system continues to increase, which has caused the problem of spectrum scarcity. Among the proposed solutions to this problem, he uses the well-researched cognitive radio (CR) technology and the recently introduced nonorthogonal multiple access (NOMA) technology. Both technologies are used to effectively use the spectrum and ensure a significant increase in spectrum efficiency [8]. He introduced the framework for implementing NOMA on CR and the feasibility of the proposed framework. In addition, he discussed the differences between the proposed CR-NOMA and the conventional CR framework. Finally, he discussed potential issues regarding CR-NOMA's implementation. Although his research has certain feasibility, it lacks necessary data [9]. Kaddoum considers that the decrease of data rate and energy efficiency caused by the transmission of an equal reference signal and data carrier signal constitutes the main disadvantage of the DCSK system. In order to overcome this main shortcoming, he proposed a short reference DCSK system (SR-DCSK). To construct the transmitted data signal, tandem copies of R are used to extend the data. This operation improves data rates and energy efficiency without adding complexity to the system architecture. He uses the receiver’s knowledge of integers R and to recover data. He analyzed the proposed system and calculated the enhanced data rate and bit energy saving percentage. Although his research enhanced the data rate, it was not accurate enough [10].
In this paper, the Turbo code is selected as the error-correcting code for the airborne data chain in consideration of hardware resources, feasibility, anti-interference ability, and other aspects, the Turbo code scheme is improved, and finally, FPGA implementation is implemented. It plays a very important role in the communication system. The research on the information coding technology of airborne data link lays a certain foundation for the design of the message frame format, transmission mode, and signal processing method of the new airborne data link and verifies its effectiveness through the computer simulation, which provides a reference basis and technical support for the formulation of the message standard of the new airborne data link.
2. Airborne Data Link Communication System
2.1. Airborne Data Link
The terminal of the wireless data link, no matter it is a source or a host, is equivalent to a microcomputer, which has the ability to process information independently and can complete the modulation and demodulation function of transmitting the information. Moreover, according to the specified communication protocol, the demodulated information can be processed by group frames, and the true meaning of information transmission can be read out to achieve the purpose of communication [11]. On the other hand, the terminal equipment can also modulate the information to be expressed according to the communication protocol and then transmit it in the channel to complete the information feedback. As for the transmission channel of wireless data link, it covers a wider range, including not only transmission media but also some other devices, such as antenna [12]. In the data link communication system of a small unmanned helicopter [13], when the information load between UAV and ground station is too large, the throughput of the network will decrease, resulting in congestion. The expression of congestion detection function is as follows:
In the formula, q is the queue space. The formula for calculating the received power of the receiving node is
In the automatic power control strategy, it is assumed that the energy consumption parameter is
In general, when k > 1, the equivalent radius of the Earth is larger than the actual radius. For the same antenna and aircraft height, atmospheric refraction means that the communication distance of the data link increases, and the equivalent radius coefficient K of standard refraction is 1.333. The limit distance of line-of-sight propagation is
During the flight, the distance between the aircraft and the ground control station is constantly changing, and it may appear at any point within the line-of-sight range. Compared with the receiver, the received signal will only be very close when it is very close to the signal source [14]. On the contrary, the farther the distance is, the worse the signal will be, and this change is not a simple linear change. When it exceeds a certain distance, the signal strength will drop sharply [15, 16]. The form of the uplink modulation signal is
In the formula, represents the pseudocode of the uplink communication branch, and represents the uplink carrier frequency.
The downlink modulation signal form is
In the formula, is the frequency difference between the target image branch and the telemetry branch [17, 18].
Assuming that the coordinates of the ground station are and the coordinates of the aircraft are , then
Then the aircraft coordinates can be obtained:
At present, the M sequence is obtained through large-scale search and detailed calculation. Using the form of feedback function, the M sequence can be expressed as
The autocorrelation function of the commonly used Barker code can be expressed as
In the AWGN channel, the receiving sequence is
Among them, is additive white Gaussian noise, and T is the symbol interval. Then, the ML probability is
The carrier insertion method system is shown in Figure 1. At the receiving end of the communication system, the carrier frequency transmitted by the system can be filtered out by using a narrow-band filter. Here, it is necessary to ensure that the center frequency of the narrow-band filter is the same as the inserted carrier frequency. At the same time, due to the orthogonal effect, the phase shift π/2 operation is also required [19]. In a word, the key of the carrier insertion method is a narrow-band filter with the same carrier frequency, which is usually completed by PLL, and its hardware implementation is [20–22].
... La résistance équivalente J %U"#&C& de ces boucles radiatives peut être décomposée en trois termes [98] [181] : 20) où J Å&$%& modélise la résistance du conducteur utilisé pour réaliser la boucle tandis que J $*0 est une résistance équivalente qui dissipe la puissance radiative contenue dans l'onde électromagnétique émise. Le dernier terme, J Ç$É , permet de prendre en compte la contribution des pertes de puissances engendrées par les courants de Foucault induits par le champ magnétique variable au voisinage de l'antenne. ...
... Y. Morag et al. [181] ont proposé une expression de J Å&$%& , maintenant couramment utilisée [98] qui tient compte de l'effet de peau et de l'effet de proximité des autres conducteurs du bobinage de la boucle : ...
... En raison de sa conductivité, les champs magnétiques variables induisent, dans l'eau de mer, des courants de Foucault, dont l'intensité dépend de la fréquence [143] [181]. Il est intéressant d'intégrer dans le modèle du transformateur équivalent, une résistance fictive destinée à prendre en compte la puissance perdue correspondante à ce phénomène. ...
La surveillance de l’environnement sous-marin nécessite le déploiement de capteurs et d’infrastructures dédiées dont le coût et l’impact sur la faune et la flore doivent être réduits. L’application cible vise des zones géographiques inférieures à 1km2 dans lesquelles les transmissions de flux vidéo et de mesures, prélevés par des capteurs immergés, doivent être réalisées sans-fil sur des distances supérieures à 10m avec un débit minimum de 80kbps pour des puissances d’émission d’une dizaine de Watts. Une étude comparative des méthodes de communication acoustiques, optiques et électromagnétiques en eau de mer est présentée. Cette analyse est introduite en définissant un ensemble de critères de performances destinés à évaluer et sélectionner la technique la mieux adaptée aux besoins applicatifs. Les méthodes électromagnétiques, dont les coûts de déploiements et l’impact environnemental sont minimaux, présentent toutefois des limitations de portée pour le débit de données souhaité. La suite de cette thèse présente les travaux de recherche qui ont été menés pour lever ces verrous technologiques. Un premier modèle simplifié de propagation des champs électromagnétiques en milieu subaquatique a été développé pour différencier les modes de propagation favorisant les pertes par conduction de celles engendrées par les propriétés diélectriques de l’eau de mer. Des prototypes d’antennes ont été développés pour tenter d’exciter le milieu en favorisant l’un ou l’autre mode. Finalement, l’étude détaillée d’un modèle de couplage magnéto-inductif a permis de réaliser et d’évaluer les performances d’une telle liaison en utilisant des techniques originales d’élargissement de bande passante qui ont été implémentées avec succès dans un prototype de MODEM sous-marin.
... The coil resistance consists of DC resistance and the resistance caused by the intrinsic skin depth loss and proximity loss of coil wires, both of which are given in [31]. The radiation resistance of a coil in a lossy medium is complicated due to the medium absorption. ...
... The path loss model in (31) can be used to design the MIC system and networks. Since in the radiative near field and the far field M can be a random number depends on the surrounding environment, the path loss model is stochastic, which can converge to the existing electromagnetic wave-based wireless channel model. ...
Magnetic induction communication (MIC) demonstrates high penetration efficiency and low propagation loss in extreme environments. It is used in underground and underwater environments to enable critical applications that cannot be achieved by using terrestrial wireless techniques. This article studies the channel and antenna modeling for MIC in inhomogeneous environments, where a transmitter and a receiver are in two different media. This problem finds a large number of practical applications such as communicating with wireless sensors in the soil, water, walls, and the human body using a wireless device in the air. This article develops a joint channel and antenna model considering the inhomogeneity of the surrounding environments. An exact full-wave model and a near field approximation model are developed and evaluated to show the characteristics of this novel wireless technique as well as the limitations of existing solutions. Using the communication with underground sensors as an example, the results show that the path loss of MIC strongly depends on the propagation media which is drastically different from electromagnetic wave-based wireless communications in terrestrial environments. Also, we find that the MIC channel in inhomogeneous media exhibits non-reciprocity due to different transmission coefficients through the boundary. Moreover, the boundary can be neglected when the carrier frequency is sufficiently low. The developed model provides a tool to design wireless sensor networks in inhomogeneous extreme environments.
... Cross-section of induction loop sensor made of a multiturn coil wrapped around a permeable core[19] ...
p class="Text">A crack detection is very important to control the quality of the composite itself that been widely used in industries. There are quite a numbers of techniques which are used to detect the crack such as visual inspection, radiography, ultrasonic, eddy current magnetic particle, and penetrant testing. In this paper, it focuses on designing and implementing the system to detect a crack on the composite material using magnetic induction concept. At the early stage, the miniature of composite detection sensor using magnetic induction concept is designed using Comsol Multiphysics software to see the current induced from the system. The current value from the sensor is measured based on magnetic induction concept. A complete design of a system then is designed which include the sensor design, the main controller unit design and Bluetooth electronic application. The experiment results show that the magnetic induction concept can be used to detect crack by changing the value of current. When crack occurs the value of current will decrease due to the changes of magnetic induction.</p
... Although [30] and [31] performs full-wave analysis, skin and proximity effects within the coil itself were not discussed. These HF aspects were partly addressed by the authors in the context of magnetic sensors [39] and induction power transfer systems [40]. ...
... The objective of this study is, therefore, to extend previous works [31,39,40], and develop a strict limit for the extracted power in MIEH systems while accounting for the HF effects. Maximal available output power is mapped as a function of frequency, and the optimal operating frequency is then derived. ...
... Explicit expressions for the resistance terms of the circuit (i.e., RAC, Rrad, and Rcore) are each described in detail in [39]. The coil Ohmic resistance increases drastically with frequency, due to skin and proximity effects. ...
Wireless power transfer systems based on magnetic induction are usually modeled using the magneto-quasi-static approximation, and by neglecting skin effects and radiation losses. These assumptions imply that the extracted power can grow unlimitedly by increasing frequency or coil size. To bridge this gap, this work proposes general expression for the actual received power of magnetic induction-based energy harvesting transducer, extracting power from a given ambient magnetic field, while accounting for the high-frequency effects. A primary result is that the receiver’s output power is inherently limited by radiation losses at high frequencies and impaired by skin and proximity effects at medium frequencies. The approach provides a design tool for estimating the maximal power that can be delivered through a given transducer, and the optimal operating frequency.
... As in any wireless communication system, achieving high data rates over a noisy channel is of prime importance [1], [12], [14], [16], [20], [27]- [33]. The channel capacity of MC systems is relatively small, due to the low frequencies involved [13], the rapid decay with distance that results in a low signal-to-noise ratio (SNR), and the narrow bandwidth (BW) dictated by the resonance operation mode [27]. ...
... The prevailing approach in the literature is to analyze MC systems under magnetoquasistatic (MQS) assumption which neglects the far-field terms [1], [2], [4]- [12], [14]- [20], [24], [26], [27], [31], as well as high-frequency (HF) effects in the coil transducers (e.g., skin and proximity effects [33], radiation losses, and the coil's self-resonance frequency (SRF) [34]- [36]). This is justified by the relatively low frequency used, in which the NF components are dominant. ...
... This is justified by the relatively low frequency used, in which the NF components are dominant. However, in free-space and low-loss media (where the field attenuation due to the medium is small), this neglect may result in a misleading insight that the performance (power, SNR, and capacity) improves monotonically with the increase in frequency and coil size [33], [37]. This may lead to nonoptimal operating frequency and overestimation of the performance. ...
Magnetic communication systems are most often analyzed assuming magneto-quasistatic conditions, which neglect full-field terms and high-frequency effects in the transmitting and receiving coils. Such approximations may lead to non-optimal designs in terms of operating frequency, size, and coil orientation. This paper presents an optimal design approach for maximizing the channel capacity, using both magneto-quasistatic and fullwave analysis, while incorporating high-frequency effects, such as skin and proximity effects, radiation losses, and the selfresonance of coils. For a given medium and required transmission distance, the optimal operating frequency is such, for which the receiver is located be in the radiative near-field, and not in the reactive near-field. The optimal power allocation and the resulting channel capacity were obtained using a "water-filling" algorithm. The high-frequency effects reduced the signal-to-noise ratio, and limited operating frequency and coil size. This is especially true for short-distance transmission through low-loss media, where the optimal signal frequency is relatively high. In addition, full-wave analysis significantly improved potential data rates compared to the typical magneto-quasistatic approach. This improvement was achieved due to a higher operating frequency, and sometimes a change of mutual orientation from coaxial to parallel. Electromagnetic simulations validated the primary effects presented here.
... The ohmic resistance increases substantially with frequency, due to the skin effect and the proximity effect. The ohmic resistance accounting for skin effect is well studied in paper [9], which is given by πµ 0 µr σw f is the skin depth, and σw is the conductivity of the wire material. The proximity effect will further increase the ohmic resistance. ...
... Consider the TX coil located at the origin of a spherical coordinate system, and assume that its axis coincides with the z-axis. The magnetic moment of the coil, m0 is given by [21] I r N NAI m av app app 2 0 (2) in which N is the number of turns, rav is the average coil radius, app is the apparent permeability of the coil [22], and I is the current. Under magneto-quasistatic approximation (MQS) valid in the near field, the magnetic field components for a point located in a position r, with respect to TX coil axis, are [23]: The first term in (3) and (4) indicates that the field decays in proportion to 1/r 3 (compared to 1/r in EM transmission). ...
... where μ 0 is the permeability of free space and B the magnetic induction field produced by a target with the moment of M at distance R. A magnetic sensor [13,14] measures a net field composed of target magnetic induction field, earth field, and magnetic noise ...
Magnetic anomaly detection (MAD) is to find hidden ferromagnetic objects, and a hidden object is often described as a magnetostatic dipole. Many detection methods are based on the orthonormal basis functions when the target moves along a straight line relatively to the magnetometer. A new kind of parabolic trail orthonormal basis functions (PTOBF) method is proposed to detect the magnetic target when the trajectory of the target is parabola. The simulation experiment confirms that the proposed method can detect the magnetic anomaly signals in white Gaussian noise when SNR is -15.56 dB. The proposed method is sensitive to the characteristic time and curvature. High detection probability and simple implementation of proposed method make it attractive for the real-time applications.
... Near field communication has recently received significant interest in the radio-frequency research community for the development of sensor tags and to enable wireless power transfer [9]. In-body sensor networks [10] face similar challenges as subsea networks, albeit to a smaller scale, since the signal passes through human tissue. Also, in [6], an MI link was studied for communication in caves, through the earth. ...
In this work, a magneto inductive (MI) link design is studied to achieve high speed transmission applied to a high density underwater network. For a small loop antenna, a design procedure is described to define the optimal operating frequency constrained on the system bandwidth and range. A coherent link is established between two nodes in a controlled underwater environment. For a small coil with radius of 5 cm, simulation results indicate that a range above 10 meters can be achieved in the low frequency spectrum spanning 10 kHz to 1 MHz. The design procedure is validated through measurements in seawater: a very high output SNR equal to 31.4 dB is realized at the output of the equalizer, and in these conditions a perfectly reliable 8-kbps link is demonstrated at a center frequency of 22.5 kHz.
