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    Radio Science

  • 中文名称: 无线电科学
  • 刊频: 1.012
  • ISSN: 0048-6604
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1927条结果
  • 机译 使用多模型集合预测系统(MEPS)进行空间天气预报
    摘要:The goal of the Multimodel Ensemble Prediction System (MEPS) program is to improve space weather specification and forecasting with ensemble modeling. Space weather can have detrimental effects on a variety of civilian and military systems and operations, and many of the applications pertain to the ionosphere and upper atmosphere. Space weather can affect over-the-horizon radars, HF communications, surveying and navigation systems, surveillance, spacecraft charging, power grids, pipelines, and the Federal Aviation Administration (FAA's) Wide Area Augmentation System (WAAS). Because of its importance, numerous space weather forecasting approaches are being pursued, including those involving empirical, physics-based, and data assimilation models. Clearly, if there are sufficient data, the data assimilation modeling approach is expected to be the most reliable, but different data assimilation models can produce different results. Therefore, like the meteorology community, we created a Multimodel Ensemble Prediction System (MEPS) for the Ionosphere-Thermosphere-Electrodynamics (ITE) system that is based on different data assimilation models. The MEPS ensemble is composed of seven physics-based data assimilation models for the ionosphere, ionosphere-plasmasphere, thermosphere, high-latitude ionosphere-electrodynamics, and middle to low latitude ionosphere-electrodynamics. Hence, multiple data assimilation models can be used to describe each region. A selected storm event that was reconstructed with four different data assimilation models covering the middle and low latitude ionosphere is presented and discussed. In addition, the effect of different data types on the reconstructions is shown.
  • 机译 从强度(S-4)和相位(sigma(phi))闪烁的单站GNSS测量中推断区域不规则漂移的技术
    摘要:The zonal drift of ionospheric irregularities at low latitudes is most commonly measured by cross-correlating observations of a scintillating satellite signal made with a pair of closely spaced antennas. The Air Force Research Laboratory-Scintillation Network Decision Aid (AFRL-SCINDA) network operates a small number of very high frequency (VHF) spaced-receiver systems at low latitudes for this purpose. A far greater number of Global Navigation Satellite System (GNSS) scintillation monitors are operated by the AFRL-SCINDA network (25-30) and the Low-Latitude Ionospheric Sensor Network (35-50), but the receivers are too widely separated from each other for cross-correlation techniques to be effective. In this paper, we present an alternative approach that leverages the weak scatter scintillation theory to infer the zonal irregularity drift from single-station GNSS measurements of S-4, sigma(phi), and the propagation geometry. Unlike the spaced-receiver technique, this approach requires assumptions regarding the height of the scattering layer (which introduces a bias in the drift estimates) and the spectral index of the irregularities (which affects the spread of the drift estimates about the mean). Nevertheless, theory and experiment suggest that the ratio of sf to S4 is less sensitive to these parameters than it is to the zonal drift. We validate the technique using VHF spaced-receiver measurements of zonal irregularity drift obtained from the AFRL-SCINDA network. While the spaced-receiver technique remains the preferred way to monitor the drift when closely spaced antenna pairs are available, our technique provides a new opportunity to monitor zonal irregularity drift using regional or global networks of widely separated GNSS scintillation monitors.
  • 机译 来自随机非均匀电离层的波反射:1.描述具有随机凹凸的反射层中波场的方法
    摘要:It has been previously proposed to describe wave propagation in inhomogeneous media in a small-angle approximation with the aid of a double weighted Fourier transform (DWFT) method. This method agrees with the methods of geometrical optics, smooth perturbations, and phase screen in domains of their applicability; therefore, it can be employed to solve direct and inverse problems of radio wave propagation in multiscale inhomogeneous ionospheric plasma. In this paper, for the DWFT wide-angle generalization a wave equation is preliminary reduced using the Fock proper-time method to a parabolic equation that then is solved by the DWFT method. The resulting solution is analyzed for the case of wave reflection and scattering by a layer with random irregularities and linear profile of average permittivity. We show the transformation of this solution into strict results in the absence of irregularities and in the single-scatter approximation, including backscattering, during weak phase fluctuations. Under certain conditions, the solution takes the form of the small-angle DWFT with respect to refraction in the layer and backscatter effects. Spatial processing in source and observer coordinates brings a beam of received waves into one wave without amplitude fluctuations, which allows an increase in resolution of vertical ionospheric sounding systems.
  • 机译 LPDA天线优化的进化算法比较
    摘要:A novel approach to broadband log-periodic antenna design is presented, where some of the most powerful evolutionary algorithms are applied and compared for the optimal design of wire log-periodic dipole arrays (LPDA) using Numerical Electromagnetics Code. The target is to achieve an optimal antenna design with respect to maximum gain, gain flatness, front-to-rear ratio (F/R) and standing wave ratio. The parameters of the LPDA optimized are the dipole lengths, the spacing between the dipoles, and the dipole wire diameters. The evolutionary algorithms compared are the Differential Evolution (DE), Particle Swarm (PSO), Taguchi, Invasive Weed (IWO), and Adaptive Invasive Weed Optimization (ADIWO). Superior performance is achieved by the IWO (best results) and PSO (fast convergence) algorithms.
  • 机译 混合递归有源滤波器,用于射频发射机前端中的双工
    摘要:Duplex filters in modern base transceiver stations shape the channel in order to perform common frequency division duplex operations. Usually, they are designed as cavity filters, which are expensive and have large dimensions. Thanks to the emerging digital technology and fast digital converters, it is possible to transfer the efforts of designing analog duplex filters into digital numeric algorithms applied to feedback structures, operating on power. This solution provides the shaping of the signal spectrum directly at the output of the radio frequency (RF) power amplifiers (PAs) relaxing the transmitter design especially in the duplexer and in the antenna sections. The design of a digital baseband feedback applied to the analog power RF amplifiers (hybrid filter) is presented and verified by measurements. A model to describe the hybrid system is investigated, and the relation between phase and resonance peaks of the resulting periodic band-pass transfer function is described. The stability condition of the system is analyzed using Nyquist criterion. A solution involving a number of digital feedback and forward branches is investigated defining the parameters of the recursive structure. This solution allows the closed loop system to show a periodic band pass with up to 500 kHz bandwidth at the output of the RF amplifier. The band-pass magnitude reaches up to 17 dB selectivity. The rejection of the PA noise in the out-of-band frequencies is verified by measurements. The filter is tested with a modulated LTE (Long Term Evolution) signal showing an ACPR (Adjacent Channel Power Ratio) enhancement of 10 dB of the transmitted signal.
  • 机译 五百米孔径球面射电望远镜项目
    摘要:The Five-hundred-meter Aperture Spherical Radio Telescope (FAST) is a Chinese megascience project funded by the National Development and Reform Commission (NDRC) of the People's Republic of China. The National Astronomical Observatories of China (NAOC) is in charge of its construction and subsequent operation. Upon its expected completion in September 2016, FAST will surpass the 305m Arecibo Telescope and the 100m Green Bank Telescope in terms of absolute sensitivity in the 70MHz to 3GHz bands. In this paper, we report on the project, its current status, the key science goals, and plans for early science.
  • 机译 计算光子学中的解析正则化方法
    摘要:We discuss the advantages of the conversion of electromagnetic field problems to the Fredholm second-kind integral equations (analytical regularization) and Fredholm second-kind infinite-matrix equations (analytical preconditioning). Special attention is paid to specific features of the characterization of metals and dielectrics in the optical range and their effect on the problem formulation and on the methods applicable to the mentioned conversion.
  • 机译 HAARP设施激发的高纬度电离层中的人为周期性不规则现象
    摘要:We present results of the new observations of artificial periodic irregularities (APIs) in the ionosphere using the High Frequency Active Auroral Research Program (HAARP) heating facility carried out in late May and early June 2014.The objective of this work is to detect API using high-latitude facility and analyze possible differences of the temporal and spatial variations of the API echoes in the high (HAARP) and middle (Sura) latitudes. Irregularities were created by the powerful wave of X mode and were sounded using the short probing pulses signals of X mode. API echoes were observed in the D, E, and F regions of the ionosphere. Amplitudes and characteristic times of the API echoes were measured. The API growth and decay times at HAARP (high latitudes) observed were similar to those at the Sura heating facility (midlatitudes).
  • 机译 从地面GPS接收器检索倾斜总电子含量测量值的三种方法和性能评估
    摘要:The high sampling rate along with the global coverage of ground-based receivers makes Global Positioning System (GPS) data particularly ideal for sensing the Earth's ionosphere. Retrieval of slant total electron content measurements (TECMs) constitutes a key first step toward extracting various ionospheric parameters from GPS data. Within the ionospheric community, the interpretation of TECM is widely recognized as the slant total electron content along the satellite receiver line of sight, biased by satellite and receiver differential code biases (DCBs). The Carrier-to-Code Leveling (CCL) has long been used as a geometry-free method for retrieving TECM, mainly because of its simplicity and effectiveness. In fact, however, the CCL has proven inaccurate as it may give rise to TECM very susceptible to so-called leveling errors. With the goal of attaining more accurate TECM retrieval, we report in this contribution two other methods than the CCL, namely, the Precise Point Positioning (PPP) and the Array-aided PPP (A-PPP). The PPP further exploits the International GPS Service (IGS) orbit and clock products and turns out to be a geometry-based method. The A-PPP is designed to retrieve TECM from an array of colocated receivers, taking advantage of the broadcast orbit and clock products. Moreover, A-PPP also takes into account the fact that the ionospheric effects measured from one satellite to all colocated receivers ought to be the same, thus leading to the estimability of interreceiver DCB. We perform a comparative study of the formal precision and the empirical accuracy of the TECM that are retrieved, respectively, by three methods from the same set of GPS data. Results of such a study can be used to assess the actual performance of the three methods. In addition, we check the temporal stability in A-PPP-derived interreceiver DCB estimates over time periods ranging from 1 to 3days.
  • 机译 基于模态匹配的轴向波纹介质杆加载牛角分析
    摘要:An efficient design procedure based on modal-matching method for axially corrugated dielectric-rod-loaded horns of complicated geometries is proposed in this paper. Calculation of the generalized scattering matrix of individual module, which is obtained by dividing the complex horn into simple sections, is carried out. Analytic expressions of power-coupling integrals between different kinds of waveguides are presented, including those derived initially, which greatly shorten the calculation time. Techniques including the field equivalence principle and the spherical mode expansion are further implemented for radiation pattern prediction. A rexolite-loaded axially corrugated horn antenna is finally investigated as a numerical experiment, with the frequency range of 17-33GHz. The results obtained by our method and by commercial full-wave simulation software are in excellent agreement, but our method is more efficient.
  • 机译 NeQuick TEC数据摄取技术针对C / NOFS和EISCAT电子密度测量的验证
    摘要:This paper investigates a technique to estimate near-real-time electron density structure of the ionosphere. Ground-based GPS receiver total electron content (TEC) at low and high latitudes has been used to assist the NeQuick 2 model. First, we compute model input (effective ionization level) when the modeled slant TEC (sTEC) best fits the measured sTEC by single GPS receiver (reference station). Then we run the model at different locations nearby the reference station and produce the spatial distribution of the density profiles of the ionosphere in the East African region. We investigate the performance of the model, before and after data ingestion in estimating the topside ionosphere density profiles. This is carried out by extracting in situ density from the model at the corresponding location of C/NOFS (Communication/Navigation Outage Forecast System) satellite orbit and comparing the modeled ion density with the in situ ion density observed by Planar Langmuir Probe onboard C/NOFS. It is shown that the performance of the model after data ingestion reproduces the topside ionosphere better up to about 824km away from the reference station than that before adaptation. Similarly, for high-latitude region, NeQuick 2 adapted to sTEC obtained from high-latitude (TromsO in Norway) GPS receiver and the model used to reproduce parameters measured by European Incoherent Scatter Scientific Association (EISCAT) VHF radar. It is shown that the model after adaptation shows considerable improvement in estimating EISCAT measurements of electron density profile, F-2 peak density, and height.
  • 机译 高纬度闪烁观测的三维建模
    摘要:Global Navigation Satellite System signals exhibit rapid fluctuations at high and low latitudes as a consequence of propagation through drifting ionospheric irregularities. We focus on the high-latitude scintillation problem, taking advantage of a conjunction of European Incoherent Scatter Radar (EISCAT) observations and a GPS scintillation monitor viewing the same line of sight. Just after 20:00UT on 17 October 2013, an auroral E region ionization enhancement occurred with associated phase scintillations. This investigation uses the scintillation observations to estimate the ionospheric electron density distribution beyond the spatial resolution of EISCAT (5-15km along the line of sight in this case). Following the approach of Deshpande et al. (2014), signal propagation is modeled through a specified density distribution. A multiple phase screen propagation algorithm is applied to irregularities conforming to the description of Costa and Kelley (1977) and constrained to match the macroscopic conditions observed by EISCAT. A 50-member ensemble of modeled outputs is approximately consistent with the observations according to the standard deviation of the phase (sigma(p)). The observations have sigma(p)=0.23rad, while the ensemble of modeled realizations has sigma(p)=0.23+0.04-0.04. By comparison of the model output with the scintillation observations, we show that the density fluctuations cannot be a constant fraction of the mean density. The model indicates that E region density fluctuations whose standard deviation varies temporally between 5 and 25% of the mean (EISCAT-observed) density are required to explain the observed phase scintillations.
  • 机译 用于学术目的的自动识别系统模块化接收器
    摘要:The Automatic Identification System (AIS) standard is encompassed within the Global Maritime Distress and Safety System (GMDSS), in force since 1999. The GMDSS is a set of procedures, equipment, and communication protocols designed with the aim of increasing the safety of sea crossings, facilitating navigation, and the rescue of vessels in danger. The use of this system not only is increasingly attractive to security issues but also potentially creates intelligence products throughout the added-value information that this network can transmit from ships on real time (identification, position, course, speed, dimensions, flag, among others). Within the marine electronics market, commercial receivers implement this standard and allow users to access vessel-broadcasted information if in the range of coverage. In addition to satellite services, users may request actionable information from private or public AIS terrestrial networks where real-time feed or historical data can be accessed from its nodes. This paper describes the configuration of an AIS receiver based on a modular design. This modular design facilitates the evaluation of specific modules and also a better understanding of the standard and the possibility of changing hardware modules to improve the performance of the prototype. Thus, the aim of this paper is to describe the system's specifications, its main hardware components, and to present educational didactics on the setup and use of a modular and terrestrial AIS receiver. The latter is for academic purposes and in undergraduate studies such as electrical engineering, telecommunications, and maritime studies.
  • 机译 一种基于曲折线环的新型平面宽带天线,用于便携式无线通信设备
    摘要:This article presents the design of a novel planar antenna structure comprising two pairs of interconnected meandered line loops that are grounded to a truncated T-shaped ground plane through two via holes. The T-shaped ground plane is used as a reflector to enhance the performance of the antenna. The resulting antenna is compact occupying an area of 38.5x36.6mm(2) (0.070(o)x0.067(o)), where free-space wavelength is 550MHz. The antenna radiates omnidirectionally in the E plane across its operational bandwidth (550MHz to 3.85GHz) with peak gain and efficiency of 5.5dBi and 90.1%, respectively, at 2.35GHz and reflection coefficient better than -10dB. These characteristics make the antenna suitable for numerous applications, in particular, JCDMA, UHF RFID, GSM 900, GPS, KPCS, DCS, IMT-2000, WiMAX, WiFi, and Bluetooth.
  • 机译 时间相关的3-D电子密度梯度对高入射角HF无线电波传播的影响
    摘要:One of the challenges for the utilization of HF radiowaves in practical applications is to understand how the signals propagate in time- and range-dependent multipath environments. For typical quiescent ionospheric conditions it is often reasonably straightforward to interpret received HF signals. For disturbed ionospheric conditions, however, such as in the presence of large tilts, irregularities, and medium-scale traveling ionospheric disturbances (MSTIDs), data interpretation and utilization often becomes challenging. This paper presents a theoretical HF propagation modeling study that exploits the capabilities of a first principles, mesoscale resolution ionosphere code, SAMI3 (Sami3 is Another Model of the Ionosphere) and a new implementation of the 3-D ray trace equations, MoJo-15 (Modernized Jones Code) in order to examine the relationship between various HF propagation observables and MSTID characteristics. This paper demonstrates the implications of MSTIDS on high angle of incidence HF propagation during typical low-latitude, postsunset ionospheric conditions and examines the spatiotemporal evolution of multiple propagation paths that may connect a given source and receiver.
  • 机译 基于耦合矩阵形式的全电感双模矩形波导技术中的流形复用器设计
    摘要:This paper presents for the first time the design of manifold multiplexers in waveguide technology using all-inductive dual-mode channel filters. It is shown that very complex transfer functions can be implemented for the channels, using simple structures that can be analyzed and manufactured with increased simplicity as compared to other commercial solutions. In this paper we adapt a standard design technique for manifold multiplexers to the new proposed technology. The paper is illustrated with the design of two triplexers, using H-type and E-type waveguide manifolds, with filters implementing two transmission zeros in the insertion loss response for maximum isolation between channels. Results show that the procedure is indeed effective and can be used for the design of practical multiplexer configurations.
  • 机译 在高频主动极光研究计划供暖设施中,通过多普勒测深和受激电磁辐射探索HF诱发的电离层湍流
    摘要:We report on the features of the F region plasma perturbations during HF heating experiments at the High Frequency Active Auroral Research Program facility in March-April 2011 and May-June 2014. The diagnostics included multifrequency Doppler (phase) sounding (MDS) and stimulated electromagnetic emission (SEE). The results concern modification of the electron density profile near the reflection and upper hybrid heights, as well as correlation of the density modification with temporal behavior of narrow continuum, downshifted maximum, and broad continuum SEE spectral features. We reveal also a new SEE spectral feature which appears in the SEE spectra for the pump frequency f(0) near the third and fourth electron gyroharmonics. It is located in the SEE spectrum well below the pump wave frequency, f-f(0)similar to-(40-220)kHz, occupies a wide frequency range till 100-150kHz, and is termed the broad downshifted emission.
  • 机译 压缩传感:电子战应用中的雷达信号检测和参数测量
    摘要:State of the art system development is very much required for UAVs (Unmanned Aerial Vehicle) and other airborne applications, where miniature, lightweight and low-power specifications are essential. Currently, the airborne Electronic Warfare (EW) systems are developed with digital receiver technology using Nyquist sampling. The detection of radar signals and parameter measurement is a necessary requirement in EW digital receivers. The Random Modulator Pre-Integrator (RMPI) can be used for matched detection of signals using smashed filter. RMPI hardware eliminates the high sampling rate analog to digital computer and reduces the number of samples using random sampling and detection of sparse orthonormal basis vectors. RMPI explore the structural and geometrical properties of the signal apart from traditional time and frequency domain analysis for improved detection. The concept has been proved with the help of MATLAB and LabVIEW simulations.
  • 机译 灵敏磁传感器表征负火箭触发的雷电中的初始电流脉冲
    摘要:We report the new measurement of initial current pulses in rocket-triggered lightning with a broadband magnetic sensor at 78 m distance. The high sensitivity of our sensor makes it possible to detect weak ripple deflections (as low as 0.4 A) that are not readily resolved in the typical measurements of channel-base current in rocket-triggered lightning experiments. The discernible magnetic pulses within 1 ms after the inception of a sustained upward positive leader from the triggering wire can be classified into impulsive pulses and ripple pulses according to the discernibility of separation between individual pulses. The time scale (usually >20 mu s) of ripple pulses is substantially longer than the leading impulsive pulses (with time scales typically <10 mu s), and the amplitude is significantly reduced, whereas there is no considerable difference in the interpulse pulse. Along with our previous finding on the burst of magnetic pulses during the initial continuous current in rocket-triggered lightning, the new measurements suggest that the stepwise propagation might be a persistent feature for the upward positive leader in rocket-triggered lightning, and the stepping of positive leader early in triggered lightning could be characterized with the observation of ripple pulses. The precedence of impulsive magnetic pulse measured at 78 m range relative to the arrival of corresponding current pulse at the channel base indicates that the ionization wave launched by individual stepping of positive leader propagates downward along the triggering wire at a mean velocity of 1.23 x 10(8) m/s to 2.25 x 10(8) m/s.
  • 机译 用于低频目标定位的某些FMCW雷达算法的研究
    摘要:FMCW (frequency-modulated continuous wave) radar is a simple and inexpensive technique for target location. The resolution is given by the available bandwidth and the directivity of the antenna. Resolution is not a problem at high frequencies, while at low frequencies (the HF and VHF band), and especially for mobile platforms, the required size of the antenna becomes impractical. In order to obtain the bearing of the targets, without relying on directivity, one may use a simple two-dimensional trilateration method that involves several platforms. Since this approach covers an area, rather than a sector, the range is reduced to some tens of kilometers. The VHF band and a bandwidth below 10 MHz is a good choice if the priority is to reduce radio interference. Fast targets, corresponding to a significant Doppler shift, have not been considered. The problem of ghost targets has been studied for both monostatic and multistatic radar. When there is a confluence of echoes, more bandwidth is required to maintain the accuracy of a few meters that is normally obtained in the simulation.
  • 机译 东非低纬度地区电离层总电子含量的变化和风暴时间电离层变化的研究
    摘要:The variation of total electron content (TEC) derived from the International Global Navigation Satellite Systems Service receiver (formerly IGS) over the East African low-latitude region from up to 12 observation stations for the period 2012 was analyzed. The diurnal and annual TEC contour plots generated from data over the region show that the equatorial anomaly crests manifest remarkable seasonal variations. The crest of the equatorial ionization anomaly is fully formed and yields the maximum values of TEC during the equinoxes (March/April and September/October) and minimum in the solstice (June/July and November/December). The results of this observation show that the crest develops between 12: 00 and 16: 00 LT and is greatly dependent on the time when the ionosphere is uplifted at the dip equator via the E x B drift force. The postsunset TEC enhancements at stations away from dip equator depict the ionospheric plasma density diffusion (flow) from the dip equator leading to the formation of ionization anomaly crests that lasts for few hours after the sunset local time. The ionospheric response to the strong geomagnetic storm of the March 2015 has also been examined. The ionospheric response to the geomagnetic storms has shown a strong thermosphere-ionosphere coupling. The negative storm effect that occurred over the anomaly crest region is more likely due to the composition disturbances associated with high energy deposits.
  • 机译 关于利用大气雷达和地面观测网络进行太阳-地面耦合过程的研究建议
    摘要:The solar energy can mainly be divided into two categories: the solar radiation and the solar wind. The former maximizes at the equator, generating various disturbances over a wide height range and causing vertical coupling processes of the atmosphere between the troposphere and middle and upper atmospheres by upward propagating atmospheric waves. The energy and material flows that occur in all height regions of the equatorial atmosphere are named as "Equatorial Fountain." These processes from the bottom also cause various space weather effects, such as satellite communication and Global Navigation Satellite System positioning. While, the electromagnetic energy and high-energy plasma particles in the solar wind converge into the polar region through geomagnetic fields. These energy/particle inflow results in auroral Joule heating and ion drag of the atmosphere particularly during geomagnetic storms and substorms. The ion outflow from the polar ionosphere controls ambient plasma constituents in the magnetosphere and may cause long-term variation of the atmosphere. We propose to clarify these overall coupling processes in the solar-terrestrial system from the bottom and from above through high-resolution observations at key latitudes in the equator and in the polar region. We will establish a large radar with active phased array antenna, called the Equatorial Middle and Upper atmosphere radar, in west Sumatra, Indonesia. We will participate in construction of the EISCAT_3D radar in northern Scandinavia. These radars will enhance the existing international radar network. We will also develop a global observation network of compact radio and optical remote sensing equipment from the equator to polar region.
  • 机译 从无线电波传播角度看无线数字传输的物理极限
    • 作者:Karasawa, Y.;
    • 刊名:Radio Science
    • 2016年第9-10期
    摘要:Under a time-invariant condition with thermal noise, the physical limit of digital transmission ability is governed by Shannon's channel capacity. However, in this formula, it does not contain factors on radio wave propagation environments. In other words, for the ultimate information transmission, a sufficiently long time for the coding and signal processing is expected. However, since wave propagation prevents its premise, there is another physical limit for digital transmission in a different perspective with Shannon's channel capacity. Even if the S/N ratio is sufficiently high, there is the limit for information transmission. This paper deals with this matter concerning physical limit of wireless transmission from a radio wave propagation viewpoint.
  • 机译 具有部分插入故障的电连接器内波相互作用的基于物理的RF /微波表征
    摘要:Electrical failures in avionics systems may result from connector faults. If fault precursors are not detected in advance, they may lead to hard failures such as open and short circuits that could ultimately result in fire or loss of flight critical systems. Therefore, It is crucial to detect, locate, and characterize fault precursors for timely preventive maintenance and mitigation before hard failures occur. In this paper, a physics-based connector model consisting of multiple coaxial line sections with different characteristic impedances and lengths is proposed. Method of Moments (MoM) analyses were performed using commercial electromagnetic simulation software, FEKO, for transverse electric and magnetic (TEM) wave propagation through a connector. The physical parameters of the connector were optimized to match the measured S parameters for multiple insertion depths. The proposed models represent the connector for multiple insertion depths by varying only two length parameters at a time while other parameters are fixed. Insertion depth-dependent resonant frequency shifts observed during measurement are also captured by the model over the full range of fully inserted to barely touching contacts. Hence, the models provide accurate representations of the connector and properly detect precursors to partial insertion faults.
  • 机译 使用适当的正交基准从雷达海杂波推断出的风管高度
    摘要:Maritime electromagnetic (EM)-based communication and detection systems are strongly influenced by meteorological conditions, as they can cause anomalous electromagnetic propagation within the surface layer. To predict the performance of such systems, detailed knowledge of the refractivity profile is required. In recent years, refractivity from clutter (RFC) methods has been developed to estimate this refractivity profile by measuring radar clutter return from the rough ocean surface. The current work proposes an RFC framework that utilizes a novel surrogate model for EM propagation. The surrogate model is based on an offline created library of sparsely sampled field data of clutter returns, compressed into proper orthogonal bases, and indexed on specific surface layer refractive parameters. By exploiting the Riemannian manifold structure of the space that proper orthogonal bases occur in, we are able to interpolate among them. This, then, enables us to use the surrogate model in an inverse problem setting, whose goal is to uncover in situ maritime EM propagation conditions efficiently. We demonstrate the feasibility of our proposed surrogate model-based RFC approach for evaporation duct by testing it with field data obtained from an experimental campaign.
  • 机译 通过事先约束源分离检测超高速冲击射频脉冲
    摘要:Hypervelocity dust impacts produce electromagnetic pulses in the radio frequency (RF) spectrum that scales with impactor mass and velocity. Due to the mass acceleration limitations of ground-based facilities, detecting emissions from impacts in a laboratory setup is difficult due to their low output power. This paper presents a general probabilistic technique to perform signal excision, which was applied to synthetic and hypervelocity impact data sets. The task of excising multiple signals from a single observation of their mixtures is referred to as underdetermined blind source separation (BSS). This paper introduces a framework for solving underdetermined BSS problems when there is only one observation signal by leveraging often overlooked prior information. The most probable solutions for the source signals are computed by solving an iterative constrained optimization problem that seeks to maximize the posterior probability of the system model. In the hypervelocity impact data set, the goal was to reduce the noise floor on an RF antenna by modeling and extracting exterior sources of noise. It was found that the algorithm described in this paper was able to model signals in the observation and subtract them while still maintaining the spectral and temporal content of the remaining signals. Through the use of this methodology, previously hidden impact emissions were able to be isolated and identified for further characterization.
  • 机译 用于通信应用的低功耗和宽调谐范围MEMS滤波器的实现
    摘要:Theory and optimization were studied in detail to find optimum dimensions of fixed-fixed beam for the sake of low-power and wide-range frequency tuning applications. This optimization also provides a method to avoid device failure due to high thermal stress. The good agreement between theory, simulation, and measurement is achieved and can serve as a guidance for future works. Two resonators, consisting of multiple metal, dielectric, and polysilicon layers, were designed; the first resonator at 303.4 kHz and the second at 2053 kHz achieve the frequency tuning ranges of 35.7%-42.6%, respectively. A power consumption of 900 mu W/beam is achieved for the first design of 152 mu m length beam while providing a frequency tuning of 35.7%. Further increase in the tuning capability was achieved by the increase in the applied DC bias voltage between adjacent beams.
  • 机译 RISR-C非相干散射雷达的初步观察
    摘要:First-light measurements from the Canadian face of the Resolute Bay Incoherent Scatter Radar (RISR-C) were taken in August of 2015. Data were taken for roughly 25 h on both RISR-C and the North face of the Resolute Bay radar (RISR-N) in an 11-beam World Day mode. Overall, the measurements from the RISR-C radar are of high quality and consistent with results from the RISR-N radar. During the 25 h period analyzed in this study, the ionosphere responded to changes in orientation of the interplanetary magnetic field. During one particular event, a change from Bz negative to positive and By positive to negative caused the antisunward flow to stall, and a strong dawn-to-dusk flow, with decreased electron density and increased ion temperature, replaced it in the RISR-C field of view. Overall, it is clear that measurements from the RISR-C radar will complement and greatly expand the scope of ionospheric polar cap measurements.
  • 机译 高频雷达干涉仪阵列的相位校准
    摘要:Elevation angles of backscattered signals are calculated at the Super Dual Auroral Radar Network (SuperDARN) high-frequency radars using interferometric techniques. These elevation angles make it possible to estimate the geographic location of the scattering point, an essential piece of information for many ionospheric studies. One of the most difficult parameters to measure is the effective time delay caused by the difference in the electrical path length that connects the main array and the interferometer arrays to the correlator (delta t(c)). This time delay causes a bias in the measured difference in the signal phase, also known as a phase bias. Phase calibration is difficult due to unknown physical attributes of the hardware and the remote location of many radars. This leads to the possibility of sudden external changes, slow temporal drift, and a dependence on transmission frequency. However, it is possible to estimate delta t(c) using the radar observations themselves. This article presents a method for estimating delta t(c) using backscatter with a known location, such as backscatter from artificially generated irregularities, meteor echoes, or distinct groundscatter, which incorporates the uncertainty in the observations and may be used autonomously. Applying the estimated delta t(c) is shown to improve elevation angle uncertainties at one of the SuperDARN radars from their current potential tens of degrees to less than a degree.
  • 机译 大地测量VLBI的宽带带宽合成算法
    摘要:A practical algorithm for wideband bandwidth synthesis (WBWS) for geodetic VLBI (very long baseline interferometry) is presented in this paper. A conventional bandwidth synthesis technique was developed for geodetic VLBI in the 1970s in order to increase the resolution of the observed delay by synthesizing multiple receiving frequency windows. The synthesized bandwidth has been expanding over the years and is now about 1 GHz. Recently, a wideband VLBI system consisting of multiple wideband frequency windows with a width of 1 GHz each and a total bandwidth exceeding 10 GHz has been proposed by the International VLBI Service for Geodesy and Astrometry (IVS) in order to achieve millimeter precision of position measurements. WBWS is a technique used for data processing in a wideband VLBI system. In conventional bandwidth synthesis, phase calibration (PCAL) signals are artificially injected at a front end and used to synthesize the channels. However, an algorithm without the use of PCAL signals was developed for WBWS so that it can be applied to a system without PCAL equipment. The algorithm includes the estimation of the differential total electron content in the ionosphere working with data with signal-to-noise ratios as low as 10 per band. The algorithm was successfully applied to 24 h continuous wideband VLBI observations.
  • 机译 基于MEMS的LC油箱,具有扩展的调谐范围,适用于多频段应用
    摘要:This paper presents the modeling, simulations, and measurements of a compact multiband microelectromechanical (MEMS)-based LC tank resonator suitable for low phase noise voltage-controlled oscillators (VCOs). The resonator is based on a high-Q spiral inductor and high capacitance ratio varicap fully integrated in FBK-irst (Fondazione Bruno Kessler) MEMS manufacturing process. The design of the varicap is based on double-actuation mechanism with a mechanical central bond that inhibits the pull-in allowing for a theoretically infinite tuning ratio. The measurements have shown a total not continuous capacitance ratio (C-r) of 5.2 with a continuous variation of the capacitance values in the range 225 fF-600 fF which corresponds to a continuous capacitance ratio (C-r*) of 2.6. The performance repeatability, the power-handling capability, and the stability over time were tested on 10 samples showing a negligible variation of the capacitance values. The spiral inductor consists of a suspended gold membrane thick 5 mu m in a circular shape which was modeled in order to optimize the quality factor (Q) in the frequency range 2-4 GHz. The measurement results show a Q of about 55 in the 2-4 GHz frequency band. The LC tank measurements show an overall tuning range better than of 45% in the 3.2-4.9 GHz frequency band, consisting of two continuous tuning ranges of 7.5% and 25%. The LC tank allowed the design of MEMS-based voltage-controlled oscillators (VCOs) with an overall tuning better than 60% in the frequency range 2.15 GHz-3.85 GHz and two separate regions of continuous tuning range. The VCO prototype will be fabricated on Surface Mount Technology on RO4350 laminate. The main figures of merit are presented in comparison with the state of the art.
  • 机译 KAGUYA / WFC获得的波偏振数据的标定方法
    摘要:A calibration method for wave polarization data obtained by waveform capture (WFC) instrument on a lunar orbiter KAGUYA is introduced. In order to obtain correct polarizations of plasma waves observed by KAGUYA, it is necessary to remove the difference of onboard delays between two orthogonal channels of the receiver. For that purpose, we use observation data of natural waves instead of onboard calibration signals which were not available due to a technical problem during the mission period. KAGUYA often observed auroral kilometric radiation (AKR) from the Earth, which had polarizations. The phase differences are determined by using AKR data obtained under a specific condition. As a result, the polarization data are calibrated with a sufficient accuracy. The proposed calibration method is not specialized for the KAGUYA data but it can be applied to wave data obtained with similar types of receivers in future missions.
  • 机译 使用美国部门GPS接收器网络观测共轭MSTID
    摘要:This study has used total electron content (TEC) values from an extended network of GPS receivers and a highly developed processing to characterize the conjugacy of medium-scale traveling ionospheric disturbances (MSTIDs) over the American continent. It was found that midlatitude nighttime MSTIDs, also named electrobuoyancy waves, map into the opposite hemisphere but the amplitude of the TEC disturbance in the Southern Hemisphere is between 8 and 13% of the amplitude in the original hemisphere. The periods of the MSTIDs vary between 50 and 65 min. MSTID dynamics is presented for two days: 20 August 2012 and 17 June 2012. On the first day, MSTIDs entered into the American sector shortly before 4 UT, last for 3 h, drifted at an average speed of 200 m/s, and dissipated in the Caribbean region. In the Northern Hemisphere, the MSTIDs were directed southwestward (SW) and 60 degrees from south. In the Southern Hemisphere, they moved northwestward (NW) or similar to 60 degrees from north. The MSTID velocity changed through the night from similar to 300 m/s to similar to 150 m/s, but the propagation direction did not vary. On 17 June 2012 a series of wide MSTIDs were seen traveling across the Caribbean region that exited through the western coast of Central America. These MSTIDs last for similar to 5 h. Number density measured with the DMSP-F15 and DMSP-F17 satellites confirm the notion that the MSTIDs consist of rising and falling sheets of plasma density driven by electric fields likely set by a Perkins-type instability. These observations support the notion that gravity waves can seed and boost the growth of the nighttime MSTIDs.
  • 机译 在C / NOFS-VEFI甚低频观测中自动识别离散的,雷电产生的,多重分散的哨声波
    摘要:Automated wave feature detection is required to efficiently analyze large archives of very low frequency broadband recordings for discrete whistler identification and feature extraction. We describe a new method to do this, even in the presence of simultaneous, multiple whistler phase dispersions. Previous techniques of whistler identification were unable to deal with simultaneous, multiple phase dispersions. We demonstrate the new method with data from the Vector Electric Field Investigation (VEFI) payload on the Communication/Navigation Outage Forecast System (C/NOFS) satellite, from the mission years 2008-2014.
  • 机译 发明了对温度不敏感的石英振荡板,可实现高度稳定的通信和时钟:Issac Koga的作品回顾
    • 作者:Iga, Kenichi;
    • 刊名:Radio Science
    • 2016年第9-10期
    摘要:This is a review article on a stable quartz oscillator. In April 1933, Issac Koga of Tokyo Institute of Technology reported R-1 cut quartz crystal plates having a zero temperature coefficient of frequency. This invention was used at first for radio transmitters and later on for clocks. Today, this type of temperature-insensitive quartz crystal oscillator has proven indispensable to all radio communication systems and much of information electronics.
  • 机译 朱诺模型流变学和模拟
    摘要:The experiment Waves aboard the Juno spacecraft, which will arrive at its target planet Jupiter in 2016, was devised to study the plasma and radio waves of the Jovian magnetosphere. We analyzed the Waves antennas, which consist of two nonparallel monopoles operated as a dipole. For this investigation we applied two independent methods: the experimental technique, rheometry, which is based on a downscaled model of the spacecraft to measure the antenna properties in an electrolytic tank and numerical simulations, based on commercial computer codes, from which the quantities of interest (antenna impedances and effective length vectors) are calculated. In this article we focus on the results for the low-frequency range up to about 4 MHz, where the antenna system is in the quasi-static regime. Our findings show that there is a significant deviation of the effective length vectors from the physical monopole directions, caused by the presence of the conducting spacecraft body. The effective axes of the antenna monopoles are offset from the mechanical axes by more than 30 degrees, and effective lengths show a reduction to about 60% of the antenna rod lengths. The antennas' mutual capacitances are small compared to the self-capacitances, and the latter are almost the same for the two monopoles. The overall performance of the antennas in dipole configuration is very stable throughout the frequency range up to about 4-5 MHz and therefore can be regarded as the upper frequency bound below which the presented quasi-static results are applicable.
  • 机译 SuperDARN标量雷达方程
    摘要:The quadratic scalar radar equations are obtained for Super Dual Auroral Radar Network (SuperDARN) radars that are suitable for the analysis and interpretation of experimental data. The paper is based on a unified approach to obtaining the radar equations for the monostatic and bistatic sounding with the use of Hamiltonian optics and ray representation of scalar Green's function and without taking into account the polarization effects. The radar equation obtained is the sum of several terms corresponding to the propagation and scattering over the different kinds of trajectories, depending on their smoothness and the possibility of reflection from the ionosphere. It is shown that the monostatic sounding in the media with significant refraction, unlike the case of refraction-free media, should be analyzed as a combination of monostatic and bistatic scattering. This leads to strong dependence of scattering amplitude on background ionospheric density due to focusing mechanism and appearance of new (bistatic) areas of effective scattering with significant distortion of the scattered signal spectrum. Selective properties of the scattering have been demonstrated as well.
  • 机译 升级后的EISCAT大功率高频设备的新功能
    摘要:The high-power HF (high-frequency) facility (commonly known as Heating) near Tromso, Norway, which is an essential part of the European Incoherent Scatter Scientific Association, has been upgraded in certain key areas in recent years. It is one of only four similar facilities in the world operating at present. An updated description of the facility is given, together with scientific motivation and some results. The main high-power parts such as transmitters, feed-system, and antennas remain essentially the same as built in the late 1970s. The improvements are in the areas of radio frequency waveform generation, computer control, and monitoring. In particular, fast stepping in frequency is now possible, an important aspect in examining features close to harmonics of the electron gyrofrequency. One antenna array has been modified to allow reception to implement an HF radar mode for mesospheric and magnetospheric probing. More realistic modeling of the antenna gain gives improved estimates of the total effective radiated power for both wanted and unwanted circular polarizations. Results are presented by using these new capabilities, but their full scientific potential has yet to be achieved.
  • 机译 具有软边界和硬边界的二维楔形的边缘积分方程
    摘要:Novel, fringe wave integral equations that account for the diffraction from nonpenetrable wedges with both soft and hard boundaries are derived. Method of moments simulation of fringe waves generated by a plane wave that excites the wedge is performed using this fringe wave integral equation. The results are compared with the exact physical theory of diffraction fringe waves.
  • 机译 动态空腔和时变介质中本征模态的瞬态演化
    摘要:In this paper, we investigate the perturbation of natural eigenmodes of dynamic cavities with boundaries moving at quasi-static speeds relative to the wave velocity. For an arbitrarily shaped source-free cavity, the amplitude of the irrotational mode is modeled as a damped harmonic oscillator with time-varying eigenfrequency, i.e., a parametric oscillator. It is found that the effect of the pure Doppler shift of the resonance frequencies of the eigenmodes is small at nonrelativistic speeds. However, it is known that any spectrum of eigenenergies that is perturbed by a space- and/or time-fluctuating medium can develop frequency shifts of arbitrary magnitude. By using a linear dynamic (time-dependent) shift for the cavity broad resonances, we find that Doppler-like large shifts result in a mere frequency modulation of the total (resultant) field amplitude, while nonuniform red or blue shift can create a hybrid amplitude and frequency modulation. Interestingly, the combined action of red and blue shifts of uniform magnitude can also create a hybrid modulation. If the angle between modal wave vector and stirrer speed is accounted for in the static (time-independent) shift, the resulting red and blue shifts lead to irregular hybrid modulations. This can occur even for regular perturbations in regular cavities. In addition, owing to the stochastic nature of mode-stirred cavities, the effect of random Doppler-like shifts is also investigated, leading to a Fokker-Planck equation whose diffusion coefficient shows quadratic dependence on the mode amplitude. Thus, the analysis of random perturbations offers an effective framework for observed instantaneous Doppler effects in closed electromagnetic environments. The mathematical framework obtained in terms of stochastic differential equations is useful to predict the nonstationary response of dynamic cavities with complicated or unknown boundary geometry.
  • 机译 使用COSMIC,C / NOFS和GPS测量,在印度经度区从赤道到中纬度的过渡区域中,午夜L波段闪烁的特征
    摘要:Occurrence of L band scintillations around midnight and postmidnight hours have not been well studied and reported from the higher equatorial latitudes in the transition region from the equatorial to midlatitudes over the Indian longitude sector. The present paper reports cases of postmidnight L band scintillation observations by COSMIC during March 2014 over the Indian longitude sector. GPS S-4 measurements from the International Global Navigation Satellite Systems Service station at Lucknow (26.91 degrees N, 80.96 degrees E geographic; magnetic dip: 39.75 degrees N) corroborate occurrence of postmidnight scintillations. The F region vertical upward velocities around the magnetic equator during evening hours have been used to understand the possibility of impact of irregularities generated over the magnetic equator at latitudes north of 30 degrees N. Postmidnight L band scintillations at latitudes greater than 30 degrees N without corresponding premidnight scintillations present interesting scientific scenario and give rise to suggestions of (1) any coupling mechanism between the equatorial and midlatitudes through which irregularities seeded in the midlatitudes may affect transionospheric satellite links at low latitudes or (2) irregularity generation at midlatitudes not connected with equatorial instabilities. Long-term analysis of S-4 at L band measured by COSMIC over the Indian longitudes during March 2007-2014 exhibits a well-defined longitude swath around 75-83 degrees E of reduced (0.2< S-4< 0.4) or no scintillations which may be attributed to the longitudinal variability of scintillation occurrence following the global four-cell pattern of ionospheric activity.
  • 机译 携带轨道角动量的波的天线增益和链路预算
    摘要:This paper addresses the RF link budget of a communication system using unusual waves carrying an orbital angular momentum (OAM) in order to clearly analyze the fundamental changes for telecommunication applications. The study is based on a typical configuration using circular array antennas to transmit and receive OAM waves. For any value of the OAM mode order, an original asymptotic formulation of the link budget is proposed in which equivalent antenna gains and free-space losses appear. The formulations are then validated with the results of a commercial electromagnetic simulation software. By this way, we also show how our formula can help to design a system capable of superimposing several channels on the same bandwidth and the same polarization, based on the orthogonality of the OAM. Additional losses due to the use of this degree of freedom are notably clearly calculated to quantify the benefit and drawback according to the case.
  • 机译 自动确定高频雷达反向散射的原点方向和传播方式
    摘要:Elevation angles of returned backscatter are calculated at Super Dual Auroral Radar Network radars using interferometric techniques. These elevation angles allow the altitude of the reflection point to be estimated, an essential piece of information for many ionospheric studies. The elevation angle calculation requires knowledge of the azimuthal return angle. This directional angle is usually assumed to lie along a narrow beam from the front of the radar, even though the signals are known to return from both in front of and behind the radar. If the wrong direction of return is assumed, large uncertainties will be introduced through the azimuthal return angle. This paper introduces a means of automatically determining the correct direction of arrival and the propagation mode of backscatter. The application of this method will improve the accuracy of backscatter elevation angle data and aid in the interpretation of both ionospheric and ground backscatter observations.
  • 机译 通过无线电链路上的降雨事件分形的队列调度来合成降雨时间序列
    摘要:Rainfall attenuation over wireless networks stems from random fluctuations in the natural process of arriving rainfall rates over radio links. This arrival process results in discernible rainfall traffic pattern which manifests as naturally scheduled and queue-generated rain spikes. Hence, the phenomenon of rainfall process can be approached as a semi-Markovian queueing process, with event characteristics dependent on queue parameters. However, a constraint to this approach is the knowledge of the physical characteristics of queue-generated rain spikes. Therefore, this paper explores the probability theory and descriptivemathematics of rain spikes in rainfall processes. This investigation presents the synthesis of rainfall queue with rain spikes at subtropical and equatorial locations of Durban (29 degrees 52'S, 30 degrees 58'E) and Butare (2 degrees 36'S, 29 degrees 44'E), respectively. The resulting comparative analysis of rainfall distributions, using error analysis at both locations, reveals that queue-generated rainfall compares well with measured rainfall data set. This suggests that the time-varying process of rainfall, though stochastic, can be synthesized via queue scheduling with the application of relevant queue parameters at any location.
  • 机译 基于杂波多目标跟踪的机会阵列雷达最优协调方法
    摘要:Opportunistic array radar is a new radar system that can improve the modern radar performance effectively. In order to improve its radio frequency stealth ability, a novel coordination method of opportunistic array radars in the network for target tracking in clutter is presented. First, the database of radar cross section for targets is built, then the signal-to-noise ratio for netted radars is computed according to the radar cross section and range of target. Then the joint probabilistic data association algorithm of tracking is improved with consideration of emitted power of the opportunistic array radar, which has a main impact on detection probability for tracking in clutter. Finally, with the help of grey relational grade and covariance control, the opportunistic array radar with the minimum radiated power will be selected for better radio frequency stealth performance. Simulation results show that the proposed algorithm not only has excellent tracking accuracy in clutter but also saves much more radiated power comparing with other methods.
  • 机译 基于压缩感知的相干雷达成像
    摘要:High-resolution radar images in the horizontal spatial domain generally require a large number of different baselines that usually come with considerable cost. In this paper, aspects of compressed sensing (CS) are introduced to coherent radar imaging. We propose a single CS-based formalism that enables the full three-dimensional (3-D)-range, Doppler frequency, and horizontal spatial (represented by the direction cosines) domain-imaging. This new method can not only reduce the system costs and decrease the needed number of baselines by enabling spatial sparse sampling but also achieve high resolution in the range, Doppler frequency, and horizontal space dimensions. Using an assumption of point targets, a 3-D radar signal model for imaging has been derived. By comparing numerical simulations with the fast Fourier transform and maximum entropy methods at different signal-to-noise ratios, we demonstrate that the CS method can provide better performance in resolution and detectability given comparatively few available measurements relative to the number required by Nyquist-Shannon sampling criterion. These techniques are being applied to radar meteor observations.
  • 机译 在GPS监测电离层扰动中减轻卫星运动
    摘要:We discuss the impact of satellite motion on the use of compact arrays of GPS receivers for estimating the velocity of traveling ionospheric disturbances (TIDs). It is shown that satellite motion has subtle effects upon standard techniques of waveform cross correlation, or time difference of arrival, which can easily lead to spurious TID velocity estimates. We present some improved techniques for cross-correlating TID waveforms while taking account of the Doppler shifts created by satellite motion. In addition, we discuss some improved techniques for separating TID waveforms from background ionospheric trends, such as diurnal variation, based on high-order polynomial fitting with well-defined frequency selectivity. The application of these techniques to a sensor array in the UK is discussed.
  • 机译 高速火车站环境中1.89 GHz的信道表征
    摘要:Channel characterization is the prerequisite condition for the research and development of the next-generation high-speed railway (HSR) communication system. Train station is one of typical HSR scenarios, where channel characteristics have not yet been investigated sufficiently. In this paper, wideband multiantenna channel measurements are performed at 1.89 GHz in an open-type train station environment based on long-term evolution networks along Beijing to Tianjin HSR in China. Large-scale characteristics of the HSR station channel, focusing on path loss, shadow fading (SF), and the autocorrelation property of SF, are studied. Moreover, small-scale characteristics, such as Ricean K-factor, delay spread, and spatial correlation, are analyzed and modeled. In addition, the stationary region is characterized using the RUN test method. The obtained results provide useful information for deployment and assessment of the future HSR communication system in the HSR station scenario.
  • 机译 通过对交织代码进行无与伦比的滤波,改善了超宽目标雷达测量的距离和滞后范围
    摘要:We propose that by using unmatched decoding for alternating codes, estimates of the autocorrelation function of the backscatter can be estimated at ranges between those resolved by matched filtering. The number of additional correlation estimates obtained in this way is twice that obtained using matched filtering, although each estimate contributes with only a quarter of the power in comparison. This leads to improvements in code performance by a factor of 1.5, and an increase in the speed of incoherent scatter radar experiments by the same factor.
  • 机译 使用COSMIC / GPS倾斜TEC测量对等离子层和上层电离层进行数据同化
    摘要:Increasing total electron content (TEC) measurements from the low Earth orbiting satellites to Global Positioning System satellites flourish the exploration of the ionosphere and plasmasphere for decades. This paper indicates a method that 3-D Var is applied to assimilate precise orbit determination antenna TEC measurements of Constellation Observing System forMeteorology, Ionosphere, and Climate (COSMIC) satellites into the background global core plasma model (GCPM). The slant TEC data archived in the COSMIC Data Analysis and Archive Center from 500 km to 20,200 km are used to reconstruct a new electron density model. This model has a temporal resolution of 2 h and spatial resolutions of 2.5 degrees in geomagnetic latitude, 5 degrees in longitude, 50 km in the upper ionosphere, and several hundred kilometers in the plasmasphere. Preliminary results show that the data assimilation modifies the initial GCPM forecast to be better coincident with actual COSMIC measurements in internal quality check. Furthermore, independent validation with upper ionosphere-retrieved electron density and TEC of global ionosphere maps implies a reasonable improvement in the estimation of plasmaspheric electron density after the assimilation.
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