A Heterogeneous Information Fusion Deep Reinforcement Learning for Intelligent Frequency Selection of HF Communication

The high-frequency(HF) communication is one of essential communication methods for military and emergency application. However, the selection of communication frequency channel is always a difficult problem as the crowded spectrum, the time-varying channels, and the malicious intelligent jamming. The existing frequency hopping, automatic link establishment and some new anti-jamming technologies can not completely solve the above problems. In this article, we adopt deep reinforcement learning to solve this intractable challenge. First, the combination of the spectrum state and the channel gain state is defined as the complex environmental state, and the Markov characteristic of defined state is analyzed and proved. Then, considering that the spectrum state and channel gain state are heterogeneous information, a new deep Q network(DQN) framework is designed, which contains multiple sub-networks to process different kinds of information. Finally, aiming to improve the learning speed and efficiency, the optimization targets of corresponding sub-networks are reasonably designed, and a heterogeneous information fusion deep reinforcement learning(HIF-DRL) algorithm is designed for the specific frequency selection. Simulation results show that the proposed algorithm performs well in channel prediction, jamming avoidance and frequency channel selection.

High Frequency Communication Network with Diversity: System Structure and Key Enabling Techniques

High frequency sky wave communication suffers from poor performance including poor link quality and low link success rate. To enhance performance, diversity technology is proposed in the high frequency communication network(HFCN) in this paper.First, we present the benefits and the challenges by introducing diversity technology into the existing HFCN. Secondly, to exploit the benefits fully and overcome the challenges, we propose a system structure suitable for deploying diversity technology in HFCN in large scale,based on the cloud radio access network and software defined network. Moreover, we present a general structure for the real-time updating frequency management system that plays a more important role especially when resource consuming(e.g., frequency) diversity technology is deployed. Thirdly, we investigate the key techniques enabling diversity technology deployment. Finally, we point out the future research directions to help the HFCN with diversity work more efficiently and intelligently.

Photonics-assisted THz wireless communication enabled by wide-bandwidth packaged backilluminated modified uni-traveling-carrier photodiode

This paper presents a wide-bandwidth back-illuminated modified uni-traveling-carrier photodiode(MUTC-PD)packaged with standard WR-5 rectangular waveguide for high-speed wireless communications.With optimized epitaxy structure and coplanar waveguide electrodes,the fabricated 4-μm-diameter PD exhibits ultra-flat frequency response and high saturation power.Integrated passive circuits including low-loss bias-tee and E-plane probe are designed to package the PD into a compact module with waveguide output.The packaged PD module has demonstrated a flat frequency response with fluctuations within±2.75 d B over a broadband of 140–220 GHz and a high saturated output power of-7.8 d Bm(166μW)at 140 GHz.For wireless communication applications,the packaged PD is used to implement 1-m free space transmission at carrier frequencies of 150.5 and 210.5 GHz,with transmission rates of 75 and 90 Gbps,respectively.

Research on Inter-turn Short-circuit Fault Diagnosis Method Based on High Frequency Voltage Residual for PMSM

Inter-turn fault is a serious stator winding short-circuit fault of permanent magnet synchronous machine(PMSM). Once it occurs, it produces a huge short-circuit current that poses a great risk to the safe operation of PMSM. Thus, an inter-turn short-circuit fault(ITSCF) diagnosis method based on high frequency(HF) voltage residual is proposed in this paper with proper HF signal injection. First, the analytical models of PMSM after the ITSCF are deduced. Based on the model, the voltage residual at low frequency(LF) and HF can be obtained. It is revealed that the HF voltage residual has a stronger ITSCF detection capability compared to the LF voltage residual. To obtain optimal fault signature, a 3-phase symmetrical HF voltage is injected into the machine drive system, and the HF voltage residuals are extracted. The fault indicator is defined as the standard deviation of the 3-phase HF voltage residuals. The effectiveness of the proposed ITSCF diagnosis method is verified by experiments on a triple 3-phase PMSM. It is worth noting that no extra hardware equipment is required to implement the proposed method.

A SYNCHRONIZATION ALGORITHM FOR HF(HIGH FREQUENCY) BROADBAND OFDM SYSTEM

In this letter,a kind of associated synchronization algorithm which is suitable for HF(High Frequency) broadband OFDM(Orthogonal Frequency Division Multiplexing) system is presented based on describing and constructing the GMW(Gorden,Mills and Welch) sequence. The algorithm is based on the Schmidl and Minn's symbol timing principle,the constructed GMW sequence is trans-mitted and disposed,and the synchronization is adjudicated using the correlation of GMW sequence. The simulation result indicates that this algorithm has high performance synchronization ability under the low SNR(Signal to Noise Ratio) at two different kinds of channel models.

Communication Resources Allocation for Time Delay Reduction of Frequency Regulation Service in High Renewable Penetrated Power System

The high renewable penetrated power system has severe frequency regulation problems.Distributed resources can provide frequency regulation services but are limited by com-munication time delay.This paper proposes a communication resources allocation model to reduce communication time delay in frequency regulation service.Communication device resources and wireless spectrum resources are allocated to distributed resources when they participate in frequency regulation.We reveal impact of communication resources allocation on time delay reduction and frequency regulation performance.Besides,we study communication resources allocation solution in high renewable energy penetrated power systems.We provide a case study based on the HRP-38 system.Results show communication time delay decreases distributed resources'ability to provide frequency regulation service.On the other hand,allocating more communication resources to distributed resources'communica-tion services improves their frequency regulation performance.For power systems with renewable energy penetration above 70%,required communications resources are about five times as many as 30%renewable energy penetrated power systems to keep frequency performance the same.Index Terms-Communication resources allocation,commun-ication time delay,distributed resource,frequency regulation,high renewable energy penetrated power system.

Digital Channelization Technology for HF Communication Base on Fast Filter Bank

Channelization typically realized by digital filter banks is an important topic in high frequency(HF) communication and software defined radios(SDR) areas. Channelization has a rigorous requirement for the characteristic of frequency response, e.g., steep transitional band and sharp decay. To address this issue, we investigated the feasibility and implementation of applying fast filter bank(FFB) in channelization in this paper. We analyzed the butterfly structure of FFB similar with fast Fourier transform(FFT), in which prototype sub-filters are cascaded to achieve a low complexity. Hence, it is suitable for designing filter bank with steep transitional band and sharp decay in stop-band. Moreover, we designed a pipelined structure of FFB to achieve a balance between area and performance. Design example shows that FFB has lower computational complexity compared with the other filter banks.

New Channel Simulator for Adaptive HF Communication Systems

The high frequency (HF) channel simulators with time-varying parameters based on the Watterson model are analyzed. The methods of simulating the HF channel with time-varying parameters are proposed. The linearly time-varying delay spread is introduced into the channel simulators to simulate the transition states between two channel modes of CCIR520-1. Two signals, including a 500 Hz and a 1 000 Hz bandwidth signal are respectively input into the standard Watterson HF channel model and the proposed channel model with time-varying parameters. Some simulation results prove that the proposed HF channel model with time-varying parameters can reflect the time-varying characteristics of frequency selected fading of HF channel.

A Novel Flexible Antenna at Very High Frequency Band for On-Body Applications

This paper proposes a novel flexible antenna design operating at very high frequency(VHF)band for on-body applications such as human body communication(HBC).The antenna consists of back-to-back E-shaped fractal and complimentary structures designed over a thin flex-ible substrate.The overall design working on the principle of fractal geometries and capacitive coupling is highly beneficial to achieve better antenna characteristics even at low frequencies around 35 MHz-45 MHz that are being used for HBC application.The proposed antenna obtained a large bandwidth of around 10.0 MHz in air and a bandwidth of around 8.0 MHz during on-body opera-tion.The antenna has been tested in three different scenarios viz.air,on-body single antenna and on-body communication using two antennas.The insertion loss is reduced to a minimum in all three scenarios,which is quite beneficial for better signal transmission.The size miniaturization with high flexibility in such low frequencies has also been achieved in the paper that makes the proposed design suitable for human body communication applications.

FSS Based Circular Polarizer for High-Speed Wireless Communication at 75 GHz

An FSS based circular polarizer for high-speed wireless communication at 75 GHz is presented. It has been designed on a low loss substrate with cross-dipole elements. Both simulation and measured results showed more than 98% circular polarization at 75 GHz. Moreover, 3 dB axial-ratio bandwidth of 6.8 GHz (Simulation) and 7.8 GHz (Measured) has been achieved. The proposed design has many advantages over the recently published research such as simplicity, low-profile, percentage bandwidth, frequency of operation and relative insertion loss.

A Novel Device for Real-Time Monitoring of High Frequency Phenomena in CENELEC PLC Band

This paper proposes the design and development of a novel, portable and low-cost intelligent electronic device (IED) for real-time monitoring of high frequency phenomena in CENELEC PLC band. A high speed floating-point digital signal processor (DSP) along with 4 MSPS analog-to-digital converter (ADC) is used to develop the intelligent electronic device. An optimized algorithm to process the analog signal in real-time and to extract the meaningful result using signal processing techniques has been implemented on the device. A laboratory environment has setup with all the necessary equipment including the development of the load model to evaluate the performance of the IED. Smart meter and concentrator is also connected to the low voltage (LV) network to monitor the PLC communication using the IED. The device has been tested in the laboratory and it has produced very promising results for time domain as well as frequency domain analysis. Those results imply that the IED is fully capable of monitoring high frequency disturbances in CENELEC PLC band.

New Developments in Maritime Communications： a Comprehensive Survey

This paper summarizes the requirements for modem maritime wireless communication networks in the marine environments including the sea- to-sea and sea-to-shore communication scenarios. The existing maritime wireless communication sys- tems are presented and the development of the state-of-the-art maritime communication systems is surveyed. Furthermore, a hierarchical and integrated maritime network architecture is proposed to satisfy the increasing various classes of services which demand different Quality of Service （QoS）. Finally, the open issues for further development of maritime communications are identified.

基于ADSP21060的HF-MODEM/ALE控制卡设计与实现

介绍了基于高速信号处理器ADSP2 10 6 0的HF MODEM/ALE控制卡的硬件原理 ,讨论了串行调制解调器和自适应选频与频率管理的实现方法 .该控制卡将HF MODEM与ALE融为一体 ,具有硬件成本低、性能稳定、可靠、数据传输效率高等特点 .

基于UHF和HF的局部放电降噪方法的研究

采用基于阿基米德螺旋天线的特高频法与基于电流传感器的高频法对比测量的方法 ,发展了一种新型的降噪方法。其基本原理是 :高频法测得的脉冲信号中包括了油中放电信号和空气中电晕造成的脉冲干扰信号 ;特高频法测得的只有油中放电信号 ;故对高频法获得的信号 ,在仅对应于特高频法获得的信号处开窗时 ,可剔除脉冲干扰而获得油中放电信号。模拟实验以及现场变压器的实测结果证明这种降噪方法可有效抑制各种干扰特别是脉冲型干扰。

低开关频率下基于高频方波电压注入法的永磁同步电机无位置传感器控制策略

文章提出了一种永磁同步电机低开关频率下利用注入的高频方波电压在低速工况下估计转子位置的方法。通过注入电压产生的q轴电流变化量获得估算转子位置误差的结论,设计龙贝格状态观测器利用q轴电流变化量估算转子位置,并给出了一种简单的龙贝格状态观测器零极点的设计方法。试验结果表明,文章所提的无位置传感器控制策略在低开关频率下估算转速与转子位置能准确跟踪真实值。

HF电台网络组网

为了实现人工观察信息的实时上报以及中心控制指令的实时下发,提出了一套解决方案。该方案针对较大规模的短波通信网络及突发性网络业务,从网络拓扑结构、站点分配及频率规划、媒体接入控制与调度策略以及频率选择和切换机制等方面分别进行分析与设计,以保证网络在相对少的设备配置下能较好满足应用需求。

基于一阶海洋回波的HF-SAR提取表层海流性能分析

将合成孔径技术用于高频地波雷达,以实现单站提取表层海流,对于降低观测成本、提高效率具有重要意义。但现有的高频合成孔径雷达(HF-SAR)信号模型是基于理想点目标的,而未考虑海域分辨单元的Bragg散射效应。针对这一问题.基于一阶海洋回波理论,该文提出了用HF-SAR提取表层海流的改进的信号模型,并分析了Bragg散射对HF-SAR方位向回波的影响。然后针对方位向回波信号的特点,给出了相应的速度估计算法。最后通过蒙特卡洛仿真分析了HF-SAR对指定海域分辨单元的速度估计性能,结果显示对于流速和流向的估计精度能够满足工程应用的要求,这表明用HF-SAR提取表层海流是可行的。

心率变异性中高频功率与IVF/ICSI-ET患者妊娠结局的关系

目的探讨心率变异性(HRV)中高频功率(HF)与接受体外受精/卵胞浆内单精子注射-胚胎移植(IVF/ICSI-ET)治疗的不孕患者妊娠结局的相关性。方法对2022年1—6月于邢台不孕不育专科医院接受IVF/ICSI-ET治疗的329例女性患者的临床资料进行回顾性分析。将研究对象根据HF水平按三分位法分成A组(HF 7.91~197.06,n=110)、B组(HF 198.22~358.03,n=109)和C组(HF 360.03~3121.14,n=110),比较3组患者的心理测评结果[焦虑自评量表(SAS)评分、抑郁自评量表(SDS)评分]、子宫内膜情况及妊娠结局。采用Spearman相关分析HF水平与心理状况及结局指标的相关性。结果3组间患者一般资料及基础内分泌水平等比较均无统计学差异(P>0.05)。3组间SAS评分存在显著性差异(P<0.05),其中C组SAS评分显著低于A组(P<0.05);3组间SDS评分比较无统计学差异(P>0.05)。子宫内膜容受性方面,C组内膜血流搏动指数、子宫内膜蠕动波频率均显著低于A、B组[分别为(1.68±0.59)vs.(1.97±0.39)、(1.88±0.39);(1.76±0.93)vs.(2.68±1.58)、(2.30±1.36)](P<0.05)。胚胎结局方面,C组的正常受精率显著高于A、B两组(66.59%vs.60.03%、63.03%,P<0.05),种植率显著高于A组(54.49%vs.40.96%,P<0.05)。相关性分析结果显示,HF水平与SAS评分、蠕动波频率呈负相关(P<0.01),与种植率呈正相关(P<0.05)。结论HRV中的HF可能反映了机体对心理压力的调整能力;较高的HF水平可能预示着较好的子宫内膜容受性及种植率;医务人员应重视HRV的检测,及时进行干预,适当提高其HF水平。

用于HF接收机的高纯度频率源的研制

高纯度频率源是HF(high frequency)大动态接收机的关键部件,对接收机性能有重要影响。目前,高纯度频率源的性能尚不能满足HF接收机的需要,需要进行不断的研究和改进。文章介绍了用于某机载HF接收机的高纯度频率源的研制,给出了方案原理和性能仿真,并进行了电路设计、加工和测试。测试结果表明,该频率源输出频率为76.8~104.8MHz,输出幅度大于+10dBm,相位噪声优于-145dBc/Hz@10KHz,杂散抑制大于86dB,换频速度小于10μs。主要指标较上一代HF接收机有了大幅提升,相噪优化了10dB,换频速度提升了4倍,而体积和功耗只有原来的1/5,具有广阔的应用前景。

短波宽带波形NVIS通信链路评估

短波宽带波形通过匹配近垂直入射天馈(NVIS)系统,可实现舰船、岸船通信的高速数据交互传输,极大提升短波通信在军事和应急通信系统中的作用。首先阐述国外典型的五种短波宽带波形的技术进展,然后分析宽带波形NVIS的可行性,利用ITU模型对不同数据速率和带宽对应信噪比下的链路评估,并进行了NVIS天波测试验证,为我国短波宽带波形在舰船、岸船使用NVIS宽带通信的实现提供评估方法和依据。