星载微波成像仪无线电频率干扰软件识别算法综述

气象卫星仪器使用的光谱中只有微波观测可以部分穿过云区,常被用来反演地表温度、海表温度等重要的地表参数.近年来随着地面通信等主动微波技术的发展和商业服务中对微波波段的使用日益增多,被动接收来自地球-大气系统辐射的星载微波仪器观测越来越受到主动微波发射的影响,尤其是在低频波段遥感探测量中增加了不可预测的噪声,造成观测亮度温度相比视场内来自自然大气和地表发射、散射辐射而言异常偏大,进而使反演的地表参数和资料同化的分析场具有较大偏差.卫星微波接收的来自地气系统的被动热辐射与主动传感器发射的信号相混合,被称为无线电频率干扰（radio-frequency interference,RFI）;星载微波辐射计接收的辐射测量受地表反射的静止电视或通信卫星下行信号干扰,称之为电视频率干扰（TV frequency interference,TFI）.如果不正确识别和去除污染资料,将大大降低星载被动微波仪器的科学价值.本文总结了谱差法、主成分分析法、平均值标准差法、模拟差法等几种常用的RFI软件识别算法,以及谱差比值法、SE法等几种较新的识别算法,并对各种算法的适用范围及优缺点进行了评述.同时详细介绍了源自反射的静止电视或通信卫星下行信号对星载微波观测造成污染的特征及识别、订正方法.     

一起雷达对民用航空专用频率干扰的查处

2004年4月20日上午，大连市无委办接到大连空管中心关于大连周水子国际机场民用航空专用频率受到不明无线电干扰的申诉，申诉称130．000MHz，132．000MHz．132．550MHz三个频率近期受到不同程度的无线电干扰。干扰现象是频繁出现“嘟，嘟，嘟”的声音，严重影响塔台指挥调度的正常工作．造成重大的飞行安全隐患。     

野战无线电频率管理中同频干扰的计算机分析预测

通过对野战无线电通信系统中同频干扰的深入分析,建立了其计算机分析预测工程模型,并利用计算机软件实现了其自动分析预测。     

对航空无线电干扰的排查及建议

随着无线电技术应用的加速普及,电磁环境日益复杂,航空专用频率受干扰的情况也时有发生。近年来,浙江省无管机构受理的航空无线电干扰数量呈上升趋势,2021年,就发生了十多起航空无线电干扰。航空无线电干扰排查有其特殊性,排查范围广,且耗时耗力。因此,建立高效的航空无线电干扰排查机制便显得至关重要。     

快速反应 果断查处 保障团队排除首例无线电频率干扰

5月1日13时57分．上海世博会无线电安全保障军地联合管控指挥所接到场馆文广部门报告,称其图像传输频率受到干扰．影响了图像传输的质量。在指挥所的统一指挥下．上海、江苏、浙江监测分队与军队监测分队一道,迅速开始对于扰信号进行定位和查找。     

对我国无线电频率规划使用现状的思考

简要介绍了美国、欧盟和我国的频率规划现状,分析了目前我国在无线电频率使用过程中存在的问题,并提出了一些建议。     

基于AMSR-2数据的多种射频干扰识别方法的比较

由于射频干扰（radio-frequency interference，RFI）对星载微波遥感的影响日益严重，为了比较各种识别方法的适用性，基于先进微波扫描辐射计（advanced microwave scanning radiometer 2，AMSR-2）2015年冬季和夏季的观测亮度温度，分别采用谱差法、多通道回归分析法、双主成分分析法和比值法，对欧洲陆地区域和海洋区域的10.65 GHz和7.3 GHz频率干扰进行识别和分析，并对比几种方法的月综合结果.结果表明，冬季时谱差法在陆地上受积雪散射的影响，会将积雪下垫面误判为RFI污染；多通道回归分析法和双主成分分析法识别出的结果类似，无论陆地和洋面还是冬季和夏季均可有效使用；当10.65 GHz和7.3 GHz波段观测同时存在RFI时，比值法将不能识别出10.65 GHz的RFI信号，并且比值法会将海陆边界及附近视场的观测误判为RFI信号.多通道回归分析法和双主成分分析法的适用范围较为广泛，而谱差法和比值法各有弊端.     

基于认知无线电改善民航无线电频率的研究

本文结合认知无线电，研究一种改善民航无线电频率资源紧张问题的方法。首先，分析导致民航频率资源紧张的原因；其次，分析利用认知无线电改善民航无线电频率紧张问题的可行性；最后，提出一种提高民航无线电地空通信频率利用率的方法，从而改善民航无线电频率资源紧张的问题。     

迅速查找无线电干扰确保民航和对讲机频率通信安全

毕节无线电监测分站监测人员在使用黔西小型站进行日常监测时,发现在航空频段A频段上有很多不明信号。查询台站数据库,在A频段只有频率a是合法频率,而且在相邻的调频广播频段B频段只有b频率、c频率和d频率是合法使用频率。使用黔西小型站监测B频段,在e频率、f频率、g频率等频率上发现了很多长发不明信号。     

Reliable adaptive modulation and interference mitigation for mobile radio slow frequency hopping channels

The long range fading prediction algorithm for Slow Frequency Hopping (SFH) systems is proposed and demonstrated to enable combined adaptive modulation and adaptive frequency diversity to mitigate the effects of fading and partial-band interference. Significant performance gains are demonstrated relative to non-adaptive methods in realistic mobile radio SFH channels where the total bandwidth does not exceed approximately 15 times the coherence bandwidth.     

A new practical interference mitigation scheme for interference cognitive radio networks

In this paper, a new practical dirty paper coding scheme and its extension is proposed for interference mitigation of a single TV broadcast station in uplink and downlink of a cognitive radio network using both a single secondary user (SU) and multiple SU scenarios. In the single SU scenario, which is called interference cognitive radio channel, derived simulation results show that the transmission rate of the SU archives the capacity of an AWGN channel with the cost of a 2.5 dB extra signal‐to‐noise ratio. In the sequel, the proposed scheme is extended to a multiple SU scenario using direct sequence spread spectrum technique in both uplink and downlink considering a TV band. Derived simulation results show that the number of supportable SUs in our proposed scheme increases to a fully loaded scenario of the same multiuser direct sequence spread spectrum system. Copyright © 2012 John Wiley & Sons, Ltd.     

电离层测高仪回波中窄带干扰消除算法与分析

针对Rife双谱线频率估计方法精度不高的问题,提出了改进的三谱线窄带干扰消除算法.利用快速傅里叶变换(Fast Fourier Transform,FFT)频谱中干扰主峰附近的3根谱线估算出窄带干扰频率,在干扰频点处做离散傅里叶变换(Discrete Fourier Transform,DFT)运算得到干扰幅度和相位.噪声背景下随机干扰估计结果表明：相比双谱线算法,三谱线算法的频率估计误差下降了约50%.应用于电离层测高仪回波干扰消除,对窄带强干扰的抑制达20～60 dB,干扰抑制能力相比双谱线方法提高了1～6 dB,消除干扰后的频高图描迹信息增多,可提高频高图反演电离层特征参数的准确性.     

Electromagnetic interference of cardiac rhythmic monitoring devices to radio frequency identification: analytical analysis and mitigation methodology

Increasing density of wireless communication and development of radio frequency identification (RFID) technology in particular have increased the susceptibility of patients equipped with cardiac rhythmic monitoring devices (CRMD) to environmental electro magnetic interference (EMI). Several organizations reported observing CRMD EMI from different sources. This paper focuses on mathematically analyzing the energy as perceived by the implanted device, i.e., voltage. Radio frequency (RF) energy transmitted by RFID interrogators is considered as an example. A simplified front-end equivalent circuit of a CRMD sensing circuitry is proposed for the analysis following extensive black-box testing of several commercial pacemakers and implantable defibrillators. After careful understanding of the mechanics of the CRMD signal processing in identifying the QRS complex of the heart-beat, a mitigation technique is proposed. The mitigation methodology introduced in this paper is logical in approach, simple to implement and is therefore applicable to all wireless communication protocols.     

On co-channel and adjacent channel interference mitigation in cognitive radio networks

Cognitive radio (CR) is an emerging wireless communications paradigm of sharing spectrum among licensed (or, primary) and unlicensed (or, CR) users. In CR networks, interference mitigation is crucial not only for primary user protection, but also for the quality of service of CR user themselves. In this paper, we consider the problem of interference mitigation via channel assignment and power allocation for CR users. A cross-layer optimization framework for minimizing both co-channel and adjacent channel interference is developed; the latter has been shown to have considerable impact in practical systems. Cooperative spectrum sensing, opportunistic spectrum access, channel assignment, and power allocation are considered in the problem formulation. We propose a reformulation–linearization technique (RLT) based centralized algorithm, as well as a distributed greedy algorithm that uses local information for near-optimal solutions. Both algorithms are evaluated with simulations and are shown quite effective for mitigating both types of interference and achieving high CR network capacity.     

高频地波雷达射频干扰抑制新算法的研究

针对高频地波雷达易受到其他设备发射的高频信号干扰的问题, 通过分析射频干扰与有效目标信号在雷达回波中的表现形式及其在雷达距离多普勒谱图中出现区域的差异, 运用多重信号分类算法估计射频干扰的频率和方位角子空间, 利用子空间投影的方法分别在频率和方位角上分解射频干扰信号和有用目标回波信号, 之后从原信号中减去射频干扰分量, 从而实现射频干扰抑制的目的.仿真结果与实测数据的处理结果都表明:该算法可以有效抑制射频干扰.     

Suppression of radio frequency interference at the distributor rotor gap

Generally, for a given spark gap length, lower breakdown voltage of the gap corresponds to a lower radio frequency interference (RFI) level. Mechanisms which lead to the reduction of breakdown voltage at the spark gap by two techniques are discussed. The first technique involves the addition of a pointed electrode near the cathode, while the second technique involves the presence of bulk dielectric material on the cathode surface near the gap. Practical distributor rotor designs based on these techniques for effective RFI control are described.     

基于误码率的软件无线电射频干扰效应分析

针对通信系统工作过程中受到外界电磁干扰而无法通信的问题,研究了基于软件无线电的电磁干扰效应及误码特征。通过分析典型软件无线电电磁信号传输特性及其信息链路电磁干扰耦合路径,设计了软件无线电通信干扰实验系统。该系统利用Simulink软件观测、记录通信信号眼图、星座图信息等受扰特征,并通过分析接收信号的误码率,给出了不同干扰信号对通信系统的影响规律：当同频干扰功率达到-40 dBm时通信开始出现误码,干扰功率每增加5 dB,误码率增加一个量级,干扰功率增加到-18 dBm时,误码率达到阈值0.25;邻频干扰误码率随干扰功率变化趋势与同频干扰一致,但出现误码的最小干扰功率更大;带外强干扰信号也会影响通信系统可靠性,在相同误码率情况下,需要更大的干扰信号功率且大小与信号频偏成正比。