一种短波有源天线供电转换器的设计

设计了一种短波有源天线供电转换器,利用直流信号和高频信号的频率差异,通过一条传输线路完成射频信号的传输和天线放大器的直流供电,根据射频器件的高频特性实现2路信号的隔离和复用,采用ADS射频仿真软件建立仿真模型。仿真结果显示在工作带宽内射频阻抗特性和直流电压平稳。制作了一台四通道短波有源天线供电转换器,在1．5～30 M Hz的工作频率范围内实测结果和仿真计算结果相吻合,可与宽带接收机实现良好的匹配。同时,供电转换器各通道之间幅度和相位一致性很好,还可满足一些有源阵列天线的需求。     

基于双谱的射频指纹提取方法

研究了基于通信辐射源射频指纹(RFF)的同类型设备分类识别理论,通过提取通信信号的围线积分双谱值来作为设备个体识别的特征向量,使用支持向量机(SVM)分类器进行识别.构建辐射源识别系统,并使用实测信号进行仿真测试.结果显示该方法具有稳定的识别效果,且在信噪比(SNR)为-22 dB时,系统可以达到接近90％的分类识别准...     

相控阵测量雷达多目标模拟器

介绍了一种雷达多目标模拟器的工作原理、组成和功能。该模拟器与雷达之间采用空间辐射的对接方式，接收雷达发射的信号，进行延时与频率的相参调制和幅度调制，产生多个模拟运动目标的射频信号，配以气球和飞机校飞，可以有效检验相控阵测量雷达的多目标跟踪性能和工作方式。     

战术数据链射频辐射特征控制技术

传统的链路自适应技术只追求高效数据传输,会导致射频暴露,在电子战中无法保障数据链载体的安全性。以战术数据链主动射频隐身和高效通信为研究对象,利用多目标优化技术联合控制战术数据链的射频辐射特征(包含辐射时间、辐射功率和辐射波形),建立了一种战术数据链链路自适应技术模型。该模型以给定距离的截获概率和给定距离的可靠传输速率为二重优化目标,以辐射特征为优化变量,并以第四代宽带无线通信系统LTE-A(Long Term Evolution-Advanced)的部分调制编码参数为实例,证实了由所述链路自适应技术模型优化所得的最优解可以同时实现数据链的射频隐身和高效数据传输。     

随机跳频噪声对FSK信号的干扰分析

区别于传统的射频噪声和单频噪声,针对FSK信号具有频率键控的特点,提出了利用构造随机跳频噪声干扰FSK信号的方法。该噪声采用与被干扰信号相同码速率的随机码调频,具有与被干扰信号相似的谱形和随机跳变的瞬时频率,从而对正交解调和基于时频分析的FSK信号解调具有好的干扰效果。以2FSK信号模型为例,假设在接收机完成同步的条件下,导出了其影响接收机正交解调的误码率公式,并通过理论分析和仿真实验给出了干扰性能评价。仿真实验表明本文提出的调频噪声在不同干信比条件下比传统射频噪声有更好的干扰效果。     

基于射频信号2阶零功率的链路色散测量技术

为了适应高速率大色散光纤信道对链路色散的精确补偿要求,研究并提出了一种基于射频信号2阶零功率点的信道色散测量方案。采用信号两边带的位相差来测量光纤链路中的色散值,通过在发射端加载射频信号,可以得到接收端射频信号功率大小随链路色散值的周期性变化关系,从仿真光纤链路色散随射频信号频率的变化曲线获得接收端射频信号2阶零功率点位置。结果表明,基于射频信号2阶零功率的信号测量方案色散测量误差可控制在±10ps/nm范围内。相较于1阶零功率点,基于射频信号2阶零功率点信道色散测量方案可满足高速率、长距离大色散光纤信道对色散值的精确测量需求。     

基于正态分布宽带信号的无源互调特征行为分析

在现代无线通信中,无源互调是影响通信信号传输质量的重要因素。双音互调测试能够有效衡量无源器件的非线性特性,却无法准确预测出器件在宽带信号激励下的非线性失真。因此本文提出了一种基于正态分布的宽带信号激励下的射频连接器无源互调特性分析方法。通过双音互调测试,建立射频连接器无源非线性传输数学模型,并将基于正态分布的等效宽带信号作为非线性传输模型的激励源进行模拟仿真。结果表明,宽带无源互调功率分布与宽带信号功率分布相同,n阶宽带无源互调带宽为原宽带信号带宽的n倍,宽带信号的无源互调产物相较于双音测试信号有所增强,且信号的信噪比下降,说明宽带信号在传输过程中受到的干扰更加严重。电路仿真和数值计算呈现出良好的一致性,证明了本分析方法的有效性。     

OPM产生四倍频光载毫米波的双向ROF系统

提出一种采用单个光相位调制器(OPM)和光纤布拉格光栅(FBG)滤波器产生四倍频光载毫米波的双向光纤无线通信(ROF)系统。在中心站(CS),系统采用基带信号与射频(RF)信号混频后去驱动OPM,以产生抑制一阶边带的多边带光信号。在基站(BS),利用FBG滤波器将信号的重复频率增至4倍。实验结果显示,经过40km光纤传输后,下行链路信号的眼图清晰可见,功率代价小于1.6dB。本文方案中,由于没有额外增加激光源使得基站结构进一步简化,同时四倍频技术降低了RF信号的频率,系统成本大大降低。     

一种基于Workbench平台的射频同轴开关热结构高频耦合仿真方法

射频同轴开关主要用于功放信号的传输与选择,在电子战中应用的开关功率达千瓦级,由发热引起的性能衰减、指标恶化以至于烧毁损坏现象经常发生,所以通过科学合理的分析同轴开关的热-结构-高频耦合仿真解决其热可靠性设计就极其重要.本文基于workbench平台,从开关生热机理、仿真理论、仿真计算等方面,阐述了一种可以对射频同轴开关在传输大功率信号时的多物理场进行仿真的方法.     

Analyses of numerical and experimental results for optical signal generation using heterodyne scheme

In this paper, we have proposed a heterodyne technique to generate an optical millimeter-wave signal for ultra-wideband communication. First, we have investigated the characteristics of semiconductor lasers locked to another semiconductor under the RF modulation having many sidebands. The RF-modulated master laser is represented by a series of Bessel functions. This model is then inserted into Lang's rate equations. By numerically solving the resulting rate equations, we have determined the locked laser output characteristics as well as the RF spectrum of the beat signals. The result is that the unselected sidebands can produce undesired beat signals whose power may be comparable to that of the desired beat signal. Furthermore, their strength is affected by the injected ML light power. With reduced ML light, undesired beat signals and the injection-locking bandwidth can be suppressed. Second, we have experimented a new technique for generating millimeter-wave signals from a semiconductor laser. A 32 GHz signal is generated using a multisection semiconductor laser operated under a continuous wave by injecting optical pulses at a repetition rate equal to the fourth subharmonic (8 GHz). The generated millimeter-wave signal exhibits a large subharmonic suppression ratio, a large frequency detuning range, low levels of phase-noise and a large locking range. These simulation results are confirmed by experimental results. The high-frequency signal can be used in the field of ultra-wideband communication employing local multipoint distribution system (LMDS), wireless local loop (WLL) and mobile broadband system (MBS).     

A Level-Crossing Approach for the Analysis of RF Modulated Signals Using Only Digital Test Resources

The test of analog & RF circuits at wafer-level suffers from both quality and throughput limitations, especially due to probing issues and limited count of expensive instrumentation resources. Since final test after packaging guarantees product performances, constraints on wafer-level test can be relaxed. This paper investigates a signal acquisition protocol based on the use of digital tester channels to perform the demodulation of analog/RF signals. Due to the large availability of such hardware resources on most testers, this approach allows to setup a multi-site strategy, thus increasing the test throughput. The fundamental concept is to capture the signal through the 1-bit comparator available in a digital tester channel and to process the resulting bit stream to retrieve the analog/RF signal characteristics. In this paper, the proposed solution is illustrated for the demodulation of Frequency-Modulated (FM) and Amplitude-Modulated (AM) signals. Both simulation and experimental results obtained with a Verigy 93K platform are presented.     

面向一体化应用的电磁信号智能检测方法研究

针对复杂电磁环境中信号检测受限于低信噪比的问题,基于信号与噪声一体化的思路,提出了一种以电磁空间的所有电磁辐射信号为背景,并结合深度学习算法的电磁信号检测方法。首先建立动态场景的电磁环境模型,包括了通信基站信号、雷达信号、干扰信号等,其次使用加高斯窗傅里叶变换提取电磁信号时频域的能量分布特征,最后采用卷积神经网络进行特征选择分类,实现信号检测。仿真结果表明,该方法在一定程度上减轻了信号检测受限于信噪比的问题,克服了传统能量检测方法和基于SVM检测方法的缺陷,提高了低信噪比下电磁信号的检测性能。      

基于改进ResNet的射频指纹识别方法

在无线网络安全和可能存在的射频设备管理应用范围内,针对多个发射同种射频信号的高度相似射频设备的分类识别问题,提出了一种信号双谱与改进的残差神经网络(Residual Neural Network,ResNet)的射频指纹识别方法.首先,将采集到的不同设备的信号做双谱变换得到双谱等高图并打上设备标签,再使用搭建好的改进残...     

光载射频信号在多模塑料光纤中的传输特性研究

实验研究了光载射频信号在多模塑料光纤(POF)中的传输特性,将24GHz的正弦波信号与1.5Gbt/s的数字信号进行混频后再通过光强度调制器产生双边带调制光信号,将双边带调制信号通过多模POF发送至接收机,在接收机转化为24GHz的射频信号。实验结果表明,这种双边带调制的光载波射频信号可以在多模POF中传输50m后而功率代价可以忽略不计。     

Low‐Cost High‐Performance TDD Synchronizer for WiBro RF Repeater

WiBro radio frequency (RF) repeater is used for solving the problem of partial shadow areas in the wireless communication field that uses time‐division duplexing (TDD) mode. In this paper, a method to efficiently generate TDD signals for WiBro RF repeater is proposed and its digital circuit is implemented. A TDD signal is detected from RF signals transmitted/received to/from RF repeater and then inputted again into the RF repeater, so that it can operate normally. First, the envelope of downlink signals is detected and then clamped to extract the basic form of a TDD signal using an operational amplifier circuit. Next, the TDD signal is generated by restoring and filtering the shape which has been distorted by the wireless channel. The algorithm and system to acquire TDD signal are developed with a goal to have simple but powerful functions with as little cost as possible. The proposed method is implemented as an RF‐digital integrated system and verified through the experiments under the same condition as actual WiBro service environment.     

Effects of signal PDF on the identification of behavioral polynomial models for multicarrier RF power amplifiers

This paper proposes an experimental study of the sensitivities of the power amplifier modelling and their influences on the system??s identification. Two memory polynomial models are widely investigated in the behavioural modelling and linearization of RF power amplifiers (PAs). In order to improve the accuracy of the behavioural modeling versus identification, we assess the performances of these models under different signal bandwidths, statistics and signal distributions. For this purpose, normalized mean square error has been used to compare the model output to measured data when the PA is driven under multi-carrier input signals. Measurement results and simulation have been carried out and the results demonstrated the effects of the signal characteristics on the performances of the model. Multi-carrier wideband code-division multiple access and multi-tone signals were used with an experimental Doherty amplifier. The obtained results revealed a degradation of the polynomial model performances when the statistics of the input signals change with similar peak-to-average power ratio.     

基于双光学频梳的超宽带射频信号信道化合成技术研究（特邀）

随着现代通信系统的发展,宽带和高频微波射频信号在雷达,通信和信号处理等领域的应用越来越广泛。基于微波光子信道化技术,文中通过两个自由频谱范围不同的光学频梳,实现了超宽带射频信号的信道化合成。在信道化合成系统中,多个独立的窄带信号输入各个信道进行上变频,并在多外差探测中被重组成为一个具有连续频谱的宽带射频信号。在多外差探测中,干扰抑制技术的使用提高了合成射频信号可达到的最高频率。在实验中,合成了一个覆盖频率范围8.4~12.4 GHz,瞬时带宽为4 GHz的宽带射频信号。实验结果显示,干扰的抑制率达到了21 dB,表明干扰抑制技术的使用提高了输出信号的最高频率的同时有效地提高了频谱利用率。     

同频段混合信号中的无人机信号盲检测识别

无人机信号的探测识别技术是应对无人机黑飞滥用的关键技术之一。在实际信号监测环境中，经常会接收到多个信号的混合信号，它们在时域和频域上混叠且各信号分量调制样式相同。为解决在同频段混合信号中检测识别出无人机信号的问题，提出了一种通过谱特征分析判断无人机信号存在性的方法。分别采用基于二次方谱特征的无人机图传和WiFi混合信号检测识别算法以及基于频谱带宽特征的多无人机混合信号检测识别算法，通过对射频电路采集的信号进行仿真验证，实现了从同频段混合信号中检测识别出无人机信号分量。理论分析和实验测试结果证实了所提检测识别算法的有效性。     

X 波段注入锁定相对论返波管设计

为实现X 波段的相干功率合成,提出了一种高功率的注入锁定相对论返波管模型。器件在结构上分为输入腔和 输出慢波结构：输入腔用于减少注入微波的泄漏,同时腔内的驻波电场可以有效调制电子束;输出慢波段实现调制电子 束的换能输出。模拟表明该结构在注入功率6 kW 的条件下,可以实现2.5 GW输出微波的相位控制。     

基于叠印啁啾光纤布拉格光栅的宽谱微波光子信道化接收方法

提出了利用叠印啁啾光纤布拉格光栅(S-CFBG)实现宽谱微波信号光子信道化接收的方法。利用一个S-CFBG产生光频梳(OFC),接收的微波信号被强度调制器调制到OFC的各个载波上。第二个S-CFBG对不同的边带进行滤波,利用波分复用(WDM)解复用器进行信道分离,实现对宽谱微波信号频率的实时测量。该方法还可以同时检测不同射频(RF)载波上所携带的数据信息,无需传统的电本振源阵列,简化了系统结构。建立了测量范围为0～20GHz,测量精度为0.5GHz的宽谱微波信号信道化接收仿真系统。实现了不同RF频率上携带信息的实时同步检测,并对接收误码性能进行了分析。