接收机畸变对辐射源个体识别中调制器指纹特征的影响

辐射源个体识别(Specific Emitter Identification,SEI)技术利用辐射源指纹特征识别发射设备,但辐射源指纹特征极易受接收机畸变的影响,无法在不同接收设备间通用.针对这一问题,基于一种利用调制畸变的辐射源个体识别方法,分析了接收机畸变对该方法特征识别结果的影响,得到了接收机畸变特性与特征估计结果的准确数学模型;并将推导结果与接收机设计指标相对应,对SEI接收机设计提出了建议;利用仿真实验和设计实例,证明了推导结果的准确性.该成果能够有效指导SEI系统接收机设计,并为跨接收机SEI系统的实现提供了可能.     

基于解调重构的跳频信号辐射源个体识别方法

现有跳频信号辐射源个体识别方法大多围绕跳变瞬态的特征进行讨论,其捕获和精准定位的难度较大。因此,提出了一种基于解调重构的跳频信号辐射源个体识别方法,能够有效利用跳频信号的稳态信息进行辐射源个体识别。首先对跳频信号进行跳变定时,提取出各跳的基带波形;然后解调出各跳的符号,并将其经过理想成型滤波器,得到理想的重构基带波形;最后将原始波形和重构波形一起送入神经网络,得到分类结果。给出发射机畸变模型和畸变参数范围,经过多次测试给出网络参数的建议取值范围,并进行验证实验。实验结果表明,该方法能够有效地完成跳频信号辐射源个体识别任务。     

基于幅度调制畸变Wiener模型的OOK辐射源指纹特征提取

通过分析生成On-Off Keying（OOK）信号的发射机系统的幅度调制畸变特性,阐明了OOK信号辐射源特征产生机理,建立了OOK辐射源的幅度调制畸变特性的Wiener模型,并根据信号模型应用差分进化算法完成OOK幅度畸变特性参数的估计,从而构建辐射源指纹特征完成对OOK信号辐射源的识别。仿真试验和实际数据测试表明,该算法具备OOK辐射源指纹特征提取和识别能力,对实测数据中4个OOK辐射源识别率为93%,优于基于暂态幅度特征的提取方法。     

窄带信号中的放大器"指纹"特征提取:原理分析及FM广播实测实验

 本文提出了一种利用放大器非线性特性来进行特定辐射源识别的多通道相关指纹识别(Multi-Channel Correlation Fingerprinting;MCCF)方法.该方法首先由功率放大器的泰勒级数模型导出窄带输出信号的载频分量和谐波分量表达式,然后利用两分量的关联性,将载频分量作为放大器激励信号的近似,代入谐波分量的表达式中,用最小二乘方法估计出"指纹"特征量.在此基础上本文分析了MCCF的指纹特征的可观测条件和估计的CRLB.该方法定义的指纹特征与放大器的级数模型有关,与激励信号的形式无关,因此是发射机固有的.依据本方法对长沙地区的调频广播的电台进行了"指纹"提取实测实验,在谐波分量功率比载频分量小60到80dB的典型条件下,对四个电台的发射机进行了有效的分类.     

基于VMD的通信辐射源个体识别方法

针对通信辐射源细微个体指纹信息难以提取的问题,根据辐射源指纹产生机理,提出了将接收信号中的数据部分过滤而保留指纹噪声的研究思路,设计了基于变分模态分解的识别方法.该方法采用变分模态分解将接收信号分解为主要包含数据信息的低频分量和主要包含指纹信息的高频分量,并设计深度卷积神经网络对分解后的高频分量进行特征提取和分类识别....     

基于瞬时频率畸变特性的FSK电台指纹特征提取

为解决FSK电台个体识别问题,需要从辐射源信号上提取特征构成辐射源指纹。通过分析构成FSK电台的各个模块的畸变特性,阐明了FSK电台指纹产生机理,建立了基于瞬时频率的指纹信号模型,并根据信号模型设计了基于辅助参数的最小二乘算法以完成FSK频率畸变特性参数的估计,从而构建指纹特征完成对FSK电台的识别。对仿真信号和实际信号的识别测试试验表明,该算法具备辐射源个体识别能力,对实际环境下的4个FSK电台的识别率大于96%,优于双谱类方法。     

一种敌我识别辐射源暂态信号指纹特征提取方法

信号的指纹特征是辐射源个体识别的重要依据。针对敌我识别辐射源的个体识别问题,提出了一种基于双树复小波和多重分形的信号暂态特征提取方法。该方法通过双树复小波变换实现信号多分辨率分解,求解分解信号Hilbert谱的信息熵和指数熵,计算信号的多重分形奇异指数和谱值,最终组成表征辐射源的特征向量。通过实验验证,提取的特征向量能充分代表辐射源个体之间的差异;被测信号的信噪比满足8 dB或9 dB的条件时,对辐射源的识别正确率能达到90%以上。统计分析表明该方法提取的特征具有很高的稳定性。     

基于指纹特征融合的辐射源识别方法

提出了一种利用辐射源＂指纹＂特征融合识别辐射源的方法。首先分析了功放信号模型、接收信号模型、频率和重复频率稳定度;然后定义了四个＂指纹＂特征;在此基础上利用获取的指纹特征构造辐射源特征数据库,结合D-S证据理论给出了识别算法的步骤和框图。依据该方法对四部雷达辐射源进行了指纹特征提取,采用融合技术进行了仿真实验,结果表明基于指纹融合的方法能有效地识别辐射源。相比于经典的模板匹配法、模糊识别法,指纹特征有更高的稳定性,对信噪比不敏感,辐射源的识别率较高。     

多径条件下的雷达辐射源个体识别方法

在实际场景中，接收机截获的雷达脉冲信号信噪比较低、多径干扰明显，从中提取的辐射源指纹特征存在畸变，给雷达辐射源个体识别带来严峻挑战.针对该问题，本文提出一种两阶段的信号处理方法.在第一阶段，以精确的脉冲对齐和迭代加权积累提高信号质量，解决低信噪比问题.在第二阶段，定义信号频谱相邻点前向商的绝对值为谱邻点商，并提取信号频谱主瓣和第一旁瓣对应的谱邻点商作为抗多径的指纹特征，解决多径干扰问题，同时利用Chirp-Z变换的局部精细化谱分析能力，进一步提高本文方法的计算精度和速度.仿真实验表明本文方法在脉冲对齐和克服多径干扰方面表现突出.实测数据实验对截获自15部同型号雷达的单频脉冲信号进行分类识别，获得超过97%的识别准确率，证明本文方法对多径条件下的雷达辐射源个体识别实际应用具有重要参考价值.     

基于脉冲包络前沿高阶矩特征的辐射源个体识别

雷达脉冲包络分析是雷达辐射源识别的常规方法,但常规的包络识别方法很难适应实际需要,无法有效地对雷达辐射源信号进行分类识别.提出了以脉冲包络前沿波形的高阶矩特征作为辐射源的"指纹"特征,进行雷达辐射源个体识别的思路.利用脉冲包络前沿波形的高阶矩特征受高斯噪声影响较小的特点,提高了辐射源个体特征参数的有效性.理论分析和实验结果表明利用雷达脉冲包络前沿波形的高阶矩特征可以较好地进行辐射源个体识别.     

基于时域RF-DNA的功率放大器射频指纹识别

射频(RF)功率放大器是辐射源射频指纹特征产生的关键器件之一,是射频指纹(RFF)产生机理和个体识别的重要突破口。设计一种功率放大器射频指纹提取实验方法,利用时域射频独特原生属性(RF-DNA)方法成功提取了功率放大器的射频指纹,并对RF-DNA指纹进行了可视化处理。研究结果表明,功率放大器的射频指纹主要反映在幅度失真特性上,利用瞬时幅度生成的时域RF-DNA指纹能够实现对放大器个体的分类,在信噪比大于12 dB时,分类正确率在91%以上。可视化后,能直观观察RF-DNA指纹及不同功率放大器之间统计特征的相似性和差异性。     

UHF频段无线收发信机前端设计

为了提高现代工厂设备的调度效率,降低仪器仪表等测控数据的传输成本,压缩设备体积等。利用收发芯片TH7122和分离器件相结合的方式设计了一款通信频段为438～470 MHz的无线音/数两用小型收发信机。数字调制方式采用MSK调制,同时可切换到音频模式。其中接收机采用超外差一次变频结构,结合PIN管带通调频滤波器和外接LNA,用于镜像抑制和降低噪声。发射部分采用晶振拉动的方式间接调制VCO输出,经过芯片内部放大、外接功率驱动电路和功率放大电路将发射功率增至5 W,再经谐波滤波发射。经过仿真实验,输出功率5 W,中频10.7 MHz,接收灵敏度为-110 dB,镜像抑制40 dB,均达到设计要求。     

Integrated X-band Sweeping Superheterodyne Receiver

The development of an integrated low-noise sweeping superheterodyne receiver is described. Based upon a receiver performance tradeoff study, a group of components were designed and integrated within a single housing occupying 5.9 in/sup 3/, less connectors. The integrated receiver weighs 6.4 oz, including magnets, and contains the following components: a wide-band low-noise tunnel-diode amplifer (TDA), an image-rejection balanced mixer, a varactor-tuned Gunn oscillator, a four-stage IF amplifier, and a quasi-complementary IF output filter. The housing also contains an interstage ferrite isolator, a bias distribution network with subminiature potentiometers, and a branch-line coupler. This coupler permits the injection of an external oscillator and allows the system to be evaluated outside the band covered by the internal Gunn oscillator. This receiver is the first kind to integrate within a minimum volume all the components necessary for a wide-band low-noise rapid-scan X-band imageless superheterodyne receiver. Varactor tuning permitted the entire receiver to be integrated in a package having about one fifth the weight and two fifths the volume of other similar receiver designs (e.g., a receiver utilizing a YIG-tuned oscillator).     

LED可见光模拟通信实验系统的设计

基于可见光通信原理设计了LED可见光模拟通信实验系统,该系统实现了短距离无线传输模拟信号。系统包括三个主要模块,分别为电源、发射端、接收端。实验系统的发射端采用大功率10W LED灯作为信号源,接收端采用高精度TDA2030音频专用功率放大器和20000HZ低通滤波器,用以提升该实验系统的传输距离和效果,经测试该系统可传输300—15000HZ的模拟信号,传输距离可达5m以上,接收到的信号强度大且无明显失真。     

Effect of chirping-induced waveform distortion on the performanceof direct detection receivers using traveling-wave semiconductor opticalpreamplifiers

The influence of chirping-induced waveform distortion on the performance of multigigabit-per-second traveling-wave semiconductor optical amplifier (TWSOA)/p-i-n direct detection receivers is evaluated. The results are based on a novel method of evaluating the probability of error in the presence of the signal-spontaneous and spontaneous-spontaneous beat noise components. Laser chirping causes the dependence of the receiver sensitivity on the fiber dispersion coefficient×length product DL to be different for TWSOA/p-i-n and avalanche photodiode (APD) receivers. Compared to the APD receiver, the sensitivity of the TWSOA/p-i-n receiver degrades less quickly. So for cases of practical interest, the TWSOA/p-i-n receiver is more tolerant of chirping-induced waveform distortion     

Graphical Presentation of Spurious Responses in Tunable Superheterodyne Receivers

The theory of intermodulation responses in superheterodyne receivers is briefly reviewed. The frequency bands of the responses are determined and factors affecting susceptibility levels as well as quantitative values for a typical crystal mixer input superheterodyne receiver are presented. On the basis of this groundwork, it is shown that the receiver's primary and spurious responses may be conveniently presented in graphical form. The graphical presentation can include the effects of input band-pass filters and tunable preselectors, and provides a grid upon which an electromagnetic environment may be superimposed.     

A Silicon 60-GHz Receiver and Transmitter Chipset for Broadband Communications

A 0.13-mum SiGe BiCMOS double-conversion superheterodyne receiver and transmitter chipset for data communications in the 60-GHz band is presented. The receiver chip includes an image-reject low-noise amplifier (LNA), RF-to-IF mixer, IF amplifier strip, quadrature IF-to-baseband mixers, phase-locked loop (PLL), and frequency tripler. It achieves a 6-dB noise figure, -30 dBm IIP3, and consumes 500 mW. The transmitter chip includes a power amplifier, image-reject driver, IF-to-RF upmixer, IF amplifier strip, quadrature baseband-to-IF mixers, PLL, and frequency tripler. It achieves output P_1dB of 10 to 12dBm, P_sat of 15 to 17 dBm, and consumes 800 mW. The chips have been packaged with planar antennas, and a wireless data link at 630 Mb/s over 10 m has been demonstrated     

Reduction of Adjacent Channel Interference in the Standard (AM) Broadcast Band

Side channel interference has been a problem in the standard (AM) broadcast band since the advent of radio broadcasting. The two major contributing factors are: 1) radiation of audio-frequency components greater than 5 kHz, and 2) receivers having poor selectivity characteristics. Other more or less controllable factors are overmodulation of the carrier and inherent distortion in the transmitter.     

Intra-chip wireless interconnect for clock distribution implementedwith integrated antennas, receivers, and transmitters

A wireless interconnect system which transmits and receives RF signals across a chip using integrated antennas, receivers, and transmitters is proposed and demonstrated. The transmitter consists of a voltage-controlled oscillator, an output amplifier, and an antenna, while the receiver consists of an antenna, a low-noise amplifier, a frequency divider, and buffers. Using a 0.18-μm CMOS technology, each of these individual circuits is demonstrated at 15 GHz. Wireless interconnection for clock distribution is then demonstrated in two stages. First, a wireless transmitter with integrated antenna generates and broadcasts a 15-GHz global clock signal across a 5.6-mm test chip, and this signal is detected using receiving antennas. Second, a wireless clock receiver with an integrated antenna detects a 15-GHz global clock signal supplied to an on-chip transmitting antenna located 5.6 mm away from the receiver, and generates a 1.875-GHz local clock signal. This is the first known demonstration of an on-chip clock transmitter with an integrated antenna and the second demonstration of a clock receiver with an integrated antenna, where the receiver's frequency and interconnection distance have approximately been doubled over previous results