正弦信号抽样序列的周期性与伪调制性

在满足抽样定理条件前提下,当抽样频率处于某个范围内时,正弦信号抽样序列的包络与抽样序列的周期性与原始信号相比产生了很大的变化,抽样序列的包络出现了不应有的调制——伪调制,这种调制干扰了对原始信号包络的分析和提取。文中首先研究了抽样序列的周期性规律,然后从理论上分析了伪调制性产生的原因,推导出了伪调制的普适公式,得到了伪调制的调制规律和调制规律的周期性,最后得出了消除伪调制两个基本的方法。     

一类新型超混沌系统的非线性反馈同步研究

一类由快变和慢变吸引子构成的新型超混沌系统,具有强的抗噪声能力,但是采用传统同步算法时,同步收敛速度较慢,同步性能对响应系统参数敏感。针对该问题,该文提出非线性反馈同步算法,根据Hurwitz稳定原理,设计非线性控制变量,使得误差方程雅可比矩阵的特征值实部均小于零,并使得特征值的绝对值较大。该算法比传统同步算法收敛速度快,并且具有对系统参数不敏感的优点。仿真结果验证了上述算法的有效性。     

On the performance evaluation of a multifrequency-tone envelope detector

The performance of an envelope detector receiver for tone detection applications is evaluated in terms of probability of false alarm and probability of correct detection as functions of the receiver type, signal and noise parameters. The single tone case is considered first. The analysis is then carried out for L (>1) simultaneous tones and it is shown how the results found for the single tone case can be conveniently exploited for evaluating the performance in the more general case. Curves of the probability of detection versus system parameters are also explicitly given for some typical system configurations.At last some practical considerations are discussed with reference to a prototype implementation of an envelope detector receiver for tone transmissions.     

RISC-DSP处理器中指令数据相关性的提前判断方法

RISC-DSP处理器中执行周期数动态可变的指令对数据相关检测造成了困难。该文通过分布式相关检测模型将检测操作转换为依赖关系集合的计算,推测不同流水线状态下后一周期中的依赖关系集合,并根据当前指令相关性和功能单元发出的信号确定当前流水线状态,从而提前判断出下一周期中的指令相关性。按照其集合操作的特点进行逻辑优化,并以所研制的RISC-DSP处理器MediaDSP64原型机为例进行电路实现。综合结果表明,在对整体电路资源和功耗影响较小的前提下,从原先流水线关键路径中隐藏了相关检测电路,其延时下降了约30%。     

Polynomial 2.1 GHz RF predistorter IC with envelope injection output

This paper presents the structure, test setup and measured results of a polynomial RF predistorter IC fabricated in a 0.35 μm SiGe BiCMOS process. The predistorter is designed for the base station WCDMA band at 2.1 GHz. The predistortion signal is generated by a 5th-degree complex polynomial. Also a squared envelope is generated that can be used as a baseband injection signal to cancel 2nd-order distortion that typically causes memory effects. The performance of the predistorter was measured by driving a three-stage discrete power amplifier chain by a 2-tone test and a 3.84 MHz wide 3GPP WCDMA modulated signal. The 2-tone test showed more than 20 dB IM3 cancellation and the WCDMA signal’s ACPR was improved by 8 dB.     

线性调频相干激光雷达的信号处理

分析了相干激光雷达线性调频脉冲的产生及其信号处理过程，讨论了该雷达信号体制的处理方法和结果。计算了采用匹配滤波和加权处理结果，对于1MHz／μs的调制速率信号的结果表明，激光相干雷达的测速和测距精度分别可达0.04m／s和0．57m.     

ADAPTIVE NONPARAMETRIC DETECTOR ON CORRELATION GAUSSIAN NOISE

The problem of adaptive nonparametric detector in correlation Gaussian noise isconsidered.The nonparametric detectors are CFAR(Constant-False-Alarm-Rate)detectors,whenthe input received reference cells are IID(Identical Independent Distribution)variances.But the falsealarm probability(P_(fa))of the nonparametric detectors could not be constant if the samples of thereference range cells are not independent.A simple and easily implemented adaptive nonparametricdetection method is proposed in the paper.In orde to maintain CFAR the weight of the detection rangecell of the detector must be changed by different output values of the IIR filter for measurement of thecorrelation coefficient(p)of the input noise.In this paper the closed form expressions for detectionprobability(P_d)and P_(fa)of the weighted nonparametric detector are derived.The ARE(AsymptoticRelative Efficiency)of the weighted detectors is investigated.In the end the detection performance ofthe adaptive nonparametric detector is determined by Monte Carlo simulation on the digital computer.     

模糊奇异性信号的检测机理

工程实际中一般很难有理想的奇异性信号,它们的奇异性往往表现得很模糊。该文从理论上分析了这种模糊奇异性信号的小波检测机理,证明了小波对模糊奇异性信号的检测相当于用一个新小波对理想奇异性信号进行检测,给出了新小波的生成定义与实例、理想奇异性信号的模糊化模拟与检测实例,也给出了一个工程实际模糊奇异性信号的奇异性检测过程,这些实例结果证明了理论分析的正确性。     

Minimum-time approach to obstacle avoidance constrained by envelope protection for autonomous UAVs

An integrated approach is needed for combining path planning for obstacle avoidance with envelop protection to ensure that a UAV is operated within its safe operational limits while maneuvering in obstacle fields. This paper presents a minimum-time approach to this problem by treating obstacle avoidance and envelope protection as inequality constraints in a state space formulation. The approach is used to study the guidance of a rotary wing UAV for aggressive maneuvering in avoiding an obstacle while staying within its operational envelope. The Nonlinear Trajectory Generator (NTG) is used as a real-time optimization solver, and load factor and rotor flapping angle are considered as limit parameters. A nonlinear simulation model of a rotary wing test bed within the Georgia Tech Unmanned Aerial Vehicle Simulation Tool (GUST) is used to evaluate the proposed approach.     

若干信号处理的总体设计思路

信号处理是目前电子战技术发展的一个关键技术。不能单纯从信号处理本身来考虑如何实现信号处理 ,必须从系统角度设计信号处理 ,同时结合工作实践对信号处理提出一些建议。     

低信噪比图象边缘提取的非线性方法

针对低信噪比图象的边缘提取问题,本文提出了一种非线性方法,即利用大窗口平滑去噪性能强与小窗口提取边缘性能好相结合的方法,此时采取大窗口滤波,小窗口中作非线性的微分算子求导。为了避免求导后阈值选取的盲目性,文中提出了一种噪声引导的阈值确定准则,并根据这个阈值分割图象。在大窗口滤波中,采用了二维卷积等于两个一维卷积级联的技术压缩滤波器的存储空间。最后对这种方法进行了性能评价,并且给出了实验结果。     

A NEW METHOD OF DECONVOLUTION IN THE FREQUENCY DOMAIN

A new deconvolution method has been presented in this paper. Like conventional Discrete Fourier Transform(DFT) method, it is also a frequency domain method. Since there are only DFT, IDFT and multiplication calculations in the new method, the singular problem appeared in the conventional DFT method can be avoid, and the deconvolution problem can always be solved with the new method. The relationship between the presented method and conventional DFT method is discussed. A numerical example is also presented to illustrate the new method.     

基于TMS320VC5402的语音检测器

本文介绍的语音检测器以DSP芯片TMS320VC5402为核心,对短波电台接收到的信号进行分析和处理。数字语音信号采用串行输入／输出方式,语音检测算法则采用对语音信号进行降噪处理后,再进行短时平均幅度差和短时能量计算的方法。该语音检测器的电路简洁小巧,语音检测准确度高。     

A digital predistortion assisted hybrid supply modulator for envelope tracking power amplifiers

In this paper, a novel digital predistortion assisted supply modulator is presented. The proposed modulator is suitable for envelope tracking power amplifiers. In this topology, a digitally controlled linear power amplifier is used to compensate the switching noise ripples of the switching modulator. The proposed structure is evaluated with a 0.18 µm CMOS process technology. The results show up to 9% static efficiency improvement in comparison with previous one-phase and two-phase architectures. It is shown that for a 5 MHz WiMAX signal with a 6.7 dB PAPR at 26.8 dBm output power, a maximum average efficiency of 73.5% is achieved in the proposed design.     

基于光电倍增管的低噪声前置放大器的设计及其信号处理

利用低噪声前置运算放大器把光电倍增管的输出信号尽可能无噪声的放大。从运放的选择,多级放大电路的设计要点,放大电路的噪声估算,PCB板布局连线和屏蔽等方面,提出了实用化的带宽达10 MHz的电路设计形式,以及注意事项及其信号调理方法。仿真结果显示了所设计电路的信号放大情况,此电路设计形式可以很好的放大并处理光电倍增管的输出信号。     

模糊神经网络在火灾探测中的应用

本文提出了串联模糊神经网络应用于火灾探测系统，首先将输入信号模糊化后迭送入神经网络进行处理，其模糊系统用指征定义隶属度函数，神经网络采用三层前馈ＢＰ网络结构，用ＢＰ算法进行网络参数的训练。其后由模糊逻辑判决火灾或非火灾。实验结果表明该网络能够准确探测各种标准试验火并有很强的抗干扰能力。     

一种检测红外点目标的方法

提出了一种用二次阈值检测红外点目标的方法，该方法对于提高红外警戒系统的探测率和控制虚警率具有较好的效果     

基于变参数随机共振和归一化变换的时变信号检测与恢复

非线性随机共振系统具有利用噪声增强微弱信号的能力,为强噪声背景下的信号检测开辟了新的途径。该文提出一种变参数随机共振(VPSR)模型,实现对非周期信号的有效检测、噪声去除和信号恢复。通过以恢复信号的拟合决定系数和互相关系数作为评判标准,研究分析了不同参数变化对系统输出的影响,分析结果表明该模型能有效地从噪声背景中恢复时变信号。该方法拓展了随机共振用于时变信号检测技术的领域,在时变信号检测和处理以及雷达通讯等方向有着一定的潜在应用价值。     

一种频域卷积反演的新方法

本文提出了一种卷积反演的新方法。这种方法也是通过离散傅里叶变换(DFT)在频域实现的,但是避免了通常所用的离散傅里叶变换方法当位于分母位置的信号频谱有零点存在时计算失效的问题。本文讨论了新方法与普通离散傅里叶变换方法之间的关系,并且给出了计算示例。