一种用于数字D类功放的伪自然采样算法

该文针对均匀采样脉冲宽度调制(UPWM)型数字D类功放,提出了一种新的伪自然采样算法以校正其在开关信号调制时产生的谐波失真。该算法融合了三阶和一阶拉格朗日插值法,并结合伪自然采样点位置判断法而形成,可在计算复杂度较低的同时,达到较好的谐波失真校正效果。该文使用FPGA搭建了一个基于该算法以及其它同类算法的开关信号调制器测试系统。测试结果表明,相比同类算法,该算法基本消除了谐波失真且硬件消耗适中,显示了更大的优越性。     

用于数字D类放大器的双边PWM调制模块

文中介绍了一种双边PWM调制的数字D类放大器调制模块,使用伪自然采样法消除谐波失真。该伪采样算法是将牛顿-拉夫森迭代法和多项式逼近法相结合而形成的。近年来,虽有较多关于前沿PWM调制（LEPWM）和后沿PWM调制（TEPWM）的数字D类放大器的文献,但基于双边PWM（DEPWM）调制的数字 D类放大器方面的文献较少。因此本文利用现有的噪声整形技术,基于牛顿-拉夫森迭代法的伪采样算法等实现了一种用于数字D类放大器的双边PWM调制模块,并使用FPGA搭建了一个24位立体声数字音频D类放大器调制系统。经测试,该调制系统THD＋N@6 kHz性能达到-80.5 dB。     

基于软采样的电网谐波检测算法及其实现

讨论了电网谐波检测算法的原理;研究了用于减小同步采样误差的线性内插软同步采样法,并以MCS-51单片机为核心设计实现了该谐波检测算法;实验数据表明,软采样可有效提高谐波检测精度.     

二维双原型完全过采样DFT调制滤波器组的快速设计方法

传统的2维大规模滤波器组的设计方法具有复杂度高的缺点。该文提出一种设计2维双原型滤波器组的快速方法,该方法利用近似完全重构的条件,并采用完全过采样的离散傅里叶变换(DFT)调制滤波器组来设计。新算法将两个原型滤波器的设计问题归结为一个无约束优化问题,其中目标函数为滤波器组的总体失真(传递失真和混叠失真)与原型滤波器阻带能量的加权和,利用目标函数的梯度向量,通过双迭代机制求解该优化问题。单步迭代中,利用矩阵求逆的等效条件和块Toeplitz矩阵求逆的快速算法,显著地降低了计算复杂度。理论分析和数值实验表明,新算法可以得到整体性能更好的滤波器组,计算复杂度大幅度降低,故可以快速设计大规模的2维滤波器组。     

一个带有采样时间误差校正的14位200MS/s时钟交织模数转换器

通道间的采样时间误差会降低时钟交织模数转换器的精度。本论文提出了一种针对采样时间误差的具有低电路复杂度和快速收敛特性的校正算法。该算法基于相关性来探测采样时间误差,并可被应用于广义平稳的输入信号,被探测到的采样时间误差被一个压控采样开关修正。实验结果显示,对于一个2通道14位200MS/s的时钟交织模数转换器,当输入信号的频率为70.12MHz时,经校正后,信号与噪声失真比改善了19.1dB,无杂散动态范围改善了34.6dB。校正的收敛时间约为20000个采样时间间隔。     

基于DSP的ADC模块采样校正算法的研究

文章设计了一种基于TMS320F2812的ADC采样校正算法,先介绍了ADC的采样原理以及采样校正技术,之后设计了一种将多次求平均值滤波算法与增益系数和偏移量相结合的新算法,以此来校正其他通道的采样数据。此算法简洁高效,可以很好地提高ADC的采样精度。     

一种减少频谱泄露的幅值和相位自校正算法

频谱泄露是影响谐波检测和频谱分析的重要原因,而采样频率与信号频率不同步是造成频谱泄露的根本原因。现提出一种幅值和相位自校正的算法,可通过自动校正减小异步采样时DFT产生的幅值和相位的误差,降低频谱泄露造成的影响,对同步采样条件下的DFT没有影响,并给出算法的实现步骤和仿真结果,证明了该算法能精确地得到信号的实际幅值和相位,对于采样点数较少的信号也能给出较高的测量精度,而且该算法具有迭代特性,原理简单,是频谱分析中的一种有效方法。     

一种改进的快速粒子滤波方法

现行的粒子滤波基本算法存在采样过程的计算复杂度高的问题,而且为避免样本枯竭而采用重采样的改进算法也增大了计算量,本文提出了替代重采样的快速粒子滤波方法,通过建立适合的充分统计量函数逼近后验概率密度,进行迭代更新的方法避免了重采样过程,有效地减小了计算量,有利于算法的快速实现。通过对非线性系统中状态和参数的联合估计问题的仿真,结果验证了本文方法的有效性。     

基于采样窗的非均匀路面图像校正算法

针对传统的灰度校正方法不能有效地校正全局光照不均匀的路面图像,提出基于采样窗的路面图像光照不均匀校正算法.算法根据路面图像相邻像素的相关性以及非均匀成像原理,利用图像的均值和残差计算某点的背景灰度因子,利用像素点的线性变换方法求出校正后的图像.仿真实验证实,该算法能有效地减少图像的光照不均匀,达到校正图像的目的.     

基于可变速率采样的SPWM算法设计及实现

SPWM调制是提高逆变电源电压利用率和减少谐波分量的重要方法。文章依据正弦信号的波形特点,从采样速率转换时刻的确定、采样速率的选择及脉冲换相点的计算等方面详细讨论了可变速率采样的SPWM算法原理和参数选择。最后给出采用STC12C5410AD系列单片机的软、硬件实现。     

Time domain comparison of pulse-width modulation schemes

This paper shows that classical space vector modulation (SVM) is functionally identical to double-sided uniform-sampled pulse width modulation (UPWM). Consequently, direct conclusions about harmonic distortion, losses, DC bus utilization, and ease of implementation are made that clarify some existing misconceptions about SVM. Since UPWM is conceptually simple and involves few steps, it is possible that computation may be reduced in practice. UPWM algorithms can avoid the sector and switch sequence tracking tasks in an SVM algorithm. The linear modulation range extension "inherent" to SVM is associated with triplen harmonic injection, and does not provide advantages over conventional third-harmonic injection techniques. The equivalence of SVM and UPWM means that SVM has spectral distortion in baseband as is known to occur in UPWM. This has implications for naturally-sampled sine-triangle PWM (NPWM)-which is known not to generate baseband distortion.     

航空交流电源畸变系数测试方法研究

为了有效的测量航空交流电源的畸变系数,文中提出了新的测量航空电源交流电压畸变系数的方法。通过对采样得到的三相电压数据进行基于FFT和IFFT的改进算法的分析运算,将电压的基波分量与谐波分量(包括整数次谐波分量和非整数次谐波分量)进行分离和提取,进而通过算法计算得到交流电压的畸变系数,设计验证算法。仿真和实验结果表明本文的方法具有测量精度高、效率高和实时性好的特点,且已应用于航空电源的测试系统中。     

Numerical analysis of nonlinear small-signal distortion in p-n structures

A numerical method is presented to derive the non-linear distortion of small ac signals in one-dimensional semiconducting diodes from the basic physical equations. The nonlinear input-output relations are obtained in terms of Volterra functional series. The application of this method is illustrated by computational results showing the influence of injection level on harmonic distortion and cross-modulation in p-i-n diodes. Computed values of cross-modulation are compared with measurements.     

A power supply error correction method for single-ended digital audio class D amplifiers

In single-ended digital audio class D amplifiers (CDAs), the errors caused by power supply noise in the power stages degrade the output performance seriously. In this article, a novel power supply error correction method is proposed. This method introduces the power supply noise of the power stage into the digital signal processing block and builds a power supply error corrector between the interpolation filter and the uniform-sampling pulse width modulation (UPWM) lineariser to pre-correct the power supply error in the single-ended digital audio CDA. The theoretical analysis and implementation of the method are also presented. To verify the effectiveness of the method, a two-channel single-ended digital audio CDA with different power supply error correction methods is designed, simulated, implemented and tested. The simulation and test results obtained show that the method can greatly reduce the error caused by the power supply noise with low hardware cost, and that the CDA with the proposed method can achieve a total harmonic distortion + noise (THD + N) of 0.058% for a –3 dBFS, 1 kHz input when a 55 V linear unregulated direct current (DC) power supply (with the –51 dBFS, 100 Hz power supply noise) is used in the power stages.     

Correction of timing mismatches between two chan-nels for photonic analog-to-digital converters

This paper presents a scheme to identify and compensate the timing mismatches between two channels for time interleaved photonic analog-to-digital converters (TIPADCs). The impact of electro-optic sampling is removed by preprocessing firstly. Then a calibration method combining chopping processing and a Hilbert transform is proposed to identify the timing mismatches, which can be further compensated by using various mature compensation algorithms. The principle of the proposed method is derived theoretically. The performance of the scheme is analyzed by simulation. The results show that the harmonic induced by timing mismatches can be suppressed by more than 30 dB using the proposed correction scheme.     

单周期控制三相VIENNA整流器

电网谐波污染已经引起世界各国的高度重视,功率因数校正（PFC）是治理谐波的一种有效方法。文章对基于单周期控制的三相VIENNA整流器进行了研究,推导了单周期控制三相VIENNA整流器的控制规律,与其它控制方案相比不需要乘法器,不需对电源电压进行检测,控制逻辑比较简单并且以恒定开关频率工作,能够实现单位功率因数校正和低电流畸变。仿真结果验证了理论分析的正确性。     

Fast multiresolution motion estimation algorithms for wavelet-based scalable video coding

Motion estimation and compensation in wavelet domain have received much attention recently. To overcome the inefficiency of motion estimation in critically sampled wavelet domain, the low-band-shift (LBS) method and the complete-to-overcomplete discrete wavelet transform (CODWT) method are proposed for motion estimation in shift-invariant wavelet domain. However, a major disadvantage of these methods is the computational complexity. Although the CODWT method has reduced the computational complexity by skipping the inverse wavelet transform and making the direct link between the critically sampled subbands and the shift-invariant subbands, the full search algorithm (FSA) increases it. In this paper, we proposed two fast multiresolution motion estimation algorithms in shift-invariant wavelet domain: one is the wavelet matching error characteristic based partial distortion search (WMEC-PDS) algorithm, which improves computational efficiency of conventional partial distortion search algorithms while keeping the same estimate accuracy as the FSA; another is the anisotropic double cross search (ADCS) algorithm using multiresolution-spatio-temporal context, which provides a significantly computational load reduction while only introducing negligible distortion compared with the FSA. Due to the multiresolution nature, both the proposed approaches can be applied to wavelet-based scalable video coding. Experimental results show the superiority of the proposed fast motion estimation algorithms against other fast algorithms in terms of speed-up and quality.     

基于定标的红外焦平面非均匀性校正算法研究

红外焦平面阵列普遍存在非均匀性,这会严重影响其成像质量。基于定标的非均匀性校正算法因其易于硬件实现,在工程应用中已被广泛采用。本文介绍了近年来基于定标的非均匀性校正算法的研究进展,对各种算法的优势及缺点进行了对比,并针对算法特点和工程需求做出了相应的分析。     

光纤干涉传感器相位生成载波解调算法研究

为了解决传统的相位生成载波解调算法中由调制深度漂移引起的解调结果失真现象,采用微分交叉相除的信号解调方法进行了相关的理论分析及仿真验证,得到了一种不受调制深度限制的高性能相位生成载波解调方案.结果表明,在采用不同幅值和频率的待测信号进行仿真时,改进算法的解调性能始终十分优异;且当调制深度的值为典型值2.63rad和2....