Optimal components selection for active filter design with average differential evolution algorithm

Component selection in electronic circuit design is an important issue to achieve a targeted performance and quality level. Particularly in filter circuits, changes in gain and phase response of the circuit are directly dependent on the component values of the filter. Therefore, the selection of component values must be done carefully. In this article, a differential evolution (DE) algorithm with a new mutation strategy, named as average DE (ADE), is introduced for analog active filter design. The ADE algorithm minimizes the total design error of the state variable filter (SVF) for the optimal selection of component values. Simulation results indicate that the proposed algorithm reduces the design error when compared to other methods.     

Optimal and self-tuning deconvolution in time domain

This paper is concerned with both the optimal (minimum mean square error variance) and self-tuning deconvolution problems for discrete-time systems. When the signal model, measurement model, and noise statistics are known, a novel approach for the design of the optimal deconvolution filter, predictor, and smoother is proposed based on projection theory and innovation analysis in the time domain. The estimators are given in terms of an autoregressive moving average (ARMA) innovation model and one unilateral linear polynomial equation, where the ARMA innovation model is obtained by performing one spectral factorization. A self-tuning scheme can be incorporated when the noise statistics, the input model, and/or colored noise model are unknown. The self-tuning estimator is designed by identifying two ARMA innovation models     

基于自适应卡尔曼的时域增强算法研究

在图像序列进行压缩感知重构的过程中,基于运动补偿的分块压缩感知重建算法利用了帧间残差图像的稀疏特性,有效提高了重构视频的质量。但该算法仅在空域对图像进行了维纳滤波,帧间存在抖动现象,视频主观质量较差。文章将自适应卡尔曼滤波算法应用到分块压缩感知重建算法的重建过程中,可以有效地去除视频帧间的噪声,使得图像的主观质量得到了改善。     

A definition of average time delay for a linear system

A definition is formulated for average time delay in a linear system having a nonlinear phase characteristic. The concept is based upon the determination of the time delay which minimizes the mean-square error between input and output signals.     

基于子波滤波的并行分布式检测融合算法分析

将软阈值决策子波域滤波算法与多传感器并行分布式检测融合系统有机地结合在一起,提出了多传感器并行分布式检测系统在Neyman-Pearson(N-P)准则下融合规则和局部判决规则之间相互关系的理论分析方法,完整地给出了两种次最佳系统和全局最佳系统判决规则的理论推导,并藉此理论对以上3种系统进行了瑞利噪声环境下的仿真,结果表明子波域滤波算法和多传感器并行分布式检测融合系统的同时引入明显提高了雷达探测系统的检测性能。     

Hardware implementation of a spatio-temporal average filter for real-time denoising of fluoroscopic images

An electronic system for the real-time denoising of fluoroscopic images is proposed in this paper. Fluoroscopic devices use X-rays to obtain real-time moving images of patients and support many surgical interventions and a variety of diagnostic procedures. In order to avoid risks for the patient, X-ray intensity has to be kept acceptably low during the clinical applications. This implies that fluoroscopic images are corrupted by large quantum noise (Poisson-distributed). Real-time noise reduction can offer a better visual perception to doctors and possible further reductions of the dose.The proposed circuit implements a spatio-temporal filter optimized for the removal of the quantum noise while preserving video edges and the prompt response of the image to the introduction of new features in the field. The filter incorporates information on the dependence of the standard deviation of the noise on the local brightness of the image and performs a conditioned average operation.The proposed circuit is implemented on FPGA (Field Programmable Gate Array) device allowing the real time elaboration of video streams composed by frames with 1024×1024 pixel and uses an external DDR2 (Double Data Rate 2) memory for the storage and the reuse of the fluoroscopic frames needed by the filter.When implemented on StratixIV-GX70 FPGA the circuit is able to process up to 49 fps (frames per second) while using 80% of the logic resources of the FPGA.     

Mixed-integrator-based bi-quad cell for designing a continuous time filter

A new mixed-integrator-based bi-quad cell is proposed. An alternative synthesis mechanism of complex poles is proposed compared with source-follower-based bi-quad cells which is designed applying the positive feedback technique. Using the negative feedback technique to combine different integrators, the proposed bi-quad cell synthesizes complex poles for designing a continuous time filter. It exhibits various advantages including compact topology, high gain, no parasitic pole, no CMFB circuit, and high capability. The fourth-order Butterworth lowpass filter using the proposed cells has been fabricated in 0.18 μm CMOS technology. The active area occupied by the filter with test buffer is only 200×170 μm2. The proposed filter consumes a low power of 201 μW and achieves a 68.5 dB dynamic range.     

用于设计连续时间滤波器的基于混合积分器的双二阶单元

摘要：提出了一种新型基于混合积分器的双二阶单元。与基于源极跟随器的双二阶单元采用正反馈综合复数极点相比,本文提出了另一种综合复数极点的机制。提出的双二阶单元采用负反馈结合不同类型积分器综合复数极点,用于设计连续时滤波器。该单元包括许多优点：电路结构简单、高增益、无寄生极点、不需要共模反馈电路和大的驱动能力。在0.18 μm CMOS 工艺上采用提出的双二阶单元实现了一个4阶巴特沃斯低通滤波器。滤波器包括测试缓冲器有源面积仅为200×170µm。提出的滤波器消耗201µW功耗,获得51dB动态范围。     

一种在时域调谐带通滤波器的新方法

文章介绍了一种基于滤波器S11响应的时域分析的调谐方法。这种方法可以区分谐振器和耦合孔各自产生的时域响应，可以用来指导调节谐振器和耦合系数，得到所需的滤波器响应。通过这种方法还可以观察滤波器内部各元件间是如何相互作用的。     

A new interpretation of the average matched filter for MSK-typereceivers

The minimum-mean-square-error approximation to a generalized minimum-shift-keying (MSK) signal using an offset quadrature phase-shift keying waveform with an elementary pulse, g(t), is considered. It is shown that the optimum shape of G(t), γ(t), coincides with the average pulse of the generalized MSK signal. Therefore, γ(-t) is the impulse response of the corresponding average matched fiber     

Moving average filter for spur reduction in subsampling fractional PLLs

A mono-bit digital receiver circuit for instantaneous frequency measurement is presented. The circuit is co-designed with Indium Phosphide Double Heterojunction Bipolar Transistor and complementary metal oxide semiconductor (CMOS) devices. The chip is fabricated by InP/CMOS three-dimensional (3D) heterogeneous integration using the wafer-level bonding technique. The measurable signal frequency within?+?15 to???25 dBm power is up to 7.5 GHz with a 14-GHz clock. Compared to an integrated circuit (IC) with a traditional InP or CMOS technologies, the proposed chip could benefit from both InP and CMOS technology. In the heterogeneous integration, InP devices provide high operating frequency, broad signal bandwidth, and large input signal dynamic range, while CMOS devices achieve complex function with low power consumption. In this way, the system FoM is improved for a mono-bit digital receiver while the system power consumption is kept the same. This work also shows the great potential of the 3D heterogeneous integration for the high-performance mixed-signal and multifunction radio-frequency ICs.

     

Calculation of the average average reframing time for digital transmission systems employing a 1-frame-delay method of reframing

This letter develops a method for calculating the time taken to restore synchronism of a digital transmission system with backward-acting framing by digital signals of periodic pattern interleaved among the transmitted data. An equation for the average average reframing time gives predictions in good agreement with experiment.     

An information flow technique for category related evokedpotentials

We report a technique for studying interactions among many subsystems of a biological system. A general mathematical technique is developed for information flow among various subsystems of a system when two or more classes of stimuli are presented to the system. The technique is validated by various simulation studies and then applied to a brain system. The usefulness of the technique is demonstrated for visual event related potentials (ERP's) obtained from human subjects suffering from phobias. The stimuli are briefly flashed words and phrases. The word classes are pleasant, unpleasant, conscious, and unconscious. The conscious class consists of words known by the patient to relate to the problem, whereas the unconscious class of words consists of words related to deep conflicts which are not recognized by the patient. It is demonstrated that information flow is suppressed under supraliminal presentation of the unconscious class, but is strong under subliminal presentation. The technique has the potential of being an objective indicator of conflictual relationships in these patients. The principle of the technique can be applied to any system in which interactions among subsystems are to be analyzed.     

Estimation of average survival time of a process having an exponential lifetime model for time censored data

Censoring is almost mandatory, especially in dealing with costly sophisticated items in a life testing experiment. Assuming the survival times to be distributed exponentially with two parameters we have proposed an estimator using a preliminary test of significance for the estimation of average survival time of the time censored life data. The bias and mean square error of the proposed estimator have been studied. Based on some mathematical results and an empirical study, recommendations have been made regarding the use of proposed estimator.     

F&H filter: a novel ultra-low power discrete time filter

A new technique for designing filters with long time constants in the discrete time domain is presented. The F&H (filter and hold) methodology halts the state of a continuous time filter every T seconds resulting in a filter implementation with time constants that can be controlled in three distinct ways: by the sampling period T, the duty cycle k=τ/T or the time constant of the continuous time filter prototype. The final filter can be constructed from a typical Gm-C technique with very low power consumption     

Lifting-based wavelet domain adaptive Wiener filter for image enhancement

A method of applying lifting-based wavelet domain Wiener filter (LBWDMF) in image enhancement is proposed. Lifting schemes have emerged as a powerful method for implementing biorthogonal wavelet filters. They exploit the similarity of the filter coefficients between the low-pass and high-pass filters to provide a higher speed of execution, compared to classical wavelet transforms. LBWDMF not only helps in reducing the number of computations but also achieves lossy to lossless performance with finite precision. The proposed method utilises the multi-scale characteristics of the wavelet transform and the local statistics of each subband. The proposed method transforms an image into the wavelet domain using lifting-based wavelet filters and then applies a Wiener filter in the wavelet domain and finally transforms the result into the spatial domain. When the peak signal-to-noise ratio (PSNR) is low, transforming an image to the lifting-based wavelet domain and applying the Wiener filter in the wavelet domain produces better results than directly applying Wiener filter in spatial domain. In other words each subband is processed independently in the wavelet domain by a Wiener filter. Moreover, in order to validate the effectiveness of the proposed method the result obtained using the proposed method is compared to those using the spatial domain Wiener filter (SDWF) and classical wavelet domain Wiener filter (CWDWF). Experimental results show that the proposed method has better performance over SDWF and CWDWF both visually and in terms of PSNR.     

Optimal filter banks for signal reconstruction from noisy subbandcomponents

Conventional design techniques for analysis and synthesis filters in subband processing applications guarantee perfect reconstruction of the original signal from its subband components. The resulting filters, however, lose their optimality when additive noise due, for example, to signal quantization, disturbs the subband sequences. We propose filter design techniques that minimize the reconstruction mean squared error (MSE) taking into account the second order statistics of signals and noise in the case of either stochastic or deterministic signals. A novel recursive, pseudo-adaptive algorithm is proposed for efficient design of these filters. Analysis and derivations are extended to 2-D signals and filters using powerful Kronecker product notation. A prototype application of the proposed ideas in subband coding is presented. Simulations illustrate the superior performance of the proposed filter banks versus conventional perfect reconstruction filters in the presence of additive subband noise     

A time domain method for producing pulse compression in a plasma

The propagation of a rectangular envelope RF pulse in a lossless homogeneous isotropic plasma is considered. It is desired to produce pulse enhancement by an appropriate choice of the phase variation. A time domain technique is developed for choosing the phase. The resulting enhancement is greater than that reported previously.     

Transform domain adaptive linear phase filter

Describes a new adaptive linear-phase filter whose weights are updated by the normalized least-mean-square (LMS) algorithm in the transform domain. This algorithm provides a faster convergence rate compared with the time domain linear phase LMS algorithm. Various real-valued orthogonal transforms are investigated such as the discrete cosine transform (DCT), discrete Hartley transform (DHT), and power of two (PO2) transform, etc. By using the symmetry property of the transform matrix, an efficient implementation structure is proposed. A system identification example is presented to demonstrate its performance