Impulse response of sinc/sup N/ FIR filters

A simple recurrence formula is presented for computing the impulse response coefficients of the sinc/sup N/ FIR filter, consisting of a cascade of N sinc filters, each of length M. A closed form expression is also given for the first M coefficients.     

Optimum discrete wavelet scaling and its application to delay andDoppler estimation

This paper studies the scaling of an arbitrary waveform from its samples. The scaling problem is formulated as a mean-square minimization, and the resulting estimator consists of two parts: noise filtering and sinc function scaling. Sinc function scaling is a time-dependent process and requires O(N²) operations, where N is the data length. A fast algorithm based on the FFT is proposed to reduce the complexity to O(Nlog₂N). This new algorithm is applied to wideband time delay and Doppler estimation, where the optimum wavelet is one of the received signal samples that has no analytic form. The scaling method is found to be very effective in that the estimation accuracy achieves the Cramer-Rao lower bound (CRLB)     

An analysis of an N-port microstrip planar disk devicewith an arbitrarily located short circuit post of arbitrary radius

An analysis technique is presented which allows the performance of a multiport microstrip planar disk device with an arbitrarily located internal short circuit (S/C) post of arbitrary radius to be predicted. The analysis approach does not rely on the determination of eigenvalues and yields analytical expressions which are ideal for CAD implementation. The technique allows the electromagnetic fields at the periphery of the disk to be dramatically altered by an appropriate choice of post size and offset. Since the operation of N-port devices is dependent on the peripheral fields, this technique offers a potentially very powerful design tool for the production of planar disk devices     

Adaptive subspace detection of extended target in white Gaussian noise using sinc basis

For the high resolution radar (HRR), the problem of detecting the extended target is considered in this paper. Based on a single observation, a new two-step detection based on sparse representation (TSDSR) method is proposed to detect the extended target in the presence of Gaussian noise with unknown covariance. In the new method, the Sinc dictionary is introduced to sparsely represent the high resolution range profile (HRRP). Meanwhile, adaptive subspace pursuit (ASP) is presented to recover the HRRP embedded in the Gaussian noise and estimate the noise covariance matrix. Based on the Sinc dictionary and the estimated noise covariance matrix, one step subspace detector (OSSD) for the first-order Gaussian (FOG) model without secondary data is adopted to realise the extended target detection. Finally, the proposed TSDSR method is applied to raw HRR data. Experimental results demonstrate that HRRPs of different targets can be sparsely represented very well with the Sinc dictionary. Moreover, the new method can estimate the noise power with tiny errors and have a good detection performance.     

FFT快速捕获算法在GPSC／A码与P（Y）码中的应用

一种快速、有效的GPS信号捕获方法是通过在整段数据上并行搜索伪码相位,对一段输入数字中频(IF)序列和一段本地复现伪码序列进行快速傅里叶变换(FFT)运算来实现。分析了用FFT实现循环相关及其在GPS C/A码捕获中的应用,采用整区间相关、扩展复现码折叠、叠加相加和叠加丢弃法实现P(Y)码快速直接捕获,用补零、线性内插、Sinc内插、平均相关和双倍长度补零法解决计算点数问题,用扩展计算点数方法解决由导航数据引起的相位反转、超长序列与短序列进行线形相关运算及用循环相关实现线形相关等应用中的具体问题。     

Hole and electron currents in diffused P+-N-N+diodes and IIL structures

The hole current due to recombination in the N epitaxial layer is calculated and compared to the electron current injected into the diffused P region. A formula is given and results are compared with computed currents for both wide and narrow (e.g., IIL) structures, including heavy doping effects.     

Reconstruction of bandlimited signal with lost samples at itsNyquist rate-the solution to a nonuniform sampling problem

We present a formula for the sample values f(n_j/2W), j=1, ..., N, of a W-bandlimited finite energy signal f in terms of the remaining sample values f(n/2W), n≠n_j, j=1, ..., N, and N sample values f(y_j), j=1, ..., N with y_j≠n/2W, n∈Z but otherwise arbitrarily chosen     

关于电视群信号对光纤副载波调频传输中的信噪比平衡问题的分析

本文对微波副载波用电视群信号调频的光纤传输中的信噪比平衡问题进行了分析,推导出VSB-AM信号在解调后的信噪比表达式,引入了信噪比恶化系数的概念.为了实现多路VSB-AM信号间的信噪比的平衡,相应的微波副载波频偏应有确定的比例关系.     

基于稀疏贝叶斯学习的超材料孔径计算微波成像系统离网格成像方法

基于超材料孔径的计算微波成像可以看作微波压缩感知成像。这种成像方式的成像效果受网格失配误差的严重影响。该文针对超材料孔径计算微波成像系统对2维场景的重构过程进行分析,构建了一种基于Sinc插值函数的2维离网格(Off-grid)观测模型,并在此基础上提出一种基于稀疏贝叶斯学习的Sinc插值离网格成像方法(OGSISBL)。在期望最大化算法的框架下,恢复散射体回波的幅值和位置,同时校准网格失配误差。通过对超材料孔径计算微波成像系统的仿真数据进行成像处理验证所提算法的性能,结果表明所提算法具有很强的鲁棒性。     

A-15型超导体临界温度的新经验公式

正 (一)引言 超导现象早在1911年就发现了,但作为一门新技术应用于不同领域,还只是本世纪60年代以后的事情。但是超导技术在最近十几年内的发展是迅速的。超导体在许多科学领域,特别是在托克马克聚变动力堆和超导输电等电工、电子技术方面已经或将得到应用。因此,超导技术近年来得到各国科学工作者的广泛重视。 临界温度是超导体重要性能之一。关于高温超导体的临界温度的变化规律,已有不     

N_2分子激光器Blumlein电路开路输出电压的研究

解回路微分方程得到了Blumlein电路开路输出电压的表示式,对W.A.Fitzsimmons等给出的Blumlein电路开路输出电压近似式以及《激光器设计基础》的表示式给以补充修正。找出了影响提高器件脉冲峰值功率的电路参数。纠正了文章《N_2分子激光器》的结论,给出了电容器转换电路开路输出电压的表示式。     

m-consecutive-k-out-of-n:F systems

An m-consecutive-k-out-of-n:F system, consists of n components ordered on a line; the system fails if and only if there are at least m nonoverlapping runs of k consecutive failed components. Three theorems concerning such systems are stated and proved. Theorem one is a recursive formula to compute the failure probability of such a system. Theorem two is an exact formula for the failure probability. Theorem three is a limit theorem for the failure probability     

The number of failed components in aconsecutive-k-of-n:F system

For a consecutive-k-out-of-n:F system an exact formula and a recursive relation are presented for the distribution of the number of components, X, that fail at the moment the system fails. X estimates how many cold spares are needed to replace all failed components upon system failure. The exact formula expresses the dependence of the distribution of X upon parameters k , n. The recursive formula is suitable for efficient numerical computation of the distribution of X     

ATSC全数字接收机的符号定时同步方法

描述了以8-ASK作为调制方式的ATSC全数字接收机解调中定时同步问题的解决方法:通过采用基于Farrow结构的sinc()响应FIR,Gardner算法的定时误差检测方法,实现了符号同步.Matlab仿真表明,Gardner算法适用于ATSC接收机的符号同步设计.     

Further Formulas for Calculating Approximate Values of the Zeros of Certain Combinations of Bessel Functions (Correspondence)

In a recent letter Gunston has presented a wonderfully simple approximate formula for the smallest z zero of the Bessel function equation J/sub p/(z) N/sub p/ (kz) - J/sub p/(kz)N/sub p/(z) =0(1) where J/sub p/ and N/sub p/ are, respectively, the Bessel functions of the first and second kinds of real-order p. This communication is intended to draw attention to the existence of similar approximate formulas for both the larger z zeros of (1) and the roots of the equally-important companion equationJ'/spl/sub p/(z) N'/sub p/ (kz) - J'/sub p/(kz)N'/sub p/(z) =0 (2) where ' indicates differentiation.     

Waiting time distribution in M/D/1 queueing systems

The well-known formula for the waiting time distribution of M/D/1 queueing systems is numerically unsuitable when the load is close to 1.0 and/or the results for a large waiting time are required. An algorithm for any load and waiting time is presented, based on the state probabilities of M/D/1. The principles are also applicable for other queueing systems     

Effect of the composition on the electrical properties of TaSi/sub x/N/sub y/ metal gate electrodes

In this letter, the effect of silicon and nitrogen on the electrical properties of TaSi/sub x/N/sub y/ gate electrode were investigated. The TaSi/sub x/N/sub y/ films were deposited on SiO/sub 2/ using reactive cosputtering of Ta and Si target in Ar and N/sub 2/ ambient. The thermal stability of TaSi/sub x/N/sub y//SiO/sub 2//p-type Si stacks was evaluated by measuring the flatband voltage and equivalent oxide thickness at 400/spl deg/C and 900/spl deg/C in Ar. It was found that under high temperature anneals, Si-rich TaSi/sub x/N/sub y/ films increased and this was attributed to the formation of a reaction layer at the electrode-dielectric interface. Reducing the Si content alone did not prevent the formation of this reaction layer while removing Si completely by utilizing TaN resulted in work functions that were too high. The presence of both Si and N was deemed necessary and their content was critical in obtaining optimized TaSi/sub x/N/sub y/ gates that are suitable for NMOS devices.     

Plasma display panel with Ne+N/sub 2/ gas-mixture discharges

The discharge characteristics of Ne+N/sub 2/ gas-mixtures were investigated for possible use in an AC Plasma Display Panel (PDP). The firing voltage increased with an increase in the N/sub 2/ concentration. When using a near ultra violet excited phosphor, (Ba,Sr)/sub 2/ SiO/sub 4/:Eu, the luminous efficiency of Ne+10% N/sub 2/ gas-mixture discharges under 400 torr was about 20% better than when using the conventional phosphor. The UV intensity emitted from the gas discharges was found to increase with an increased N/sub 2/ concentration. Furthermore, the UV efficiency increased with an increase in the N/sub 2/ partial pressure at a low N/sub 2/ concentration, yet became saturated at a high N/sub 2/ concentration.     

Equivalent capacity for on/off sources in ATM

A formula is presented for the `equivalent capacity' required to support a given cell loss probability in an ATM buffer fed by a single on/off source. This formula can be applied as a component in connection admission control and bandwidth management algorithms in ATM telecommunications networks     

Characteristics of the Schottky barriers of two-terminal thin-film Al/nano-Si film/ITO structures

The temperature dependence of the Schottky-barrier height and series resistance of two-terminal thin-film Al/nano-Si film/ITO structures are determined from the current—voltage (I–V) characteristics in the temperature range of 20–150°C. It is found that the form of the I–V characteristic at all investigated temperatures can be described by a model of two Schottky diodes connected back-to-back. For these diodes, the general formula is obtained, which allows the construction of functions approximating experimental curves with high accuracy. Based on this formula, a computational model is built, which generalizes the theoretical data obtained by S.K. Cheung and N.W. Cheung widely used for analyzing the I–V characteristics of single Schottky diodes. A technique is developed for calculating the Schottky-barrier heights in a system of two Schottky diodes connected back-to-back, their ideality factors, and the series resistance of the system. It is established that the barrier heights in the investigated temperature range are ~1 eV. According to the temperature dependence of the barrier height, such large values result from the presence of a SiO _x (0 ≤ x ≤ 2) oxide layer at the nanoparticle boundaries. Charge carriers can overcome this layer by means of thermal excitation or tunneling. It is established that the intrinsic Schottky-barrier height of the Al/nc-Si film and nc-Si film/ITO junctions is ~0.1 eV. The activation dependences of the series resistance of the Al/nc-Si film/ITO structures and impedance spectra show that combined electric-charge transport related to ionic and electronic conductivity takes place in the structures under study. It is shown that the contribution of the electronic conductivity to the total transport process increases as the sample temperature is raised.