A new carrier recovery circuit for land mobile satellitecommunication

A DCF (dual carrier filter) reverse-modulation-type carrier recovery circuit is proposed to achieve a low carrier skipping rate and satisfactory phase tracking performance for coherent detection of PSK (phase shift keying) signals in fast Rician fading channels. The proposed scheme employs both narrow and wide bandwidth carrier filters simultaneously for the reverse-modulation-type carrier recovery circuit. It is clarified by computer simulation that the Pe performance of a QPSK (quadriphase shift keying) modem employing the proposed scheme shows an improvement of 1.5 dB in required E_s/N_O at Pe=10⁴ (after Viterbi decoding (R=7/8, K=7), C/M (direct-to-multipath signal power ratio)=10 dB, interleaving size=64×64), compared with conventional coherent detection employing the reverse modulation tank-limiter scheme or the Costas loop scheme     

A new nonlinear capacitance model of millimeter wave power PHEMT for accurate AM/AM-AM/PM simulations

A new one-dimensional (1-D) nonlinear gate-source Cgs and gate-drain Cgd capacitance model designed for power-PHEMT transistors is presented. The capacitance values are extracted from measured [S] parameters, along a load-line corresponding to a power performance of an optimum amplifier design. The reliable resulting model predicts adequate power performances with small or large signals in reduced CPU time. This new model is validated by comparisons between load-pull power measurements at 25.5 GHz and harmonic balance simulations. It reveals good accuracy for AM/AM and AM/PM predictions.     

一种实现非等带宽多载波调制的新方法

传统的多载波调制都是采用对传输信道进行等带宽划分的方式。为了更好地适应信道传输特性，一个很有应用前景的发展方向是采用非等带宽划分信道的多载波调制方式。本文提出了一种利用正交小波包变换实现的非等带宽划分信道的多载波调制方法。理论分析和实验结果表明，这种方法对于提高信道的传输性能有很大的潜力。     

非平稳信号的一种ARMA模型分析方法

该文提出了一种新的非平稳信号的时变参数ARMA模型分析方法,用它分析数据需两个基本步骤:首先,用一种信号分解方法把信号分解成一些基本模式分量。接着,对分解得到的基本模式分量建立时变参数ARMA模型,从而得出时颇平面上的时变参数ARMA模型谱。该方法可用于复杂的非线性、非平稳信号的处理。     

A NEW METHOD OF BISPECTRAL ESTIMATION FOR TRANSIENT SIGNAL

Estimation of model parameter for transient signal is very important in many aspects. This paper presents a new Markov ARMA model Q-slice estimation algorithm for transient signal based on bispectrum. Simulation results show that this new method has some special features, such as higher estimation precision, lower amount of calculation, higher fitting effect even in lower signal-to-noise ratio (SNR) situation.     

A NEW ITERATIVE SIGNAL RESTORATION METHOD

A new iterative method for signal, restoration has been presented. An estimateoperator W_κ which is related to error operator B_κ in the restoration process is introduced todecrease the estimate error and increase the convergence rate. The effect of noise on the estimateprocess has also been described. Finally, the method has been applied to the deconvolution of ablurred signal, and the results validate the method. A comparison between the presented methodand the general method has also been given.     

一种新的跳频信号检测方法

本文针对跳频信号检测的问题,研究并设计了一种新的检测算法.该方法对信道进行由"粗"到"细"的分层检测,降低了很多无谓的资源消耗.文章首先介绍了传统信道化处理的思想并推导出其模型的数学表达式.然后分析了这种模型在跳频信道数较多时难于实现的原因,进而提出分层信道化处理的检测模型.接下来对该模型的运算量进行了推导并与传统结构...     

Resonance-based signal decomposition: A new sparsity-enabled signal analysis method

Numerous signals arising from physiological and physical processes, in addition to being non-stationary, are moreover a mixture of sustained oscillations and non-oscillatory transients that are difficult to disentangle by linear methods. Examples of such signals include speech, biomedical, and geophysical signals. Therefore, this paper describes a new nonlinear signal analysis method based on signal resonance, rather than on frequency or scale, as provided by the Fourier and wavelet transforms. This method expresses a signal as the sum of a ‘high-resonance’ and a ‘low-resonance’ component—a high-resonance component being a signal consisting of multiple simultaneous sustained oscillations; a low-resonance component being a signal consisting of non-oscillatory transients of unspecified shape and duration. The resonance-based signal decomposition algorithm presented in this paper utilizes sparse signal representations, morphological component analysis, and constant-Q (wavelet) transforms with adjustable Q-factor.     

A method for the characterization of p+-n-n+diodes using DC measurements

An experimental technique using only dc terminal measurements with a special set of masks is presented for characterizing device properties of single diffused p⁺-n-n⁺diodes. The vertical and lateral current components are separately obtained. The carrier lifetimes in the epitaxial layer and the p⁺diffusion, and the recombination velocity at the oxide-silicon p⁺interface are experimentally determined. Examples are given and possible sources of errors are discussed.     

多路光信号功率分配与设计新方法

提出了一种基于规格型光二分路器的多路光功率分配方法,将多路分光比的设计及其分路器的制作转化为用各种规格型号的光二分路器的组合实现多路光功率的合理分配.给出了一种新的光二分路器规格表,并通过具体实例详细介绍了这种多路光功率分配的方法和过程.事实证明,该方法具有简单、易行、网络成本造价低、利于网络器件的备用和维修的优点.     

A new method for calculating correction factors for near-field gain measurements

A new method is presented for calculating near-field antenna gain correction factors directly from measured far-field pattern data by using a spherical wave expansion of the pattern. This eliminates the need for any assumptions regarding antenna aperture field distributions. The only significant assumption in the new method is to neglect multiple scattering between the antennas. The method is applied to the case of a horn antenna. Calculated results are compared to direct measured results, demonstrating agreement to within 0.03 dB. The method is also compared to the method of Chu and Semplak, with similar agreement. The sensitivity of the results to truncation error and noise in the data is also investigated and contrasted to sensitivity of prior methods to errors in the assumed field distribution.     

一种新的高灵敏度GPS信号捕获方法

针对全球定位系统(global position system,GPS)信号的高灵敏度捕获问题,提出了一种基于阵列双稳随机共振( stochastic resonance,SR)的GPS信号捕获方法.该方法首先用部分匹配滤波器对GPS信号进行分段相关预处理,并进行二次采样,得到符合阵列双稳SR系统输入要求的信号,然后应...     

一种三维调制信号快速解调新方法

根据三维调制信号的特性,提出了一种新的三维调制信号的快速解调方法。该方法基于MUSIC算法,首先利用单次快拍来建立阵列数据的协方差矩阵,然后根据调制信号的先验信息对所得信号空间谱进行判决,来估计其极化辅角与极化相位角等信息,从而恢复出基带信号。分析与仿真结果表明,所提方法不仅可以避免谱搜索,大大降低MUSIC方法的运算量,而且适用于瞬时信号和快速运动信号的解调。     

Performance capabilities of HBT devices and circuits for satellitecommunication

The heterojunction bipolar transistor (HBT) performance is studied, with emphasis on its possible utilization in satellite power amplifiers. After a review of the requirements of satellite power amplifiers, the suitability of HBTs is discussed in depth, including the output power capabilities, the realizable power-added efficiency and linearity, reliability considerations, and circuit aspects. Models and simulation tools for HBTs in power amplifiers are discussed, and the results obtained so far are given. A comparison of realized HBTs and various FET devices and circuits demonstrates that the HBT is a promising device for applications in satellite power amplifiers. The HBT will be a preferable device for microwave power amplification if the problems concerning the reliability can be solved, and further investigations will be performed to obtain larger devices with higher rated output power     

A new signal processing technique for ISAR ranging: the Vernierranging method

A new technique for inversed synthetic aperture radar (ISAR) ranging, which resembles the principle of the Vernier measuring system, is presented. In this technique, the transmitted ISAR pulse comprises a train of chirp subpulses with uniformly stepped up center frequencies. The return ISAR echo is first processed, using hardware, to determine a coarse estimate of the target range. Further refinements of the range estimate are achieved through software processing, consisting of two stages of discrete Fourier transform operation. The ranging accuracy can be increased without the need for increased bandwidth, but at the expense of a slight increase in computational complexity. Numerical evaluation shows that a noiseless system is capable of achieving high-ranging accuracy, of the order of millimeters, even in the presence of dispersion and target motion. From computer simulations, the proposed system is also found to be robust against additive system noise and frequency jitter under practical conditions     

一种新的去强相关信号方法的波达方向研究

波达方向估计（DOA估计）是智能天线中实现目标精确定位的关键算法。文中针对DOA估计中相干信号源的问题,提出了一种能有效解相关的关于TOPETIZE矩阵的DOA估计算法。该算法利用了阵列接收数据互相关矢量的内在关系,对噪声子空间进行处理,实现了相干源的完全解相干。该算法不牺牲阵元有效数目,同时能分辨低信噪比信号和强相关信号。仿真结果表明了该算法的有效性。     

A new direction-of-arrival estimation method exploiting signal structure information

A new method is proposed to estimate the direction-of-arrival (DOA) based on uniform linear array sampling and named as sparsity and temporal correlation exploiting (SaTC-E). By exploiting the structure information of source signals, including spatial sparsity and temporal correlation of sources, SaTC-E accomplishes DOA estimation with superior performance via block sparse bayesian learning methodology and grid refined strategy. SaTC-E is applicable into time-varying manifold scenario, such as wideband sources, time-varying array, provided that the array manifold matrix is determinable. It has improved performance with some other merits, including superior resolution, requirement for a few snapshots, no knowledge of source number, and applicability to spatially and temporally corrected sources. Real data tests and numerical simulations are carried out to demonstrate the advantages of SaTC-E.     

一种雷达信号综合分选方法研究

为了能够从同时存在常规PRI信号和复杂PRI信号并带有脉冲信号干扰或丢失的环境中正确分选出雷达信号,本文提出了一种序列差值直方图法(SDIF)与修正PRI变换法相结合的雷达信号分选方法,经过matlab仿真验证,该方法有着很好的分选效果。