Performance analysis of an all-digital BPSK direct-sequence spread-spectrum

Performance analysis of an all-digital BPSK direct-sequence spread-spectrum IF receiver architecture1993.pdf

jquery api ui 设计

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Android中文API.chm

Android中文API合集（6） Android中文翻译组

Time Domain and Frequency Spectrum Analysis

This paper introduces an approach for drill wear detection. Tool failure in machining processes will result in damages to workpiece. In this approach sound signal of drilling operation is recorded and analyzed in both time and frequency domains. Trend of sound signal statistical features are extracted as the drill becomes worn. Sound signal frequency spectrum is calculated using Fast Fourier Transform (FFT) to detect the effect of drill wear on frequency components of signal. In continue Wavelet Packet Decomposition (WPD) is implemented to focus on detected frequency bands. Finally a Feedforward Backpropagation Neural Network (FBNN) is designed and trained based on sound signal features extracted from wavelet packets. The FBNN classifies the tool state into three classes of wear. This approach provides a tool wear detection strategy with capability of online implementation.

Analysis of Time Series Structure:SSA and Related Techniques

<<Analysis of Time Series Structure:SSA and Related TechniquesN>>为N. Golyandina, V. Nekrutkin, and A. ZhigljavskyGolyandina,所著。本书为一完整籍PDF文档，共记310页，是奇异分析学习的最原始、最权威的教材。

英文原版-Autism Spectrum Disorders 4th Edition

The fourth edition of Autism Spectrum Disorders: Identification, Education, and Treatment continues the mission of its predecessors: to present a comprehensive, readable, and up-to-date overview of the field of autism; one that links research, theory, and practice in ways that are accessible to students, practitioners, and parents. During the last decade, autism spectrum disorders (ASD) have emerged as the fastest growing developmental disability, and, in response to the dramatic increase in diagnoses, diagnostic criteria in the newly published DSM-5 are significantly different than they were in the DSM IV-R. The structure, content, and format of Autism Spectrum Disorders, 4th Edition have been revised to accommodate changes in the field and to illuminate the current state of the art in the study of autism. New information on early identification, transition education from adolescence through to adulthood, neurobiological research, and technology-based solutions is included.,解压密码 share.weimo.info

Some properties of the Logistic map over the finite field and its application

The Logistic map is a classical chaotic system and has been used as a chaotic cipher in the real number field. This inevitably leads to the degradation of finite precision under the computer environment, and it also is very difficult to guarantee the security of the cryptosystem using the Logistic map over the real number field. To overcome these drawbacks, in this paper, we extend the Logistic map-3 to the finite field Z 3 n , and give theoretical analysis about some period properties of the Logistic map-3 over Z 3 n . Moreover, we discuss the control parameters which can change the behavior of the mapping, and also find that the maximum period can change with the control parameter. Furthermore, we analyze some characteristics including maximum period, generation time, NIST test, power spectrum, correlation property, phase diagram and Lyapunov exponent. Simulation results show that the period of Logistic map-3 over Z 3 n is longer than Logistic map-1 over Z 3 n , and much longer than Logistic map-1 over Z 2 n , and the same as Logistic map-2 over Z 3 n . Simulation experiments also show that the Logistic map-3 over the finite field has some good features including non-periodic, random, noise-like properties, continuous spectrum, good correlation, well uniform distribution, controllable length of generated sequence, positive Lyapunov exponent, and good sequence generation speed. Therefore, we attempt to design a nonlinear transformation based key stream generator by using the Logistic map-3 over Z 3 n and apply to image encryption. The performance analyses including statistical analysis, Shannon entropy analysis, differential attack analysis, and speed analysis also show that our proposed method may be suitable for practical cryptographic application

THE LAPLACIAN SPECTRUM OF GRAPHS.pdf

The paper is essentially a survey of known results about the spectrum of the Laplacian matrix of graphs with special emphasis on the second smallest Laplacian eigenvalue λ 2 and its relation to numerous graph invariants, including connectivity, expanding properties, isoperimetric number, maximum cut, independence number, genus, diameter, mean distance, and bandwidth-type parameters of a graph. Some new results and generalizations are added.

Acquisition Time Performance of PN Spread-Spectrum Systems_Holmes1977

Acquisition Time Performance of PN Spread-Spectrum Systems_Holmes1977

On the Law of Distribution of Energy in the Normal Spectrum

普朗克1901年写的关于量子力学的经典论文，7页却具有划时代的意义

Fundamentals of Spread Spectrum Modulation

扩频调制 This lecture covers the fundamentals of spread spectrum modulation, which can be defined as any modulation technique that requires a transmission bandwidth much greater than the modulating signal bandwidth, independently of the bandwidth of the modulating signal. After reviewing basic digital modulation techniques, the principal forms of spread spectrum modulation are described. One of the most important components of a spread spectrum system is the spreading code, and several types and their characteristics are described. The most essential operation required at the receiver in a spread spectrum system is the code synchronization, which is usually broken down into the operations of acquisition and tracking. Means for performing these operations are discussed next. Finally, the performance of spread spectrum systems is of fundamental interest and the effect of jamming is considered, both without and with the use of forward error correction coding. The presentation ends with consideration of spread spectrum systems in the presence of other users

second simulation of satellite signal in the solar spectrum

this code predicts the satellite signal from 0.25 to 4.0 microns assuming cloudless atmosphere.the main atmospheric effects (gaseous absorption by water vapor,carbon dioxyde,oxygen and ozone; cattering by molecules and aerosols) are taken into account. non-uniform surfaces may be considered,as well as bidirectional reflectances as boundary conditions . the following input parameters are needed geometrical conditions,atmospheric model for gaseous components, aerosol model (type and concentration), spectral condition , ground reflectance (type and spectral var.), at each step, you can either select some proposed standard conditions (for example,spectral bands of satellite for spectral conditions) or define your own conditions(in the example,you have to define the assumed spectral response).

CSS 2.0样式表中文手册

CSS 2.0样式表中文手册

英文原版-Spectrum Sharing in Wireless Networks 1st Edition

Spectrum Sharing in Wireless Networks: Fairness, Efficiency, and Security provides a broad overview of wireless network spectrum sharing in seven distinct sections: The first section examines the big picture and basic principles, explaining the concepts of spectrum sharing, hardware/software function requirements for efficient sharing, and future trends of sharing strategies.The second section contains more than 10 chapters that discuss differing approaches to efficient spectrum sharing. The authors introduce a new coexistence and sharing scheme for multi-hop networks, describe the space-time sharing concept, introduce LTE-U, and examine sharing in broadcast and unicast environments. They then talk about different cooperation strategies to achieve mutual benefits for primary users (PU) and secondary users (SU), discuss protocols in a spectrum sharing context, and provide different game theory models between PUs and SUs.The third section explains how to model the interactions of PUs and SUs, using an efficient calculation method to determine spectrum availability. Additionally, this section explains how to use scheduling models to achieve efficient SU traffic delivery. The subject of the fourth section is MIMO-oriented design. It focuses on how directional antennas and MIMO antennas greatly enhance wireless network performance. The authors include a few chapters on capacity/rate calculations as well as beamforming issues under MIMO antennas.Power control is covered in the fifth section which also describes the interference-aware power allocation schemes among cognitive radio users and the power control schemes in cognitive radios. The sixth section provides a comprehensive look at security issues, including different types of spectrum sharing attacks and threats as well as corresponding countermeasure schemes. The seventh and final section covers issues pertaining to military applications and examines how the military task protects its data flows when sharing the spectrum with civilian applications.,解压密码 share.weimo.info

Second Simulation of the Satellite Signal in the Solar Spectrum使用手册翻译

以下手册介绍了6S（在太阳光谱中卫星信号的二次模拟），一个能够上述问题模拟的代码。6S代码是由Laboratoire OPTIQUE Atmospherique 10年前开发的5S升级版。

Principles of Spread-Spectrum Communication Systems 3rd

国外大牛著作，全面介绍了扩频通信的基础技术原理，分步骤详细降解了扩频解扩、调制解调等内容，是扩频通信入门的超级经典书籍。 目录： 1 Channel Codes and Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Block Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Error Probabilities for Hard-Decision Decoders . . . . . . . . . . . . . . . 6 Soft-Decision Decoders and Code Metrics for Pulse Amplitude Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Code Metrics for Orthogonal Signals . . . . . . . . . . . . . . . . . . . . . . . . 20 Detection of Uncoded FSK Symbols . . . . . . . . . . . . . . . . . . . . . . . . 24 Performance Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 1.2 Convolutional Codes and Trellis Codes . . . . . . . . . . . . . . . . . . . . . . 28 Chernoff Bound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Trellis-Coded Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 1.3 Interleavers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 1.4 Classical Concatenated Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 1.5 Turbo Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 MAP Decoding Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Turbo Codes with Parallel Concatenated Codes . . . . . . . . . . . . . . . 52 Serially Concatenated Turbo Codes . . . . . . . . . . . . . . . . . . . . . . . . . 59 1.6 Iterative Demodulation and Decoding . . . . . . . . . . . . . . . . . . . . . . . 61 Bit-Interleaved Coded Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . 65 Simulation Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 1.7 Low-Density Parity-Check Codes . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Irregul

Measurement of Er3+-doped concentration in optical fiber by using fiber Bragg grating Fabry-rerot cavity ring-down spectrum

We propose and experimentally demonstrate a novel approach to measure the Er3+ concentration in Er3+-doped silica fiber by fiber Bragg grating Fabry-Perot (FBG-FP) cavity ring-down spectrum. The relationship between the cavity ring-down time and the Er3+-doped concentration is derived. The results demonstrate that the cavity ring-down time is a function of the temperature of FBG, and an Er3+-doped concentration of 0.3 × 1025 m-3 at the FBG operation temperature of 25℃ is obtained, which is consi

Identification of pour point depressant by terahertz time-domain spectroscopy

The frequency-dependent absorption coefficients and refractive indexes of three selected pour point depressants (PPDs) are extracted within the spectral range of 0.2–2.5 THz using terahertz time-domain spectroscopy (THz-TDS). The selected PPDs are also characterized by the middle-infrared spectrum. The experimental results reveal that PPD is more sensitive in the THz range than that in the middle-infrared range. Moreover, the different compositions of PPD can be identified according to their dif