Computer science as an academic discipline began in the 1960’s. Emphasis was on
programming languages, compilers, operating systems, and the mathematical theory that
supported these areas. Courses in theoretical computer science covered finite automata,
regular expressions, context-free languages, and computability. In the 1970’s, the study
of algorithms was added as an important component of theory. The emphasis was on
making computers useful. Today, a fundamental change is taking place and the focus is
more on a wealth of applications. There are many reasons for this change. The merging
of computing and communications has played an important role. The enhanced ability
to observe, collect, and store data in the natural sciences, in commerce, and in other
fields calls for a change in our understanding of data and how to handle it in the modern
setting. The emergence of the web and social networks as central aspects of daily life
presents both opportunities and challenges for theory.
基于TMS320F28335的超聲波流量計硬件原理圖+軟件源碼本文以TMS320F28335 處理器為核心，設計一種用于管道流量測量的超聲波流量計。系統硬件由核心板，超聲波發射和接收電路，切換電路，超聲換能器，基于ADS805 的高速信號采集電路，人機交互以及電源等模塊構成。采用時差法進行管道流量測量，時差測量采用SCOT 加權的廣義互相關時延估計算法。本論文設計的超聲波流量計具有測量速度快、準確性好、成本低等優點。關鍵字：C2000，超聲波，流量，廣義互相關算法AbstractA kind of ultrasonic flowmeter using for the pipe flow measurement is designed based onTMS320F28335 in this paper. The system hardware consists of the following parts: the core board,ultrasonic signal transmitter and receiver circuits, switch circuit, ultrasonic transducer, signalacquisition circuit based on ADS805, human-computer interaction module and power supplymodule, etc. The system use the method of time difference for pipeline flow measurement and thetime difference is calculated by the time-delay algorithm of SCOT weighted generalizedcross-correlation. The ultrasonic flowmeter has the features of high testing speed, high precisionand low cost, etc.Keywords: C2000,Ultrasonic, Flow, Generalized Cross-Correlation Algorithm
INTRODUCTION In the past, adding speech recording and playback capability to a product meant using a digital signal processor or a specialized audio chip. Now, using a simplified Adaptive Differential Pulse Code Modulation(ADPCM) algorithm, these audio capabilities can be added to any PICmicro device. This application note will cover the ADPCM compression and decompression algorithms, performance comparison of all PICmicro devices, and an application using a PIC16C72 micro-controller.DEFINITION OF TERMS step size -value of the step used for quantization of ana-log signals and inverse quantization of a number of steps.quantization -the digital form of an analog input signal is represented by a finite number of steps.adaptive quantization -the step size of a quantizer is dramatically changed with time in order to adapt to a changing input signal.inverse quantizer -a finite number of steps is converted into a digital representation of an analog signal.
PrefaceDuring the past years, there has been a quickly rising interest in radio access technologies for providingmobile as well as nomadic and fixed services for voice, video, and data. The difference indesign, implementation, and use between telecom and datacom technologies is also becoming moreblurred. One example is cellular technologies from the telecom world being used for broadband dataand wireless LAN from the datacom world being used for voice-over IP.Today, the most widespread radio access technology for mobile communication is digital cellular,with the number of users passing 5 billion by 2010, which is more than half of the world’s population.It has emerged from early deployments of an expensive voice service for a few car-borne users,to today’s widespread use of mobile-communication devices that provide a range of mobile servicesand often include camera, MP3 player, and PDA functions. With this widespread use and increasinginterest in mobile communication, a continuing evolution ahead is foreseen.This book describes LTE, developed in 3GPP (Third Generation Partnership Project) and providingtrue 4G broadband mobile access, starting from the first version in release 8 and through the continuingevolution to release 10, the latest version of LTE. Release 10, also known as LTE-Advanced,is of particular interest as it is the major technology approved by the ITU as fulfilling the IMTAdvancedrequirements. The description in this book is based on LTE release 10 and thus provides acomplete description of the LTE-Advanced radio access from the bottom up.Chapter 1 gives the background to LTE and its evolution, looking also at the different standardsbodies and organizations involved in the process of defining 4G. It also gives a discussion of the reasonsand driving forces behind the evolution.Chapters 2–6 provide a deeper insight into some of the technologies that are part of LTE and itsevolution. Because of its generic nature, these chapters can be used as a background not only for LTEas described in this book, but also for readers who want to understand the technology behind othersystems, such as WCDMA/HSPA, WiMAX, and CDMA2000.Chapters 7–17 constitute the main part of the book. As a start, an introductory technical overviewof LTE is given, where the most important technology components are introduced based onthe generic technologies described in previous chapters. The following chapters provide a detaileddescription of the protocol structure, the downlink and uplink transmission schemes, and the associatedmechanisms for scheduling, retransmission and interference handling. Broadcast operation andrelaying are also described. This is followed by a discussion of the spectrum flexibility and the associated
