One of the prerequisites for the development of telecommunication services is the understanding of the propagation of the waves, either acoustic, electromagnetic, radio or light waves, which are used for the transmission of information. In this work, we shall limit ourselves to the study of radio waves: this term apply to the electromagnetic waves used in radio communications. Their frequency spectrum is very broad, and is divided into the following frequency bands : ELF waves (f < 3 kHz), VLF (3-30 kHz), LF waves (30-300 kHz), MF waves (300-3000 kHz), HF (3-30 MHz), VHF waves (30-300 MHz), UHF waves (300-3000 MHz), SHF waves (3-30 GHz), EHF waves (30-300 GHz) and sub- EHF waves (300-3000 GHz).
标签： Propagation Radio Wave
上传时间： 2020-06-01
上传用户：shancjb
The idea for this book was born during one of my project-related trips to the beautiful city of Hangzhou in China, where in the role of Chief Architect I had to guide a team of very young, very smart and extremely dedicated software developers and verification engineers. Soon it became clear that as eager as the team was to jump into the coding, it did not have any experience in system architecture and design and if I did not want to spend all my time in constant travel between San Francisco and Hangzhou, the only option was to groom a number of local junior architects. Logically, one of the first questions being asked by these carefully selected future architects was whether I could recommend a book or other learning material that could speed up the learning cycle. I could not. Of course, there were many books on various related topics, but many of them were too old and most of the updated information was either somewhere on the Internet dispersed between many sites and online magazines, or buried in my brain along with many years of experience of system architecture.
标签： Telecommunication Gateways System Design for
上传时间： 2020-06-01
上传用户：shancjb
Notwithstanding its infancy, wireless mesh networking (WMN) is a hot and growing field. Wireless mesh networks began in the military, but have since become of great interest for commercial use in the last decade, both in local area networks and metropolitan area networks. The attractiveness of mesh networks comes from their ability to interconnect either mobile or fixed devices with radio interfaces, to share information dynamically, or simply to extend range through multi-hopping.
标签： Multi-hop Networks WiMAX WiFi Mesh LTE and
上传时间： 2020-06-01
上传用户：shancjb
Welcome to the world of wireless communications and the logical extension to the broadband architectures that are emerging as the future of the industry. No aspect of communications will be untouched by the wireless interfaces;no part of our working environment will be left untouched either. As the world changes and the newer technologies emerge, we can expect to see more in the line of untethered communications than in the wired inter- faces.
标签： Broadband Wireless Handbook
上传时间： 2020-06-01
上传用户：shancjb
n the first part of this book, we give an introduction to the basic applications of wireless com- munications, as well as the technical problems inherent in this communication paradigm. After a brief history of wireless, Chapter 1 describes the different types of wireless services, and works out their fundamental differences. The subsequent Section 1.3 looks at the same problem from a different angle: what data rates, ranges, etc., occur in practical systems, and especially, what combination of performance measures are demanded (e.g., what data rates need to be transmitted over short distances; what data rates are required over long distances?) Chapter 2 then describes the technical challenges of communicating without wires, putting special emphasis on fading and co-channel interference. Chapter 3 describes the most elementary problem of designing a wireless system, namely to set up a link budget in either a noise-limited or an interference-limited system. After studying this part of the book, the reader should have an overview of different types of wireless services, and understand the technical challenges involved in each of them. The solutions to those challenges are described in the later parts of this book.
标签： Communications Wireless Edition 2nd
上传时间： 2020-06-01
上传用户：shancjb
This chapter provides extensive coverage of existing mobile wireless technologies. Much of the emphasis is on the highly anticipated 3G cellular networks and widely deployed wireless local area networks (LANs), as the next-generation smart phones are likely to offer at least these two types of connectivity. Other wireless technologies that either have already been commercialized or are undergoing active research and standardization are introduced as well. Because standardization plays a crucial role in developing a new technology and a market, throughout the discussion standards organizations and industry forums or consortiums of some technologies are introduced. In addition, the last section of this chapter presents a list of standards in the wireless arena.
标签： Networking Wireless Complete
上传时间： 2020-06-01
上传用户：shancjb
There’s a story (it’s either an old vaudeville joke or a Zen koan) in which a fisherman asks a fish, “What’s the water like down there?” and the fish replies “What is water?” If the story is just a joke, the point is to make us laugh; but if it’s a koan, the point is that the most obvious and ubiquitous parts of our immediate environ- ment are, paradoxically, often the easiest to overlook.
标签： Atmospheric Monitoring Arduino With
上传时间： 2020-06-09
上传用户：shancjb
This book is either ambitious, brave, or reckless approaching a topic as rapidly evolving as industrial control system (ICS) security. From the advent of ICS-targeted malicious software such as Stuxnet to the advanced persistent threats posed by organized crime and state-sponsored entities, ICS is in the crosshairs and practices and controls considered safe today may be obsolete tomorrow. Possibly more so than in more traditional IT security, because of the differences inherent in ICS.
标签： Industrial Control Systems
上传时间： 2020-06-10
上传用户：shancjb
THIS PUBLICATION IS COPYRIGHT PROTECTEDCopyright © 2014 IEC, Geneva, SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any formor by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing fromeither IEC or IEC's member National Committee in the country of the requester. If you have any questions about IECcopyright or have an enquiry about obtaining additional rights to this publication, please contact the address below oryour local IEC member National Committee for further information.Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduiteni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopieet les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez desquestions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisezles coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.
标签： iec标准
上传时间： 2021-10-21
上传用户：kent
If register should be written or read.This value is passed to the calback functions which support either reading or writing register values. Writing means that the application registers should be updated and reading means that the modbus protocol stack needs to know the current register values.See also: eMBRegHoldingCB(), eMBRegCoilsCB(), eMBRegDiscreteCB() and eMBReglnputCB().Enumeration values: MB_REG_READ Read register values and pass to protocol stack.MB_REG_WRITE Update register values.Note: Note all ports implement this function.A port which wants to get an callback must define the macro MB_PORT_HAS_CLOSE to 1.Returns: If the resources where released it return eMBErrorCode:: MB_ENOERR. If the protocol stack is not in the disabled state it returns eMBErrorCode:: MB_EILLSTATE.Examples: LINUX/demo.c, MCF5235TCP/demo.c, STR71XTCP/demo.c, WIN32/demo. cpp, and WIN32TCP/demo. cpp.his function disables processing of Modbus frames.Returns: If the protocol stack has been disabled
标签： FreeModbus
上传时间： 2022-05-31
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