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همه چیز در مورد مخابرات

همه چیز در مورد مخابرات

گلچین بهترین لینک های الکترونیک و مخابرات

سخنی با بازدید کننده گان

سلام  به  مهندسین  عزیز

ممنون از  اینکه  وقت گذاشتید و  از  این وبلاگ  دیدن میکنید امیدوارم که مطالب این  وبلاگ  بتونه  کمکی به  دانشجویان  رشته مخابرات کرده باشه

اگر  کسی  مقاله IEEE یآ ISI   خواست  تو قسمت نظرات کامنت  بذاره در اولین فرصت تو وبلاگ قرار خواهم داد

به دلیل زیاد بودن مطالب برای دسرسی  بهتر از   ارشیو موضوعی استفاده کنید

گلچینی  از  بهترین و به روز ترین نرم افزارها  رو تو  وبلاگ جدیدم  قرار  دادم   http://b3tlink.blogfa.com/

لطفا  با نظر  خودتون  منو در  هرچه بهتر کردن وبلاگ یاری  کنین  .

کپی برداری  از  مطالب  با ذکر  منبع  مجاز میباشد ..

+ نوشته شده در  شنبه یکم اسفند 1388ساعت 11:37  توسط بهرام   | 

HFSS V10

+ نوشته شده در  شنبه یکم اسفند 1388ساعت 9:36  توسط بهرام   | 

Guide to Wireless Mesh Networks

Guide to Wireless Mesh Networks
Guide to Wireless Mesh Networks
Springer | August 27, 2009 | ISBN: 1848009089 | Pages: 527 | PDF | 10 Mb


Wireless communication technologies continue to undergo rapid advancement. The attractiveness of Wireless Mesh Networks (WMN)s, in general, can be attributed to their characteristics: the ability to dynamically self-organize and self-configure, coupled with the ability to maintain mesh connectivity, leads in effect to low set-up/installation costs, simpler maintenance tasks, and service coverage with high reliability and fault-tolerance. As a result, WMNs have found many useful applications in a broad range of domains.

WMNs represent a key technology for future generation wireless networks, and this broad-ranging and comprehensive guidebook presents new ideas and results from research to address the challenges ahead. This unique resource describes all the fundamental key topics and covers both the important core and specialized issues in the field. Each chapter is written by topical area experts, with the first chapters devoted to the basics of WMNs and subsequent ones dealing with some of the more specialist topics, such as the WiMAX metro area mesh networks and the symbiosis of cognitive radio with WMNs.

لینک دانلود

+ نوشته شده در  شنبه بیست و چهارم بهمن 1388ساعت 22:58  توسط بهرام   | 

CompTIA RFID+ Study Guide

CompTIA RFID+ Study Guide: Exam RF0-001
CompTIA RFID+ Study Guide: Exam RF0-001
Publisher: Sybex | ISBN: 047004232X | edition 2006 | CHM | 293 pages | 11,1 mb


This comprehensive study guide thoroughly covers the CompTIA RFID+ exam, the only certification offered for radio frequency identification (RFID), the technology that is rapidly gaining popularity and is expected to completely replace bar codes. Your study will focus on interrogation zone basics, testing and troubleshooting, standards and regulations, tag knowledge, design selection, installation, site analysis, RF physics, and RFID peripherals.
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لینک دانلود

+ نوشته شده در  جمعه بیست و سوم بهمن 1388ساعت 16:0  توسط بهرام   | 

Basics of MATLAB and Beyond

Basics of MATLAB and Beyond
Basics of MATLAB and Beyond
Publisher: Chapman & Hall/CRC (August 27, 1999) | 216 pages | ISBN : 0849320399 | PDF | 6 MB

MATLAB -the tremendously popular computation, numerical analysis, signal processing, data analysis, and graphical software package-allows virtually every scientist and engineer to make better and faster progress. As MATLAB�s world-wide sales approach a half-million with an estimated four million users, it becomes a near necessity that professionals and students have a level of competence in its use. Until now, however, there has been no book that quickly and effectively introduces MATLAB�s capabilities to new users and assists those with more experience down the path toward increasingly sophisticated work.Basics of MATLAB and Beyond is just such a book. Its hands-on, tutorial approach gently takes new users by the hand and leads them to competence in all the fundamentals of MATLAB. Then, with equal effectiveness, it covers the advanced topics that lead to full, creative exploitation of MATLAB's awesome power

دانلود.1

دانلود.2

+ نوشته شده در  یکشنبه هجدهم بهمن 1388ساعت 21:47  توسط بهرام   | 

Signal Processing for Communications

Signal Processing for Communications
Signal Processing for Communications
EFPL Press | 2008-08-19 | 300 pages | ISBN:1420070460 | 10 MB | PDF | Rapidshare&Megaupload


Taking a novel, less classical approach to the subject, the authors have written this book with the conviction that signal processing should be fun. Their treatment is less focused on the mathematics and more on the conceptual aspects, allowing students to think about the subject at a higher conceptual level, thus building the foundations for more advanced topics and helping students solve real-world problems. The last chapter pulls together the individual topics into an in-depth look at the development of an end-to-end communication system. Richly illustrated with examples and exercises in each chapter, the book offers a fresh approach to the teaching of signal processing to upper-level undergraduates.

لینک دانلود.1

لینک دانلود.2

+ نوشته شده در  شنبه هفدهم بهمن 1388ساعت 21:0  توسط بهرام   | 

اصول مخابرات ماهواره ای

 

ایده ی مخابرات از طریق یک ماهواره، به خصوص توسط یک ماهواره ی همزمان، توسط آرتور سی. کلارک که یک نویسنده ی مشهور افسانه های علمی بریتانیایی بود، در سال 1945 ارائه گردید. کلارک قبلا نشان داده بود که یک ماهواره در مدار استوایی دایروی با شعاع حدود 42242 کیلومتر سرعت زاویه ای برابر با  سرعت زاویه ای زمین خواهد داشت. بنابراین، آن ماهواره در بالای همان نقطه از زمین باقی مانده و می تواند سیگنال ها را از اکثر نقاط نیمکره دریافت و دوباره پخش نماید. سه ماهواره با فواصل 120 درجه نسبت به هم، کل کره زمین را با قدری همپوشانی پوشش می دهند، مشروط بر اینکه پیغام ها بتوانند بین ماهواره ها دوباره پخش شوند. بنابراین ارتباط مطمئن بین هر دو نقطه از کره ی زمین ممکن می شود. کلارک همچنین اظهار کرده بود که انرژی الکتریکی مورد نیاز ماهواره نیز می تواند از طریق تبدیل تشعشعات خورشید توسط سلول های خورشیدی تأمین شود. به مقاله ی کلارک تقریباً توجهی نمی شد تا اینکه با اولین ماهواره ی ساخت بشر، یعنی اسپوتنیک 1 (4 اکتبر1957) به واقعیت پیوست. با وجود این، قابل ذکر است که بشر تا سال 1963 به مدار همزمان نائل نگردید.


ادامه مطلب
+ نوشته شده در  جمعه شانزدهم بهمن 1388ساعت 19:15  توسط بهرام   | 

Altium Designer Summer 09 Build 9.2.0.18802
Altium Designer Summer 09 Build 9.2.0.18802 | 1.7 GB


Altium Designer Summer brings significant new and enhanced features to unify the design process, make project management easier, expand access to FPGAs and improve design productivity - helping you create a return on your innovation and stay ahead of today's complexity with the latest technology. Design Insight, for example, makes project navigation through complicated design projects faster, easier and more intuitive. Automatic previews and context-sensitive navigation allows you to preview documents and trace nets without having to physically open multiple schematic, PCB, or text documents - a real convenience and timesaver! More flexible generation of output files and documentation allows better data management and design collaboration for your projects with Multiple Output Publishing.

That’s what Altium Designer is all about – freeing you from the constraints of traditional design limitations and the old "divide and conquer" approach. Altium Designer provides one single unified solution for the entire design process. It allows you to explore and do more, do it in new ways, and design things that haven’t even been thought of yet. Think and design beyond the confines of the device itself and start designing your customer's total product experience


ادامه مطلب
+ نوشته شده در  پنجشنبه پانزدهم بهمن 1388ساعت 20:55  توسط بهرام   | 

EPLAN Electric P8 1.9.11 2010
EPLAN Electric P8 1.9.11 2010 | 970 MB

Description: The company presents EPLAN your attention updated version of the EPLAN Platform 1.9 SP1 Hotfix1! Thanks to the many innovative improvements in this version, you will increase the efficiency of design!
''We are more than ever, focused on the practical needs of our clients to improve and accelerate the processes of engineering. Increased functionality and fixes have been implemented according to the wishes and requirements of users of EPLAN. "

Export PDF documents improves system performance, which significantly speed up the work with the volume of project documentation. Speed and flexibility - as the main advantages of using macros, and devices. Update 1.9 SP1 Hotfix1 also includes improvements in image editor, selection of items, macros, reports.

System requirements: Minimum requirements for single-user
mode and projects 100 logical pages:
Comparable Processor Intel Pentium 4 3 GHz
Comparable Intel Core 2 Duo 2 GHz
2 GB RAM

ادامه مطلب
+ نوشته شده در  پنجشنبه پانزدهم بهمن 1388ساعت 19:29  توسط بهرام   | 

Nuts and Volts - February 2010

Nuts and Volts - February 2010


Nuts and Volts - February 2010
English | PDF | 84 Pages | 14 Mb



Nuts and Volts is a monthly American magazine for the hands-on hobbyist, design engineer, technician, and experimenter. It has been published by T&L Publications since 1980 and leans heavily toward microcontroller and digital electronics projects.
لینک دانلود.1

لینک دانلود

+ نوشته شده در  پنجشنبه پانزدهم بهمن 1388ساعت 12:47  توسط بهرام   | 

مقدمه اي بر ساختار شبکه GSM

: معماري شبکه GSM
شبکه GSM یک سیستم ارتباطی سلولی دیجیتال است که با ایده سلولی کردن منطقه جغرافیایی و استفاده مجدد از فرکانس 1 و پوشش دادن منطقه جغرافیایی بوسیله سلولها شروع بکارکرد.شبکه سلولی سیار را به علت اینکه مشترکین تلفن هاي متحرك معمولأ در خشکی از آن استفاده میکنند ] شبکه عمومی زمینی سیار [ 2(PLMN) می نامند.
تکنیک استفاده مجدد از فرکانس با در نظر گرفتن کمترین تداخل فرکانسی در GSM بعلت کمبود فرکانس و پهناي باند بکار گرفته می شود. معماري شبکه GSM در شکل (1-1) آمده است.
شبکه GSM به 4 قسمت اصلی تقسیم می شود که عبارتنداز:
• MS3 واحد سیار
• BSS 4 زیر سیستم ایستگاه ثابت
• NSS 5 زیر سیستم سوئیچینگ و شبکه
• OSS 6 زیر سیستم نگهداري و پشتیبانی
اینترفیسهایی(Interface) بین قسمتهاي مختلف شبکه GSM عبارتند از:
• اینترفیس A بین MSC و BSC7
• اینترفیس Abis بین BSC و BTS8
• اینترفیس Um یا Airبین MS و BTS

بقیه مطالب  در  ادامه مطلب


ادامه مطلب
+ نوشته شده در  سه شنبه سیزدهم بهمن 1388ساعت 19:45  توسط بهرام   | 

Proteus 7.6 SP4 (2009)

Proteus 7.6 SP4 (2009)
Proteus 7.6 SP4 (2009) | 141MB


Proteus Professional - a software package for computer-aided design of electronic circuits. The package is a system of circuit simulation, based on models of electronic components made in PSpice. Distinctive feature of the package Proteus Professional is the possibility of simulating the operation of programmable devices: microcontrollers, microprocessors, DSP and others. In addition to the package Proteus Professional is a system design of printed circuit boards. Proteus Professional can simulate the work of the following microcontrollers: 8051, ARM7, AVR, Motorola, PIC, Basic Stamp. The library contains the components of reference data.

Year: 2009
Version: 7.6 SP0
Developer: Labcenter Electronics
Platform: Windows
Compatibility with Vista: complete
Language: English
Medicine: Present


ادامه مطلب
+ نوشته شده در  دوشنبه دوازدهم بهمن 1388ساعت 18:36  توسط بهرام   | 

Mathworks Matlab R2009b For Mac, Linux and Solaris (32-bit & 64-bit)

 

Mathworks Matlab R2009b For Mac, Linux and Solaris (32-bit & 64-bit


ادامه مطلب
+ نوشته شده در  شنبه دهم بهمن 1388ساعت 18:52  توسط بهرام   | 

Microprocessor And Microcontrollers Video Tutorials

Microprocessor And Microcontrollers Video Tutorials IIT Kharagpur
Microprocessor And Microcontrollers Video Tutorials IIT Kharagpur | DAA | 1.4 GB

 

Microprocessor And Microcontrollers Video Tutorials


These courses developed for use as self-learning material, are suitable for individual/group viewing by students, faculty, practising engineers. The courses are recorded on professional quality video tapes in a specially designed studio and copied onto good quality CDs / DVDs. Courses are also available in the Video On Demand mode ( VOD Mode ).
Lecture no:

2# Architecture and Organization of 8085
4# Instruction Set : Vocabulary of the Machine
5# Instruction Set : Vocabulary of the Machine(Cont.)
6# Instruction Set : Vocabulary of the Machine(Cont.)
7# Instruction Set : Vocabulary of the Machine(Cont.)

لینک ها در ادامه  مطلب


ادامه مطلب
+ نوشته شده در  پنجشنبه هشتم بهمن 1388ساعت 22:39  توسط بهرام   | 

حل المسائل کتاب ها و منابع مهندسی برق

 

حل المسائل کتاب ها و منابع مهندسی برق

Control Systems Engineering (4th Edition, 2004) - Nise - Solution Manual
http://rapidshare.com/files/14568582...Nise4e2004.rar
Automatic Control Systems (8th Edition, 2002) - Kuo & Golnaraghi - Solution Manual
http://rapidshare.com/files/14676983...n8eKuo2002.rar
Wireless Communications (2nd Edition, 1998) - Rappaport - Solution Manual
http://rapidshare.com/files/14568648...ManRap2e98.rar
Schaum's Outline of Electric Circuits (2003)
http://rapidshare.com/files/14568690...Circ4e2003.rar
Schaum's Outline of Electronic Devices & Circuits (2002)
http://rapidshare.com/files/14568736...cDev2e2002.rar
Schaum's Outline of Feedback & Control Systems (1990)
http://rapidshare.com/files/14676731...ntSyst2e90.rar
Advanced Engineering Electromagnetics (1989) - Balanis
http://rapidshare.com/files/14676967...MBalanis89.rar


ادامه مطلب
+ نوشته شده در  چهارشنبه هفتم بهمن 1388ساعت 19:31  توسط بهرام   | 

"4G Wireless Video Communications


 

4G Wireless Video Communications


 


Haohong Wang, Lisimachos Kondi, Ajay Luthra, Song Ci, "4G Wireless Video Communications"
Wiley | 2009 | ISBN: 0470773073 | 420 pages | PDF | 9,65 MB



A comprehensive presentation of the video communication techniques and systems, this book examines 4G wireless systems which are set to revolutionise ubiquitous multimedia communication.4G Wireless Video Communications covers the fundamental theory and looks at systems’ descriptions with a focus on digital video. It addresses the key topics associated with multimedia communication on 4G networks, including advanced video coding standards, error resilience and error concealment techniques, as well as advanced content-analysis and adaptation techniques for video communications, cross-layer design and optimization frameworks and methods. It also provides a high-level overview of the digital video compression standard MPEG-4 AVC/H.264 that is expected to play a key role in 4G networks.


Material is presented logically allowing readers to turn directly to specific points of interest. The first half of the book covers fundamental theory and systems, while the second half moves onto advanced techniques and applications. This book is a timely reflection of the latest advances in video communications for 4G wireless systems.

لینک دانلود

+ نوشته شده در  دوشنبه پنجم بهمن 1388ساعت 21:20  توسط بهرام   | 

Matlab Recorded Webinars

Matlab Recorded Webinars

Matlab Recorded Webinars | RapidShare | RAR 2 Gb


Matlab webinars from the company Mathworks - are small (duration 1 hour) video lessons for both beginners and experienced users matrix laboratory Matlab.

Manufacturer: The MathWorks
Language: English
Format: swf (Flash movie version: 7)
Video: Flash SWF 850x638
Audio: Flash

اموزش تول باکس های  تخصصی  متلب  به صورت  تصویری 

لیست موارد اموزش داده شده  در ادامه مطلب..


ادامه مطلب
+ نوشته شده در  جمعه دوم بهمن 1388ساعت 11:3  توسط بهرام   | 

MATLAB: An Introduction with Applications

MATLAB: An Introduction with Applications
MATLAB: An Introduction with Applications
Publisher: Wiley ( 2003-02-28 ) | 304 pages | ISBN : 0471439975 | PDF | 52 MB



•Assuming no prior MATLAB experience, this clear, easy-to-read book walks readers through the ins and outs of this powerful software for technical computing
•Generously illustrated through computer screen shots and step-by-step tutorials that are applied in the areas of mathematics, science, and engineering
•Clearly shows how MATLAB is used in science and engineering

دانلود

 

+ نوشته شده در  پنجشنبه یکم بهمن 1388ساعت 21:36  توسط بهرام   | 

Babylon Pro v8.0.5 (r7) Full Package

Babylon Pro v8.0.5 (r7) Full Package

Babylon Pro v8.0.5 (r7) Full Package | 7.79 Mb


Babylon 8 is the world's leading dictionary and language translation software. Babylon offers you the most intuitive tool for all your translation needs. With Babylon you can quickly translate emails, web pages, documents, instant messages, and more. All you have to do is click on the word or text that you want to translate and a small window instantly appears with the desired results from Babylon's extensive database of language dictionaries, glossaries and conversion tools.

Babylon offers its users a wide range of titles from the world's premier publishing houses including Oxford University Press, Britannica, Merriam-Webster, Larousse, Vox, Langenscheidt, Pons, and Taishukan. New version Babylon six offers text translation in 17 languages in addition to single word and phrase translations - all in a single click, results from Wikipedia encyclopedia in nine languages, automatic spelling feature, and accurate results in a single-click from a wide range of authoritative sources. Babylon 8 - an easy and intuitive translation and dictionary software in over 75 languages. With Babylon 8, text translation has never been easier, no more "copy/paste" or unnecessary browser windows. Just click on any text in Word, Excel, emails, instant messaging, web pages and other desktop applications. All you need is a single click away.

Babylon 8 features:
• Single Click activation
• Text translation - in 31 languages
• Results from the world's leading publishers
• Encyclopedias including Wikipedia content
• Translations in more than 75 languages
• Unit Conversions - Convert currencies, measurements and time
• Writing Tools for English
• Spelling Alternatives
• Technical Requirement

Download

Download

+ نوشته شده در  چهارشنبه سی ام دی 1388ساعت 17:15  توسط بهرام   | 

Wireless Communications & Networks

Wireless Communications & Networks
Wireless Communications & Networks
Prentice Hall | 2004 | ISBN: 0131918354 | 576 pages | PDF | 50,8 MB


For courses in wireless networking, wireless communications, wireless data communications or wireless technology in departments of Computer Science, Engineering, IT, and Continuing Education. The rapid growth of mobile telephone use, satellite services, and the wireless Internet are generating tremendous changes in telecommunications and networking. Combining very current technical depth with a strong pedagogy and advanced Web support, this new edition provides a comprehensive guide to wireless technology--exploring key topics such as technology and architecture, network types, design approaches, and the latest applications

لینک دانلود

لینک دانلود

+ نوشته شده در  سه شنبه بیست و نهم دی 1388ساعت 20:51  توسط بهرام   | 

مجموعه ای بی نظیر از کتب الکترونیکی در زمینه میکروکنترلر PIC


Programming the PIC Microcontroller with MBASIC


Programming the PIC Microcontroller with MBASICProgramming the PIC Microcontroller with MBASIC
Publisher: Newnes ( 2005-06-14 ) | 800 pages | ISBN : 0750679468 | PDF | 12 MB


The Microchip PIC family of microcontrollers is the most popular series of microcontrollers in the world. However, no microcontroller is of any use without software to make it perform useful functions. This comprehensive reference focuses on designing with Microchips mid-range PIC line using MBASIC, a powerful but easy to learn programming language. It illustrates MBASICs abilities through a series of design examples, beginning with simple PIC-based projects and proceeding through more advanced designs.
 
لینک دانلود .1
 
لینک دانلود.2
 
بقیه در ادامه مطلب
The Quintessential PIC® Microcontroller (Computer Communications and Networks) Interfacing PIC Microcontrollers: Embedded Design by Interactive Simulation

ادامه مطلب
+ نوشته شده در  یکشنبه بیست و هفتم دی 1388ساعت 21:41  توسط بهرام   | 

mobile E-books

دانلود چند کتاب  در مورد شبکه های  سلولی

Wireless Internet and Mobile Computing: Interoperability and Performance
2007 | 731 pages | ISBN: 0471679682 | PDF | 32 Mb
This book describes the technologies involved in all aspects of a large networking system and how the various devices can interact and communicate with each other. Using a bottom up approach the authors demonstrate how it is feasible, for instance, for a cellular device user to communicate, via the all-purpose TCP/IP protocols, with a wireless notebook computer user, traversing all the way through a base station in a cellular wireless network (e.g., GSM, CDMA), a public switched network (PSTN), the Internet, an intranet, a local area network (LAN), and a wireless LAN access point. The information bits, in travelling through this long path, are processed by numerous disparate communication technologies. The authors also describe the technologies involved in infrastructure less wireless networks

لینک دانلود .1

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+ نوشته شده در  جمعه بیست و پنجم دی 1388ساعت 19:3  توسط بهرام   | 

MATLAB Demystified

MATLAB Demystified
MATLAB Demystified
Publisher: McGraw-Hill Professional ( 2007-04-06 ) | 336 pages | ISBN : 0071485511 | PDF | 6 MB


Need to Learn MATLAB? Problem SOLVED!
Get started using MATLAB right away with help from this hands-on guide. MATLAB Demystified offers an effective and enlightening method for learning how to get the most out this powerful computational mathematics tool.
Using an easy-to-follow format, this book explains the basics of MATLAB up front. You'll find out how to plot functions, solve algebraic equations, and compute integrals. You'll also learn how to solve differential equations, generate numerical solutions of ODEs, and work with special functions. Packed with hundreds of sample equations and explained solutions, and featuring end-of-chapter quizzes and a final exam, this book will teach you MATLAB essentials in no time at all.
 
 
+ نوشته شده در  پنجشنبه بیست و چهارم دی 1388ساعت 21:16  توسط بهرام   | 

TDMA چيست؟

  آنتن موبايل به عنوان واسط بين گوشي موبايل با شبكه موبايل مي باشد
در شبكه موبايل گزارش آخرين مكان مشترك موبايل و ارسال و دريافت شماره تلفنها و مسائلي از اين دست به عهده كانال سيگنالينگ مي باشدو رد و بدل شدن مكالمات كه هدف اصلي مي باشد به عهده كانالهاي ترافيكي مي باشد.
به طور قطع BTSوظيفه ارائه اين كانالها را به مشترك موبايل دارا مي باشد.
يكي از مشكلات اساسي شبكه هاي موبايل كمبود فضاي فركانسي مي باشد  كه به روشهاي متنوعي توانسته اند اين مشكل را برطرف كنند يكي از اين روشها استاندارد TDMAمي باشد  .
در فرستندهاي محلي تلويزيون وراديو براي هر شبكه راديويي و تلويزيوني از يك فركانس استفاده مي شود ولي در شبكه موبايل از يك فركانس براي ارسال يا دريافت اطلاعات 8 مشترك استفاده مي شود .

چگونه؟
به روش TDMA
در اين روش هر 8 تايم اسلات بر روي يك فركانس مدوله (سوار) مي شود و هر تايم اسلات مسئول حمل اطلاعات صحبت يك مشترك مي باشد يعني با يك فركانس و با ايجاد تاخير زماني اندك بين 8 مشترك (بدون اينكه براي مشتركين قابل احساس باشند)  آنها را به خوبي پوشش مي دهد در BTSواحدي به نام TRXوجود دارد كه نشان دهنده ظرفيت يك BTSمي باشد.
هر TRXيك فركانس مخصوص دارد و 8 تايم اسلات براي آن تعريف شده است
يعني 8 كانال دارد بسته به نوع تعريف نرم افزاري مي تواند سيگنالينك يا ترافيكي تعريف شود

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ادامه مطلب
+ نوشته شده در  چهارشنبه بیست و سوم دی 1388ساعت 19:24  توسط بهرام   | 

تفاوت فرکانس در GSM 900-1800

Which is better, 850 or 1900?  In general, you are going to get more performance out of 850 than you are going to get out of 1900 for several reasons. 1. As mentioned earlier, back when the 850 licenses were issued, they had to cover a certain amount of land cover. This required deploying their system throughout many rural areas (not ALL though). 1900 licenses only need to cover up to 67% of the population, and in many cases they don't even have to meet that. 2. The higher the frequency, the shorter the usable range.  You need approximately twice as many 1900 MHz towers to cover a given area than 850 MHz towers. Most 1900 MHz towers are in urban and suburban areas. A properly built 1900 system will work as well as a properly built 850 system, but it will likely cost more to deploy and operate. Sometimes 1900 will work better in a city because 1900 MHz signals tend to work better in the middle of the city with large buildings as the shorter wavelength allows the signal to go around corners easier.  Also, due to network loading, 850 towers have to be "turned down" in urban areas so as to not overload, so the playing field is leveled. 3. Leaving the technical details aside, it seems that 850 MHz signals penetrate most modern buildings better than 1900 MHz signals.  There are many factors involved such as the material of the walls, the proximity of the local cell towers and various other factors.  The fact that 850 MHz carriers have been in operation longer and have optimized their coverage is an important factor to consider. If there is a window nearby, chances are that either system will work, assuming that there is some sort of signal available at the window!  The bottom line is this: when you try out a service, make sure you bring your phone to all the areas you'll be using to make sure it works where you need it.

+ نوشته شده در  چهارشنبه بیست و سوم دی 1388ساعت 18:13  توسط بهرام   | 

Cell Size

Cell Size : یا Cell type
اندازه سایتها یا Cell ها نظر به شعاع ان به کیلومتر و یا متر و نظر به کاربرد :
  1. · Macrocells
  2. · Microcells
  3. · Selective or sectorized cells                                  
  4. · Umbrella cells
  5. · Nanocells
  6. · Picocells

                                                                                          

 


ادامه مطلب
+ نوشته شده در  دوشنبه بیست و یکم دی 1388ساعت 17:42  توسط بهرام   | 

مجلات الکتور 2009

+ نوشته شده در  پنجشنبه هفدهم دی 1388ساعت 9:45  توسط بهرام   | 

Proteus Professional 7.6 (+ Rus

سری نرم افزار های ازمایشگاه مجازی در رشته الکترونیک نرم افزار proteusپروتیوس میباشد که سادگی کار ، قدرت بالا و پشتیبانی از میکرو کنترلر ها باعث شده تا طرفداران زیادی را جذب خود نماید.

در این نرم افزار براحتی و در عین سادگی میتوانید تمام قطعات الکترونیکی را پیدا کنید و مدارات خود را با ان ببندید هم چنین میتوانید اگر برنامه نویس هستید برنامه های خود را که برای کار با میکرو کنترلر ها نوشته اید را در آن اجرا کنید و از کم و کیف و مشکلات برنامه خود آشنا شوید

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ادامه مطلب
+ نوشته شده در  شنبه دوازدهم دی 1388ساعت 19:44  توسط بهرام   | 

سرگرمی با پروژه های بی سیم(Wi-Fi Toys

سلام

تو این پست  میخوام یه کتاب جالب  از انتشارات وایلی  رو  معرفی  کنم  که  بیشتر  جنبه سرگرمی داره   این کتاب شامل ۱۵  پروژه جالب  در  رابطه با  تکنولوژی  وایرلسه  که   از  جمله ساخت  چند نوع  انتن  و  داشتن GPS  روی  لپ تاپ  رو اسم  برد  

در  کل  کتاب  کاربردی  و جالبی  هست  و خواندنش  خالی  از  لطف  نیست

   

توصیحات بیشتر به همراه لینک دانلود در ادامه مطلب


ادامه مطلب
+ نوشته شده در  شنبه دوازدهم دی 1388ساعت 14:24  توسط بهرام   | 

OPTICAL FIBER TELECOMMUNICATIONS

 

 

OPTICAL FIBER TELECOMMUNICATIONS IIIB (Optics and Photonics)
515 pages | Dec 12, 2000 |ISBN:0123951712 | PDF | 20 Mb


Updated to include the latest information on light wave technology, Optical Fiber Telecommunication III, Volumes A & B are invaluable for scientists, students, and engineers in the modern telecommunications industry. This two-volume set includes the most current research available in optical fiber telecommunications, light wave technology, and photonics/optoelectronics. The authors cover important background concepts such as SONET, coding device technology, andWOM components as well as projecting the trends in telecommunications for the 21st century.

         لینک دوم

+ نوشته شده در  چهارشنبه نهم دی 1388ساعت 9:33  توسط بهرام   |