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Aug. 7, 2015, 8:39 a.m.

Data Transmission Technologies

PDH, SDH, Sonet, STM1, Мультиплексор ввода-вывода, Терминальный мультиплексор

Specific technologies PDH deficiencies have been addressed and overcome technology developers synchronous optical networks (Synchronous Optical NET, SONET), the first version of the standard which appeared in 1984. It was then standardized Committee of T-1 ANSI Institute. As a result of long work ITU-T and ETSI managed to prepare an international standard SDH (Synchronous Digital Hierarchy - Synchronous Digital Hierarchy).

The main goals of SDH developers were:

  • Continuity of existing digital channels T1-T3, E1-E3
  • Ensuring the hierarchy of speeds far exceeding the speed of plesiochronous digital hierarchy (PDH)
Aug. 6, 2015, 8:28 a.m.

Data Transmission Technologies

E1, PDH, T1, бит-стаффинг, мультиплексор

PDH technology was developed in the late 60s by AT & T to address the problem of large communication switches, telephone networks among themselves. Communication links the FDM, applied previously to solve this problem, have exhausted their opportunities in terms of organization of high-speed multi-channel communication over a single cable. The FDM technology for the simultaneous transmission of 12 user channels used twisted pair, and had to lay cables with a large number of pairs of wires or coaxial cables are more expensive to increase the communication speed.

Aug. 4, 2015, 8:08 a.m.

Data Transmission Technologies

CWDM, dwdm, HDWDM, WDM, волс, мультиплексирование, усилители

The technology packed wavelength division multiplexing (Dense Wave Division Multiplexing, DWDM) is designed to create a new generation of optical backbones running at multi-terabit speeds and. Information in fiber-optic communication lines passed at the same time a large number of light waves. DWDM networks operate on the principle of channel switching, each light wave is a single spectral channel and is essential information.

Aug. 4, 2015, 1:30 a.m.

AVR

EEPROM, Atmega

Microcontrollers AVR Atmega48 / 88/168/328 contain the EEPROM memory of 256/512/512 / 1K bytes , respectively. EEPROM in AVR microcontrollers can support up to 100,000 write cycles. Access to non-volatile memory is carried out through three types of registers:

  • EEARH, EEARL - registers the addressing of memory cells. In case Atmega48 EEARH absent, because in this type of microcontroller 256 is present in all memory cells. EEARH responsible for the high byte of memory address, EEARL for the least significant byte;
  • EEDR - register for writing and reading data;
  • EECR - register control, this register is setting the actions to be performed with the memory.
Aug. 3, 2015, 9:28 a.m.

Fiber Optic Transmission Lines

fiber, волс, компоненты

Passive Components Fiber-optic communication lines are divided into the following types:

  • optic connectors and splitters;
  • optical converters;
  • optical isolators;
  • optical switches.

Splitters

The most important passive components are FOL optic connectors and splitters, which are used for consolidation or separation of optical signals.

Functional diagram of the splitter
Aug. 2, 2015, 9:18 a.m.

Fiber Optic Transmission Lines

fiber, волс, монтаж

Installation of couplings

Mounting of couplings shall be in accordance with installation instructions for the particular type of coupling of the manufacturer (supplier) couplings. Connection of optical fiber mounting couplings should be carried out under the control of the welding method of attenuation OTDR. The value of a welded joint fiber attenuation, calculated in the direction A - B, B - A, should not exceed 0.1 dB. Each coupling after installation should be the marked sheet of lead or plastic ring tag. Each mounted clutch must be drawn up in duplicate passport. One copy is placed in the sleeve, the second is attached to the as-built documentation. If it provided by the project, and then the optical coupling OK stock placed in a specially made case, which must be secured to the support.

On the local communication networks, mainly to be used optical coupling of domestic manufacturers, designed to meet current technical requirements and compliance with the declaration of the Ministry of Information Technologies and Communications of the Russian Federation. Is allowed to use on the local networks of optical coupling of the foreign producers if the certificate of conformity and standard solutions for installation, mounting and protection of optical couplers in their places of assembly.

Optical Coupler for armored OK, laid in the ground, should ensure that:

  • the ability to electrically connect the screens or metal power elements matched OC structural elements of at least 2.5 mm2;
  • the ability to lead wires of the metallic elements construction OC, separately for each OC to connect to an external ground.
Aug. 1, 2015, 9 a.m.

Fiber Optic Transmission Lines

fiber, волс, конструкция

Introduction

Currently, the Russian market is widely featured products, both domestic and foreign manufacturers of optical couplings for installation of cables. Widely known and used clutch of such manufacturers as: Raychem (Belgium), Reichle & DeMassari (Switzerland), RXS / Simens (Germany), ZM (USA), Fujikura (Japan), Ericsson (Sweden), the Nokia (Finland), AT & T (USA), Pirelli (Italy), Alcatel (Germany).

These companies provide a wide choice of all types of couplings each customer to solve any problem. Along with the delivery of the coupling component manufacturers of the necessary additional accessories such as brackets, housings, additional accessories and consumables items. Deliver them also the necessary equipment and tools, including even the tables of the installation work.

July 31, 2015, 1:06 a.m.

Android

Android, read, write, file

Read and write operations to file are standard functionality of any applications that are logging the events, work with files, up to the transfer of data over the network. In this article, we consider methods of recording information in the files, and read from a file recorded line.

Project structure

Esthetic changes to the standard buttons or ListView will not be made in this lesson, since we work with what is hidden from the eyes of the user, namely, to work with files.

The entire structure of the project respectively is at this time only one class: MainActivity

Also, the project contains the following resource files:

  1. activity_main.xml
  2. strings.xml
  3. styles.xml - in the file does not have any changes relating to a project.
July 30, 2015, 7:49 a.m.

Data Transmission Technologies

виртуальный канал, дейтаграммная передача, коммутация каналов, коммутация пакетов, составной канал, элементарный канал

Circuit switching and packet - it's methods for solving the generalized problem of switching data in any network technology. Complex technical solutions of the generalized switching tasks in its entirety consists of the particular problems of data transmission networks.

By the special problems of data networks include:

  • define flows and appropriate routes;
  • fixation route configuration parameters, and tables of network devices;
  • recognition flows and data transfer between one device interface;
  • multiplexing / demultiplexing streams;
  • separation medium.
July 29, 2015, 8:47 a.m.

Fiber Optic Transmission Lines

fiber, волс, монтаж

Basic concepts and definitions

The most responsible operation in the process of construction of fiber-optic, predetermining the quality and range is the installation of optical fibers. Such a combination of fibers and installation cables are produced in the manufacturing process as well as during the construction and operation of cable lines.

Installation is divided into permanent (fiber welding) and temporary (plug connectors). Fiber optic connectors typically are valves designed for adjusting and fixing the fibers to be connected, as well as mechanical protection for the splice.

The main requirements for connectors are:

  • simple structure;
  • small transient loss;
  • resistance to external mechanical and climatic influences;
  • reliability;
  • In addition to the detachable connectors are required constancy of parameters during re-docking.

Insertion loss connection of optical fibers in a cable transmission path, are divided into external and internal.

External referred to the losses associated with the features of the connection method, including the preparation of the ends of optical fibers, and comprising lateral displacement of the core, diversity ends, the slope of the axes, the angle of the fiber end face, the Fresnel reflection.

I nternal losses are associated with the properties of the resulting optical fiber and, for example, variations in core diameter, numerical aperture, the refractive index profile, netsirkulyarnostyu core Concentricity core and cladding.

Last comments
March 19, 2019, 12:57 p.m.
AlexanderBardin

Добрый день. А проверить работоспособность локально как-то можно не указывая реальнй сайт (еще в разработке)
March 16, 2019, 1:55 p.m.
Дмитрий

Спасибо за статью. Давно итересует следующий вопрос: с помощью переменных QMAKE_TARGET_COMPANYQMAKE_TARGET_PRODUCTQMAKE_TARGET_DESCRIPTIONможно задать свойства компилируемой программы, о...
JS
March 12, 2019, 10:19 a.m.
Jean Stefanovich

Большое спасибо за разъяснения!
March 12, 2019, 10:04 a.m.
Евгений Легоцкой

Hello, In fact, this functionality or is not implemented, or is not documented. I'm not sure. But I think, that it should be implemented in Text QML Type. Because of we can write text in...
March 12, 2019, 9:51 a.m.
Евгений Легоцкой

Да вы правы. На самом деле проще через QSqlQueryModel, сколько не пытался использовать эти дженерики типо QSqlTableModel и QSqlRelationalTableModel, то всегда упирался в какие-то их ограничени...
Now discuss on the forum
March 19, 2019, 1:43 p.m.
AlexanderBardin

Очень интересная тема. У вас случайно нет статьи с полным циклом интреграции нескольких языков?Так сказать с нуля, что нужно, какие пакеты ставить, что куда писать. Тут вроде информации не ма...
March 17, 2019, 10:47 p.m.
Евгений Легоцкой

Добрый день. Вот, нашлось у меня немного времени. Делается это через шаблон проектирования наблюдатель. GraphKS_mfvSlup.zip
ЧГ
March 15, 2019, 9:52 p.m.
Чарльз Грин

спасибо, попробую, отпишусь
m
March 15, 2019, 7:41 p.m.
mihamuz

Сори догадался)
n
March 12, 2019, 4:57 p.m.
newbie.works.with.QT

Большооооое спасибо!!!!!Не передать как я вам благодарен, спасибо что всегда отзываетесь.Теперь я смогу продолжить работу в QT!!! (пробую писать бота (Я как вы могли догадаться немного не пр...
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