July 28, 2015, 2:56 a.m.

Fiber Optic Transmission Lines

ВОК, fiber, волс

Classification of fiber optic cables

Fiber-optic cables (FOC) - a cable products, containing a number of optical fibers and the reinforcing member enclosed in a common envelope, on top of which, depending on the operating conditions of the protective cover can be imposed.

Fiber-optic cables are classified by purpose and conditions of use, as shown in the figure below.

Since FOC less durable than electric cables, they must be protected from the harmful effects of the environment and human activities, which include mechanical stress (tension, bending, compression, torsion, shock, vibration); temperature changes; water penetration.

Fiber-optic cable can consist of the following components:

  1. Outer PE shell - protects the cable from external influences;
  2. Armid thread - protects the cable from the squeezing and stretching;
  3. Inner polyethylene shell - separates the optical module from armid shell and the outer shell;
  4. Binding tapes - connect optical modules in the overall braid;
  5. Filling unit - empty unit without the optical fiber cable is designed to form a shape;
  6. Optical module - module with optical fibers. Usually there is one module 8 to the fibers;
  7. Optical fibers;
  8. Fiberglass bars - reinforcing the central element, also protects the cable from stretching. It is used often in self-supporting cables;
  9. **The hydrophobic filler - filler, protects from moisture.

Basic requirements for the fiber-optic cable, and the material of its main components

Common basic requirements for physical and mechanical characteristics of the fiber optic cable are:

  1. high tensile strength;
  2. moisture resistance;
  3. sufficient buffer protection to reduce losses caused by mechanical stresses;
  4. thermal stability in the operating temperature range (–40—+50 о С);
  5. flexibility and the possibility of laying on the actual routes;
  6. radiation resistance;
  7. chemical and impact resistance;
  8. ease of installation and gaskets;
  9. reliability in operation for 20 years.

Also during the design must take into account the relative POC location strength members and optical fibers. There are two main options for such a mutual arrangement:

  • In the first reinforcing member is located in center of the cable, and fiber - concentrically relative to the central element.
  • In the second optical fibers are arranged in the center and power elements - around

Typical designs of optical fiber cables

Currently in different countries developed and produced a large number of construction POC. The most widely used group of four cable designs:

  • with a free tube;
  • free-fiber bundle;
  • with core-core;
  • belt type.

The construction of the FOC with the free fiber bundle

With this structure, the optical fiber bundles are placed freely inside the core tube. This design reduces the tensile, compressive and compressive loads on the optical fibers. Fume cables are used for the convenience of cutting the outer sheath of the optical cable.

The construction of the FOC core with core

With this structure, there is a core shaped with cavities for placing the optical fibers. The advantage of this type of construction is that the center of figure of the core is a steel strength member that receives the compressive and tensile impact.

Design ribbon fiber optic cable

In this structure, all the optical fibers are combined into bands, which are located within the core tube.

The construction of ocean-going fiber optic cable

It designs cables laid on the seabed, there are special requirements. Cables of this type are experiencing particularly heavy loads. Therefore, more than 90% of the data cable constructions make up the protective and reinforcing elements.

Fiber Optic Cables urban telephone networks

Cables used for urban telephone networks have, as a rule, lightweight design, as laid in cable ducts, pipes, reservoirs and inside buildings. Such cables are designed according to the principle of free tube with a large number of optical fibers in each module.

JSC "Samara Optical Cable Company" FOC makes the city the following brands: OKL 01 OKL 02..

NF JSC "Wiring harness" produces urban brands EQA OK M M ACS (TU 16.K12 16, 97).

"Plant Saransk Cable" in addition to long-distance FOC has mastered the production of cables and urban telephone networks of the following brands: JAG (laying in cable ducts) and CPR (laying directly in the ground).

Fiber-optic cables for internal wiring

The design of the fiber-optic cable for internal wiring consists of the following main elements:

  1. an optical fiber;
  2. buffer shell;
  3. power element;
  4. outer shell

Cables are designed for internal wiring, divided into:

  1. Simplex cables;
  2. duplex cables;
  3. multi-fiber cables;
  4. cables for heavy duty;
  5. fireproof cables.

July 27, 2015, 2:32 a.m.

Data Transmission Technologies

Кампусные сети, корпоративная сеть, сеть отдела, сеть предприятия, сеть рабочей группы

Introduction

Corporate Network - a network whose primary purpose is to maintain the operation of a particular enterprise that owns this network. Corporate network users are the only employees of the company.

In contrast to the prodier networks, enterprise networks, in general, do not render services to third parties or users.

Local networks of end-users are included in the corporate network. The names of the structural units of the corporate network reflect not only the territory of coverage, but also the organizational structure of the enterprise. So, we decided to share a corporate network on a network of divisions and working groups, building a network, campus network backbone.

July 27, 2015, 2:21 a.m.

Data Transmission Technologies

Стандартизация, ЛВС, ШПД

Standardization and sources of standards

Universal argument about the benefits of standardization, which is valid for all industries, computer networks is of particular importance. The essence of the network - the connection of various equipment, and therefore there is a problem of compatibility of the most critical one. Without coordination by all producers generally accepted standards for the equipment and protocols progress in the "construction" of networks would be impossible. Therefore, all the development of the computer industry is ultimately reflected in the standards - any new technology only assumes a "legal" status, where its content is fixed in the relevant standard.

July 26, 2015, 9:12 a.m.

Android

Android, Toast

Give customization of all applications under OS Android !!!

With the slogan I want to tell today about customization pop-up message (Toast) in the Android OS. In any application that is designed and developed with great care, the question may arise about the customization of even such an element as a popup message. After the success of the application depends not only on ideas and utility, but also from the sale of the appearance of the parts, even the smallest and seemingly not very important.

Project structure

This lesson is to write an application that will display a customized pop-up message by pressing a button, which will not be subject of customization.

In the Project there are two classes:

  1. MainActivity
  2. MyListAdapter - which is responsible for the transmission of data in the form of a list item

Also, the project contains the following resource files:

  1. activity_main.xml
  2. toast_info.xml - pop-up message marking
  3. toast_border:xml - additional markup for background of pop-up message
  4. ic_info.png - Image Information icon, which will be used in the pop-up message
  5. string.xml - string constants file
July 21, 2015, 8:55 a.m.

Android

ListView, ListAdapter, Android

Customization ListView is common in developing applications for Android OS. ListView (List) allows you to display the same type of information in your application, for example, show the products with prices and features, if you develop applications for online sales. At the same time being in fact a routine operation, however, some questions for novice developers deliver a lot of inconvenience. Some of these inconveniences and questions will be discussed in this article.

Project structure

This lesson is proposed to establish a small list with the flags of countries, called the currencies of these countries, and the abbreviation of the country.

Total is used to create a list of four countries: Russia, South Africa, Singapore, Turkey. Flags of these countries are in the drawable folder. Also there is an xml file to create backgrounds ListViewi flags. For storing names and abbreviations used strings.xml file. Also, a separate xml file to create the ListView layout.

In the Project there are three classes:

  1. MainActivity
  2. MyListAdapter - which is responsible for the transmission of data in the form of a list item
  3. DataFlags - class that is designed to facilitate the transfer of data to the adapter ListView
July 20, 2015, 1:57 a.m.

Data Transmission Technologies

иерархическая звезда, кольцевая топология, топология ЛВС, полносвязная топология, ячеистая топология

Under the topology of the network refers to the configuration of the graph, whose vertices correspond to the end nodes of the network (such as computers) and communications equipment (eg, routers), and the edges of the physical or informational communication between nodes.

Full mesh

Full mesh

This topology requires communication nodes N N (N-1) / 2 duplex physical links. The advantage of this layout is that it connects each node to each. Thus, in the event of a node failure, there is no malfunction of other nodes in the network based on this topology.

But in practice, this type of topology is not applicable, because it is a very expensive option of building a network.

July 20, 2015, 1:38 a.m.

Data Transmission Technologies

network, transmission

Decomposition of the tasks of networking

Network architecture - a view of the network as a system of interrelated elements, each of which is assigned a specific private function.

In addition, each of the network elements solves a common problem. All common task is broken down into a number of small tasks that solve different network elements, ie one single task is decomposed. The interaction between all network elements through a formalized set of rules, called the protocol.

Decomposition of the task

Decomposition - splitting a complex task into several simple.

June 29, 2015, 2:47 a.m.

Fiber Optic Transmission Lines

fiber, волс, модовая дисперсия

Distinguish mode dispersion, which is caused by a large number of modes in the optical fiber and the chromatic dispersion associated with the incoherence of light sources actually operating in a certain range of wavelengths.

Consider the propagation of the light beam along the multimode fiber. In this case there are two modes, the two beams. The first extends along the longitudinal axis of the fiber, while the other is reflected from the interfaces of media. Thus the path of the second light beam is greater than the first. As a result, when the two beams carrying the electromagnetic energy are added together, compared oblique beam with an axial beam is the time delay, which is calculated by the following formula:

c – speed of light
l – fiber length
n 1 , n 2 – refractive indices of the core and shell

June 29, 2015, 2:36 a.m.

Fiber Optic Transmission Lines

fiber, волс, потери

The most important parameters are the optical fiber loss and attenuation of the transmitted energy. These parameters define the range of the FOC and on its effectiveness. Attenuation in optical fibers due to manifestation of the following losses:

α c – own loss of fiber waveguides
α k – additional cable losses
α ik – absorption loss in the infrared region
α pr – the loss caused by the presence of impurities in the optical fibers

Proper loss fibers consist, in turn, an absorption loss of α p and scattering loss α r :

Attenuation due to the absorption due to the losses on the dielectric polarization depends strongly on the properties of the fiber material and is calculated by the following formula:

tgδ – dielectric loss tangent

The attenuation in the infrared region, situated in the wavelength range of more than 1.6 microns, calculated by the formula:

C and k – constant coefficients. For quartz glass C = 0,9; k = (0,7—0,9) мкм.

June 28, 2015, 8:22 a.m.

Fiber Optic Transmission Lines

fiber, волс, типы волс

Depending on the number of the operating frequency propagating waves (modes) of the fibers and is separated into one multimode. The number of modes is dependent on the ratio of the diameter of the fiber core and the wavelength for optical fibers having step-index is calculated as follows.

α – fiber core radius,
λ – wavelength,
Δ – relative refractive index difference.

Since n 1 and n 2 have very similar meanings, the nominal value ∆ for most optical fibers is within

Donate

Hello, Dear Users of EVILEG!!!

If the site helped you, then support the development of the site financially, please.

You can do it by following ways:

Thank you, Evgenii Legotckoi

a
Feb. 25, 2020, 4:40 a.m.
ayb

C++ - Test 005. Structures and Classes

  • Result:83points,
  • Rating points4
DZ
Feb. 24, 2020, 1:47 p.m.
Dmitrij Zlobin

C ++ - Test 004. Pointers, Arrays and Loops

  • Result:40points,
  • Rating points-8
p
Feb. 17, 2020, 1:41 p.m.
pstMem

C++ - Тест 003. Условия и циклы

  • Result:85points,
  • Rating points6
Last comments
Feb. 24, 2020, 2:54 a.m.
Evgenij Legotskoj

Добрый день. Там будет url, на который указывает ссылка тега a в пагинаторе, если правильно помню )) Написал этот код и забыл.
B
Feb. 23, 2020, 11:37 p.m.
BahaMeirman

Евгений Здравствуйте! Не могу понять вот эту часть кода: url: jQuery(this).attr('action') наверное здесь должен быть путь к url, тогда 'action' на какой url указывает?
Feb. 17, 2020, 2:22 a.m.
Evgenij Legotskoj

Добрый день. Это кастомный тег, помещается в файл, который находится в каталоге templatetags myapp/ templatetags/ myapp.py
B
Feb. 16, 2020, 12:36 p.m.
BahaMeirman

Добрый вечер! Монжно по подробней о теге get_companion? ссылка не работает.
Now discuss on the forum
a
Feb. 25, 2020, 7:06 a.m.
ayb

Да
Feb. 24, 2020, 11:04 a.m.
Evgenij Legotskoj

Добрый день. Вот пример с дружественного ресурса с движением камеры
Feb. 24, 2020, 5:29 a.m.
Evgenij Legotskoj

Qt не предоставляет функционала по запросу root прав во время выполнения программы. Поэтому нужно использовать платформозависимый функционал, для Linux это будет выглядеть так: #include…
Feb. 24, 2020, 2:47 a.m.
Evgenij Legotskoj

Добрый день. Что означает клиентская область? Это изображение? Вам нужно распознавать символы текста или всё-таки пользователь будет вводить текст с клавиатуры, просто в любом месте "абстр…
VZ
Feb. 21, 2020, 4:19 a.m.
Vladimir Zhitkovsky

void sendImage(int sessid, int type, int dest, int format, QString imgBase64Data){ QNetworkRequest request; request.setUrl(QUrl(ipAddress + "ctlapi/cmd=preparereportimg&sessid=…
EVILEG
About
Services
© EVILEG 2015-2019
Recommend hosting TIMEWEB