How CAT 5 cables work?

What is CAT 5?

• Cat 5, is a twisted pair cable for carrying signals.
• This type of cable is used in structured cabling for computer networks such as Ethernet.
• The cable standard provides performance of up to 100 MHz and is suitable for 10BASE-T, 100BASE-TX (Fast Ethernet), 1000BASE-T (Gigabit Ethernet), and 2.5GBASE-T.
• Cat 5 is also used to carry other signals such as telephony and video.

How CAT 5 cables work?

• CAT 5 cables contain four pairs (8 wires ) of copper wire supporting Fast Ethernet speeds (up to 100 Mbps).
• The four wire pairs in a CAT 5 cable are distinguished by the color of their insulation. The four colors are (in order) blue, orange, green and brown.
• Each colored pair consists of (in order) a white wire with a colored stripe and a colored wire with a white stripe.





• Each pair is twisted together to reduce signal interference.
• Twisted pair allows greater data capacity over longer distances.
• The tighter twists also suppress noise created by the cable.
• When terminating data cables (with crimp-on connectors or at punch-down terminals), it is important to untwist the pairs as little as possible.

How to connect CAT 5 cable to the connectors?

There are two types of connectors, RJ-11 and RJ-45:

RJ-11

• RJ-11 connectors are used by phones.
• Wires in RJ-11 connectors do not follow a linear order (left-to-right), instead they follow a centric order, working from the center pins out.
• To make connections compatible with both ends of a logically "crossed" cable, it is necessary for every pair in the cable to have each wire equidistant from the center of the connector.

RJ-45

• RJ-45 connectors used by networks, which are a bit wider.
• Wires in RJ-45 connectors have a mix of centric and linear ordering.
• The two middle pairs are centric ordered, the two outer pairs are in linear order. Means the middle pair will swap.

My notes

Who Invented?

• Invention means creation of new, useful process, machines etc that did not exist previously.
• Following are the some inventions:

Internet

• The development of internet started in 1957 when the first satellite Sputnik was launched by the Soviet Union.
• The team of experts set to work as the Americans felt the need of network system for security.
• Defence Advance Research Project Agency was set up in 1958 to work and save the country from missile attacks.
• Joseph Licklider was appointed as the chief of New Information Processing Technique office (IPTO) and his was the main contribution in the development of internet.
• J.Licklider was not a computer programmer so he hired Lawrence Robert to work on his ideas.
• Lawrence headed the team and developed ARPANET in 1967.
• He used packet switching developed by Leonard for transferring data.
• The UCLA (University of California, Los Angeles) put out a press release introducing the public to the Internet on July 3, 1969.

Google Search Engine

• Invented by the Soviet born Sergey Brin and American Larry Page in 1998.
• They named it Google, after the Googol.
• The Googol is the term for the number 1 followed by 100 zeros.
• The name itself was chosen to represent the infinite amount of information that the search engine aimed to organise.

Computer Mouse

• The first computer mouse was invented in 1964 by Dr. Douglas C Engelbart.
• The first mouse was made of wood, with a circuit board, two metal wheels which remained in contact with the surface it was being used on and a button.
• In 1972 that the mouse had its’ first upgrade. Bill English developed the design to create a ‘ball-mouse’.
• In 1980 when the optical mouse was invented.

Wireless Remote Control

• Wireless remote control was invented by Austrian Robert Adler in 1956.

Telegraph

• Samuel F. B. Morse invented the first telegraph in 1837.
• The device he developed used an electric circuit, an overhead wire and Earth as another conductor to complete the circuit.
• the first telegraphic message was “What Hath God wrought?” officially inaugurated on May 24, 1844.

Airplane

• In the late 1800s Orville and Wilbur Wright were the men who dreamt of inventing the airplane.
• In 1900 they tested their first glider at Kitty Hawk.
• For the next two years the brothers plied from Kitty Hawk to their home in Dayton, Ohio. These test drives were a great success.
• The first successful flight was launched on December 17, 1903 by Wright Brothers.
• Wright Brothers received a patent for their air machine on May 22, 1906.

Train

The train was first invented and patented in 1784, by James Watt.

The first working model to be made and successfully run was created in 1804 by Richard Trevithick.

It used for supplies or materials from location to location.

In 1825 George Stephenson built the "Locomotion" that trains came into public use.

Ink

• The first writing ink was invented in 2500 B. C. by the Egyptians (Gelatin) and the Chinese (Tien-Lcheu).
• It is believed that this ink was made by mixing carbon with gum.
• It was then shaped into sticks and dried, before use it was dipped in water and made ready for writing.

Data Compression

• Data compression also known as source coding or bit-rate reduction.
• Data compression is a reduction of bit to reduce the size of files.
• It can be done all type of file like audio, video, images.
• Compressing data can save storage capacity, speed file transfer, and decrease costs for storage hardware and network bandwidth.

Types

Lossy compression

• Lossy compression reduces bits by removing unnecessary or less important information.
• This type of compression is done mainly on media files such as image, audio and video files.

Lossless compression

• Lossless compression ensure that you can recreate the original file bit for bit in its entirety.
• There is no data loss during the compression and decompression.
• This type of compression is usually a must if you are compressing text files, data files or certain proprietary formats.

Why to do data compression?

Backups and Archiving files

• If you have many older files that you do not need to access on an everyday basis, but would like to preserve for other reasons then you want to archive them for safe keeping.
• You can compress and bundle the files together or in separate archive files and save it.

File transfer

• If you are uploading one or several large files to a website or moving files to another machine, you could benefit from a smaller file size.
• This reduces your bandwidth usage as well as the time needed to transfer the files.

Web use of media files

• If you plan to use the media file on the website, then using a lossy compression on your image and media files will allow you to reduce the size of the files.

File Encryption and Protection

• Many simple file formats do not provide much of a file protection or security.
• This provides a method to secure a complete set the files as they can be encrypted and protected using a single password.

Advantages

• Less disk space.
• Faster writing and reading.
• Faster file transfer.
• Variable dynamic range.
• Byte order independent.

Disadvantages

• Added complication.
• Effect of errors in transmission.
• Slower for sophisticated methods (but simple methods can be faster for writing to disk).
• Unknown byte / pixel relationship.
• Need to decompress all previous data.

Numbers Totalled

• Totalled means adding or grouping the numbers together.
• Numbers totalling is dependent on the concept of numbers always to the right.
• We have to the arrange the numbers according to the type of numbers.
• Integers always aligned to the right because the values is increases from right to left.





• If we arrange the numbers proper manner then only we get the correct result otherwise we will get the wrong result.

• In fractional numbers the digit after decimal is increases from left to right, so after decimal the numbers should be aligned to the left.





• Fractional numbers have to align the decimal places should be aligned, with the units digits all in a vertical line.

Compression losses

• Some amount of data may be lost during the compression process is called compression losses.
• Thus after a compression or decompression cycle, the data set will be modified from the uncompressed original and information may be lost.
• Compression losses is occur using the lossy compression techniques.
• In many cases file or data streams contain more information than is needed for a particular purpose. Developing lossy compression technique you can make it easier for human.
• Lossy compression technique used for pictures and music files that can be trimmed at the edges.

Advantages

Transparency

• Compression losses gives us transparency. Means when a user acquires a lossily compressed file, (for example, to reduce download time) the retrieved file can be quite different from the original at the bit level while being indistinguishable to the human ear or eye for most practical purposes.

Compression ratio

• The compression ratio (that is, the size of the compressed file compared to that of the uncompressed file) of lossy video codecs is nearly always far superior to that of the audio and still-image equivalents.

My notes

Text Formatting

• Alongside photo and image manipulation Photoshop allows you to define text style for both paragraph and characters.
• It also allows you to create unique artwork, company logos, presentation backdrops etc.
• Text formatting can be done using Type Tool, Character Panel and Paragraph Panel.

Type Tool

• It allows you to add text to your document.
• There are several type tool like horizontal, vertical, choose your desired Type Tool.
• Choose the styles from the top of the screen then drag anywhere in the document to create a text box.
• You can also resize, rotate and skew the text using Type Tool.

Character Panel

• The Character Panel present in the right side of the Photoshop window.
• The Character Panel offers size, color, style spacing, kerning and many others formatting option on the text.

Paragraph Panel

• It controls both character and paragraph attributes such as indents and spacing, alignment, hyphenation etc.
• When paragraph style apply to the whole paragraph, character style are used to format selected text within paragraph.
• First create the paragraph style after that you can apply the character style.

My notes

DXF File Format

• DXF stands for drawing exchange format, first created in 1982.
• It is created to exchange drawing between different CAD programs like AutoCAD, Adobe Illustrator, Scan2CAD and CoreICAD.
• DXF can act as a conduit between different vector graphics programs. For example, a file could be created in AutoCAD, saved as a DXF and opened in Adobe Illustrator.
• DXF file can be opened in any text editor, to see the drawing units.

File Structure

ASCII version of DXF can be read with any text editor. The basic organization of a DXF file is as follows:-

• Header section: It contains general information about the drawing. For eg. which AutoCAD version the file uses.
• Classes section: Holds the information for application-defined classes, appears in the Blocks, Entities, and Objects section of the database.
• Tables section: This section contains definitions for several different tables, each of which contains a number of different symbol entries. For eg. Application ID (APPID) table, Block Record (BLOCK-RECORD) table.
• Blocks section: This section contains Block definitions entities describing the entities compressing each Block in the drawing.
• Entities section: It contains the drawing entities, including any Block references.
• Objects section: Contains the data that apply to non-graphical objects. For eg. AutoCAD dictionaries are stored here.
• Thumbnail-image section: Contains the preview image for the DXF file.

Advantages

• DXF file is an open source file format.
• DXF file is supported by all the CAD programs.
• It is easily exchangeable across formats.
• It is compatible with vector file format.

Disadvantages

• DXF does not support application specific CAD elements.
• Complex DXF files can becomes large in size.
• Some applications can not deal with line widths in DXF Files.

Examples

• An architectural designer receives a layout design from a subcontractor from a PDF file. He’d convert the PDF file to DXF and load the DXF file for editing CAD.





• An archaeologist has a database with the XY coordinates of her surveyed sites. She exports the data from her specialized data measurement program and converts it into a DXF file. Then, she can load the DXF file into a CAD software and visualize her findings.

My notes