Transmission Media for Networks : Data transmission is the way or method to transfer any kind of information from one space to another. Transmission Media for Networks By
Sugandha Singh
sugandha06@gmail.com
+91-9785774032
Contents : Data transmission is the way or method to transfer any kind of information from one space to another. Contents Basis for Data Transmission
Types of data transmission
Criteria for Media Evaluation
Categories of Transmission Media
Theoretical : Data transmission is the way or method to transfer any kind of information from one space to another. Theoretical Information can be transmitted through a medium by varying some physical property.
The physics of the universe places some limits on what can be sent over a channel.
Purpose of the physical layer -- to transport a raw bit stream from one machine to another
Guided and Unguided media
Protocols : Data transmission is the way or method to transfer any kind of information from one space to another. Protocols The protocol determines the following:
Type of error checking to be used if any
Data compression method.
Method for sending device to indicate that it has finished sending a message.
Method for receiving device to indicate that it has received a message
Rate of transmission (in baud or bit rate)
Whether transmission is to be synchronous or asynchronous
Types of data transmission : Data transmission is the way or method to transfer any kind of information from one space to another. Types of data transmission Serial Transmission
Parallel Transmission
Criteria for Media Evaluation : Data transmission is the way or method to transfer any kind of information from one space to another. Criteria for Media Evaluation Bandwidth
Bit rate - expresses the data rate capacity of a networking system
Delay - The time required to send a signal across a network
Cost of medium material
Ease of installation and Maintenance
Categories of Transmission Media : Data transmission is the way or method to transfer any kind of information from one space to another. Categories of Transmission Media A. Guided media
and
B. Unguided Media
A. Guided Media : Data transmission is the way or method to transfer any kind of information from one space to another. A. Guided Media Guided Transmission Media uses a "cabling" system that guides the data signals along a specific path.
The data signals are bound by the "cabling" system. Guided Media is also known as Bound Media.
There 4 basic types of Guided Media:
1. Open Wire
2. Twisted Pair 3. Coaxial Cable
4. Optical Fiber
Bandwidth comparison : Data transmission is the way or method to transfer any kind of information from one space to another. Bandwidth comparison Cable Type Bandwidth
Open Cable 0 - 5 MHz
Twisted Pair 0 - 100 MHz
Coaxial Cable 0 - 600 MHz
Optical Fiber 0 - 1 GHz
1. Open Wire : Data transmission is the way or method to transfer any kind of information from one space to another. 1. Open Wire
2. Twisted Pair : Data transmission is the way or method to transfer any kind of information from one space to another. 2. Twisted Pair
Slide 12 : Data transmission is the way or method to transfer any kind of information from one space to another. Each pair would consist of a wire used for the +ve data signal and a wire used for the -ve data signal.
Any noise that appears on 1 wire of the pair would occur on the other wire. Because the wires are opposite polarities, they are 180 degrees out of phase.
Numbers of pairs are bundled together. Twisting decreases crosstalk. When the noise appears on both wires, it cancels or nulls itself out at the receiving end.
It is mainly used for telephone system and for subscriber’s loop like LAN.
The degree of reduction in noise interference is determined specifically by the number of turns per foot. Increasing the number of turns per foot reduces the noise interference.
Shielded Twisted Pair : Data transmission is the way or method to transfer any kind of information from one space to another. Shielded Twisted Pair
Slide 14 : Data transmission is the way or method to transfer any kind of information from one space to another. Advantages:
1. Easy to string 2. Cheap
Disadvantages:
Subject to interference is static and garble.
In comparison to others ( Coax & optical fiber) twisted pair is limited in bandwidth, distance and data rate Like if used for digital systems it requires repeater after every 2-3 Kms.
Susceptible to noise weather shielded and unshielded
3. Coaxial Cable : Data transmission is the way or method to transfer any kind of information from one space to another. 3. Coaxial Cable Coaxial Cable consists of 2 conductors. The inner conductor is held inside an insulator with the other conductor woven around it providing a shield.
An insulating protective coating called a jacket covers the outer conductor.
The outer shield protects the inner conductor from outside electrical signals.
The distance between the outer conductor (shield) and inner conductor plus the type of material used for insulating the inner conductor determine the cable properties or impedance.
Slide 16 : Data transmission is the way or method to transfer any kind of information from one space to another. (a.)
Slide 17 : Data transmission is the way or method to transfer any kind of information from one space to another. Advantages:
Not susceptible to interference
Transmits faster
With FDM it can carry 10,000 voice channels
Disadvantages:
Heavy & bulky
Needs booster over distance. Like repeaters or amplifiers are needed every few Kms.
4. Optical Fiber : Data transmission is the way or method to transfer any kind of information from one space to another. 4. Optical Fiber Optical Fiber consists of thin glass fibers that can carry information at frequencies in the visible light spectrum and beyond.
The typical optical fiber consists of a very narrow strand of glass called the Core.
Around the Core is a concentric layer of glass called the Cladding.
A typical Core diameter is 62.5 microns (1 micron = 10-6 meters). Typically Cladding has a diameter of 125 microns.
Covering the cladding is a protective coating consisting of plastic, it is called the Jacket.
Slide 19 : Data transmission is the way or method to transfer any kind of information from one space to another.
Principle working of Optical Fiber : Data transmission is the way or method to transfer any kind of information from one space to another. Principle working of Optical Fiber Characteristic of Fiber Optics is Refraction.
The core refracts the light and guides the light along its path.
The cladding reflects any light back into the core and stops light from escaping through it - it bounds the media!
Slide 21 : Data transmission is the way or method to transfer any kind of information from one space to another. Advantages:
Noise immunity: RFI and EMI immune (RFI - Radio Frequency Interference, EMI –Electro Magnetic Interference)
Security: cannot tap into cable.
Large Capacity due to BW (bandwidth)
No corrosion
Longer distances than copper wire
Smaller and lighter than copper wire
Faster transmission rate
Slide 22 : Data transmission is the way or method to transfer any kind of information from one space to another. Disadvantages :
Physical vibration will show up as signal noise.
Limited physical arc of cable. Bend it too much & it will break.
Difficult to split.
Copper:
It has low resistance to electrical current and signal travels farther.
guided medium
bandwidth - depends on the thickness of the wire and the distance traveled.
interference - susceptible to electromagnetic waves generated by neighboring wires.
Two main types - twisted pair and coaxial cable (coax)
Slide 23 : Data transmission is the way or method to transfer any kind of information from one space to another. The Advantages of Fiber over Copper:
Interference - does not cause interference; and is not susceptible to interference.
Bandwidth - handles much higher bandwidth than copper
Low attenuation - requires fewer repeaters and amplifiers (every 30 Km vs. 5Km)
Immune to power surges, failures, and other electromagnetic interference
thin and lightweight
don’t leak light; tough to tap (secure)
B. Unguided Media : Data transmission is the way or method to transfer any kind of information from one space to another. B. Unguided Media ??????
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