Monday, March 17, 2014
Physical Layer - Data Transmission
Chapter 3
Two types of circuit :
#Logical circutit
#Physical circuit(Could have one or more logical circuits)
Two fundamental types of data could follow through a circuit :
*Digital
*Analog
Data convertors :
#Modem (Converts Digital to Analog) e.g. Home modem
#Codec (Converts Analog to Digital)r e.g. Voip telephone lines which converts the voice (which is analog to digital)
Three types of Data flow :
1.Simplex (One way traffic)
2.Half Duplex (One way at a time)
3.Full Duplex (Both ways at the same time)
Multiplexing
Multiplexing - To combine multiple signals (analog or digital) for transmission over a single line or media.
A common type of multiplexing combines several low-speed signals for transmission over a single high-speed connection.
Multiplexing is done by using a device called multiplexer (MUX) that combines n input lines to generate one output line i.e. (many to one). Therefore multiplexer (MUX) has several inputs and one output.
At the receiving end, a device called demultiplexer (DEMUX) is used that separates signal into its component signals. So DEMUX has one input and several outputs.
Types of Multiplexing :
#FDM (Frequency division multiplexing) - Different frequency used in one media which are separated by guard bands.
#TDM (Time Division multiplexing) - Time is the key, each of the pc get a time token or are in a queu and gets their chances to be part of it.
#STDM (Statistical Time Division multiplexing)- IF 4 computers transfer data 64kbps then then you need a multiplexing system with a capability of 64 * 4 = 256 kbps, however if the statistic shows that you could use 128 as only two of the computers use transmission at the same time. This way you save money and use STDM. Problem will occur when all the computer will perform transmission at the same time.
#WDM (Wavelenght Division myltiplexing) - FDM used by optic fiber- Laser sends diff frequencey of ligt in same fiber optic cable. Step index, Graded index, single mode.
Ref for multiplexing photo
Inverse Multiplexing:
IMUX - Reverse process of multiplexing. Multiplexing combines lower speed circuits and transmitt as high speed one. IMUX
Modulation-
Modulation is the process of changing the characterstics of the signal before / after transmitting.
Modulation Explained
#FM - Frequency Modulation
#AM - Amplitude Modulation
#PM - Phase Modulation
Analog Transmission explained
Digital Transmission of Digital data:
-Polar
-Bipolar
#NRZ (Non Return Zero)
#Return Zero
#AMI (Alternate Mark Inversion)
-Manchester
Digital Data Transmission
Analog Transmission of Digital Data:
Easy definition of Analog Transmission
Digital Transmission of Analog data:
Interesting :
Modem - Named from Modulator + Demodulator = MOD + DEM = MODEM
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Tutorial 17/03/2014
Http - Hyper Text Transfer Protocol
* Normal Protocal
* Standard Protocal
HTTP is a standard protocal
Http used in World wide web
Client - server (web server) These two communicate via http
Http Request Message (packet) :
#Request line
#Rquest header
#Req body
Response :
Response line (200-ok)
Response Header
Response body(HTML language normally) Hyper text marker language
Things to know about http :
CR - Carriage reun
LF - Line feed
GET
PUT - UPLOAD
POST - ADDITIONAL INFORMAION
RESPONSE MESSAGE :
200 MEANS OK
301 MEANS MOVED PERMANANTLY
404 MEANS NOT FOUND
500 MEANS INTERNAL SERVER ERROR
There are enter keys and has related ASCII
In the querry or filter box of wire shirk to narrow down any specific search you type the following :
# http and ip.addr
# use and or
# do sort
Answer to tutorial questions :
1.Identify HTTP packets, requests and responses related to downloading my web page. Give the related frame numbers.
2. How many HTTP and TCP packets are needed to complete each request?
Frame no 35 http req = Frame 38 tcp res (2 segments)
Frame no 42 http req = Frame 113 tcp res (47 segments)
Frame no 114 http req = Frame 116 tcp res (2 segments)
3. In particular, note that my web page contains a photo. Find the HTTP packets where the photo is being requested and response being completed.
Frame no 42 request for the photo
Frame no 116 response
Wireshark and Ping related Learning
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Lecture Topic: Physical Layer
Review Questions
Use these questions to review the important material from the Topic Notes and chapter 3 of the prescribed textbook.
The review should take place in your own time. Where possible you should work with your colleagues.
You can discuss your answers with your tutor in the week 4 tutorial
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1. Describe the three types of data flows.
2. Describe three types of guided media.
3. Describe four types of radiated media.
4. How does analog data differ from digital data?
5. Explain the differences among analog data, analog transmission, digital data,
and digital transmission.
6. Explain the benefits for a telecommunication company circuits to use digital transmission.
7. Describe the ASCII coding scheme.
8. How does bipolar signaling differ from unipolar signaling? Why is Manchester
encoding more popular than either?
9. What are three important characteristics of a sound/electrical signal wave?
10. Describe how data could be transmitted using amplitude, frequency and phase modulation.
11. What is the purpose of multiplexing? Describe and compare FDM, TDM and STDM?
12. Describe Pulse Amplitude Modulation.
Two types of circuit :
#Logical circutit
#Physical circuit(Could have one or more logical circuits)
Two fundamental types of data could follow through a circuit :
*Digital
*Analog
Data convertors :
#Modem (Converts Digital to Analog) e.g. Home modem
#Codec (Converts Analog to Digital)r e.g. Voip telephone lines which converts the voice (which is analog to digital)
Three types of Data flow :
1.Simplex (One way traffic)
2.Half Duplex (One way at a time)
3.Full Duplex (Both ways at the same time)
Multiplexing
Multiplexing - To combine multiple signals (analog or digital) for transmission over a single line or media.
A common type of multiplexing combines several low-speed signals for transmission over a single high-speed connection.
Multiplexing is done by using a device called multiplexer (MUX) that combines n input lines to generate one output line i.e. (many to one). Therefore multiplexer (MUX) has several inputs and one output.
At the receiving end, a device called demultiplexer (DEMUX) is used that separates signal into its component signals. So DEMUX has one input and several outputs.
Types of Multiplexing :
#FDM (Frequency division multiplexing) - Different frequency used in one media which are separated by guard bands.
#TDM (Time Division multiplexing) - Time is the key, each of the pc get a time token or are in a queu and gets their chances to be part of it.
#STDM (Statistical Time Division multiplexing)- IF 4 computers transfer data 64kbps then then you need a multiplexing system with a capability of 64 * 4 = 256 kbps, however if the statistic shows that you could use 128 as only two of the computers use transmission at the same time. This way you save money and use STDM. Problem will occur when all the computer will perform transmission at the same time.
#WDM (Wavelenght Division myltiplexing) - FDM used by optic fiber- Laser sends diff frequencey of ligt in same fiber optic cable. Step index, Graded index, single mode.
Ref for multiplexing photo
Inverse Multiplexing:
IMUX - Reverse process of multiplexing. Multiplexing combines lower speed circuits and transmitt as high speed one. IMUX
Modulation-
Modulation is the process of changing the characterstics of the signal before / after transmitting.
Modulation Explained
#FM - Frequency Modulation
#AM - Amplitude Modulation
#PM - Phase Modulation
Analog Transmission explained
Digital Transmission of Digital data:
-Polar
-Bipolar
#NRZ (Non Return Zero)
#Return Zero
#AMI (Alternate Mark Inversion)
-Manchester
Digital Data Transmission
Analog Transmission of Digital Data:
Easy definition of Analog Transmission
Digital Transmission of Analog data:
Interesting :
Modem - Named from Modulator + Demodulator = MOD + DEM = MODEM
************************************************************************************************************************************************************************
************************************************************************************************************************************************************************
************************************************************************************************************************************************************************
Tutorial 17/03/2014
Http - Hyper Text Transfer Protocol
* Normal Protocal
* Standard Protocal
HTTP is a standard protocal
Http used in World wide web
Client - server (web server) These two communicate via http
Http Request Message (packet) :
#Request line
#Rquest header
#Req body
Response :
Response line (200-ok)
Response Header
Response body(HTML language normally) Hyper text marker language
Things to know about http :
CR - Carriage reun
LF - Line feed
GET
PUT - UPLOAD
POST - ADDITIONAL INFORMAION
RESPONSE MESSAGE :
200 MEANS OK
301 MEANS MOVED PERMANANTLY
404 MEANS NOT FOUND
500 MEANS INTERNAL SERVER ERROR
There are enter keys and has related ASCII
In the querry or filter box of wire shirk to narrow down any specific search you type the following :
# http and ip.addr
# use and or
# do sort
Answer to tutorial questions :
1.Identify HTTP packets, requests and responses related to downloading my web page. Give the related frame numbers.
2. How many HTTP and TCP packets are needed to complete each request?
Frame no 35 http req = Frame 38 tcp res (2 segments)
Frame no 42 http req = Frame 113 tcp res (47 segments)
Frame no 114 http req = Frame 116 tcp res (2 segments)
3. In particular, note that my web page contains a photo. Find the HTTP packets where the photo is being requested and response being completed.
Frame no 42 request for the photo
Frame no 116 response
Wireshark and Ping related Learning
######################################################################################################################################################################
######################################################################################################################################################################
######################################################################################################################################################################
Lecture Topic: Physical Layer
Review Questions
Use these questions to review the important material from the Topic Notes and chapter 3 of the prescribed textbook.
The review should take place in your own time. Where possible you should work with your colleagues.
You can discuss your answers with your tutor in the week 4 tutorial
----------------------------------------------------------------------------------------------------------------------------------------------
1. Describe the three types of data flows.
2. Describe three types of guided media.
3. Describe four types of radiated media.
4. How does analog data differ from digital data?
5. Explain the differences among analog data, analog transmission, digital data,
and digital transmission.
6. Explain the benefits for a telecommunication company circuits to use digital transmission.
7. Describe the ASCII coding scheme.
8. How does bipolar signaling differ from unipolar signaling? Why is Manchester
encoding more popular than either?
9. What are three important characteristics of a sound/electrical signal wave?
10. Describe how data could be transmitted using amplitude, frequency and phase modulation.
11. What is the purpose of multiplexing? Describe and compare FDM, TDM and STDM?
12. Describe Pulse Amplitude Modulation.
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