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Member ID: 52

Shriyank Raj


Profile: I have done my mechanical engineering from Bhopal. I am currently pursuing an MBA from Ansal Institute of Technology in a twinning program with TSU, USA.

Prof. Ashay Dharwadker's Courses (1):

Computer NetworksSpring 2004View

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Seminars (1)

Seminar ID: 47
Course: Computer Networks
Topic: Fourier Series
Description: Generally it is the physical layer through which data is transmitted from one computer to the other. Wires are attached to the physical layer. For example if we have to transmit the letter b, the ASCII CODE is 98. We will convert it into binary, i.e. 1 multiply by 2 power 6 + 1 multiply by 2 power 5 + 0 multiply by 2 power 4 + 0 multiply by 2 power 3 + 0 multiply by 2 power 2 + 1 multiply by 2 power 1 + 0 multiply by 2 power 0. It comes out to be 1100010. Since we need 8 bits we will add one 0 in the beginning i.e. 01100010. If taken in binary form it is 01100010. Now 0 and 1 will be transmitted to the other computer. 0 and 1 i.e. the digital signal is converted into an electrical sinusoidal signal by a Fourier series and is sent to the other computer through cables. See my research note below for a computation of the Fourier series of the step function shown below.

Research Notes (2)

Research Note ID: 61
Course: Computer Networks
Topic: The OSI Model
Description: The ISO based in Geneva develops standards for international and national data communications. In the early 1970's the ISO developed a standard model for data communications systems and called it the open system interconnection model, OSI model.

The OSI model consists of 7 layers that describe what happens when a terminal talks to a computer or when one computer talks to another.

The OSI model is like a layered cake. At the top, running the software which the user actually sees, is the application layer. At the bottom, holding everything up, is the physical layer which is made up of wiring, cables or radio signals.

These are the layers-

  • 7. Application layer-at this level software follows standards for look and feel.
  • 6. Presentation layer-here the data is formatted for viewing and for use on specific equipment.
  • 5. Session layer-this layer provides a standard way to move data between application programs.
  • 4. Transport layer-this layer of software is particularly important to local area networks. Transport layer software provides for reliable and transparent transfer of packets between stations.
  • 3. Network layer-software operating at this layer provides an interface between the physical and data link layers and the higher level software which establish and maintain connections.
  • 2. Data Link layer-this layer provides for the reliable transfer of information across the physical layer. It synchronizes the block of data, recognizes errors and controls the flow of data.
  • 1. Physical layer-the most fundamental layer is concerned with transmitting a stream of data over the physical cables and wires. Hardware and software operating at this level deal with the type of connectors, signaling and media sharing schemes used on the networks.

Research Note ID: 72
Course: Computer Networks
Topic: Computation of Fourier Series
Description: Consider the 0 and 1 step function f(x) as shown in my seminar description above. We compute the Fourier series as follows.

f(x)= 0     0<x<pi/2

     =  1     pi/2<x<pi

f(x)= ao/2+summation an cosnwx+summation bn sinnwx

w=2pi/T where T is time


Therefore w=2pi/pi


ie time taken by 0 and 1


ao =2/T( (integration 0 dx limit 0 to pi/2)+ (integration 1 dx limit pi/2 to pi))

     =2/pi(pi-pi/2)limit pi/2 to pi


an=2/T ((integration 0 cos2nx dx limit 0 to pi/2)+( integration 1 cos2nx dx limit pi/2 to pi))

    =2/pi (sin2nx limit pi/2 to pi)


      sin2npi=0 sin npi=0


bn=2/T((integration 0 sin2nx dx limit 0 to pi/2)+(integration  1 sin2nx dx limit pi/2 to pi))

    =2/pi n(-cos2nx limit pi/2 to pi))


cos npi=(-1)power n

cos 2npi=1

            =1/n pi (-1+(-1)power n)

bn=if n=1,3,5 ie odd

    = -2/pi(sin 2 pi+ sin 6 pi/3 + sin 10 pi/5 . . . . .

 f(x)= 1/2 – 2/pi ( sin 2 pi+ sin 6 pi/3 + sin 10 pi/5 . . . . . . . . infinity

now the function f(x)  which is determined by the Fourier series will overlap the digital function f(x)  as shown in above graph and it will superpose it. Thus the digital  signal is converted into sinusoidal electrical signal and data is send from one computer to the other by electrical cables.

Last updated on Friday, 2nd April 2004, 05:09:11 PM.

Prof. Ashay Dharwadker