1. EP301 COMPUTER NETWORKING SYSTEM
DATA TRANSMISSION AND NETWORKING MEDIA
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2. WHAT IS DATA TRANSMISSION?
 The physical transfer of data (a digital bit stream) over a point-to-point or point-to- multipoint communication channel. 
While analog transmission is the transfer of a continuously varying analog signal, digital communications is the transfer of discrete messages.

3. BASIC DATA TRANSMISSION CONCEPT
ANALOG AND DIGITAL SIGNALLING
DATA MODULATION
SIMPLEX,HALF-DUPLEX AND FULL-DUPLEX
MULTIPLEXING
POINT-TO-POINT TRANSMISSION
BROADCAST TRANSMISSION
THROUGHPUT
BANDWITH

4. ANALOG SIGNALLING
Analog signal is a continuous signal that contains time-varying quantities.
Using of continuous signals to represent information/data.
An analog signal can be used to measure changes in some physical phenomena such as light, sound, pressure, or temperature.

5. ANALOG SIGNALLING
An analog signal is characterized by four fundamental properties:
Amplitude
Frequency
Wavelength
Phase.

8. DIGITAL SIGNALLING
 A physical signal that is a representation of a sequence of discrete values.
A pulse of positive voltage represents a ‘1’. A pulse of zero voltage represents a ‘0’.
Every pulse in the digital signal is called a binary digit, or bit.

9. DIGITAL SIGNALLING
Using of discrete signals to represent information/data.
Number, letters or icons are all examples of digital signal.
Advantage:
more reliable than analog transmission
noise affects digital transmission less severely

11. DIFFERENCES BETWEEN ANALOG AND DIGITAL SIGNALS

12. ANALOG DIGITAL Analog signal are continuous.
Analog signal is continuously variable.
The primary disadvantage of an analog signal is noise.
Sound waves are a continuous wave and as such are analog in the real world.
Analog signal required lesser bandwidth capacity than digital capacity.
Digital signal is discrete.
Digital signal are based on 0's and 1's.
Noise is much easier to filter out of a digital signal.
Most computers used such as the PC work using digital signals.
Digital signal required greater bandwidth capacity than analog signals.

13. DATA MODULATION
Modulation is the process of conveying a message signal, for example a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted.
The data signals issued by your computer must be converted into analog form before they get to the media transmission.

14. DATA MODULATION
They must be converted back into digital form when they arrive at the ISP’s access server.
A modem (modulator/demodulator) accomplishes this translation.
Modulates digital signals into analog signals at the transmitting end, then demodulates analog signals into digital signals at the receiving end.

15. DATA MODULATION
Is a technology used to modify analog signals to make them suitable for carrying data over a communication media.
In modulation, a simple wave, called a carrier wave, is combined with another analog signal to produce a unique signal that gets transmitted from one node to another.
The carrier wave has preset properties (including frequency, amplitude, and phase)

17. TRANSMISSION MODE The transmission is characterised by:
the direction of the exchanges
the transmission mode: the number of bits sent simultaneously
synchronization between the transmitter and receiver

18. TRANSMISSION MODE
SIMPLEX
HALF-DUPLEX
FULL-DUPLEX

19. SIMPLEX
Simplex refers to one-way communications where one party is the transmitter and the other is the receiver.
Exp: Radio

20. HALF-DUPLEX
A connection in which the data flows in one direction or the other, but not both at the same time.
Exp: Walkie-talkie

21. FULL-DUPLEX
 A connection in which the data flow in both directions simultaneously.
Can transmit and receive at the same time
Exp: Telephone.

22. MULTIPLEXING
A form of transmission that allows multiple signals to travel simultaneously over one medium.
Process of transmitting two or more individual signals over a common path.
A device that performs the multiplexing is called a multiplexer (MUX), and a device that performs the reverse process is called a demultiplexer (DEMUX)

25. FREQUENCY DIVISION MULTIPLEXING
An analog technique.
Analog multiplexing technique that combines signals by using the different carrier frequencies.

27. TIME DIVISION MULTIPLEXING
The digital technique.
A digital multiplexing technique to combine data by using the time slot.
The process of dividing up one communication time slot into smaller time slots.

29. WAVELENGTH-DIVISION MULTIPLEXING
The process by which multiple channels of information carried over the same fiber, each using an individual wavelength.
Using two wavelength that utilizes 1320nm and the other 1550nm.

31. RELATIONSHIP BETWEEN NODES
POINT-TO-POINT TRANSMISSION
BROADCAST TRANSMISSION
THROUGHPUT
BANDWIDTH

32. POINT-TO-POINT TRANSMISSION
Carrying a communication signal between two locations without branching to other locations.
Refers to a communications connection between two nodes or endpoints.(one transmitter and one receiver)
An example is a telephone call, in which one telephone is connected with one other, and what is said by one caller can only be heard by the other.

33. BROADCAST TRANSMISSION
Sending the same signal to many different places,like a television broadcasting station.(one transmitter and multiple receiver).

35. THROUGHPUT
the average rate of successful message delivery over a communication channel.
This data may be delivered over a physical or logical link, or pass through a certain network node.
The throughput is usually measured in bits per second (bit/s or bps), and sometimes in data packets per second or data packets per time slot.

36. BANDWIDTH
Measure of the difference between the highest and lowest frequencies that a medium can transmit.

37. IDENTIFY THE COMMON TRANSMISSION FLAWS AFFECTING DATA:
Noise
Attenuation
Latency

38. TRANSMISSION FLAWS: NOISE
Electromagnetic interference (EMI): waves emanating from electrical devices or cables
Radiofrequency interference (RFI): electromagnetic interference caused by radiowaves
Crosstalk: signal traveling on a wire or cable infringes on signal traveling over adjacent wire or cable

39. TRANSMISSION FLAWS: NOISE
Certain amount of signal noise is unavoidable
All forms of noise measured in decibels (dB)

40. TRANSMISSION FLAWS: ATTENUATION
The strength of a signal falls off with distance over any transmission medium
Problems are dealt by the use of amplifiers or repeaters.

41. TRANSMISSION FLAWS: ATTENUATION
A device that regenerates a analog signal is called a amplifier.
Analog signals pass through an amplifier, an electronic device that increases the voltage, or strength, of the signals.
A device that regenerates a digital signal is called a repeater.

42. An analog signal distorted by noise and then amplified
A digital signal distorted by noise and then repeated

43. TRANSMISSION FLAWS: LATENCY
Delay between transmission and receipt of a signal
Many possible causes:
Cable length
Intervening connectivity device (e.g., modems and routers)
Round trip time (RTT): Time for packets to go from sender to receiver and back

44. TRANSMISSION FLAWS: LATENCY
Cabling rated for maximum number of connected network segments
Transmission methods assigned maximum segment lengths