1. Encoding and Modulating

2. Different Conversion Schemes
Encoding digitizing Modulating Modulating
Digital Signal Analog Signal

3. Digital to Digital Encoding

4. Types of Digital to Digital Encoding
NRZ- Nonreturn to zero
RZ-return to zero

5. Unipolar Encoding
It uses only one polarity, its has a voltage level taken as 0 and another is 1
Disadvantages
DC Component
Synchronization

6. Polar Encoding Uses two voltage levels NRZ- Nonreturn to Zero
Level of the signal is always positive or negative.
Two types of NRZ
NRZ-L
+ve voltage is represents a bit 0
NRZ-I
Synchronization is provided
RZ- Return Zero

8. NRZ-L and NRZ-I Encoding

9. RZ Encoding

10. Manchester and Diff. Manchester Encoding

11. Types of Bipolar Encoding

12. Bipolar AMI Encoding

13. B8ZS Encoding

14. HDB3 Encoding

15. Example
Using B8ZS, encode the bit stream Assume that the polarity of the first 1 is positive.

16. Analog to Digital Encoding

17. Pulse Amplitude Modulation (PAM)

18. Quantized PAM Signal

19. PCM

20. From Analog to PCM

21. From Analog to PCM

22. From Analog to PCM

23. From Analog to PCM

24. Digital to Analog modulation
In digital to analog modulation two basics issues are defined: Bit/Baud rate & Carrier signal

25. Amplitude Shift Keying(ASK)
The figure depicts operation of ASK modulation. As shown in the figure, binary 1 will be represented by carrier signal with some amplitude while binary 0 will be represented by carrier of zero amplitude(i.e. no carrier).ASK is susceptible to noise interference.

26. Amplitude Shift Keying(ASK)

27. Formulas for ASK
For Half duplex the bandwidth remains the same as given
For Full duplex:
Bandwidth(BW)=Given Bandwidth/2
Formula for calculating carrier frequencies
Fc(forward)=Fc(min)+Nbaud/2
Fc(backward)=Fc(max)-Nbaud/2

28. Frequency Shift Keying(FSK)
The figure depicts the FSK modulation. As shown, binary 1 and 0 is represented by two different carrier frequencies. Figure depicts that binary 1 is represented by high frequency 'f1' and binary 0 is represented by low frequency 'f2'.

29. Frequency Shift Keying(FSK)

30. Formulas for FSK
For Calculating the Bandwidth:
BW=Baud rate+(Fc1-Fc0)
For Calculating Bit rate or Baud rate
Baud rate/Bit Rate=BW - (Fc1-Fc0)
Where
(Fc1-Fc0)-Difference between two carrier frequencies

31. Phase Shift Keying(PSK)
Figure depicts Binary Phase Shift Keying modulation type of PSK. As shown in the figure, Binary 1 is represented by 180 degree phase of the carrier and binary 0 is represented by 0 degree phase of the carrier.

32. PSK Constellation

33. 4-PSK
Characteristics

34. Phase Shift Keying(PSK)

35. 4-PSK

36. Bit Rate and Baud Rate

37. Analog to Analog Modulation

38. Amplitude Modulation

39. Frequency Modulation

40. Transmission of Digital Data Interfaces and Modems
Digital Data Transmission
DTE-DCE Interface
Other Interface Standards
Modems

42. Parallel Transmission

43. Serial Transmission

44. Asynchronous Transmission

45. Synchronous Transmission

46. DTEs and DCEs

47. DTE-DCE interface

50. Twisted-Pair Cable

51. Shielded Twisted-Pair Cable

52. Coaxial Cable

53. Fiber Construction

54. Refraction

55. Critical Angle

56. Reflection

57. Transmission Impairment
Attenuation

58. Distortion:

59. Noise: