Data Communication 5t SEM CSE

1. Digital-To-Digital Conversion
LINE CODING: data element signal element

2. DATA RATE AND SIGNAL RATE
The data rate is measured in bps (bits/sec). The data
rate is also called bit rate.
The signal rate is measured in baud. The signal rate
is also called pulse rate, modulation rate, or baud
rate.

4. Unipolar Scheme
Polar Scheme

5. Return to Zero (RZ)
BIPHASE
Manchester and Differential Manchester

6. BIPOLAR SCHEMES (MULTILEVEL BINARY)
(i)AMI (alternate mark inversion)
(ii)Pseudoternary

7. MULTILEVEL SCHEMES
2B1Q (Two binary, one Quaternary)
Transition Table
Previous level=positive Previous level=negative
Next bits Next level Next level
00 +1 -1
01 +3 -3
10 -1 +1
11 -3 +3

8. ANALOG TO DIGITAL CONVERSION
Pulse Code Modulation (PCM)
1.Sampling:

9. 2. Quantization:

10. 3. Encoding:
For example, if a sample has quantization code of 2, then it is
encoded as 010, similarly, 5 is encoded as 101, and so on.
The bit rate will be
SNRdB = 6.02nb + 1.76 dB

11. DIGITAL-TO-ANALOG CONVERSION
An analog signal carries 4 bits per signal element. If 1000 signal elements are sent per second, find the bit rate.

12. Amplitude Shift Keying (ASK)
Implementation

13. Frequency Shift Keying (FSK)
Implementation

14. Phase Shift Keying
Implementation

15. Quadrature PSK (QPSK)

16. Constellation Diagram

17. Quadrature Amplitude Modulation
(QAM)

18. ANALOG-TO-ANALOG CONVERSION
Amplitude Modulation:

19. Frequency Modulation:
Phase Modulation: