1. Digital Modulation and Transmission
Principles of Communication Systems, Third Edition Herbert Taub, Donald L Schilling, Goutam Saha
Chapter 6 : Part A
Digital Modulation and Transmission
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2. Binary Phase Shift Keying (BPSK)
Sinusoidal carrier changes phase depending on binary
signal level of digital data.
If message signal b(t) is either +1 V or -1 V

3. BPSK reception Received signal has the form Squaring,
BP Filtering above after frequency divider generates carrier.
Multiplying carrier with received signal
The integrator and dump (bit-synchronized) of above gives

4. BPSK Block Diagram

5. BPSK Spectrum

6. BPSK : Geometric Representation
BPSK signal can be represented in terms of one
orthonormal signal
Distance between the signal,
d is inversely proportional to the probability of error
in presence of noise.

7. Quadrature Phase Shift Keying (QPSK)-1

8. QPSK-2

9. QPSK-3 The QPSK system discussed is called offset or staggered QPSK
abbreviated OQPSK. Phase change only by 900. In non-offset
QPSK there is an additional D-FF in one line of Fig. 6.10, thus
even-odd could be same time, phase change could be 1800.

10. Symbol vs. Bit Transmision
In BPSK, each bit of duration Tb is individually treated.
In QPSK, two bits are lumped together to form what is termed a symbol. The symbol can have any of the four possible values corresponding to the two-bit sequences 00, 01, 10 and 11.
At the receiver, each signal represents one symbol and correspondingly, two bits.
When bits are transmitted, as in BPSK, the signal changes occur at the bit rate. When symbols are transmitted, the changes occur at the symbol rate which is one-half the bit rate. Thus, symbol time is Ts =2Tb

11. QPSK Receiver

12. QPSK : Geometric Representation

13. M-ary Phase Shift Keying-1

14. M-ary Phase Shift Keying-2
Bandwidth,

15. M-ary PSK Transmitter

16. M-ary PSK Receiver

17. Binary Frequency Shift Keying (BFSK)

18. BFSK Spectrum

19. BFSK Receiver

20. BFSK : Geometric Representation

21. Non-Orthogonal BFSK
When two FSK signals are not orthogonal Gram-Schmidt procedure can be used for geometric representation

22. M-ary FSK

23. M-ary Communication System

24. End of Part A Chapter 6