Download presentation

Presentation is loading. Please wait.

Published byBrooklynn Rivett Modified over 3 years ago

1
Coherent phase shift keying In coherent phase shift keying different phase modulation schemes will be covered i.e. binary PSK, quadrature phase shift keying and M-ary PSK Binary PSK will be studied in the next slides 1

2
Binary Phase shift keying 2

3
3

4
4

5
Signal constellation for binary Phase shift keying 5

6
If we plot the transmitted symbols for BPSK we may got the following constellation diagram 6

7
Error probability of BPSK In order to compute the error probability of BPSK we partition the constellation diagram of the BPSK (see slide 28) into two regions If the received symbol falls in region Z 1, the receiver decide in favor of symbol S 1 ( logic 1) was received If the received symbol falls in region Z 2, the receiver decide in favor of symbol S 2 (logic 0) was received 7

8
Error probability of BPSK- Receiver model 8

9
Error probability of BPSK 9

10
10

11
Error probability of BPSK The conditional probability of the receiver deciding in favor of symbol 1, given that symbol zero was transmitted is given by 11

12
Error probability of BPSK 12

13
Error probability of error In similar manner we can find probability of error that symbol 1 was sent and the receiver detect 0 mistakenly The average probability as we did in the baseband can be computed as This average probability is equivalent to the bit error rate 13

14
Generation of BPSK signals 14

15
Generation of BPSK signals The resulting binary wave and the carrier (basis function) are applied to product multiplier as shown below 15

16
Detection of BPSK signals 16

17
Power spectra of binary PSK signals The power spectral density of the binary PSK signal can be found as described for the bipolar NRZ signaling (see problem 3.11 (a) Haykin) This assumption is valid because the BPSK is generated by using bipolar NRZ signaling 17

18
Power spectra of binary PSK signals The power spectral density can be found as 18

19
Quadrature phase shift keying QPSK 19

20
Signal space diagram of QPSK If we expand the QPSK equation using the trigonometric identities we got the following equation Which we can write in vector format as 20

21
Signal space diagram of QPSK 21

22
Detailed message points for QPSK 22 iInput DibitPhase of QPSK signaling Coordinate of Message point s i1 s i2 110 200 301 411

23
Signal space diagram of QPSK 23 22 11 s4s4 s1s1 s3s3 s2s2 (10) (00) (01)(11)

24
Signal space diagram of QPSK with decision zones The constellation diagram may appear as shown below 24 22 11 s4s4 s1s1 s3s3 s2s2 (10) (00) (10)(11) Z4Z4 Z1Z1 Z3Z3 Z2Z2

25
Example Sketch the QPSK waveform resulting from the input binary sequence 01101000 solution 25

26
Error probability of QPSK 26

27
Error probability of QPSK 27

28
Error probability of QPSK 28

29
Error probability decision rule 29

30
Error probability of QPSK 30

31
Error probability of QPSK If symbol is to be received correctly both bits must be received correctly. Hence, the average probability of correct decision is given by Which gives the probability of errors equal to 31

32
Error probability of QPSK Since one symbol of QPSK consists of two bits, we have E = 2E b The above probability is the error probability per symbol With gray encoding the average probability of error per bit Which is exactly the same as BPSK 32

33
Error probability of QPSK summery 33

34
Generation and detection of QPSK 34 Block diagrams of (a) QPSK transmitter and (b) coherent QPSK receiver.

35
Power spectra of QPSK 35

Similar presentations

OK

CHAPTER 4. OUTLINES 1. Digital Modulation Introduction Information capacity, Bits, Bit Rate, Baud, M- ary encoding ASK, FSK, PSK, QPSK, QAM 2. Digital.

CHAPTER 4. OUTLINES 1. Digital Modulation Introduction Information capacity, Bits, Bit Rate, Baud, M- ary encoding ASK, FSK, PSK, QPSK, QAM 2. Digital.

© 2018 SlidePlayer.com Inc.

All rights reserved.

To ensure the functioning of the site, we use **cookies**. We share information about your activities on the site with our partners and Google partners: social networks and companies engaged in advertising and web analytics. For more information, see the Privacy Policy and Google Privacy & Terms.
Your consent to our cookies if you continue to use this website.

Ads by Google

Ppt on natural and manmade disasters Best ppt on water cycle Ppt on cisco packet tracer Ppt on paintings and photographs related to colonial period lighting Ppt on field study 5 Free ppt on agriculture in india Kid after dentist appt on your birthday Ppt on computer network security Ppt on switching networking Ppt on media research institute