Understanding Performance Analysis of Digital Modulation Techniques

 
Performance Analysis of Digital
Modulation Techniques
 
 
 
 
Binary modulation schemes
 
ASK, FSK, PSK
n =  1,
M  = 2  (Only Two output conditions are possible)
Baud is equal to the bit rate
 
M-ary Modulation Techniques
 
QPSK, 8-PSK, 18-PSK, QAM, 16-QAM
n > 1
 M > 1 (
number of output conditions increases)
Minimum bandwidth decreases
Baud rate decreases
Achieves 
BANDWIDTH COMPRESSION
Less bandwidth is required to propagate a given bit rate
Higher data transmission rates are possible for a given
bandwidth
 
BANDWIDTH EFFICIENCY
 
Also called as 
Information density 
or 
Spectral
efficiency
Used to compare the performance of one digital
modulation technique to another
 
BANDWIDTH EFFICIENCY
 
“Bandwidth efficiency is the ratio of the
transmission bit rate to the minimum bandwidth
required for a particular modulation scheme”
Generally normalized to a 1-Hz bandwidth
Indicates the number of bits that can be
propagated through a transmission medium
for each hertz of bandwidth
 
BANDWIDTH EFFICIENCY
 
 
 
 
 
 
 
Bandwidth efficiency can also be given as a
percentage by simply multiplying 
Bη by 100
 
Problems
 
 
Example - 1
 
For an 8-PSK system, operating with an
information bit rate of 24 kbps,
Determine
       (a) baud
       (b) minimum bandwidth
       (c) bandwidth efficiency
 
Formula To Remember
 
For all Modulation types except FSK
Minimum Bandwidth is given by
 
 
Baud rate is given by
 
Answer
 
Minimum Bandwidth is given by
 
 
 
 
Baud rate is given by
 
Answer
 
 
Example - 2
 
For 16-PSK and a transmission system with a
10 kHz bandwidth, determine the maximum
bit rate.
 
Answer
 
The bandwidth efficiency for 16-PSK is 4
i.e four bits can be propagated through the system
for each hertz of bandwidth
Maximum bit rate is simply the product of the
bandwidth and the bandwidth efficiency
 
Example -3
 
For the following modulation schemes,
construct a table showing the number of bits
encoded, number of output conditions,
minimum bandwidth, and baud for an
information data rate of 12 kbps:
QPSK, 8-PSK, 8-QAM, 16-PSK, and 16-QAM
 
To Find
 
 
Answer
 
 
Summary
 
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Explore the realm of digital modulation techniques such as ASK, FSK, PSK, QPSK, QAM, and more. Learn about bandwidth efficiency, baud rates, minimum bandwidth, and how to calculate them. Discover the importance of M-ary modulation and how it impacts data transmission rates and bandwidth requirements. Dive into examples and formulas to solidify your understanding.


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  1. Performance Analysis of Digital Modulation Techniques

  2. Binary modulation schemes ASK, FSK, PSK n = 1, M = 2 (Only Two output conditions are possible) Baud is equal to the bit rate

  3. M-ary Modulation Techniques QPSK, 8-PSK, 18-PSK, QAM, 16-QAM n > 1 M > 1 (number of output conditions increases) Minimum bandwidth decreases Baud rate decreases Achieves BANDWIDTH COMPRESSION Less bandwidth is required to propagate a given bit rate Higher data transmission rates are possible for a given bandwidth

  4. BANDWIDTH EFFICIENCY Also called as Information density or Spectral efficiency Used to compare the performance of one digital modulation technique to another

  5. BANDWIDTH EFFICIENCY Bandwidth efficiency is the ratio of the transmission bit rate to the minimum bandwidth required for a particular modulation scheme Generally normalized to a 1-Hz bandwidth Indicates the number of bits that can be propagated through a transmission medium for each hertz of bandwidth

  6. BANDWIDTH EFFICIENCY Bandwidth efficiency can also be given as a percentage by simply multiplying B by 100

  7. Problems

  8. Example - 1 For an 8-PSK system, operating with an information bit rate of 24 kbps, Determine (a) baud (b) minimum bandwidth (c) bandwidth efficiency

  9. Formula To Remember For all Modulation types except FSK Minimum Bandwidth is given by Baud rate is given by

  10. Answer Minimum Bandwidth is given by Baud rate is given by

  11. Answer

  12. Example - 2 For 16-PSK and a transmission system with a 10 kHz bandwidth, determine the maximum bit rate.

  13. Answer The bandwidth efficiency for 16-PSK is 4 i.e four bits can be propagated through the system for each hertz of bandwidth Maximum bit rate is simply the product of the bandwidth and the bandwidth efficiency

  14. Example -3 For the following modulation schemes, construct a table showing the number of bits encoded, number of output conditions, minimum bandwidth, and baud for an information data rate of 12 kbps: QPSK, 8-PSK, 8-QAM, 16-PSK, and 16-QAM

  15. To Find

  16. Answer

  17. Summary

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