1. Advanced Communication Systems
Lecture # 1
Instructor
Kashif Shahzad
2013

2. Course Details
Text Book: Electronic Communication System by Kennedy and Davis
Reference Text: Modern Digital and Analog Communication System by B.P. Lathi
(Soft copy will be provided)
Course Instructor: Kashif Shahzad
Cell:
Course homepage:

3. Course Breakdown Assignments: 10% Quizzes: 10% Others: 05%
Mid Term: 25%
Terminal: 50%

4. Learning Objective Explain the principles of a communication systems
Discuss the nature of information, different types of signals involved and their characteristics
Make the distinction between Analog and Digital communication systems
Determine the need of modulation and differentiate various type of modulation techniques in time, frequency domain
Important steps in analog to digital conversion, PCM, PAM, PPM etc
Discussion of principles and phenomenon related to physical layer of communication systems

5. Data, Information & Redundancy
Useful part of data,
Has low probability
Redundancy
Part of data which adds to the reliability of information
Has no information itself but adds to reliability
Data
Combination of Info and Redundancy

6. Data, Information & Redundancy
Aim is to transfer max info
Increased reliability with minimized redundancy

7. Data and Signals
Data is to transmitted to the destination in appropriate propagatable form
Data travels in form of signal
In custom defined as voltage representation of information
Representation of information/data as a function of some independent variable e.g. v(t), f(x,y), g(x,y,z,t)

8. Signal and Systems System An algorithm or set of processes
Takes input(s) performs processes to produce output(s)
Nature of system depends upon the nature of signal it is dealing with
Filtering, Amplifying, Modulation etc are examples of systems on modular level

9. Types of Signals Analog Digital Continuous Discrete Periodic Aperiodic
Energy
Power
Stochastic/Random/Probabilistic
Deterministic

10. Classification of Signals (1/5)
Analog vs. Digital signals:
Analog signals are signals with magnitudes that may take any value in a specific rang
Digital signals have amplitudes that take only a finite number of values.

11. Classification of Signals (2/5)
Continuous-time vs. discrete-time:
Continuous-time signals have their magnitudes defined for all values of t. They may be analog or digital.
Discrete-time signals have their magnitudes defined at specific instants of time only. They may be analog or digital.

12. Classification of Signals (3/5)
Periodic vs. aperiodic signals: Periodic signals are signals constructed from a shape that repeats itself regularly after a specific amount of time T0, that is: f(t) = f (t+nT0) for all integer n Aperiodic signals do not repeat regularly.

13. Energy and Power

14. Classification of Signals (4/5)
Energy Signals: an energy signal is a signal with finite energy and zero average power (0 ≤ E < , P = 0)
Power Signals: a power signal is a signal with infinite energy but finite average power (0 < P < , E  ).

15. More on Energy and Power Signals
A signal cannot be both an energy and power signal.
A signal may be neither energy nor power signal.
All periodic signals are power signals (but not all non– periodic signals are energy signals).
Any signal f that has limited amplitude (|f| < ) and is time limited (f = 0 for |t |> t0) is an energy signal.
The square root of the average power of a power signal is called the RMS value.

16. Evaluate E and P and determine the type of the signal
It is a Power signal 1 2 8

17. Evaluate E and P and determine the type of the signal
It is an energy signal

18. Classification of Signals (5/5)
Stochastic
These are the random signals which are known by probabilistic means only and are estimated instead of exact computations
Deterministic
The are calculated on the basis of exact determined value and can be expressed explicitly

19. Typical Modulation Case
Information Signal
Analog, Continuous, Aperiodic, Random, Energy signals
Carrier
Analog/Digital, Continuous, Periodic, Deterministic and Power signals

20. Note
The lecture slide contents are taken from Reference text chapter 2.