1. Electrical Communications Systems ECE.09.433
Introduction
Dr. Shreek Mandayam
Electrical & Computer Engineering
Rowan University

2. Plan Why are we studying ECOMMS? What is a communications system?
Technology successes, Trends and Decisions
What is a communications system?
Objectives
Block diagram
What limits our ability to communicate?
Fundamental limits - Shannon’s Theorem
Wireless communications evolution
What are we studying in this course?
Course logistics

3. Communications: Where are we?
???
(what the consumer sees……………………………)

4. Communications: Where are we?
(what the consumer sees……………………………)

6. What is a communications system?
Communications Systems: Systems designed to transmit and receive information
Info
Source
Sink
Comm
System

7. Block Diagram m(t) message from source n(t) noise Transmitter Tx s(t)
Info
Source
n(t)
noise
Transmitter Tx
s(t)
transmitted
signal
Receiver Rx
received
message to
sink
Channel
r(t)
received
signal
Info
Sink

8. What limits our ability to communicate?
NOISE!!!!!
Noise: an unwanted, random fluctuation in the signal
Without the effects of noise, a message with infinitesimally small power could be transmitted over infinitely large distances
ALL advances in communications technology are advances to combat the effects of noise

9. Fundamental Limit: Shannon’s Theorem (1948,1949)
Theoretical limit for error-free transmission in a communications system in the presence of noise
Source Data Rate: R [bits/sec]
Channel Capacity:
C = B log2(1 + S/N) [bits/sec]
R < C: No Error!!!

10. Mars Orbiter
(Odyssey/Mars Global Surveyer)
12k – 3.5k bps
DSN Antenna
(on Earth)
X-Band
128 kbps
Mars Rover
(Spirit/Opportunity)

11. ECOMMS: What are we studying?
Electrical Communications Systems
Measures of information and noise
Capacities for information transmission
Design of communications systems
Measures of performance
Communications circuits
Communications protocols
Hardware
INdependent
dependent

12. ECOMMS: Topics Receiver Rx Transmitter Tx s(t) Channel r(t) m(t) Noise
Wire/wireless
Antennas/
Coupling
Antennas/
Coupling
Demodulation circuits and systems
DSP
Modulation circuits and systems
DSP
Analog/digital
Protocols
Fundamental limits

13. ECOMMS: Details

14. Textbook and Resources
Leon W. Couch II, Digital and Analog Communication Systems, 8th Edition, Pearson,  
Professor Couch's Companion Website for the Textbook:
Communications Toolbox

15. Summary