S. Mandayam/ ECOMMS/ECE Dept./Rowan University
Electrical
Communications Systems
ECE.09.331
Spring 2010
Lecture 7b
March 3, 2010
Shreekanth Mandayam
ECE Department
Rowan University
http://engineering.rowan.edu/~shreek/spring10/ecomms/
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
•
•
•
•
Plan
Recall: Costas Loop
QAM
Complex Envelope
SSB Modulation
Signals
Time Domain
Complex Envelope
Spectrum
Power
Systems
Performance
Transmitters
Receivers
Standards
Modulation
Index
Efficiency
Bandwidth
Noise
• Angle Modulation Systems
• Definitions - Phase and Frequency Modulation
• Complex Envelope
• Time Domain
• Analyzing FM Signals - Battle Plan!!!!
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
ECOMMS: Topics
Electrical Communication Systems
Signals
Discrete
Systems
Continuous
Analog
Probability
Power & Energy Signals
AM
Switching Modulator
Envelop Detector
Information
Continuous Fourier Transform
DSB-SC
Product Modulator
Coherent Detector
Costas Loop
Entropy
Discrete Fourier Transform
SSB
Weaver's Method
Phasing Method
Frequency Method
Channel Capacity
Baseband and Bandpass Signals
Frequency & Phase Modulation
Narrowband/Wideband
VCO & Slope Detector
PLL
Digital
Digital Comm Transceiver
Baseband
CODEC
Bandpass
MODEM
Source Encoding
Huffman codes
ASK
PSK
FSK
Error-control Encoding
Hamming Codes
BPSK
Sampling
PAM
QPSK
Quantization
PCM
M-ary PSK
Line Encoding
QAM
Complex Envelope
Gaussian Noise & SNR
Time Division Mux
T1 (DS1) Standards
Random Variables
Noise Calculations
Packet Switching
Ethernet
ISO 7-Layer Protocol
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
Recall: Costas PLL
I-Channel
Product
Modulator
Baseband
LPF
VCO
s(t)
v4(t)
v1(t)
v3(t)
LPF
-90o
Phase Shift
Product
Modulator
~ (t)
m
X
Phase
Discriminator
Baseband
LPF
Q-Channel
v2(t)
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
Quadrature Amplitude
Modulation (QAM)
Tx
m1(t)
Rx
I-Channel
S
Product
Modulator
s(t)
Product
Modulator
Local
Oscillator
~ (t)
m
1
Local
Oscillator
o
m2(t)
LPF
o
-90
Phase Shift
-90
Phase Shift
Product
Modulator
Product
Modulator
Q-Channel
LPF
~ (t)
m
2
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
Complex Envelope Representation
message: m(t)
Modulator
s(t): radio signal
carrier: c(t)
• We want a common mathematical representation for
• information transfer from baseband to bandpass
• any bandpass signal
• any time of modulation
• signal/noise and signal+noise
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
Spectrum of a Bandpass
Signal
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
Single Sideband (SSB)
Modulation
• Recall: DSB-SC Spectrum
|S(f)|
-fc-B
-fc
-fc+B 0
fc-B
fc
fc+B
f
• USSB - Signal with zero-valued spectrum for |f| < fc
• LSSB - Signal with zero-valued spectrum for |f| > fc
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
The Hilbert Transform
1.5
w(t)
1
» t=0:0.1:2*pi;
» w=sin(t);
» plot(t,w)
» hold
Current plot held
» H=hilbert(w);
» plot(t,imag(H),'r');
» xlabel('time, t in sec')
ŵ(t)
0.5
0
-0.5
-1
0
1
2
3
4
time, t in sec
5
6
7
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
SSB Generation
Phasing Method
S
Product
Modulator
s(t)
m(t)
o
-90
Phase Shift
Product
Modulator
o
-90
Phase Shift
Carrier
Filter Method
m(t)
Product
Modulator
Carrier
Sideband
Filter
s(t)
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
SSB Generation:
Weaver’s Method
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
ECOMMS: Topics
Electrical Communication Systems
Signals
Discrete
Systems
Continuous
Analog
Probability
Power & Energy Signals
AM
Switching Modulator
Envelop Detector
Information
Continuous Fourier Transform
DSB-SC
Product Modulator
Coherent Detector
Costas Loop
Entropy
Discrete Fourier Transform
SSB
Weaver's Method
Phasing Method
Frequency Method
Channel Capacity
Baseband and Bandpass Signals
Frequency & Phase Modulation
Narrowband/Wideband
VCO & Slope Detector
PLL
Digital
Digital Comm Transceiver
Baseband
CODEC
Bandpass
MODEM
Source Encoding
Huffman codes
ASK
PSK
FSK
Error-control Encoding
Hamming Codes
BPSK
Sampling
PAM
QPSK
Quantization
PCM
M-ary PSK
Line Encoding
QAM
Complex Envelope
Gaussian Noise & SNR
Time Division Mux
T1 (DS1) Standards
Random Variables
Noise Calculations
Packet Switching
Ethernet
ISO 7-Layer Protocol
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
Angle Modulation Systems
Phase Modulation (PM)
Frequency Modulation(FM)
• Signal Representation
Instrument Demo
• Complex Envelope
• Time Domain Representation
• Terminology
•
•
•
•
Phase Sensitivity
Frequency Deviation
Instantaneous Frequency
Phase & Frequency Modulation Indices
Matlab Demo:
anglemod.m
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
Angle Modulation Systems
Phase Modulation (PM)
Frequency Modulation(FM)
• Signal Representation
Instrument Demo
• Complex Envelope
• Time Domain Representation
• Terminology
•
•
•
•
Phase Sensitivity
Frequency Deviation
Instantaneous Frequency
Phase & Frequency Modulation Indices
Matlab Demo:
anglemod.m
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
Analyzing FM Signals Battle Plan!!!
Instrument Demo
Signals
Systems
Time Domain
Performance
Complex Envelope
Transmitters
Modulation
Index
Efficiency
Spectrum
Receivers
• Single-tone FM
• Narrowband FM
Standards
• Wideband FM
• Bessel Functions
Power
Bandwidth
Noise
S. Mandayam/ ECOMMS/ECE Dept./Rowan University
Summary