Upload
muhammad-rehan
View
87
Download
6
Embed Size (px)
Citation preview
0 - 0 - 11
© 2007 Texas Instruments Inc,
Content developed in partnership with Tel-Aviv University
From MATLAB® and Simulink® to Real Time with TI DSPs
Amplitude Modulation
Slide Slide 22© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
Amplitude Modulation
• Amplitude Modulation is a process where the amplitude of a carrier signal is altered according to information in a message signal.
• The frequency of the carrier signal is usually much greater than the highest frequency of the input message signal.
Slide Slide 44© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
AM – Basic Definitions (cont.)
The Envelope:
The AM Signal
ttmkAts cc cos 1
tmkAts c 1
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2-5
-4
-3
-2
-1
0
1
2
3
4
5
Slide Slide 55© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
The AM Spectrum
0 500 1000 1500 2000 2500 3000 3500 4000 4500 50000
0.5
1
1.5
Frequency (Hz)
|M(f
)|
0 500 1000 1500 2000 2500 3000 3500 4000 4500 50000
0.5
1
1.5
Frequency (Hz)
|Y(f
)|
tm ts
Carrier
Side Bands
Slide Slide 66© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
AM Modulation Scheme
tA cc cos k
1
tm ts+ Xk
Slide Slide 77© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
Square-Law Demodulation
2
ttmkAtmkA
ttmkAts
ccc
cc
21515
12222
22
cos..
cos
LPF ts
offset
c
DCtm
tmkAty
125.
22 15 tmkAc .
ty
Slide Slide 88© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
Coeherent Demodulation
tccos
ttmkAtmkA
ttmkA
ttmkA
tttmkAts
ccc
cc
cc
ccc
2cos15.15.
2
2cos11
cos1
coscos12
LPF ts
offset
c
DCtm
tmkAty
15.
tyX
Slide Slide 99© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
Hands-On
• Simulation
• Implementation using the DSK6713
Slide Slide 1010© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
The Simulation Environment
Modulator
VirtualScope
DemodulatorInformation
Signal
Demodulated
Signal
Slide Slide 1111© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
The Simulation Environment
Slide Slide 1212© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
Real Time Environment
DSK6713
CODEC
TMS320C6713
AMModulator
D/A(Left)
AMDemodulator
A/D(Left)
A/D(Right)
D/A(Right)
ts
ty
Line In
Line In
Line Out
Line Out
Signal Generator
Scope
PCRTDX
Slide Slide 1313© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
GUI
Slide Slide 1414© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
SQRT Detector – Real Time
Slide Slide 1515© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
Coherent Detection – Real Time
Slide Slide 1616© © 2007 Texas Instruments Inc, 2007 Texas Instruments Inc,
Configurable Carrier
nf
fj
s
csc
s
c
enf
fnT
2
Re2coscos
nf
fj
s
csc
s
c
enf
fnT
2
Re2coscos