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Baseband PPM and PAM Algorithm Implementation. Kenneth Rice, Joel Simoneau, and Dr. L. Wilson Pearson. Introduction. Modulation Techniques. Pulse Amplitude Modulation:. Pulse Position Modulation:. - PowerPoint PPT Presentation
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Kenneth Rice, Joel Simoneau, and Dr. L. Wilson Pearson
The purpose of this research is to implement two baseband communication algorithms: Pulse Position Modulation (PPM) and Pulse Amplitude Modulation (PAM). The two techniques implemented to demodulate PPM and PAM are the Matched Filter and Time Limited Accumulation (TLA) filter.
Another purpose of this research is to test several implementations for demodulating PPM for efficiency and productivity. This is done using two noise channel models: Direct/Reflected Path Noise and Random Inversion Noise.
The amplitude of the pulses denote the transmitted information. An example is shown in Figure1A.
The location of the pulse within the specified transmission frame indicates the transmitted information. Figure1B gives an example of this kind of modulation.
Matched Filter:
Modulation Techniques
Demodulation TechniquesTime Limited Accumulation Filter:
Introduction
Direct/Reflected Path Noise Model:
Random Inversion Noise Model:
Summer Undergraduate Research Experience
Noise Channel Models
When the transmitted signal changes path during transmission in such a way that the signal becomes inverted. Figure3A is an example.
A more complicated version of the Direct/ Reflected Path Noise Model. This can be seen in Figure3B
PAM Implementations:
PAM: RECEIVER
xlbalancez-k -1
SyncScope2
xlrelationalz-1
a
b a>b
en
Relational
xlp2sp sPtoS5
fpt dblOut2
xlmultz-3
ab (ab)
MultOut
Matched xlconvertcast
Conv1
1
Con8
0
Con5
52Con3
xladdsubz-1a-b
aba
AddSub2q
brst
Accum
Out1
Out2
Out3
ADC
Receiver (Matched):
PPM Implementations:
PAM: TRANSMITTER
Out
Digital Input
In Out
DSP
In1
In2
Out1Out2Out3
DAC 20.20313
Cont1
xladdsubz-1a+b
aba
AddSub1
Transmitter:
ONE
ZERO
In1
Signal
F.Half
Reset
S.Half
Enable
Timing Controller
Scope2
xlrelational
z-1
a
b a<b
en
Relate2
fpt dbl
Out4
Out1
Out2
Out3
ADC
InOut
ABS
q
b
en
rst
2Accum
q
b
en
rst
1Accum
PPM: MATCHED FILTER RECEIVER
In1Out1Out2Out3
Timing
xlbalancez-k -1
Sync
Scope2
xlrelationalz-1
ab a<ben
Relational2
fpt dblOut4
xlmultz-3
ab (ab)
Mult2
Out
Matched Waveform 0Con7
qbrst
Accum
Out1
Out2
Out3
ADC
PAM: TRANSMITTER
ZERO
ONE xlp2sp sPtoS6
xlp2sp sPtoS10
xlmux
sel
d0
d1d1
Mux1
Out
Digital Input
In Out
DSP
In1
In2
Out1Out2Out3
DAC 2
3.277e+004
Con81024
Con14
Transmitter:
Receiver (Matched):
Receiver (TLA):
TestingDesign 101 bits 1001 bits
Matched 44 errors N/A
Matched (Altered) 0 errors 0 errors
TLA 0 errors 5 errors
TLA (Altered) 0 errors 0 errors
Direct/Reflected Path Results
Design 101 bits 1001 bitsMatched 42 errors N/A
Matched (Altered) 24 errors 266 errors
TLA 0 errors N/A
TLA (Altered) 24 errors 266 errors
Random Inversion Results
Future Work
Algorithm Implementation
References[1] L.C. Ludeman, Fudamentals of Digital Signal Processing. New York: Harper and Row, 1986.
[2] M.B. Pursley, Introduction to Digital Communications. New Jersey: Pearson Prentice Hall, 2005.
Figure1A Figure1B
Figure2A Figure2B
Pulse Position Modulation:
Figure3A
Figure3B
Figure4A Figure4B
Figure4A shows the Xilinx blocks used in MATLAB’s Simulink to implement PAM. Graph1A shows the transmission of ‘001100’.
Pulse Amplitude Modulation:
Figure4B shows the PPM implementation and some of the demodulation schemes used for testing. Graph1B shows the transmission of ‘01101’.
Graph1A
PAM Transmission
Graph1B
PPM Transmission
•bits were randomly transmitted and received with each design
•Additive White Gaussian Noise with a 4.8 SNR was added to the transmitted signal along with being manipulated by the noise model.
A possible direction that can be taken would be to do further testing with more accurate noise channel models and to quantify the relative complexity of the various algorithms to give a performance versus FPGA memory trade-off.
Table1A
Table1B
In testing the efficiency of the PPM demodulation implementations:
Note that N/A in Table1A and Table1B indicate that the design performed above or below average and did not need to be repeated.