NI Academic Day June 30, 2005 Beirut, Lebanon Modem Design, Implementation, and Testing Using NI’s LabVIEW http://www.wncg.org http://www.ece.utexas.edu Prof.
Download ReportTranscript NI Academic Day June 30, 2005 Beirut, Lebanon Modem Design, Implementation, and Testing Using NI’s LabVIEW http://www.wncg.org http://www.ece.utexas.edu Prof.
NI Academic Day June 30, 2005 Beirut, Lebanon
Modem Design, Implementation, and Testing Using NI’s LabVIEW
http://www.wncg.org
http://www.ece.utexas.edu
Prof. Brian L. Evans Dept. of Electrical and Computer Engineering The University of Texas at Austin, Austin, Texas USA [email protected]
Visiting Associate Professor American University of Beirut, Beirut, Lebanon Contributions by Vishal Monga, Zukang Shen, Ahmet Toker, and Ian Wong, UT Austin
Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Outline
Real-Time Digital Signal Processing (DSP) Laboratory Course
Single Carrier Transceiver
Sinusoidal Generation
Digital Filters
Data Scramblers
Pulse Amplitude Modulation
Quadrature Amplitude Modulation
Conclusion
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Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Real-Time DSP Course: Overview
Objectives of undergraduate class
Build intuition for signal processing concepts
Translate signal processing concepts into real-time digital communications software Over 600 served since 1997
Lecture: breadth (three hours/week)
Digital signal processing algorithms
Digital communication systems
Digital signal processor architectures
Laboratory: depth (three hours/week)
Deliver voiceband modem
“Design is the science of tradeoffs” (Prof. Yale Patt, UT) Test/validate implementation
Web site: http://www.ece.utexas.edu/~bevans/courses/realtime/ Download site: http://www.ece.utexas.edu/~bevans/courses/realtime.zip 3
Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Real-Time DSP Course: Overview
Embedded system demand: volume, volume, …
400 Million units/year: automobiles, PCs, cell phones 30 Million units/year: ADSL modems and printers
Consumer electronics products
Product Wireless phone Digital cameras Portable CD players MP3 players Compact audio systems Average Unit Price $136 $271 $ 48 $137 $111 Annual Revenue $11.5 Billion $ 4.2 Billion $ 0.9 Billion $ 0.7 Billion $ 0.5 Billion Source: CEA Market Reseach. Data for 2004 calendar year.
How much should an embedded processor cost?
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Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Real-Time DSP Course: Overview
Digital signal processor market 1990-2000
40% annual growth #1 in growth within semiconductor market
Worldwide revenue (US dollars)
$6.1B ‘00 , $4.5B ‘01, $4.9B ‘02, $6.1B ‘03 , $8.0B ‘04 Estimated annual growth of 23% for 2003-2008
Market share (based on 2002 revenue)
43% TI, 14% Freescale, 14% Agere, 9% Analog Dev.
Fixed-point vs. floating-point DSPs
>90% of digital signal processors sold are fixed-point Floating –point DSPs used for initial real-time prototype
How many digital signal processors are in a PC?
Revenue figures from Forward Concepts ( http://www.fwdconcepts.com
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Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Real-Time DSP Course: Which DSP?
Students are next-to-final year (junior) and final year (senior) undergraduate students Fixed-point DSPs for high-volume products
Battery powered: cell phones, digital still cameras …
Wall powered: ADSL modems, cellular basestations … Fixed-point issues
Using non-standard C extensions for fractional data
Converting floating-point programs to fixed-point
Manual tracking of binary point prone to error Floating-point DSPs
Feasibility for fixed-point DSP realization
Shorter prototyping time
Program TI TMS320C67x DSP in C
TI Code Composer Studio 2.2
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Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Real-Time DSP Course: Textbooks
C. R. Johnson, Jr., and W. A.
Sethares, Telecommunication Breakdown, Prentice Hall, 2004.
Intro to digital communications and transceiver design
Rick Johnson
Matlab examples
(Cornell) Bill Sethares (Wisconsin)
S. A. Tretter, Comm. System Design using
DSP Algorithms with Lab Experiments for
the TMS320C6701 & TMS320C6711, 2003.
Assumes DSP theory and algorithms Assumes access to C6000 reference manuals Errata/code: http://www.ece.umd.edu/~tretter
Steven Tretter (Maryland)
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Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Lab 1. QAM Transmitter Diagram
Lab 4 Rate Control LabVIEW demo by Zukang Shen (UT Austin) Lab 6 QAM Encoder Lab 3 Tx Filters Lab 2 Passband Signal http://www.ece.utexas.edu/~bevans/courses/realtime/demonstration
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Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
LabVIEW Control Panel
Lab 1. QAM Transmitter Diagram
QAM Passband Signal Eye Diagram
LabVIEW demo by Zukang Shen (UT Austin)
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Prof. Brian L. Evans NI Academic Day
Lab 1. QAM Transmitter Diagram
June 30, 2005 Beirut, Lebanon
square root raise cosine, roll-off = 0.75, SNR = passband signal for 1200 bps mode raise cosine, roll-off = 1, SNR = 30 dB passband signal for 2400 bps mode 10
Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Lab 2. Sine Wave Generation
Aim: Evaluate three ways to generate sine waves in signal quality vs. complexity
Function call
Lookup table Difference equation Three output methods
Polling data transmit register
Software interrupts
Direct memory access (DMA) transfers Expected outcomes are to understand
Signal quality vs. implementation complexity tradeoff
C6701 EVM board’s stereo codec operation Interrupt mechanisms and DMA transfers
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Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Lab 2. Sine Wave Generation
Evaluation procedure
Validate sine wave frequency on scope, and test for various sampling rates (14 sampling rates on board) Method 1 with interrupt priorities Method 1 with different DMA initialization(s)
Fall 2003 Spring 2004 HP 60 MHz Digital Storage Oscilloscope
C6701 LabVIEW DSP Test Integration Toolkit 2.0
Code Composer Studio 2.2
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Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Lab 3. Digital Filters
Aim: Evaluate four ways to implement discrete-time linear time-invariant filters
FIR filter: convolution in C and assembly IIR Filter: direct form and cascade of biquads, both in C Q
IIR filter design gotchas: oscillation & instability
In classical designs, poles sensitive to perturbation Quality factor measures sensitivity of pole pair: Q
[ ½ ,
) where Q = ½ dampens and Q =
oscillates Elliptic analog lowpass IIR filter
d
p
20 rad/s and
d
s
= 0.31 at
w
s
= 0.21 at = 30 rad/s
w
p
[Evans 1999] = poles zeros Q poles zeros 1.7
-5.3533
± j16.9547
0.0
± j20.2479
0.68
-11.4343
± j10.5092
-3.4232
± j28.6856
61.0
-0.1636
± j19.9899
0.0
± j28.0184
10.00
-1.0926
± j21.8241
-1.2725
± j35.5476
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Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Lab 3. Digital Filters
IIR filter design for implementation
Butterworth/Chebyshev filters special cases of elliptic filters
Minimum order not always most efficient
Filter design gotcha: polynomial inflation
Polynomial deflation (rooting) reliable in floating-point Polynomial inflation (expansion) may degrade roots Keep native form computed by filter design algorithm
Expected outcomes are to understand
Speedups from convolution assembly routine vs. C Quantization effects on filter stability (IIR) FIR vs. IIR: how to decide which one to use
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Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Lab 3. Digital Filters
Test Equipment
Agilent Function Generator
HP 60 MHz Digital Storage Oscilloscope
Spectrum Analyzer Evaluation Procedure
Sweep filters with sinusoids to construct magnitude and phase responses
•
Manually using test equipment, or
•
Automatically by LabVIEW DSP Test Integration Toolkit Check filter output for cut-off frequency, roll off factor… FIR: Compare execution times (in Code Composer) of
• • •
C without compiler optimizations C with compiler optimizations C callable assembly language routine
IIR: Compute execution times (in Code Composer)
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Prof. Brian L. Evans NI Academic Day June 30, 2005 Beirut, Lebanon
Conclusion
Objectives Build intuition for signal processing concepts Translate signal processing concepts into real-time digital communications software
Deliverables and takeaways Deliver voiceband transceiver Tradeoffs in signal quality vs. implementation complexity Test/validate implementation Extend hands-on experience to broadband modems
Role of technology TI DSPs and Code Composer Studio NI LabVIEW and DSP Test Integration Toolkit
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