Real-time digital signal processing from MATLAB to C with the TMS320C6x DSK

REAL-TIME

DIGITAL SIGNAL

PROCESSING

from M a t l a b ® to C with

the TM S320C6x DSK

2.50 MSa/s

File Control Setup Measure Analyze Utilities Help

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M ichael G. M o rro w

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REAL-TIME

DIGITAL SIGNAL

PROCESSING

fro m M a tla b ® to C w ith

th e TMS320C6X DSK

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REAL-TIME

DIGITAL SIGNAL

PROCESSING

from M atlab® to C w ith

the TMS320C6X DSK

Thad B. W elch

United States Naval Academy, Annapolis, Maryland

Cam eron H.G. W right

University of Wyoming, Laramie, Wyoming

M ichael G. M o rro w

______University of Wisconsin, Madison, Wisconsin

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To Donna...

To Robin...

To J a n ...

Foreword

Digital signal processing is at the “heart” of most technologies that we use today. Our

cell phones use digital signal processing to generate the DTM F (dual tone multi-frequency)

tones that are sent to wireless networks. O ur noise-canceling headphones use adaptive

digital signal processing to cancel the noise in the environment around us. Digital cameras

use digital signal processing to compress images into JPEG formats for efficient storage so

th at we can store hundreds of images in a single memory card. It is digital signal processing

that allows us to play compressed music in our iPODs. Digital signal processing controls

even the anti-lock brakes in our cars today. And these are just a few of the examples of

real-time signal processing in the world around us.

There are many good textbooks today to teach digital signal processing—bu t most of

them are content to teach the theory, and perhaps some M a t l a b simulations. This book has

taken a bold step forward. It not only presents the theory, it reinforces it with simulations,

and then it shows us how to actually use the results in real-time applications. This last step

is not a trivial step, and that is why so many books and courses present only theory and

simulations. W ith the combined expertise of the three authors of this text -T h ad Welch,

Cam Wright, and Mike Morrow the reader can step into the real-time world of applications

with a text that presents an accessible path.

I have been fortunate to co-author several papers with the authors of this text, and can

speak from first-hand experiences of their dedication to engineering education. They go the

extra mile to continue to expand their understanding and their abilities to present com￾plex material in a logical, straightforward manner. They attend conferences on engineering

education; they chair sessions 011 engineering education; they write papers on engineering

education; they live engineering education! So, I am delighted to be able to have an op￾portunity to tell the readers of this text that they are in for, in the authors’ own words, “a

rid e...

Delores M. E tter

Professor, Electrical Engineering

Distinguished Chair in Science and Technology

United States Naval Academy

Annapolis, Maryland

(Dr. Etter is member o f the National Academy o f Engineering and a Fellow of the IEEE and

the American Society of Engineering Education. She served as the Deputy Under Secretary

of Defense for Science and Technology from 1998 2001. She is also the author o f a nwnber

of engineering textbooks, including several on M A T L A B .)

A bout the A uthors

T h a d B. W elch, P h .D ., P .E ., is an Associate Professor and Perm anent Military Pro￾fessor in the Departm ent of Electrical and Com puter Engineering at the U.S. Naval

Academy (USNA). Annapolis. Maryland, and previously taught at the U.S. Air Force

Academy (USAFA) in the Departm ent of Electrical Engineering. He is a Commander

in the U.S. Navy, and won the 1997 Clements Outstanding Educator Award at US￾AFA, the 2001 ECE O utstanding Educator Award, 2002 Raouf Award for Excellence

in the Teaching of Engineering, and the 2003 ECE Outstanding Researcher Award

at USNA. Dr. Welch is the former chairman and a founding member of the Tech￾nical Committee on Signal Processing Education for the Institute of Electrical and

Electronic Engineers (IEEE) Signal Processing Society. He is a senior member of the

IEEE and a member of the American Society for Engineering Education (ASEE).

C a m e ro n H . G . W rig h t, P h .D ., P .E ., is an Assistant Professor in the D epartm ent of

Electrical and Com puter Engineering at the University of Wyoming, and previously

taught for nearly ten years at the U.S. Air Force Academy (USAFA) in the Departm ent

of Electrical Engineering where he was Professor and Deputy Departm ent Head. A

retired Lieutenant Colonel in the U.S. Air Force, he won the Brigadier General R.

E. Thomas Award for O utstanding Contributions to Cadet Education in 1992 and

1993. In 2005, he won the IEEE Student Choice Award for O utstanding Professor

of the Year and the M ortar Board “Top Prof" Award at the University of Wyoming.

Dr. W right is a founding member of the Technical Com mittee on Signal Processing

Education for the IEEE Signal Processing Society. He is a senior member of the

IEEE, and a member of ASEE, the National Society of Professional Engineers, and

the International Society of Optical Engineers.

M ich ael G . M o rro w , M .E n g .E .E ., P .E ., is a Faculty Associate in the D epartm ent of

Electrical and Com puter Engineering at the University of W isconsin-Madison. A

retired Lieutenant Commander in the U.S. Navy, he previously taught in the Elec￾trical Engineering D epartm ent at the U.S. Naval Academy. Mr. Morrow won both

the 2002 D epartm ent of Electrical and Com puter Engineering O utstanding Educator

Award and the 2003 Gerald Holdridge Teaching Excellence Award at the University

of W isconsin-Madison, and was designated a Microsoft Most Valuable Professional

(MVP). He is the founder and president of Educational DSP (eDSP), LLC. developing

affordable DSP education solutions. He is a member of the Technical Com mittee on

Signal Processing Education for the Institute of Electrical and Electronic Engineers

(IEEE) Signal Processing Society, a senior member of the IEEE, and a member of the

American Society for Engineering Education (ASEE).

'

C ontents

P re fa c e xxxi

A ck n o w led g m e n ts xxxiii

E n d u rin g F u n d a m e n ta ls 1

1 In tro d u c tio n a n d O rg a n iz a tio n 3

1.1 Why Do You Need This B o o k ? .............................................................................. 3

1.1.1 Other DSP Books ............................................................................................ 3

1.1.2 Demos and DSP Hardware ........................................................................... 4

1.1.3 Philosophy of This B o o k .................................................................................. 4

1.2 Real-Time D S P .............................................................................................................. 4

1.3 How to Use This B o o k ................................................................................................. 5

1.3.1 Transition to R eal-T im e.................................................................................. 8

1.3.2 Chapter Coverage ............................................................................................ 8

1.3.3 Hardware and Software Installation .......................................................... 9

1.3.4 Reading Program L istin g s.............................................................................. 9

1.4 Get S t a r te d ..................................................................................................................... 10

2 S am p lin g a n d R e c o n s tru c tio n 11

2.1 T h eo ry ............................................................................................................................... 11

2.1.1 Choosing a Sampling Frequency ................................................................. 11

2.1.2 Input/O utput Issues: Samples or F ram es?................................................ 11

2.1.3 The Talk-Through C o n c e p t........................................................................... 12

2.2 winDSK6 Demonstration .......................................................................................... 12

2.2.1 Starting w in D S K 6 ............................................................................................ 12

2.2.2 Talk-Thru A pplication..................................................................................... 13

2.3 Talk-Through Using W indow s.................................................................................... 15

2.4 Talk-Through Using MATLAB and W in d o w s..................................................... 16

2.4.1 Talk-Through Using MATLAB O n ly .......................................................... 18

2.4.2 Talk-Through Using M A T L A B .................................................................... 21

2.5 DSK Implementation in C .......................................................................................... 22

2.6 Follow-On Challenges ................................................................................................. 23

3 F IR D ig ital F ilte rs 25

3.1 T h eo ry ............................................................................................................................... 25

3.1.1 Traditional N o ta tio n ......................................................................................... 25

3.1.2 FIR Filters Compared to HR F 'ilte rs ........................................................... 26

3.1.3 Calculating the O utput of a F i l t e r .............................................................. 26

xi