27-11-2012, 05:28 PM
Making DSP Fun for Students Using Matlab and the C31 DSK
Making DSP Fun for Students Using Matlab and the C31 DSK.pdf (Size: 186.75 KB / Downloads: 54)
Abstract
This paper describes some innovative programs us-
ing a graphical user interface (GUI) for Matlab and the C31
DSK which makes DSP concepts interesting and entertain-
ing, yet educational. The programs eliminate the need to pur-
chase any expensive specialized software or hardware, relying
on the commonly available Matlab program and the inexpen-
sive Texas Instruments C31 DSK for this purpose.
The programs described in this paper are a follow-on to the
one presented at DSPS Fest '98. The new programs are far
more capable and even easier to use than their predecessor:
one author (TBW) even managed to get 4th graders to design
real-time digital lters then run them on a C31 DSK with one
of these programs, and college students love the graphical user
interface and the ease of interfacing with the DSP hardware.
The programs have been used with great success at both the
U.S. Air Force Academy and the U.S. Naval Academy.
INTRODUCTION
MODERN software tools such as Matlab greatly fa-
cilitate the professor's ability to demonstrate the
concepts of digital signal processing (DSP) in class, and to
assign realistic projects to reinforce these concepts [1{3].
An increasing number of DSP textbooks are becoming
available which take advantage of this ability [4{8], and a
growing trend is for DSP concepts to be introduced ear-
lier in the curriculum [9]. These concepts can be further
reinforced, and greater interest generated by the students,
if they can be easily implemented in real-time on modern
DSP hardware [10]. Aordable hardware is now available
to schools: Texas Instruments, for example, markets DSP
Starter Kits (DSKs) for $99 [11]. While xed-point pro-
cessors are more prevalent in industry [12] (albeit floating
point is gaining in use), floating-point processors are be-
coming more popular for schools due to pedagogical rea-
sons. We will examine how Matlab, already accepted
as a powerful learning tool for DSP, can be closely inte-
grated with a DSK for teaching purposes while avoiding
the tedium of manually programming the DSP processor.
COMBINING MATLAB WITH THE C31 DSK
The authors identied a pressing need for a GUI-based
program which would run under Matlab, be able to
directly utilize the benets of sptool mentioned above,
and also communicate seamlessly with the C31 DSK.
While the capabilities provided by sptool are impressive
and greatly facilitate students' comprehension of various
DSP topics, there is no straightforward way to use it
directly with a DSK. Also lacking in sptool is the abil-
ity to simulate for teaching purposes certain xed-point
eects, suitable for presentation to our senior-level EE
majors, such as lter coecient quantization. Matlab
performs double precision calculations in sptool, thus a
lter design could perform far dierently than expected
if implemented on a xed-point processor [14]. While
floating-point DSP hardware (such as Texas Instruments
TMS320C3x series) is much easier to present from a peda-
gogical standpoint, the fact remains that xed-point DSP
hardware (such as the Texas Instruments TMS320C5x se-
ries) is still more prevalent due to it's cost and speed
advantages. It therefore behooves the professor to ex-
pose the students to the important dierences between
floating-point and xed-point hardware. Specialized soft-
ware programs exist which address this design issue, but
they are typically expensive, require the student to learn
another interface, and/or are not written for educational
purposes.
CONCLUSIONS
The programs qlt and polezero written by the authors
provide the educator with easy to use, inexpensive, and
interactive methods to teach various concepts of digital l-
ter design so important in DSP classes. The programs are
completely compatible with sptool provided with version 5
of the Student Edition of Matlab and also with version
Fig. 2. Magnitude plot of 8th order IIR Elliptic digital lter, quantized to 16 bits and implemented as a Direct Form II transpose.
4.2 of the Signal Processing Toolbox. They both easily
communicate with the C31 DSK that is used by many
universities, they eliminate the need for tedious program-
ming of the DSK, and both are freely available from the
following Web site.