June 28, 1998
June 28, 1998
July 1, 1998
3.535.1 - 3.535.9
Teaching Real-World DSP Using MATLAB Cameron H. G. Wright Department of Electrical Engineering U.S. Air Force Academy, CO Thad B. Welch Department of Electrical Engineering U.S. Naval Academy, MD
ABSTRACT An enhancement to MATLAB written by the authors makes teaching various real-world DSP concepts easier and more effective. These enhancements eliminate the need to purchase expensive specialized software programs for this purpose. The particular DSP concept described in this paper is an interactive demonstration showing how quantization of digital filter coefficients, which is inevitable with widely-used fixed-point DSP hardware, adversely affects filter performance.
INTRODUCTION Modern software tools such as MATLAB greatly facilitate 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 earlier in the curriculum.9 MATLAB is an excellent learning tool when used for DSP education in this way. It enables an easier transition for the student to apply concepts to real-world DSP hardware such as the widely-used Texas Instruments TMS320C5X series of fixed-point DSP microprocessors. For example, the sptool program supplied with the latest release of the student edition of MATLAB (version 5) and also available in the latest Signal Processing Toolbox (version 4, written for MATLAB 5 Professional) provides an excellent interactive graphical interface for designing both FIR and IIR digital filters.10 The sptool program also allows interactive viewing and analysis of signals and their spectra, but this paper concentrates on the filter design capabilities.
For the student to design a digital filter, sptool is executed from the MATLAB command window, and the “New Design” button is clicked under the column for filters. This executes the Filter Designer tool, as shown in Figure 1. Various filter specifications can be easily selected by the student, with an immediate display of the resulting magnitude response. For a more complete analysis of the filter design, the student can click the “View” button from the filter column of the main sptool window, executing the Filter Viewer tool, which displays magnitude, phase, impulse response, step response, poles and zeros on the z-plane, group delay, etc., all at the click of a button. See Figure 2. The student can switch back to the Filter Designer tool with a click of the mouse to modify the design parameters and interactively see the results. By clicking the “Apply” button from the filter column of the main sptool window, the student can process any selected signal with the selected filter and view the resulting output signal and its associated spectrum.
Wright, C., & Welch, T. (1998, June), Teaching Real World Dsp Using Matlab Paper presented at 1998 Annual Conference, Seattle, Washington. https://peer.asee.org/7456
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