DEVELOPMENT AND EVALUATION OF A WEB-BASED SIGNAL AND SPEECH PROCESSING LABORATORY FOR DISTANCE LEARNING + Andreas Spanias * , Susan Urban, Argyris Constantinou, Maya Tampi, Axel Clausen, Xiaopeng Zhang, Jeff Foutz and Georgios Stylianou Department of Electrical Engineering and Department of Computer Science & Engineering Multidisciplinary Initiative on Distance Learning Arizona State University, Tempe, AZ 85287-7206, U.S.A. + Supported in part by the Arizona State University Vice President for Research * For any questions regarding the use of J-DSP contact A. Spanias (spanias@asu.edu) ** MATLAB and SIMULINK are registered by The MathWorks ABSTRACT In this paper, we describe an internet-based signal processing laboratory that provides hands-on learning experiences in distributed learning environments. The laboratory is based on an object-oriented Java tool called Java Digital Signal Processing (J- DSP). J-DSP has been developed at Arizona State University (ASU) and is being used for a virtual laboratory in a senior-level DSP course. J-DSP is written as a platform-independent Java applet that resides on the web and is thereby accessible by all students through the use of a web browser. J-DSP has a rich suite of signal processing functions that facilitate interactive on-line simulations of modern statistical signal and spectral analysis algorithms, filter design tools, QMF banks, and state-of-the-art vocoders. J-DSP is accompanied by administrative software tools for secure internet-based lab-report submission and evaluation including servlets for maintaining web-based grade books. A series of J-DSP laboratory exercises has been developed and delivered using the ASU distance learning facilities. Student evaluations as well as assessments by experts have been compiled and preliminary results are quite encouraging. 1. INTRODUCTION The development of the world wide web (WWW) has had a profound impact in distance learning education. Browsing technologies have enabled asynchronous distance learning education and many universities are eager to expand their clientele by reaching students outside their campus borders. To this date, there are some fine examples of Internet use in engineering education. Examples of using the Internet include web publishing of supplemental course material, concept visualization software, web courses accompanied by streaming audio/video, or even entire degree programs based on WWW courses. In the field of signal processing, several important contributions [1-5] associated with this theme appeared in special sessions organized by the DSP Education committee in previous ICASSPs. Although there have been several notable attempts to post DSP educational material with interactive visualization applets, there has not been enough done for DSP laboratory experiences for distance learners. In this paper, we present a comprehensive virtual laboratory environment that was tailored to provide hands-on laboratory experiences to distance learning students over the WWW. The virtual, on-line DSP laboratory described in this paper, consists of the graphical DSP editor, called J-DSP, and a software environment for electronic lab report submission and grading. Students use the J-DSP editor to establish and execute DSP simulations of several important algorithms. The editor includes a suite of built-in signal processing functions ranging from simple signal manipulators to complex filter design functions as well as speech, statistical, and adaptive signal processing algorithms. A suite of laboratory exercises that promotes hands-on DSP learning experiences of distance learners has also been developed for J- DSP. Although the DSP simulation capabilities provided by J-DSP are also typically provided by commercial packages such as MATLAB and SIMULINK ** , J-DSP is platform independent, user- friendly, and universally accessible through the use of common WWW browsers. In fact, J-DSP represents a new paradigm of an object-oriented DSP simulation environment built from the ground up for WWW laboratory education. J-DSP is accompanied by tools that facilitate secure lab-report submission including servlets for maintaining web-based grade books. Lab report submission and grading is achieved through a three-tier Client/Application Server/Database Server model described later in the paper. 2. THE J-DSP EDITOR 2.1 Overview J-DSP provides a user-friendly environment through Java’s graphical capabilities. Its highly intuitive graphical user interface (GUI) is easy to understand and students quickly learn to use it with very little assistance. All functions appear in J-DSP as graphical blocks that are divided into groups according to their functionality. Selecting and establishing individual blocks can be done by a drag-and-drop process. Each block is associated with a specific signal processing function. Figure 1 shows the J-DSP editor environment. By connecting blocks together, a variety of DSP systems can be simulated. Signals at any point of a simulation can be examined through the appropriate graphics blocks. Blocks can be edited through dialog windows, allowing