An interactive DSP tutorial on the Web

This paper describes an interactive, self-study DSP tutorial package built for the World Wide Web (WWW, Web). The package includes concept explanation, graphical presentations, listening-ready audio examples and interactive exercises and demonstrations of basic concepts of signal processing. The WWW is a convenient and easy-to-use hypermedia tool. From the point of view of DSP education, the main problem is how to implement interactivity and signal processing. Our solution is to apply CGI (Common Gateway Interface) and Java in tasks that they are best suited for. A Common Lisp based WWW server CL-HTTP together with the QuickSig environment is used for providing signal processing routines in a CGI-like manner. Java applets are used for taking care of the user interface at the client end. 1. BACKGROUND AND MOTIVATION At the ICASSP '95 [1] we described a Computer Based Education (CBE) system that was built on top of the object-oriented, Common Lisp based, QuickSig DSP programming environment [2]. The CBE application "Introduction to Signal Processing", an interactive, selfstudy tutorial covering the basic concepts of signal processing, was also presented. The application was then used within acoustics course "Fundamentals of Acoustics 1" by approximately 100 students and the results were encouraging: nearly all the students felt that DSP concepts are easy to learn with CBE methods [3]. "Introduction to Signal Processing" was designed to be a stand-alone Macintosh application exploring multiand hypermedia features of new computers. Still, audio and signal processing features stated some extra demands for the computer, so the usage of the application was restricted to only one computer located at the laboratory. Therefore, a need for multi-user capabilities arose. Natural tool for such development is the WWW. The main goal for the application is to give undergraduate students a practical but yet general enough view on signal processing especially from the viewpoint of audio. The application has been integrated into one self-study multimedia package with concept explanation, graphical and audio presentations and interactive experiments. Special attention was paid in order to design an easy-to-use user interface. This project aims for a WWW version of the original CBE application sharing the same goals and without compromizing the exibility and e ciency provided by the QuickSig system.