Development of An Improved Swept RF Tagging System and its Musical Applications

Building on the previous work and an earlier design by Dr. Joe Paradiso and Kai-Yuh Hsiao, an improved swept frequency tag reader has been developed and built. The tag reader uses an AC magnetic field to detect the presence and coupling strength of magnetically-coupled resonators, in this case, passive resonant LC circuits and magnetostrictors. The previously designed swept RF tag reader is capable of simultaneously detecting the continuous motion of up to 20 distinct tags in real-time within roughly 12” distance from a 12’’ diameter search coil. The new reader is capable of matching that performance, but also features increased sensitivity, vastly improved tolerance to frequency drift and support for up to 3 coils to be run asynchronously, a useful feature for multicoil geometries that enable multi-axis tracking and response Using a single coil, a new musical application, Musical-Navigatrics has been developed for the tag reader. This application works to provide an expressive and complex free space musical interaction for composition and performance specifically suited to the tagged object interface. Moving tags above the search coil, the user is able to play and record up to 4 pitched voices and a percussive line. These voices can then be distorted and explored through the use of a variety of effect inducing tags. Through this application, the capabilities and the usability of the tag interface has been explored for usage as a pitched musical instrument, effects controller, and basic sequencer, features that can create an entirely new and revolutionary performance controller for computer music. Thesis Supervisor: Joseph A. Paradiso Title: Principal Research Scientist, Media Arts and Sciences