Construction of a Firewire Signal Cable for Electronic Textile Integration

1. Construction of a Firewire Signal Cable for Electronic Textile Integration Ansoft Maxwell 2D Transmission Line Simulation Ansoft Corp.’s Maxwell 2D software was used to simulate the intrinsic impedance of transmission lines. Technical Hurdles Fig. 1 Cross section view of traditional Firewire cable. Note the twisted signal pairs. James Scire’, Dr. L. Wilson Pearson, & Danna Blankenship Impedance Measurement Introduction Electronic textiles (eTextiles) incorporate new electronic technologies into the fibers of clothing. The US Army intends to assist its soldiers with eTextiles as they maintain technical superiority over our enemies. By incorporating support electronics into a soldier’s uniform, he/she is not encumbered or discomforted by hard packaged circuits. The potential uses for such a product are limited only by the designer’s imagination. The present research focuses on the creation of a garment with an integrated IEEE 1394 Firewire bus. Firewire was chosen as the standard to integrate due to its technical specifications. Firewire is the industry standard for transferring video between camcorders and personal computer,due to its ultra-fast data transmission rate of50MB/s. Intrinsic impedance calculations were done on transmission lines of known values to gain experience using the HP 4291B Impedance/ Material Analyzer. Fig. 4 Picture of Test Transmission Line. Note the balun on the left to couple the unbalanced coaxial output of the Impedance Meter to the balanced transmission line. Fig. 5 Schematic of testing apparatus. The Distance between the lines can be changed, as well as the load resistance. Fig. 2 Simulation of two conductor transmission line with uniform dielectric encapsulate. • The simulation of a transmission line with two insulated conductors wrapped with shielding is pending Ansoft’s response to requested technical support. Insulation Creation Mold A mold was created to coat the Aracon yarn with the correct insulation thickness to set the intrinsic impedance between the conductors at 110Ω. Fig. 6 Table of Actual and Theoretical Intrinsic Impedances. Note the percent error for each measurement is below 5% Conclusions and Future Work Calculations have been done to determine the design of an insulation creation mold in order to achieve an intrinsic impedance of 110Ω in the signal carrying wires. Simulations have verified these calculations, technical support is pending to simulate shielding around the two conductors. The hand-weaving of certain grades of Aracon fibers into a textile has been successful. The next step will be to use the finished mold to create insulated yarns and integrate these conductors into a textile. • Intrinsic Impedance of twisted signal pairs = 110Ω • Twisted signal pairs are twisted at 40 twists/m Fig. 3 Insulation creation mold. The diameter of the hole in the longer piece is the distance needed between the yarns to have an intrinsic impedance of 110Ω. Special Thanks to Clemson University Center for Apparel Research