Construction of a Firewire Signal Cable for Electronic Textile Integration

1
Construction of a Firewire Signal Cable for
Electronic Textile Integration
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 soldiers uniform, he/she is
not encumbered or discomforted by hard packaged
circuits. The potential uses for such a product
are limited only by the designers 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 Ansofts 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
110O.
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 110O 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
  110O
• 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 110O.
Special Thanks to Clemson University Center for
Apparel Research