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Proceedings Paper

Asynchronous spread spectrum communication for a microminiature transponder: implementation and test results
Author(s): David R. Holmes III; E. Brian Welch; Rick A. Philpott; Jonathan D. Coker; Timothy M. Schaefer; Barry K. Gilbert; Erik S. Daniel
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Paper Abstract

While the field of wireless communication has developed dramatically over the past several decades, there are several notable applications of wireless technologies which impose constraints on power-consumption and form-factor that are not compatible with cutting edge technologies. These applications include implantable devices and remote monitoring devices. Using a well-defined set of functional needs and system restrictions, we have developed an ultra-compact and ultra-low-powered transponder which contains spread spectrum (SS) logic for wireless communications. The transponder chip was designed and built in the Jazz BiCMOS SiGe technology. The device is activated via a pure tone and emits a SS response which is modulated over the carrier with binary phase shift keying (BPSK). The SS signal is a gold-code generated from two 9-bit m-sequence generators. One of the m-sequences is seeded with a fixed value while the other 9-bit register is pinned out and can be a fixed ID or a bus to transmit data from a microcontroller. The data is received and decoded by a standard PC with a high-speed acquisition board. In order to support multiple devices at various distances, asynchronous decoding is applied. When active, the device draws less than 35 mA of current. Because the duty cycle of this device is likely less than 1%, the device can be powered for several hours using a very small coin battery. The device has been tested both in the lab and natural environment testing is underway. Future work will combine the device with a microcontroller in the field to achieve specific monitoring goals.

Paper Details

Date Published: 2 June 2005
PDF: 6 pages
Proc. SPIE 5819, Digital Wireless Communications VII and Space Communication Technologies, (2 June 2005); doi: 10.1117/12.604255
Show Author Affiliations
David R. Holmes III, Mayo Clinic and Foundation (United States)
E. Brian Welch, Mayo Clinic and Foundation (United States)
Rick A. Philpott, Mayo Clinic and Foundation (United States)
Jonathan D. Coker, Mayo Clinic and Foundation (United States)
Timothy M. Schaefer, Mayo Clinic and Foundation (United States)
Barry K. Gilbert, Mayo Clinic and Foundation (United States)
Erik S. Daniel, Mayo Clinic and Foundation (United States)

Published in SPIE Proceedings Vol. 5819:
Digital Wireless Communications VII and Space Communication Technologies
Rabindra Singh; Raghuveer M. Rao; Sohail A. Dianat; Michael D. Zoltowski, Editor(s)

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