Keywords: High Precision Localization, Time-of-Flight, Time-Difference-of-Arrival (ToA), 20 ps Resolution, Barn Owl Nucleus Laminaris, Low-Cost Embedded System
Motivation: In several application domains, such as smart-appliances ensembles, the precise localization of an object, such as a beamer, a laptop, the presenting person, or even the finger of the presenter, is of significant interest. Existing research has been considering typical indoor methods, such as ultra-sonic signals, RFID tags, and the signal strength of electromagnetic signals. The X-ORCA project considers the time-of-flight of electromagnetic signals, which is still challenging for most digital signals, since these signals travel with the speed of light c≈300.000 km/s. The focus of this project is the localization of active devices, such as the WiFi card of a laptop, as an off-center position leads to a phase shift at two receiving antennas.
Developing of a high-precision phase shift measurement system
that has the following properties:
(1) easy to implement on standard, low-cost field programmable gate arrays (FPGAs),
(2) high-resolution, way below both the system clock and the inherent, technology-dependent gate delays, and
(3) high tolerance with respect to gate placement, and internal time delays induced by internal wire lengths
This project has explored the following approaches:
(1) exploring tapped delay lines (TDLs),
(2) exploiting the delays induced by internal wire lengths on which signals propagate wuth two third of the speed of light, and
(3) utilizing basis concepts of the barn owl nucleus laminaris
The first prototypical implementation of the X-ORCA system
on an Altera Stratix II EP2S60 has shown that
(1) a resolution of 20 ps is easy to obtain,
(2) the frequency of the external signal can be as high as 19 MHz, and
(3) the frequency of an internal signal can be beyond the clock frequency.
Poster: Further information can be found on the poster.
Contact: Ralf Salomon