One of the pioneers in ultra-wideband (UWB) real-time location systems (RTLS) is Æther Wire and Location, Inc. In the Æther Wire approach, an antenna differentiates current pulses so as to yield equal and opposite impulses time-spaced according to the duration of the current impulse. This produces a time varying series of impulse doublets that can be designed for spectral whitening or to convey data (~1Mb/s). Æther Wire Localizers create an ad-hoc, peer-peer mesh network and determine round-trip propagation times between nodes so as to enable geolocation via multilateration.
Based in Silicon Valley, Æther Wire takes a relatively low-frequency (<1 GHz) approach to UWB. Æther Wire’s low frequency approach gives their signals excellent penetration and propagation. Using such long wavelengths (>30cm) poses a significant antenna design challenge, however. Æther Wire employs the Large Current Radiator (LCR) concept, first pioneered by Henning Harmuth, to address this challenge. Earlier Æther Wire designs were relatively elaborate 3-D structures. More recently, the company has devised planar implementations of their antennas that can be directly implemented on a printed circuit board. The company’s sixth generation Localizers employ planar LCR antennas.
In addition, Æther Wire devised a family of custom, low-power, digital CMOS chips to implement their concepts, and employed direct sequence coding to cope with operation in a multipath environment.
One of Æther Wire’s top technologists, Vince Coli, gave a Google Tech Talk last year on the subject of the company’s technology and its development over the past decade. This talk provides a wealth of technical detail that will be of interest to anyone seeking to learn more about UWB RTLS and Æther Wire’s contributions to the state-of-the-art.
More information about Aether Wire’s approach to UWB RTLS and indoor/urban location may be found by contacting Aether Wire through their website.