Ultrasound Identification is a real-time locating system (RTLS) or

indoor positioning system An indoor positioning system (IPS) is a network of devices used to locate people or objects where GPS and other satellite technologies lack precision or fail entirely, such as inside multistory buildings, airports, alleys, parking garages, and u ...

(IPS) technology used to automatically determine and identify the location of objects with room accuracy. The approach is using simple, inexpensive nodes (badges/tags) attached to the surface of persons, objects and devices, which then transmit an ultrasound signal to communicate their locations to microphone sensors. Because ultrasound signal

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

s have short reach, they are confined to lesser distant locations than with wireless transmissions with higher susceptibility to multiple reflection, multipath and through-the-wall multiple room responses. Hence ultrasound-based RTLS is considered a more robust alternative to passive

radio-frequency identification Radio-frequency identification (RFID) uses electromagnetic fields to automatically Automatic identification system, identify and Tracking system, track tags attached to objects. An RFID system consists of a tiny radio transponder called a tag, ...

(pRFID) and even to active radio-frequency identification (aRFID) in complex indoor environments (such as hospitals), where radio waves get multiply transmitted and reflected, thereby compromising the positioning accuracy. Generally the ultrasound signal does not interfere with sensitive medical equipment.Greenemeier, Larry.
"A Positioning System That Goes Where GPS Can't"
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Scientific American ''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it, with more than 150 Nobel Pri ...

'', 2008-01-23. Retrieved on 2008-04-04. A handicap of ultrasound nodes is the exposition of the sound transducer at the surface, which prevents from hermetically encapsulating the node. Vapour sterilisation is not offered with these nodes.

References

{{reflist Automatic identification and data capture Geopositioning Ubiquitous computing