The global
positioning system, or GPS, has its limitation (i.e. it cannot work indoors).
Potential solutions for indoor positioning continue to fire up the imaginations
of scientists. The latest news involves a form of echolocation. MIT Technology
Review reported on the approach for indoor localization based on sound. Researchers
at the University of California, Berkeley developed a simple, cheap mechanism
that can identify rooms based on a relatively small dataset. Their method is
based on the extraction of acoustic features of rooms. The team said they can
acquire RIRs (room impulse responses) by using built-in speakers and
microphones on laptops.
Also, a noise
adaptive reverberation extraction algorithm was developed for feature
extraction from the noisy RIRs. The researchers tested their system in ten
rooms on the Berkeley campus. Data was taken using the built-in microphone and
speakers on an ordinary laptop. The laptop produces a set of sound waves and
then listens for the echo. They took 50 samples at each location, which
included background noise such as footsteps, talking and heating and
ventilation sounds. They processed this data to find the echo fingerprint for
each room. The team said there was a 97.8 percent accuracy in identifying the
individual rooms.
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