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An acoustic radar is a device acting as the well known radars, with
the difference that the transmitted and the received signals have
frequencies in the acoustic region. An alternate name for this class
of instruments is 'Sodar', due to the SOund Detection And Ranging'. A
short acoustic pulse is transmitted in the atmosphere. While it is
travelling in there, it is scattered from the atmospheric
irregularities. Here, the irregularities don't mean a 'target' object,
as in the usual electromagnetic or microwave radars. A change in the
wind velocity, a turbulent layer, a temperature inversion e.t.c. cause
scattering of the acoustic waves. A part of the scattered signal
returns to the receiver, where it is collected and processed.
Additional information available at
"http://cgi.di.uoa.gr/~tliaskas/Welcome.html"
[Summary provided by University of Athens]
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