An important part of the SONAR process is the ability to display and interpret the recorded data that has been collected. There are two ways to display the recorded information after an echo has returned: aurally, or visually.
Aural -- uses a noise in the form of a "ping" for outgoing pulses and is followed by the returning echoes.
Visual -- can be subdivided into three categories:
A range recorder uses an instrument called a stylus which moves across chemically treated paper. The paper will darken as a signal is received. Range is then determined by the distance along a trace of an echo.
A two-dimensional video presentation may also be used. After emitting multi-directional sound pulses, one receiving beam rotates electrically on a horizontal plane. This method gives the searcher both the range and direction of the target.
Lastly a video tube is a variable-displacement indicator. A video tube displays the amplitude of a signal as a function of time and range.
