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NT UF 831 CO GB (b) / March 2014
5.4.10 "Echo display" menu
Warning: The Echo display/analysis mode blocks the measurement function (The measurement values are
no longer calculated, the logger no longer records data).
The Echo analysis mode is used to view the acoustic signal of each chord, which is of use during the
commissioning or maintenance phase, or for example:
 to check the connection of the probes and their good working order,
 to check that the probes are placed at the correct distance,
 to find the origin of a measurement incident (clogging of the probes, obstruction of the structure
between the probes, unforeseen pollution, rupture of a probe cable, etc.).
Comment: Various characteristic signals are analysed in appendix 1.
The "Echo analysis" includes two screens per chord:
 The first displays the acoustic signal between the emission (peak to the left of the screen) and the
echo analysis zone. This screen is called the "landscape display":
Comment
:
If no acoustic signal reaches the expected zone (for example if one of the probes is
not connected, or if one of the probe cables is damaged), the screen displays a "!" sign in place of
the acoustic signal.
 The second screen shows a zoom on the echo chosen for the measurement. This screen is called the
"zoom display":
o
The two dashed vertical lines show the zone in which the
echo is expected. An echo received outside this zone is not
taken into account.
o
The dotted vertical line shows the measuring point on the
echo.
o
The number of the chord is indicated below the graph.
o
The top-left of the screen shows the gain applied to the
echo and the wave travel time.
o
The continuous horizontal bar indicates the noise level.
o
The dotted vertical bar shows the position at which the
travel time measurement is taken. If there is no such
line, it means that no measurement is taken (for example
if there is too much interference).
o
The dotted horizontal line indicates the measurement
threshold. The measurement is taken the first time the
alternation crossing this threshold reaches 0.