Ultraflux Uf 841, Руководство пользователя

Страница: 52 / 105

52
NT UF 841 CP GB (d) / June 2015
5.4.6 "Echo display" menu
Warning: Echo display mode blocks the measurement function (The measurement values are no longer
calculated, the logger no longer records data).
"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 that they are working correctly,
•
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.
"Echo analysis" mode includes two screens per chord:
•
The first displays the acoustic signal between the emission (for short travel times) 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 area where the echo
is expected. An echo received outside of this area will not be
taken into account.
o
The dotted vertical line shows the measuring point on the
echo.
o
The chord number is shown underneath the graph.
o
On the top left of the screen is shown the gain applied to the
echo and the travel time of the wave.
o
The continuous horizontal line shows the noise level.
o
The vertical dotted bar marks the location where the
travel time is measured. Its absence means that no
measurement was carried out (for example if there were
too many interfering signals).
o
The horizontal dotted bar shows the measurement
threshold. The measurement is carried out on the first
movement to 0 of the cycle which crosses this threshold.
o
On the bottom left is shown the travel time difference of
the ultrasounds (does not include
∆ T0).