Typical Receiver Signal; Near Blanking; Loss Of Echo (Loe) - Siemens Sitrans Probe LR Operating Instructions Manual

The measurement response limits the maximum rate at which the display and analog
output respond to changes in measurement. P003 should be set to a measurement
response just faster than the maximum filling or emptying rate (whichever is greater).
When the echoes are received, the relevant echo algorithm (P820) is applied to determine
the true material echo.

Typical Receiver Signal

End of
Transmit
Distance from process empty level to reference point P006

Near Blanking

1
Near Blanking programs SITRANS Probe LR to ignore the zone in front of the antenna.
The default blanking distance is 0.3 m (1 ft) plus any shield length, from the reference
2
point .
P800 allows you to increase the near blanking value from its factory setting. But Auto
False-Echo Suppression (P837) is generally recommended in preference to extending the
blanking distance from factory values.

Loss of Echo (LOE)

A loss of echo (LOE) occurs when the calculated measurement is judged to be unreliable
because the confidence value (P805) is less than the threshold value (P804).
If the LOE condition persists beyond the time limit set by the Failsafe timer (P070), the
Reliable Echo indicator will be replaced by the Unreliable Echo indicator. The reading will
alternate at two second intervals with the letters LOE.
Reliable Echo indicator
P070 determines the time to elapse after the last valid reading before a Failsafe state is
activated. P071 determines the level to be reported when the Failsafe timer expires. Upon
receiving a reliable echo, the loss of echo condition is aborted, the Reliable Echo indicator
replaces the Unreliable Echo indicator, and the reading and mA output return to the
current level.
1.
Also referred to as "Blanking".
2.
For the reference point, see
7ML19985HR02
P800
Near Blanking
Unreliable Echo indicator
SITRANS Probe LR: Dimensions
SITRANS Probe LR – INSTRUCTION MANUAL
Empty
Level
Range Extension
(P801) as % P006
.
on page 15.
Page 93