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Reference Manual
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May 2016
that the disturbance is fixed at a certain tank level. Disturbing echoes which may appear
different from time to time can be filtered out by raising the whole ATC.
Figure 7-11. Disturbing Echoes Can Be Filtered out by Creating an Amplitude Threshold
7.6.2
Disturbances at the top of the tank
In addition to using the ATC, the Rosemount 5300 Transmitter supports alternative
methods to filter out disturbances at the top of the tank, such as the Trim Near Zone and
the Hold Off Distance/Upper Null Zone functions, which can be used to handle disturbances
from narrow nozzles or nozzles with rough edges. See
“Handling of disturbances from
for more information.
7.6.3
Signal quality metrics
Build up on the probe and different surface conditions are factors that can affect signal and
noise levels. Signal Quality Metrics can give an indication of how good the surface signal is
compared to the noise. For more information, see
“Signal Quality Metrics” on page 324
7.7
Interface measurements with fully submerged
probes
The Rosemount 5300 Series has a measurement option which makes it possible to handle
interface measurements when the probe is fully submerged into the upper product, see
, and only the interface level is detected by the transmitter. Even if the upper
product level drops, it is ignored by the transmitter which continues to measure only the
interface level, but the measurement accuracy is reduced since the transmitter does not
take into account the influence of the air gap above the product surface. To achieve high
accuracy in this measurement mode, the probe must be fully submerged, or a Rosemount
5302 for Level and Interface measurements should be used.
The Measurement Mode parameter is available via the HART command [2, 3, 3].
F
OUNDATION
Fieldbus parameter: TRANSDUCER 1100 > MEAS_MODE
Amplitude Threshold Curve
Measurement signal
Am
p
litude
, mV
Distance, m
Disturbing object