Parameterization
D184B140U02 FSM4000
91
7.4.1.7 Determining
the signal-to-noise ratio
x
x
Z
-1
+
x
x
+
1
2
G00578e
1
Signal from flowmeter
sensor
2
Filtered signal
Detect changes in fluid, e.g., gas bubbles, increased/reduced
amount of solids.
To determine the signal-to-noise ratio (SNR), the electrode AC
voltage - raw signal of the flowmeter sensor is set in relation to
the digitally filtered signal.
The SNR can be determined without affecting the flowrate
measurement, i.e. no error or warning has to be activated in the
submenu "Diagnostics / Alert Settings".
SNR =
sensor
flowmeter
from
Signal
signal
Filtered
7.4.1.8 Determining the magnetic linearity
I
U
R
G00578f
ML =
1
R
2
2
R
1
U
I
U
I
∗
∗
Detect magnetic field interference. This can affect the accuracy
of the measurement.
When measuring magnetic linearity (ML), the coil current I
1
is
measured at current reference voltage U
R1
and coil current I
2
at
approximately half the reference voltage U
R2
.
The operating time at half the reference voltage is approx. 1
sec. During this period, the last valid flowrate value is retained.
To perform this test, it is necessary to switch on one of the
relevant errors or warnings in the submenu "Diagnostics/Alert
Settings" (see page 82).
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