Siemens SITRANS FUH1010, Product Instruction Manual, Page: 150 / 264

Troubleshooting
10.3 Test Facilities Graph Screen
FUH1010 IP65 NEMA 4X Precision Volume
Operating Instructions, 01/2013, A5E32122003-AA
149
Envelope Threshold Adjustment: (Hot Key 5 & 6)
Pressing the <=> key causes the graph to toggle between the default signal waveform
screen and the signal envelope screen (see example below). This envelope screen can aid
in the diagnosis of Tn errors caused by unusual receive waveform distortion. Signal
distortion is sometimes caused by poor sensor selection or poor pipe wall conditions, which
may result in an incorrectly measured fluid sound velocity. To improve the automatic
measurement of Tn, the envelope threshold limit can be adjusted to exclude portions of the
envelope, which may be causing the Tn detection problem.
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① ④
Envelope Signal Crossover Marker
② ⑤
HiSet Envelope Threshold TN Marker
③
LoSet Envelope Threshold
⑥
Zero Baseline
Figure 10-4 Envelope Threshold Adjustment
1. If it appears that the default placement of the Tn marker is incorrect or unstable, it can be
adjusted by pressing the <5> key on the keypad to invoke the [Hi Set #] command or by
pressing the <6> key to invoke the [Low Set #] command (while viewing the envelope
screen). A horizontal line representing the envelope threshold level will appear along with
a number indicating the percentage level. The High and Low thresholds can then be
moved either up or down on the envelope using the <+> or <-> keys. While viewing the
Tn marker position, adjust the thresholds so that they are well above the baseline "noise"
level but below the first major peak.
2. To exit this mode, press the <0> key.