Envelope Threshold Adjustment (Hot Key 5); Signal Masking Function (Hot Key 6) - Siemens SITRANS FUG1010 IP65 NEMA 4X Instruction Manual

Section 4
ure the transit-time delta. This crossover will generally be close to the peak of the receive signal with at
least one well formed (non-aberrated) receive cycle on each side of the crossover. If it appears that the
placement of this crossover is unsatisfactory then it can be adjusted by pressing the <4> key on the
keypad, which will invoke the [ZCOSet] command. The crossover point can then be moved in either
direction on the waveform using the <+> or <-> keys. The change from the default value (in receive
cycles) will appear in the number to the right of the command. To exit this mode, press the <0> key.
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 trans-
ducer 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.
F
VS 1469.73
[ ] 1691:1929 476
D 4:4 4
Tn
dT
S 72 1
SN 124:1
CQ 17:1
HiSet
Command Line appears here
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 [EnvSet] 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. To exit this mode, press
the <0> key.
Signal Masking Function: (Hot Key 7)
Under conditions of extremely low signal amplitude, a noise spike associated with FUG1010GCN's re-
ceive signal window may be present on the extreme left side of the graph display. If this spike is large
enough it may interfere with the signal detection routines. To eliminate this noise from the signal pro-
cessing routines, press the <7> key to invoke the [MaskSet] command, then press the <+> key until the
noise is no longer present in the receive waveform. Press <0> to exit this command.
0.73
55.06 55.06
3.11
91
3
TN marker
Envelope Signal
Envelope Threshold
Lo Set
Crossover Marker
4-73
1010GCNFM-3C
HiSet