2-80
1010ENFM-3B
Section 2
Zero Crossover Adjustment: (Hot Key 4)
Observe the small “X” mark located on the zero crossing line near the middle of the receive signal in the
Graph Screen above. This “X” indicates the central crossover which the 1010 is using to measure 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.
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.
F 0.73
VS 1469.73
[ ] 1691:1929 476
D 4:4 4
Tn 55.06 55.06
dT 3.11
S 72 1
SN 124:1
CQ 17:1
Envelope Signal
TN marker
Crossover Marker
Command Line appears here
Envelope Threshold
91
3
HiSet
To Next Page
Loading...
