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Operation manual
Ultrasonic Flaw Detector NOVOTEST UD3701
Figure 2.38 – Setting the measurement mode - «MEAS» parameter
2. Flaw detector allows DTC activation neither when signal is higher nor lower than the gate
level (DTC is activated when signal is higher than the gate level in «MORE» mode and in
«LESS» mode - when signal is lower than the gate level). To select mode for DTC user has to
set «MODE» parameter («MORE» or «LESS»).
Also, the device allows setting of additional levels in the gate: control and search. Additional
levels are set in dB for every gate separately in dependence to the main level of the gate.
To set additional control levels user has in «DTC» parameters group input the necessary values for
parameters «CONTR» and «SEARCH» for the particular gate.
Additional control and search levels of the gate are displayed on the screen, below the main level
of the gate (Figure 2.39).
а) additional search level
Figure 2.39 – Additional levels of the gate - parameters «CONTR» and «SEARCH»
2.4.8 «TVG» mode
TVG mode allows to compensate damping influence and display signals from reflectors with
different depths as signals with equal height (amplitude). It is possible because of different gain in
different A-scan points in dependence with depth and signal damping in tested material.
Usually reference points are determined by standard calibration block (or standard sample – SS)
with reference reflectors of equal size and located on different depths. The first reflected signal of
every of these reflectors should be recorded. The only one chain of reference points could be input per
one time (in one setting).
To turn on and set TVG user has to enter «TVG» parameter group.
To input reference points following operations are to be made:
1. Keep sure, that input function for reference points is turn on («TVG – ON»).
2. Clear (in case of previous TVG points are recorded and new ones are to be created). For this,
in «CLEAR» parameter set «ON».
3. Put the probe on the SS and set the scanning time so, that signals of all the reflectors in
probable tested zone would be displayed on the screen.
4. Find the maximum signal from the nearest reflector, and set the signal top on the screen level
of 50-80 % by changing the gain (Figure 2.40).
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b) additional control level
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