Kistler-Morse KM ultrawave - Manual (Page 69)

the vessel full point. TVG affects the sensitivity of the system in detecting return echoes by amplifying the return
signal in relation to the time it takes the signal to reach the transducer (which is related to the distance from
transducer to measured material). TVG has eight submenus:
• High Limit is the highest value the TVG will go in an effort to achieve an echo above the echo
threshold (Echo) and below the peak threshold (Peak). The range for High Limit is from 0 to 200.00%. The
default value is a function of the Span entered during the Startup Procedure.
• Low Limit sets the low limit for the TVG. This value is the lowest the TVG will go to get the echo below the
peak threshold (Peak) and above the threshold (Echo). The range for Low Limit is from 0 to 200.00%.
• Monitor allows you to monitor the current TVG amplification.
• Exponent controls the shape of the TVG curve. Exponent can range from 0 to 2.55. Values of Exponent
greater than 2.0 reduce the gain between the transducer and the middle of the vessel, often necessary for
tall, narrow vessels. Values of Exponent less than 2.0 increase the gain between the transducer and the
middle of the vessel.
• Delay shifts the TVG curve that is past the point where the blind space gain algorithm (BGN) is in effect.
The default for Delay is 0’.
• Decrease Step controls the rate of TVG decrease. The value ranges in percentage from 0.00% to
100.00%.
• Decrease Qualify controls the number of steps decreased at one time. The value ranges from 0 to 255.
• Mode allows you to switch from the standard TVG algorithm (Mode = 1) to an algorithm designed for a
specific application for a vessel filled with a very fine talcum powder (Mode = 2). The default for Mode is
1.
For Mode=1, the TVG algorithm is applied to the closest target encountered.
For Mode=2, the TVG algorithm is applied to the largest amplitude target.
For Mode=3, same as Mode 1 yet only adjusts if return echo is outside the echo or peak thresholds.
For Mode=4, same as Mode 2 yet only adjusts if return echo is outside the echo or peak thresholds.
Note Setting High Limit equal to Low Limit puts the UltraWave Series into a Fixed TVG mode, as it prevents the
UltraWave Series from raising or lowering the TVG curve in response to echoes below the Echo threshold or above
the Peak threshold.
66 neAr gAin
Near Gain specifies the near gain of the system and ranges from 0 to 100.00%. The near gain affects the ability
to pick up targets in the first 4’ (1.2m) to 6’ (1.8m) from the face of the transducer. The default for Near Gain is
dependent on the type of transducer and application.
• Value is used to change the entry for this parameter.
• Blind Space Gain (BGN) controls the gain in the ‘blind space’ region of the transducer to help reduce
ringing. BGN can be set from 0 to 100%. The default for BGN is dependent on the type of transducer
and Quick Configuration settings.
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