Olympus 27MG, Руководство пользователя

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DMTA-10043-01EN, Rev. C, July 2016
Additional 27MG Gaging Features 45
7.2 Activating the Freeze Mode
The Freeze function allows the operator to freeze the thickness display when the
[FREEZE] key is pressed. The display is returned to an active status by pressing
[FREEZE] a second time or by pressing [MEAS] . This function is useful when the user
wishes to hold a displayed thickness reading. This helps limit the transducer contact
time during high temperature thickness measurement applications. The Freeze
function can also be used in combination with the Min/Max function.
7.3 Adjusting the Gain
The gain adjustment increases or decreases the normal measurement sensitivity by a
fi xed amount (approximately 10 dB high gain and − 6 dB low gain). This function is
available for those applications for which more or less than the default sensitivity is
required but the use of a fixed sensitivity increase rather than a sensitivity
proportional to the measured noise is preferred. Use of the gain adjustment function
is generally recommended for all high temperature measurements.
To adjust the gain from the default gain value

From the measurement mode, press [2
nd
F] , [

] (GAIN) to toggle between GAIN
HIGH , to GAIN LOW , and DEFAULT GAIN .
7.4 Optimizing Material Gain Sensitivity
The material gain sensitivity optimization feature allows the normal measurement
sensitivity to be increased or decreased by an amount related to the measured peak
noise in a specific transducer and material combination. Normally, the 27MG
Ultrasonic Thickness Gage adjusts the receiver gain and detection level depending on
both the transducer type and the received echo characteristics. Also, each transducer
type imposes its own maximum gain and detection threshold to prevent any
transducer-related or material-related noise from being seen as a thickness echo. This
works well in most corroded material gaging applications. However, in certain special
cases, it is advantageous to modify these fixed limits on the sensitivity.
The material gain sensitivity optimization feature optimizes actual material noise
level measurements rather than fixed gain boost or fixed attenuators. While the
transducer is coupled to a thick sample of the material of interest, the gage measures