Dakota Ultrasonics MMX-7 - Manual (Page 54)

Dakota Ultrasonics
50
3) Press the LEFT and RIGHT arrow keys to scroll the value. When the
correct Bscan Start is being displayed, proceed to step 8.
4) Alternatively , press the ENTER key to display the Digits Edit Box.
5) Press the UP and DOWN arrow keys to scroll the highlighted value.
6) Press the LEFT and RIGHT arrow keys to scroll the digit locations.
7) Repeat steps 5 & 6 until the Bscan Start number is correctly displayed.
8) Press the OK key to set the Bscan Start and return to the menu screen, or
ESC to cancel entering the Bscan Start.
9) Finally, press the MEAS key to return to the measurement screen and begin
taking readings.
7.4 Gain
The gain, or amplification of the return echoes, can be adjusted in the MMX-7 to
accommodate a variety of applications. The setti ng of the gain is crucial in order to
obtain valid readings during the measurement process. Too much gain may result in
erroneous measurements, by detecting on noise rather than the actual material back
wall itself. Not enough gain may result in intermittent detection. It may also result in
lack of detection on internal flaws, pits, or porosity. The gain can easily be compared
to the volume control of a home stereo system. If you turn it up too much, you can’t
hear the music clearly. If it’s turned down too much, you can’t hear it at all.
The MMX-7 has three gain settings (low, med, high). Note: The MMX-7 has been
optimized for the MED gain setting for all common performance racing applications.
It should be operated in this mode as standard. However, some applications may
require the low or high gain setting. When? The low set ting may be necessary for
certain cast aluminum materials, or very extremely granular cast iron materials. How
do I know when to lower the gain? If the reading becomes sporadic and won’t settle
down or resolve on a thickness value, the user can assume that the material is either
very noisy aluminum, or granular cast iron. This would be a good time to change the
MMX-7 to low gain setting and see if the reading settles down and become stable.