Dakota Ultrasonics MVX User Manual

Page 82

Dakota Ultrasonics

Setting the Alarm HI Limit

1) Assuming the ALARM STATUS is ON,use the UP and DOWN arrow keys to

scroll through the sub menu items until ALARM HI LIMIT is highlighted.

2) Press the LEFT and RIGHT arrow keys to scroll the value. When the

correct alarm value is being displayed, proceed to step 8 .

3) Alternatively, press the ENTER key to display the Digits Edit Box.

4) Press the UP and DOWN arrow keys to scroll the highlighted value.

5) Press the LEFT and RIGHT arrow keys to scroll the digit locations.

6) Repeat steps 4 & 5 until the ALARM HI value is correctly displayed.

Press the OK key to set the ALARM HI value and return to the menu

screen, or ESC to cancel entering the ALARM HI value.

Press the MEAS key to return to the measurement screen and begin taking

readings.

9.5 Polarity

The MVX is equipped with an option to select the polarity, or phase +/-, for the
purpose of detection. The phase can be a very valuable feature to have when the
signal returning from the test material is marginal, a low frequency transducer is
being used, and the user has a very weak positive or negative cycle, while trying to
measure very thick materials. There is a possibility that signal will become so weak
that it falls below the threshold, and peak jumps to the next cycle altogether. This
peak jump represents a shift of the detection further out in time, resulting incorrect
measurements. The material being measured will appear thicker than it actually is.
Refer to the diagram below: