Naris
Naris
User’s
Manual V14 14/02/20 Page 36 of 52
A1TEST
In the A1 folder, you will find a program called
A1TEST.EXE
–
this folder will be wherever
you declared as the location during the installation process.
Double-clicking on the name will start the application.
For board type
USB-201
select Gain = +10
volts, Digital Port =
AUX,
Sample Rate
=
100000.
Click on
Sample
. You should see the microphone response on the screen. If you point the
mouse cursor under the trace, it will tell you the amplitude of the trace at each point.
The baseline should be between 1950 and 2050 units.
The value is only updated when you click on
Sample
. The picture below shows a typical
display when the calibration plug is fitted to the sound tube and sample is selected.
The peak pulse size is also documented in the table on the left-hand side as
Maximum
.
It should peak at a level greater than that set within the A1 program for
Trigger
, and, using
VR2, is normally set to
between 3200 and 3500
.
If the peak height is smaller than this the level can be increased by using the
gain
control
resistor, VR2, on the A1 circuit board.
The trace above shows the microphone signal output plotted against sample numbers.
The first large peak shows the response when the click sound reaches the microphone on its
way up the tube.
The second peak shows the reflected signal from the calibration plug returning back down
the tube and reaching the microphone again.
Each pair of pulses that follow show the event repeating, as the sound travels up and down
the closed tube.