3B SCIENTIFIC PHYSICS U40205 Instructions D'utilisation page 16

pop-up menu. Then you can choose the first point for
the drift correction. This procedure is then repeated to
select the points P2 and P3.
In order to carry out a correction, click the "Apply
Corrections" button. If the correction is unsatisfactory,
there are two methods for modifying it. The first
involves deactivating "Apply Corrections" by clicking
the button again, then the points can be chosen again
and the full procedure is then repeated. The second
way to modify the correction is to change the function
coefficients directly. To do this, click on the trace
window and choose "Set coef." from the pop-up
menu. New values for A, B and C can then be entered.
Click "OK" to confirm these and click on the trace
window again. Then click "Manual Coefficients OFF" in
order to start the "Manual Coefficients On" function
and to view the correction with the modified values.
The coefficients can be changed as often as necessary
until the correction is satisfactory.
5.5 Low-pass filters
The "LPF Time Constant" button allows users to select
from 12 different low-pass filters or turn them all off.
This function is only required in some unusual
circumstances. All experiments should be started with
the "No LPF" option selected. If the movement of the
inner support beam differs significantly from simple
turning movements, a function to suppress matching
periods causes such movement not to be recorded. If
this is not the case, use of a low-pass filter may help.
5.6 "Reset" button
Once a set of measurements has been made
successfully, the acquisition parameters for the
measurements, such as sampling rate, number of
points, measuring mode, etc. can then be reset.
Clicking the "Reset" button activates the function.
5.7 "Record" button
Clicking the "Record"
measurements. The button then becomes a "Stop"
button with which the measurements can be brought
to a halt manually. Once a set of measurements is
finished, either automatically
notification is shown, asking of the data acquired
should be saved.
5.8 "Save" and "Load"
Clicking the "Save" button causes data to be saved.
The standard format is *.cav. Two other formats (*.txt
and *.xls) are available to allow for further analysis of
data in a spreadsheet.
The "Load" button allows previously saved data to be
loaded into the program.
After acquiring data for 2 minutes, the program will
save a file called temp.cav. The measurements are
saved in this temporary file to stop data being lost in
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starts recording of
or manually, a
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the event of a power failure, for example. The data
can then be restored up to the point where the temp
file was last saved before the power cut. Every time a
new set of measurements is started, this file is
overwritten.
5.9 Print
Clicking the "Print" button allows the data to be
printed out. In addition to the trace itself, the
sampling rate, the number of points and the filename
are all shown on the print-out. Comments from the
comment field can be added to the print-out if the
relevant option is selected.
5.10 "Setup" button
This button allows the min. and max. limits for the
torsion balance's measuring range to be defined.
"Y minimum" and "Y maximum" define the overall
range for the torsion balance. Changing these values
allows the read-outs from the balance to be modified.
The buttons "Adjust left border" and "Adjust right
border" set the display such that the upper (adjust
right border) or lower (adjust left border) edges of the
trace window is matched to the position of the
support beam.
5.11 Calibration of zero point
The button directly to the right of the "Reset" button
determines the zero point for the support beam. The
zero point of the beam's oscillation will be set to the
point at which the button is clicked. To determine the
centre point, the support beam is set in the centre
under the sensor plates and temporarily fixed there
using the centring rod. The button is then pressed.
The geometric centre of the sensor boards is thus
defined as the zero point and movement away from
this axis on either side is then displayed in
milliradians (mrad).
5.12 "Exit" button
Clicking the "Exit" button closes the program.
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