8.3. FFT Data Memory
To view stored FFTs press F3 to open the menu
and select “Data memory” / “View/delete FFT
data”. Use the keys ▲▼ to select the desired
FFT. A cursor function using the keys ◄► is
also available (Figure 36).
Stored FFT data can be transferred to a PC using
the Excel macro file vm31.xlsm. The file also
provides a graphical output.
9. Keypad Lock
To prevent manipulation during ongoing mea-
surement, it can be advantageous to activate the
key lock. This function can be found in the main
menu under “Key lock”
To release the key lock press all four arrow keys ◄▲▼► simultaneously, until the
device displays “unlocked”.
10. Device Settings
10.1. Sensor Calibration
If a connected sensor is not TEDS compatible, the
VM31 will automatically open the menu “Trans-
ducer calibration” (see section 4.2). It can also be
opened from the menu “Device settings” to check
or to change the entered sensitivities.
Sensitivities are entered one after another for chan-
nels X/Y/Z and, if connected, for channel A. The
sensitivity value is a five-digit number with the
measuring unit mV/ms
-2
. You find the correct val-
ues in the transducer calibration sheet. The decimal
point can be shifted by pressing F1. The allowed
sensitivity range is 0.800 to 12.000 mV/ms
-2
or
8.00 to 120.00 mV/ms
-2
.
10.2. Time and Date
When saving measurement values the date and
time need to be correctly recorded. To set the date
and time, open the main menu by pressing F3 and
select “Device settings”. Within this sub menu se-
lect “Date and time”. Using keys ▲▼ you can ad-
just the chosen value. Upon reaching the maximum
value, e.g. in the 23
rd
hour, the counter starts again
from the beginning. Press ◄► to skip between
hour, minute, month, day and year. The date takes
account of the leap year. It is, however, important
to ensure that no invalid day-month combinations
are entered.
24
Figure 37: Sensitivity
Figure 36: FFT memory
Figure 38: Time and date