70
SVANTEK 974 User Manual
11. FFT ANALYSER
The instrument operates as
FFT
analyser in a very similar way to the
Level Meter
. Moreover,
FFT
analysis is
performed in parallel with the
Level Meter
operations.
The results of
FFT
analysis (spectra) can be examined by the user on a display
in the
Spectrum
view. The availability of this mode can be switched on or off by
the user (
path: <Menu> / Display / Display Modes)
.
FFT
spectra with the single
Total
overall value, measured with preselected
frequency
weighting filters and windows, are presented in the
Spectrum
mode
if selected in the spectrum display menu. The read-out of the spectrum value
can be done using a vertical cursor.
11.1. Selection of FFT function
To select the
FFT
analysis function the user
should enter the
Function
list by pressing
the
<Menu>
push-button, then select the
Function
text and press
<ENTER>
. In the
Measurement Function
window select the
FFT
position and press
<ENTER>
.
<ENT>
Note: It is not possible to change the current function during a measurement.
In this case, the instrument displays for about 2 seconds the text:
“Measurement in Progress”.
To change the current function, the measurement must be stopped!
11.2. Configururing FFT analyser
Execution of the
FFT
analysis depends on a certain number of parameters, which can be set in the different
windows of the
Measurement
list. Some parameters are fixed: filter (
HP
) and the measurement range.
The
FFT
analysis is performed based on the parameters selected in the
General Settings
list of
Measurement
menu:
Integration Period
and
Repetition Cycles
.
The spectra are stored as main results in a results file with the same step
(
Integr. Period
) as the other main results, measured by the
Level Meter
function.
The user can switch on or off the history of spectra recording in the logger file
(
path: <Menu> / Measurement / Logging / Logger Results / Spectrum:
). If
spectra history is switched on, the spectra will be logged also with the step,
defined by the
Logger Step
parameter (
path: <Menu> / Measurement /
Logging / Logger Setup / Logger Step
).
