10. 1/1 AND 1/3 OCTAVE ANALYSER
The instrument operates as a real time 1/1 Octave or 1/3 Octave analyser (RTA) in a very similar way to the
Level Meter. Moreover, 1/1 Octave or 1/3 Octave analysis is performed in parallel with the Level Meter
operations. All 1/1-octave (with 15 centre frequencies from 16kHz down to 1.0Hz; in base two system) and 1/3-
octave (with 45 centre frequencies from 20kHz down to 0,8Hz; in base two system) digital pass-band filters are
working in real-time with the HP weighting filter (class 1 in accordance with IEC 61672-1) and the linear RMS
detector.
Note: The TOTAL RMS results are measured with the weighting filters (HP, HP3 and HP10)
regardless of what settings were selected in the profiles for Level Meter calculations. The spectra are
always linearly averaged. Thus, the Total values for 1/1 Octave or 1/3 Octave analysis can be
different from those obtained for the profiles (if the RMS Integration was set as Exp).
The results of 1/1 Octave and 1/3 Octave
analysis (spectra) can be examined by the user
on a display in the Spectrum view. The
availability of this view can be switched on or off
by the user (path: <Menu> / Display /
Display Modes).
The 1/1 Octave and 1/3 Octave spectra are presented for all centre frequencies of pass-band filters together
with the Total overall values measured with preselected frequency weighting filters. The read-out of the spectrum
value can be done using a vertical cursor.
10.1. Selection of 1/1 Octave or 1/3 Octave functions
To select the 1/1 Octave or 1/3 Octave
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
required (1/1 Octave or 1/3 Octave)
position and press <ENTER>.
Note: The 1/1 Octave and 1/3 Octave functions are optional and should be unlocked by entering the
activation code in the text editor screen, which is opened after first attempt to select them. Once
unlocked these options will be ready to use permanently.
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!
10.2. Configuring 1/1 Octave or 1/3 Octave analyser
Execution of 1/1 Octave or 1/3 Octave 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), frequency range (from
1.0 Hz to 16 kHz for octave and from 0.8 Hz to 16 kHz for the third octave), and the measurement range.
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