Svantek SVAN 979 - Setting Spectra - Spectrum; Selecting Microphone Compensation - Compensation Filter

57
SVAN 979 User Manual
4.5 SETTING SPECTRA – SPECTRUM
The Spectrum position appears in the Measurement list when the 1/1 Octave,
1/3 Octave, 1/6 Octave, 1/12 Octave or FFT function is selected in the
Measurement Function list (path: <Menu> / Function / Measurement Function)
- see Chapters 10 and 11 for details.
4.6 SELECTING MICROPHONE COMPENSATION – COMPENSATION FILTER
The Compensation Filter position is
available only in the Sound meter modes. It
allows you to select the appropriate
compensation filter for different measurement
situations.
The Compensation Filter screen comprise a
list of options (Off, Free Field, Diffuse Field,
SA279 (90
o
), SA279 (0
o
)) and the
Windscreen position that should be set.
<ENT>
The microphone inner noise and thermal compensation is switched on by default, however it is possible and
necessary to switch it off (Off) for electrical measurements (e.g. laboratory calibration measurements).
The Free Field and Diffuse Field filters are intended to compensate sound measurements in the free field or
diffuse field conditions. `The microphone supplied with SVAN 979 (GRAS 40AE) is designed for sound
measurements in the free field conditions. The Free Field option means that the correction filter for the diffuse
field conditions is switched off. In case of sound measurements performed with the use of different specific
diffuse field response microphone types, the Diffuse Field option should never be used and the microphone
inner noise and thermal compensation should be turned off (Off option).
SA279 (90
o
) and SA279 (0
o
) compensations are dedicated for the permanent outdoor monitoring applications
with the use of the SA 279 outdoor microphone outdoor kit (usually when SVAN 979 is working as a part of the
SV 279 monitoring station). The characteristics of the outdoor filters depend on the dominating sound incidence
angle: environmental monitoring (incidence angle 90 deg) or airport monitoring (incidence angle 0 deg).
Windscreen filter can be switch Off, On or set to automatic detection – Auto.
Note: When using windscreen SA22 the Windscreen compensation
must be On during windy conditions to maintain good tolerances
margin of the SVAN 979 frequency response.
Note: For the free filed evaluation with the SA 279 microphone
outdoor kit the SA279(90
o
) or SA279(0
o
) compensation must be
selected.