SVAN 977A User Manual - Appendixes
C.7. USING OF THE SA 277 OUTDOOR MICROPHONE PROTECTION UNIT
The SA 277 outdoor protection unit protects the SVAN 977A
preamplifier and microphone from weather conditions. The use of the
outdoor kit requires an extension cable between the instrument and its
preamplifier (SC 277). The SA 277 is made of lightweight materials
and is easy to install on a tripod. This solution is recommended for
short term and semi-permanent outdoor noise measurements.
The outdoor microphone kit has ¾” screw on its bottom which enables
the use of standard tripods or other user specific mountings.
As an option the user may use desiccator - Silikogel. The desiccator
absorbs moisture commonly contained in the air. The desiccator
should be regenerated after some period of use, when it changes
colour to red, by drying it for 3 hours in a temperature of 150°C. The
colour of the silica gel is visible through the hole on the top of the
desiccator
Note: See also SA 277 Assembly Guide to learn how to
assemble and disassemble the microphone’s outdoor protection.
Note: Using SA 277 changes the frequency response and measuring ranges of SVAN 977A. Please
check the below given specification.
Depending on the measurement task SA 277 can be used in two operational modes:
1. With reference incidence angle 90 deg – so called “environmental mode”
2. With reference incidence angle 0 deg – so called “airport mode”
The wave incidence angle is oriented to the microphone membrane surface. 0 deg means direction orthogonal
to the membrane surface. 90 deg means direction parallel to the membrane surface.
Frequency response of SVAN 977A with SA 277 outdoor protection unit is compensated by means of two
digital filters:
• Environmental compensation filter improving the complete instrument frequency
response in the free field for the reference acoustic wave
incidence angle 90 deg
• Airport compensation filter improving the complete instrument frequency
response in the free field for the reference acoustic wave
incidence angle 0 deg
Note: For the conformance of acoustical tests with SA 277, the Microphone Compensation must be
set to “Outdoor Environment” or “Outdoor Airport”! (path: <Menu> / Measurement / Compensation
Filter).
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