Norsonic Nor1212, Instruction Manual

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Norsonic Nor1212
User Guide
9
If the mast is high and you need to make regular calibrations or other
service operations, we recommend the use a tiltable or a telescopic mast.
Norsonic can supply different masts on demand.
Fasten the microphone cable along the mast properly. A cable flapping
onto the mast in windy conditions may create excessive noise and ruin the
measurement accuracy.
3.4 Grounding and lightening protection
If the outdoor microphone assembly is the highest object in the vicinity
when mounted, it may be exposed to lightening strikes. We recommend
that the mast, if conductive, is properly grounded.
A lightening rod in proper contact with a conductive mast will form a
suitable protection against the effects of a lightening strike and a
recommended configuration is given below.. The rod should be placed at
least 25 cm to the side of the microphone assembly and have a diameter
not more than 10 mm in order not to interfere with the direction properties
of the microphone. Its height should be at least 10 cm above the tip of the
microphone assembly (the microphone is located 14 cm below the
insulated tip). If the mast is not conductive, the lightening rod should be
connected to a proper lightening conductor.
Safety considerations may require that the screen of the microphone cable
to be properly grounded. We recommend making the combined
grounding for the cable and instrument at one point only in order to
reduce the risk of pick-up of hum and electro-magnetic noise. Verify the
noise floor of the complete system after installation is completed to
ensure it is below the lower end of the required measurement range. If a
quiet location is not available, the noise floor may be measured by
substituting the microphone with a dummy microphone like Nor1448. As
an alternative the Nor1447 adaptor terminated with a short-circuit or a 50
ohm BNC termination is also a suitable device for making this test.
.
Figure 3.3 Lightening
protection