Norsonic Nor265, User Manual

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Nor265 User Guide
Norsonic AS
5
1 Introduction
The Microphone boom/Turntable
N o r 2 6 5
may be used as a stand-
alone device to obtain the spatial average of sound level by moving a
measurement microphone back and forth continuously. Main
applications are building acoustic measurements (ISO 140-series),
measurement of sound absorption in a reverberation room (ISO 354)
and determination of sound power levels of sources using sound
pressure (ISO 3741). Due to the oscillating back and forth movement
a normal microphone cable may be fed through the hollow main shaft
without the need for slip rings thereby ensuring very low electrical
noise levels are maintained.
The unit may be equipped with a turntable plate or chuck for
mounting of different test objects. In this configuration the main
application is measurement of directional responses of acoustic
transducers like microphones and loudspeakers.
The unit is manually operated by the rotary switch on the front. As
delivered from the factory eight of the switch positions (1, 2... 8)
corresponds to ±90° and ±180° sweeps with different sweep speeds.
These settings may be redefined by using remote commands if the unit
is equipped for remote operation.
Extended control of the device is possible by
remote commands from a computer by use of the
optional serial interface. This allows accurate
control of angular position, speed and acceleration.
The unit is robust and constructed for years of
maintenance-free operation.
When a movement or sweep is started, the speed
will gradually increase as specified by the
acceleration instruction until the selected speed is
obtained. The reversed speed-profile is used for
deceleration. By specifying a higher value for the
acceleration time, even a large or heavy object may
be handled.
Nor-265 uses a digital signal processor (DSP) to
obtain accurate positioning with simple and robust
mechanical design. Accuracy in speed and
acceleration are ensured by the use of a precision a
crystal clock. The design allows a unique
combination of specifications suitable for
microphone boom applications as well as a general
turntable.
The sound emission from the unit is very low,
especially when operated at the slower speeds.