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Time Weighting
This refers to a special filter that applies an exponentially decaying weighting
factor to the signal. Several rates are available:-
Slow-Weighting
The rise and fall times applied for Slow Weighting are both 1 second.
Fast-Weighting
The rise and fall times applied for Fast Weighting are both 125m seconds.
Impulse-Weighting
The rise and fall times for Impulse Weighting are 35m Seconds and 1.5
seconds respectively.
Under Range
When the sound pressure level tends towards the noise floor for the selected
range of the instrumentation then an under range condition occurs and a
warning is displayed on the instrumentation.
This value where the warning is displayed is generally specified by the
manufacturer and usually just the below the bottom of the selected range.
When an under range condition occurs your instrumentation is likely to be
operating out of specification.
Where appropriate change to a lower range on your instrumentation. See also
‘Noise Floor’, ‘Overload’ and ‘Pre-Amplifier’.
White Noise
This is a random signal where each frequency contains equal energy and whose
power spectrum remains constant.
Z-weighting
See ‘Frequency Weighted Filter’.