Norsonic nor140, Instructional Manual

Page: 44 / 220

26
Chapter 4
Simple sound measurements
The percentiles table sequence
Displaying the result table using the other
spectral weighting function
Spectral weighting network indicator
Units without statistics
Units equipped with statistics
There are two spectral weighting functions available
A- and C- or Z-weighting. The latter should be set by
you prior to the measurement.
Even before you enter the table you may use the
NETW
key to view the results of applying the two
spectral weighting functions.
The actual spectral weighting function used in the
table depends on the setting active before the
TBL
key was pressed. At any rate, press
NETW
to toggle
between primary and secondary weighting function.
Statistics – displaying the percentiles
Instruments equipped with the optional extension 4 –
statistics – will measure the statistics every time. This
cannot be switched off.
The sampling for the statistical calculations is made
with F time constant and the class width is 0.2 dB over
the entire 130 dB dynamic range – always!
You may think that storing all these data will require a
huge memory, and you’re absolutely right. Therefore, we
refrain from that, we store just eight percentiles instead.
Seven of them are fixed and one is user-editable.
Your user-editable percentile can be set to anything
in the range 0.1–99.9 %, both extremes included. The
procedure is explained next page.
Data measured, - not recalled - may be subject to
changes in the user-defined percentile. This means
that you may change the percentile as many times
as you want. For stored and later recalled data any
changing of the user-editable percentile is no longer
possible.
5
NETW