Norsonic nor118, Instruction Manual

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28 Chapter 5
Frequency analysis
29 Norsonic Nor118
User Guide
To move the graph cursor about the frequency bands
• Use the ← & → keys. Use the | ← & → | keys to move
to the extreme left and extreme right.
To adjust the display top scale:
• If the bar graph fails to match the level measured use the
 and  keys (the vertical arrow keys to the right
of the display) to alter the display top scale setting.
To switch between the spectral weighting functions:
• Use the  key to switch between -weighted and
- or -weighted or the -weighted and the – (–)
weighted functions.
To produce the results in tabulated form:
• Press  to produce a result table.
Resuming an ended measurement
Assume that you have set up the instrument to measure
for  minutes and that you start the measurement. After 
minutes the measurement will end since the measurement
time elapsed equals the preset duration.
The measurement has now ended successfully, as
opposed to if you press the  key to forcefully termi-
nate an ongoing measurement.
If you now press the / key, the instrument
will resume the measurement and go on measuring for
another  minutes so that the total measurement time
assumes  minutes, i.e. twice the initial setting. If you do
this again, the total measurement time will be  minutes,
i.e. three times the initial setting and so on.
is way of prolonging a measurement will not activate
the back-erase feature.
The back-erase feature
When you press the / key during an ongo-
ing measurement, the instrument will temporarily halt
the measurement. Pressing the key again will cause the
instrument to resume the measurement while at the same
time erasing the data acquired during the last ten seconds
immediately preceding the pause.
If you’ve measured for less than ten seconds
If the measurement has been running for less than 
seconds when you press the / key, the entire
measurement will be erased upon resuming the measure-
ment.
If less than  seconds have elapsed since the last time
you resumed a paused measurement, only the part of the
measurement acquired since the last resume will be erased.
Data acquired earlier are assumed to be accepted.
e measurement time elapsed counter will be updated
to reflect the back-erase. Note that the statistics buffers
(optional extension) will be updated similarly.
Displaying the functions measured
e instrument measures the -weighted and - or -
weighted , 
MAX
, 
MIN
, 
eq
, 
E
and the 
PEAK
. Note
that the , 
MAX
and 
MIN
are all measured with the
selected time constant while the rest do not make use of
the time constant at all.
e same functions are available in the frequency
analysis with the exception of 
PEAK
. e peak level is
not measured per frequency band. In addition, 
Max5
is not
available for frequency analysis (applies to units equipped
with the optional extension ).