Larson Davis System 824, Руководство по обучению

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3-10 824 Training Manual 3/22/01
A pulsing noise generator may be
very helpful. Each pulse can trigger
a new measurement without any user
intervention. Press the RUN/STOP key on the 824 to put the 824 in the
“Ready” mode. Start the generator to energize the room with
noise. As the noise pulses ON and reaches a level > 80 dB
the 824 will change to the “Armed Mode”. When the gener-
ator pulses OFF and drops below 80 dB the 824 will change
to the trigger mode and start recording an autostore. After 3
seconds the autostore will end and the 824 will be ready for
the next average. Repeat this four times until the 824 is in
the STOP mode. You now have five averaged records for
one location. Move to another location in the room and press
the RUN/STOP key again to average five more pulses as a
new autostore record.
End Time
It is very likely the room you are measuring may have a
shorter or longer reverberation time than the 3 seconds
selected in the “End” menu. If the reverberation time is
much shorter it is not necessary to store additional unneeded
samples which would take more memory. If the reverbera-
tion time is longer you will need to increase the “End” time.
Trigger and Arm Levels
As you get a feel for the sound in the room and the triggering
capabilities of the 824 you will be able to fine tune the 824
to optimize room measurements. The trigger and arm levels
can be easily adjusted to work with your noise source.
Remember that the level adjustment is also tied to trigger
time and arm time. The sound must meet both the level that
is set for a certain amount of time before it changes to the
next state.
Autostore Display
Use the “Autostore” display to see the energy distribution in
the Leq and Max spectra.
Press the VIEW
key and select “Autostore”. Press the
right
arrow key to open up the “Autostore” menu. Select
“Autostore” again and press the right
arrow key. High-
light “Leq” or “Max” and press the Check
key.