Larson Davis 824 User Manual

9/29/09 RTA (optional) 11-9
Save ByTime
When Autostore is turned on, ByTime
records are automatically stored.
This feature allows the user to enable or disable storage of
ByTime data in an autostore record. With this feature turned
off and the Autostore function turned on, the 824 will only
store Leq, Max, and Min spectra.
Triggering
Turns triggering on or off. There are four parts to triggering:
Arm, Trigger, End, and Then. Arm and Trigger work in
tandem to create a two step trigger to start an Autostore. End
and Then work together to determine when to stop
measuring.
Trigger Source
You can also set the trigger source
from the Trigger Status display by
moving the cursor to the desired
band, press the
c check key and
select “Set Source” from the menu.
Allows the user to select a filter or flat overall level as a
trigger source.
Arm Settings Menu
Arm Mode
Elapsed time and qualifying times
are evaluated only when a new
ByTime sample is created. This
causes the minimum effective time
resolution to become the same as the
update interval.
The 824 becomes armed when the following conditions are
met:
• Now - The 824 will arm immediately.
• L < - When the level is less than the “Arm Level” for the
“Arm Time”, then, the 824 will arm.
“L” indicates the level of the filter
specified by the Trigger Source
setting.
• L = - When the level is equal to the “Arm Level”, +/-0.5
dB, for “Arm Time” then the 824 will arm.
• L > - When the level is greater than the “Arm Level” for
“Arm Time”, then, the 824 will arm.
• Input - The 824 arms when the logic input line changes
to “Arm Logic In” state.
A typical trigger having the
following settings,
Trigger Source: 1 kHz
Arm Level: 80.0 dB
Arm Mode: L >
Arm Time: 2.0 second
would transition to arm after the 1
kHz filter level was greater than 80
dB for 2 seconds.

Larson Davis 824 Specifications

General

Brand	Larson Davis
Model	824
Category	Measuring Instruments
Language	English