Larson Davis System 824, Reference Manual

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11/8/00 RTA (optional) 10-9
•
Count - The 824 arms after “Arm Count” samples of
data have been received.
Arm Level
Arm Time is used in conjunction with
Arm Level as a qualifier for the level
setting. See example below. This trigger level is used when the “Arm Mode” is set to a
level state (L<, L=, L>). This level must be reached before
the 824 will arm.
• 0.0 - 255.9 dB
Arm Time
When the “Arm Mode” is set to Time, the “Arm Time” must
expire before the 824 will arm.
This is also a qualifier for the level settings. If the time is
non-zero, then the level condition must be met for the speci-
fied time before Arm Mode is entered.
• 00.0000 to 99.9975 seconds
Arm Samples
When the “Arm Mode is set to Count; “Arm Samples” is the
number of samples that will be taken before the 824 is
armed.
• 0 - 65535
Arm Logic In
When the “Arm Mode” is set to Input, the 824 will arm
when the state of the Logic In line changes to this level.
Logic In is sampled 32 times each second.
• Low
• High
A typical trigger having the follow-
ing 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.