About Sound Recording Constraints - Larson Davis SoundAdvisor 831C Reference Manual

FIGURE 18-4 Sound Event Live Example
1.

18.3.1 About Sound Recording Constraints

SoundAdvisor Model 831C
Step 4
Save the Setup, set it as the Active setup file, and Close (
Manager.
Step 5
Run a measurement and examine the resulting sound recordings. Based on the
settings shown in Figure 18-3, when the measured sound is above 65 dB (SPL 1
Trigger Level) for at least 4 seconds (Trigger Time) the event recording would
include 11 seconds of sound (Pre-trigger + Snapshot Time).
1.
changes from gray to red during the designated Snapshot Time.
TAKE NOTE
manually triggered sound recording) begins during an ongoing
sound recording, the sound recording extends. This continues
until there are no more events. When you examine the recording
after the measurement, you will find that the sound recording is
associated to the first event even though it contains sound
recordings for the subsequent events.
Because of sound buffering demands, there are constraints on the values you
can set for the Minimum Duration and Pre-trigger. If the values you enter
require more buffer than is available, an error message appears and the
values automatically adjust to accommodate the recording.
Table 18.1 displays the maximum values you can indicate for the Minimum
Duration (Event History) and Pre-trigger (Sound) when using automated
Event Sound Recording.
The 51.2 ksps sample rate serves a unique function— when used with Time
TAKE NOTE
History records, the sound recording and the Time History record are synced.
At any other sample rate, filter delays prevent this time synchronization.
Making an Automated Event Sound Recording
If you monitor the measurement, notice that the record icon
If a second event (such as a measurement history or
Table 18.1 Sound Recording Constraints
Sample Rate
8 ksps
16 ksps
24 ksps
48 ksps
51.2 ksps
/*/
Minimum Duration
+
Pre-Trigger ≤
60 s
30 s
20 s
10 s
9.375 s
) the Setup
18-4