Enabling Measurement History Sound Recording - Larson Davis SoundAdvisor 831C Reference Manual

FIGURE 19-4 Sound Event Live Example
1.
19.3.1 About Sound Recording Constraints

19.4 Enabling Measurement History Sound Recording

SoundAdvisor Model 831C
Step 4.
Run a measurement and examine the resulting sound recordings. Based on the
settings shown in Figure 19-3, 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).
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 19.1 displays the maximum values you can indicate for the Minimum Duration
(Event History) and Pre-trigger (Sound) when using automated Event Sound Recording.
Table 19.1 Sound Recording Constraints
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.
With both 831C-ELA and 831C-SR, or 831C-MSR, firmware options installed, you can set up
the 831C to automatically initiate a sound recording snapshot at the beginning of each
measurement history period.
1.
If you monitor the measurement, notice that the record icon
changes from gray to red during the designated Snapshot Time.
If a second event (such as a measurement history or
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.
Minimum Duration
Sample Rate
8 ksps
16 ksps
24 ksps
48 ksps
51.2 ksps
Enabling Measurement History Sound Recording
+
Pre-Trigger ≤
60 s
30 s
20 s
10 s
9.375 s
155