GHM DeltaOHM HD2010UC, Operating Manual, Page: 23 / 134

HD2010UC
- 23 -
V4.2
EVENT TRIGGER FUNCTION
The Event trigger function is available with the “ Advanced Data Logger” option and can
be enabled only with the single integration mode. During measurement this function can be used to
isolate a sound event identifiable by
sound level variation or by synchronization to an external sig-
nal or, manually , by pressing a key.
The acoustic descriptor used by the trigger function is selected in the PROFILE view (Menu
>> Trigger >> Source: LEV). The level variation that triggers the event can be positive or negative
(Menu >> Trigger >> Trigger Polarity) and the trigger threshold (Menu >> Trigger >> Trigger
Threshold and Menu >> Trigger >> Bottom Threshold) can be different from the deactivation
threshold (Menu >> Trigger >> Trigger Threshold and Menu >> Trigger >> Bottom Threshold).
The following figure shows an example of a positive polarity sound event capture. The sound level
(L
AF
) exceeds the trigger threshold for time T0 and, later, the bottom threshold for time T2.
Fig. 8 -
Description of the event trigger parameters
To prevent short duration pulses being detected as sound events, a minimum trigger duration
can be set up to a maximum of 10s (Menu >> Trigger >> Minimum Duration). If the threshold is
exceeded for less than the set time, the event is neglected. Also a
minimum deactivation duration
can be set: when the deactivation threshold is exceeded, the event close is delayed for the set time,
up to a maximum of 255s (Menu >> Trigger >> Stop Delay).
In the example, since the trigger conditions exceed the minimum duration, that is, they persist at
least for time T1, the event levels integration begins, including the 2 seconds before the threshold is
reached (
pre-trigger ). This pre-trigger time cannot be modified.
The event levels integration ends at time T3, that is, after the stop delay from the T2 time corre-
sponding to the bottom threshold being reached.
The event trigger feature can be activated also by pressing the ENTER key (Menu >> Trigger
>> Source: MAN). In this case the minimum duration parameter has no effect and the event begins
as soon as the trigger is detected.