Svantek SVAN 971, Руководство пользователя

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SVAN 971 User Manual
37
Level type trigger
The Level + / Level - trigger enables logging of the time-history results
( Logger Results ) averaged by the Logger Step period under the condition: the
value of the LEQ result ( Source ) averaged by the Logger Step period is greater
/ lower than the threshold level ( Level ). In other cases, the logging is skipped.
Due to this type of trigger it is possible to separate results related to the low/high
noise level.
The logging can be performed only when
the measurement is performing (e.g. the
instrument performs a series of 1-second
averages), from the measurement start till
the measurement stop.
This means, for example, that when the
measurement is skipped because the
measurement trigger condition is not met,
logging is also skipped, even if the logger
trigger condition is met.
Note: When logging
is waiting for the level trigger the “trigger level” icon
appears alternatively with the „curve” icon.
/
Source result
Only one measured result can be used as a source ( Source ) for checking trigger condition in the
Level Meter mode, namely the output signal from the LEQ detector coming from the first profile, which
is denoted here as Leq(1) . This position does not become active (it is not displayed inversely) and the
text stated here remains unchanged.
Threshold level
The threshold level for the logger trigger ( Level ) can be set in the range from
24 dB to 136 dB range. An instantaneous value of the LEQ result calculated with
selected Filter and Detector constant for the first profile ( path: <Menu> /
Measurement / Profiles ) compares with the Level value every 0,5 milliseconds.
Pre and post trigger recording
In the Pre Trigger position, the number of results
registered in the logger file before the fulfilment of the
triggering condition can be set. This number is limited to
0..10.
In the Post Trigger position, the number of the results
registered in the logger file after the fulfilment of the
triggering condition can be set. This number is limited to
0..200.
►
These parameters can perform double role. Firstly, if you wish to collect data right after or before the
event that caused triggering of the logging. Secondly, when it is necessary to have continuous logging,
but the source is oscillated near the threshold level. The extension of the registration window allows to
avoid the effect of pulsation on the continuity of registration.
Periods of measurements that are saved in the logger before or after fulfilment of the trigger condition
can be calculated by multiplying the value set in the
Pre Trigger or Post Trigger positions by the value
set in the Logger Step position ( path: <Menu> / Measurement / Logging / Logger Setup ). The result of
such calculation is presented in the same line in the format 0m00s .