Soft dB Opus Suite SLM 4-Ch Module - Manual (Page 41)

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8.2.1 DataSet and Leq Alignment
In several cases, it is useful to align the Leq measurements to match the time on the clock. For
example, it may be useful to align the 1 hour Leq periods of a 24 hours acquisition (in Multiple Auto-
Store Mode) in order for the Leq to start exactly at the beginning of a new hour on the clock. A
measurement started at 7:35 AM would then start a new Leq at 8:00 and every hour afterward.
Moreover, using the Every Day mode of ID increment would allow the user to switch to a new file
every day on a specified time. With time alignment being set to 06:00:00, the data recording would
change to a new file every day at exactly 6:00 AM. All the Leq period would represent one full hour
on the clock except for the first Leq period when the acquisition was started on the first day. The
alignment is forced to the time alignment specified. It is common to use an exact hour as alignment,
but one could want to align the measurement on the middle of the hour. Indeed, the user could
specify an alignment of 6:30:00. The first Leq of the example would than goes from 7:35 to 8:30. The
following Leq periods would last one hour afterward until 6:30 AM the next day. A new DataSet
would then be created and would normally include 24 one-hour Leq spanning from 6:30 AM to 6:30
AM the next day.
In order to achieve the Leq alignment to the clock it is necessary for the Leq Average Period to be a
common multiple of the DataSet period. With the Every Hour/Day/Week modes, the Leq Average
period will be forced to the nearest common multiple. With the On Start Only and the Every ‘X’ Leq
modes, the alignment parameter also limits the Leq Average period to match with the clock unit.
8.2.2 DataSet File Size
Multiple DataSets are useful when performing a long term measurement lasting several days and it is
desirable to have a separate DataSets for each day or for each hour. Moreover, the application limits
the DataSet file size to 200 MB. Therefore, the user is informed of the limitations as the parameters
of the measurement are modified. The size limitation also applies when the ID increment is set to On
Start Only. This means that the application will automatically switch to a new DataSet before the size
limitation is reached.