This algorithm is often used in
strong motion seismic instruments, where high sensitivity is not an issue, and where
consequently man-made and natural seismic noise is not critical. This type of trigger can be
implemented in very simple instruments and many analog-recording accelerographs had it.
The level trigger is now largely replaced by the STA/LTA trigger, since computer power no
longer is an issue. However, although many instruments still keep the level option for
historical reasons.