AutoRec allows the recording to start when the signal measured passes a preset limit. The recording stops after the signal has been measured below the preset limit for at least equal the preset duration.

AutoRec is mainly used to record raw signals. When recording raw signals, the memory consumption grows very rapidly with time. So in order to monitor raw signals over a long time, only short segments can be captured at a time.

When statistics are being monitored, the instrument has enough memory to be able to record non-stop for weeks and months. So AutoRec is not really necessary.

AutoRec will capture a certain number of pre-trig samples (256 samples).

For instance AutoRec can be setup to:

•Start recording a raw acceleration signal whenever the acceleration passes 0.2g.
•Stop recording whenever the acceleration signal is < 0.2g for at least 10s.

AutoRec setup always requires two parameters:

•A threshold to start the recording (Acceleration or Velocity). The recording will start as soon as the signal passes the threshold.
•A minimum duration to stop the recording. The recording will stop after the preset duration has elapsed with the signal staying below the threshold.

The threshold is set in m/s2 for accelerations, and in m/s for velocities.

The threshold applies to the raw signal if the instrument is set to record raw signal or signal statistics. In that case, the threshold value T defines a positive threshold +T and a negative threshold -T. The recording starts whenever the raw signal goes outside of the interval [-T, +T]. When measuring acceleration signals without high-pass filter, the threshold is applied relative to the static acceleration at the time when AutoRec is started. This way it is also possible to trigger a recording when the tilt of the instrument changes by a predefined amount.

The threshold applies to the RMS level if the instrument is set to record RMS levels. In that case the threshold value defines a positive threshold +T. The recording starts whenever the RMS value goes outside of the interval [0,+T].

In order to trigger the recording, the signal must pass the threshold on any individual axis. For instance, if the instrument is set to record raw velocity signals the trigger value V represents a cube around the origin (0,0,0), with a side-length of 2V.