wiki:ShmDocMenuAmplitudeAmplitudePeriodAutoZero
Last modified 14 years ago Last modified on 02/05/2009 10:59:22 AM

Menu entry Ampl & Period auto Zero

Measure absolute amplitude on waveform. Amplitude and period ist determined automatically by SHM within a given time window.

After calling this menu entry the next two phase clicks (left mouse button) are used for setting this time window, unless the entry Abort Selection is activated. Select the time window by clicking on its left and right border with the left mouse button, like selecting phases.

The algorithm finds minimum and maximum within the window which are not at the windows border. Then it searches for the zero line crossings of the waveform next to each extremum in left and right direction. If these cannot be found within the marked time window it aborts with an error message. If these are found for both extrema, it takes the extremum with the larger absolute value. The found extremum is taken as plain amplitude, twice the time difference between the zero crossings are taken as signal period.

From the plain amplitude the absolute amplitudes of ground velocity and ground displacement are estimated dividing by the transfer function of the current simulation filter applied at the measured period (see Work with simulation filters).

Amplitude determination works currently only after application of simulation filters. The results of the amplitude determination are written to the terminal window where SHM was called or may be viewed with menu entry Show Parameters.


back to documentation index