# Waterfall

Create waterfall plots from XY force response data and input pulses.

If a waterfall plot exists in the current window, HyperGraph 3D automatically populates the default values. Otherwise, you can enter information into the panel's fields.

## Plot Type

- Frequency
- Default.
- Order (scaled)
- Calculates orders by scaling the frequency values by the input magnitude values.
- Order (resampled response)
- Modifies the time values of the response curve so the FFT returns order instead of frequency.
- Order (variable DFT)
- Calculates orders by scaling the frequency values by the input magnitude values. Uses a DFT with a varying sample size to ensure a consistent density of points along each waterfall slice.

- Time
- Default.
- Input magnitude
- Instead of plotting against time, plot against the units of the input curve's magnitude (RPM, RPS, driving frequency, and so on.)

## Data Curves

- Click the curve selection button, , in the Response text box to display the Response dialog.
- Choose a curve from the Curve tree and click Select.
- You can also click Preview to view the curve in the Preview dialog before selecting it.
- Click Close to close the Curve dialog.

- Select the curve from an XY plot window.
- Enter the PWC math reference and press Enter.
- Press and hold Shift and left-click on the curve.

## Input

Select the input vector used to generate the response vector and press Enter. Input curves can be selected in the same way as Response curves (see above).

- Input vector is in RPM
- Select this option to scale the response curve by 60 to use RPS.

## Waterfall Slices

- Number
- Enter the number of samples.
- Step size
- Enter the step size. A sample will be taken at each step increment.
- Contour waterfall
- Display a contour on the waterfall plot based on "Z".

## Parameters

For each of the following parameter fields, select an item from the drop-down menu. Click Apply to apply the parameters.

- Sample size
- Number of data points to use in each FFT.
- Window function
- The windowing function for FFT.
- Amplitude type
- Peak, PSD_RMS, or Auto spectrum.
- Amplitude scale
- None, DBA, DBC, DB4, or DB.
- Show all options
- Select this option to display additional parameters.

## Summary and Frequency

The following parameters are displayed if you select Show all options.

**Summary**- Freq resolution
- Twice the delta frequency returned from "freq(response_curve.x)". Or, the third point minus the first point returned from the frequency calculations.
- Nyquist freq
- Half the maximum value returned from "freq(response_curve.x)".
- Max order
- The Nyquist frequency divided by the maximum value in the input curve’s magnitude.
- Number of points
- The number of points in the Response curve.
- Time increment
- The delta time in the Response curve or the difference between the first two points of the X axis in the Response curve.

**Frequency**- From/To
- Two sets of From/To fields are displayed at the far right of the panel. The headings above From/To change depending on the Plot type options selected. For example, if you select Frequency and Time, those headings are displayed above the From/To fields. If you select Order (scaled) and Input magnitude, those headings are displayed. For any option you select under Plot type, enter the desired range in the From/To fields.
- Apply
- HyperGraph 3D creates or modifies the waterfall plot based on your selections.
- Undo
- Restores the waterfall plot to its previous state.