# Rise Time

The Rise Time is a measure of the mean transition time of the data on the upward slope of an eye diagram. The data crosses through the following three thresholds: the lower, middle, and upper thresholds, as well as through the eye crossing point. Annotation labels are placed on the lower level and the upper level thresholds of the data on the upward slope of an eye diagram. The labels are dependent upon the threshold levels you have configured. The default setting for the threshold levels are the 10% to 90% points on the transition.

This measurement uses the top and base levels of the signal to compute the location of the lower, middle, and upper threshold levels. A histogram is first constructed to find the Vtop and Vbase values from which the mean location of the crossing points are located relative to the V top and Vbase. Histograms are then constructed at each of the three threshold levels (for example, the 10%, 50%, and 90% points on the transition). Each histogram is analyzed to determine the histogram mean at which the data crosses the separate threshold levels. Once the mean location for each threshold crossed is determined, the rise time is computed.

If the rise time relative to the time/division is a small value, the data acquired at the threshold levels on the rising edge will not yield accurate measurement results. (The rising edge will appear very steep on the display screen.) If the rising edge of the eye diagram is steep, decrease the horizontal time base scale on the display so that the rising edge covers at least half a graticule division.

This measurement applies to NRZ waveforms and not to PAM waveforms.

## Configurable Measurement Parameters

This measurement is affected by the following settings (choose Measure > Thresholds...):

- Thresholds tab
- Eye tab

## To measure

1. Click the measurement toolbar's Eye Meas tab.
2. Click Auto Scale in the menu bar.
3. Click the More buttons to locate the Rise Time button.
4. Click the button.

## SCPI Command

`:MEASure:EYE:RTIMe`