Lightwave Analyzer Event Table vs. Peak Find discrepancies

Some users have noticed on the Lightwave Analyzers that the peak find (snapping the cursors to the highest peak within the highlighted region) places the cursor at a slightly different point than the corresponding RL event shown in the Events Table.  This is due to the peak find function and event tables using different methods to calculate the location of highest peak.

The plot cursor finds the location with the highest local amplitude in dB.  The event table shows the location that has the highest calculated return loss (RL) within the event area.  

These are usually very close but are not the same thing. Unless the return loss event has a very symmetrical shape, the location with the highest return loss is likely to be different from the location with the highest RL value.

When considering this detail, it is important to keep in mind the extremely fine resolution of the Lightwave Analyzer.  RL events may be multiple samples wide and the RL value is calculated by integrating over a region that defined by the user.  Therefore, the RL value and location, when integrated over the highlighted area, is affected by energy reflected in nearby samples.  An asymmetrical RL event may cause the center of the integrated RL event to move slightly away from the location of the sample with the highest local amplitude.