186 Keysig ht N9923-90001 User’s GuideData Analysis FeaturesAll about Limit Lines——Upper - FAILS any measured data point ABOVE the line.——Lower - FAILS any measured data point BELOW the line.—Off/On – Press Ed it to toggle between the following:——On - Limit line is drawn on the screen and PASS/FAIL testingoccurs.——Off - Limit line is NOT drawn on the screen and testing doesNOT occur.—Frequency – Enter a numeric X-axis value of the data point.—Amplitude – Enter a numeric Y-axis value of the data point.— Press Add then choose from the following:—Add Point - Adds a blank X/Y data point below the cursor.—Add Limit - Adds a default limit line below the current limit.— Press Clear then choose from the following:—Clear Point - Removes the X/Y data point on which the cursor resides.—Clear Limit - Removes the limit Line on which the cursor resides.—Clear All - Removes ALL limit lines.— Press to return to the Limit menu.Relative Limit LinesRelative limit lines are X/Y coordinates that are referenced to the centerfrequency (X-axis) and Reference level (Y-axis).Use relative limits to test devices or signals that are identical except for thecenter frequency or amplitud e. With relative limit lines in place, you change thecenter frequency of the measurement and the limits look as though they are inthe same location.The same is true for Reference Level. When you expect to measure a differentpower level, instead of changing the Y-axis value of all of the fixed limits,simply change to relative limits. The limits will then remain a constant Y-axisdistance from the Reference Level.Each limit line can be changed at any time from Fixed to Relative, and Relativeto Fixed.How to Create a Relative Limit LineThe easiest way to create a Relative limit line is to create a Fixed Limit at aspecific center frequency and reference level. Learn how “Relative Limit Lines”on page 186. Then change the limit line to Relative. The X/Y data points will bere-calculated relative to the center frequency and reference level.
