98 Keysight N9923-90001 User’s GuideDTF (Distance to Fault) MeasurementsDTF Measurement SettingsDTF UnitsThe DTF Units setting is available ONLY on the DTF Settings table.By default, X-axis units for DTF measurement settings are displayed in Meters.How to change DTF units— With a DTF measurement present, press Freq/Dist.— Then More then Distance Unit m feet.— The current selection is underlined m (meters) Feet.Calculated DTF valuesPress Next Page on the DTF Settings Table to view the following calculatedValues noted on the FieldFox screen with c - Start Frequency – Start frequency that is used to calculate DTF.Stop Frequency – Stop frequency that is used to calculate DTF.Range Resolution. Indicates the accuracy of the distance to faultmeasurement. For example, with range reso lution of 500 mm, if the distance tofault is 10 meters, this value could be inaccurate by +/- 500 mm or between9.5 to 10.5 meters. This value is calculated from frequency span / resolution(points).Response Resolution, not displayed, indicates the distance that could bebetween two faults and still show as separate faults. Learn more in “WindowSettings” on page 97.Maximum Distance. The distance that could be viewed with the currentsettings. Defined by: Vf *c*Points/(2*Bandwidth) where:— Vf = velocity factor— c = speed of light— Points = resolution— Bandwidth = frequency rangeAlias-free Range (On/Off)— On=NoAliasimages— Off = Alias images may appear in the response.About Alias FaultsAn alias fault is not a true device response. An alias fault appears because ofthe method used to convert frequency to time.On the DTF Settings page (above) the c - Alias-free Range = Off settingindicates alias images MAY appear on the screen.
