Keysight N9923-90001 User’s Guide69Time Domain – Option 010Time Domain (Transform) SettingsNetwork Analyzer Windows Frequency Span and TDR WindowSelection for Step Rise Time (Approximated)The following table shows the approximated relationship between thefrequency span and the window selection for impulse width and step rise time.Refer to Figure 4-1 on page 69.Figure 4-1 Network Analyzer TDR Rise TimeLine Loss and Velocity FactorBy default, the FieldFox does NOT correct Time Domain measurements toaccount for the inherent loss of a cable. However, to make more accuratemeasurements, Line Loss and Velocity Factor should be considered.About Velocity Factor and Line Loss— Velocity Factor is a property of the physical material of a cable. A VF of 1.0corresponds to the speed of light in a vacuum, or the fastest VF possible. Apolyethylene dielectric cable has VF = 0.66 and a cable with PTFE dielectrichas VF = 0.7.— Line Loss is specified in dB/m (or ft). In addition to the length of the cable,loss is also directly proportional to the frequency of the signal that passesthrough the cable.The following is an example showing how Line Loss works:Window Low-pass step(10% to 90%)Low-pass impulse Bandpass impulseMinimum 0.45/ f span 0.60 / f span 1.20 / f spanMedium 0.99 / f span 0.98 / f span 1.95 / f spanMaximum 1.48 / f span 1.39 / f span 2.77 / f span
