Measuring Long Cable Lengths Accurately

Table of Contents

In CAT and NA Modes, the FieldFox signal source and receiver step frequency at the same time. To make accurate 1-port reflection measurements, the signal must travel to the end of the transmission line and back to the FieldFox receiver before stepping to the next frequency. With a long cable length, the default sweep time settings may not be adequate, and inaccurate measurements occur as a result.

To make these measurements accurately, it may be necessary to slow the sweep speed allowing the signal time to return to the receiver before it steps to the next frequency.

In CAT or NA Modes, for both Loss and DTF measurements:

  1. Press Sweep   3.

  2. Then Min Swp Time.

  3. Then type a value, then press a multiplier softkey to change the sweep speed as desired. When the trace no longer changes as more Sweep time is added, then an accurate measurement is being made.

  4. For cables with high loss, add Averaging to reduce noise.