Keysight N9923-90001 User’s Guide 129Power Meter (USB) ModeUSB Power Meter SettingsIn addition, once External Zeroing has started, the power source must be OFFfor the entire time that the Zeroing message is present. Otherwise, thecalibration will be compromised but NO warning is shown.FrequencyA table of correction factors versus frequency is stored within Keysight PowerSensors. The frequency of the power to be measured is entered in the FieldFoxso that the appropriate correction factor can be used.The frequency of the power measurement is NOT limited by the frequencyrange of the FieldFox, but the frequency range of the power sensor, which canbe much wider.How to enter Frequency of the Power Measurement— Press Freq/Dist or Meas Setup 4.— Then Frequency.— Then type a value using the numeric keypad. The default frequency is 50MHz.— Then press a multiplier key. Learn about multiplier abbreviations in“Multiplier Abbreviations” on page 34.The current frequency is shown on the FieldFox screen.Source ControlThis feature may require an option on some FieldFox models.With the FieldFox internal source enabled, these settings allow you to makesimple, absolute power measurements. The source and the power sensor canbe physically separated by a long distance when using a long USB cable.Set the internal source frequency by setting the frequency of the powermeasurement. Learn how in the previous section.Power Meter measurements are limited by the combined frequency ranges ofthe internal source when enabled and the frequency range of the powersensor. For example, assume the frequenc y range of your sensor is 9 kHz to 18GHz and the frequency range of the FieldFox is 2 MHz to 6 GHz.— With the Source ON, measurements are limited to 2 MHz to 6 GHz.— With the Source OFF, measurements are allowed from 9 kHz to 18 GHz.How to Set Source Control and Power Level— Press Freq/Dist
