Keysight Technologies X Series Measurement Manual page 42

Disturbance Analyzer (Click) Measurements
Setup Table Menu Features
Factor f
For certain types of products that must be cycled to emit discontinuous
disturbances (rather than run continuously), CISPR 14-1 requires users to
operate the product over enough cycles to product 40 clicks.
Factor f is used to calculate the click rate for these types of devices. See CISPR
14-1, Annex A Table A.2 for the factor to use for your specific DUT.
This information is given as an example. CISPR 14-1 is the reference document for
disturbance measurement requirements. Refer to CISPR 14-1 to identify the test
requirements for your specific DUT.
42 Keysight N6141A Measurement Guide