The built-in EMI filter is used for specific
measurement situations such as EMI average
detection, where a higher level of sensitivity is
required compared to the standard
configuration. When turned on, the RBW is set
to -6dB, indicated by an asterisk (*).
When any measurement functions are turned
on (see page 123 for details), the EMI filter is
automatically disabled. Conversely if the EMI
filter is turned on, any measurement functions
are turned off.