NB FHSS: Narrow Band Frequency Hopping Spread Spectrum. Use this setting when the signal being measured is 802.11b.
WB FHSS: Wide Band Frequency Hopping Spread Spectrum. Use this setting when the signal being measured is 802.11a or 802.11g.
Broadband: Use this setting when the signal being measured is a digital modulation format such as CDMA and GSM.