In this mode the scanner scans a narrow band centered around a specific RF channel, identifying other sufficiently strong RF channels as interferers. For the cellular (800) band the scanned bandwidth is 30 kHz, and for the PCS (1900) band it is 50 kHz.

The narrowband interference scan has lower resolution than the spectrum analysis scan (see section "Spectrum Analysis") but is considerably faster. Once you have done a narrowband interference scan to identify interferers, you can proceed to perform a spectrum analysis in the relevant frequency range, thereby obtaining an even clearer view of the problematic signals.