how can i determine if the FM is narrow or wide band?

check the BW of the signal , if the BW is like AM , it is narrow band FM and if it isn't it is wide band

khouly

Depending on the bandwidth of the signal required by the Digital part (DSP). Generally FM have about 270KHz of bandwidth for a signal with IF 384KHz

Usually only broadcast transmitters are using WFM, when other types of standard FM communications use NFM (two-way radios, analog cell phones, cordless phones, etc).