Do negative frequencies count towards null-to-null bandwidth? I am aware that negative frequencies do not normally count towards the bandwidth when transmitting in the baseband. However when specifically asked to look at the null-to-null or zero-crossing bandwidth, should the negative frequencies count? For example, in the sinc plot below, is the bandwidth 1 or 2?
It is null-null when the signal is bandpass and zero-null when the signal is baseband. So you will always take the positive frequencies.