 The resulting signal is then band-pass filtered with a Nyquist filter to remove redundancies in the side lobes, and then shifted up to the broadcast frequency.Vestigial sideband modulation (VSB) is a modulation method which attempts to eliminate the spectral redundancy of pulse-amplitude modulation (PAM) signals.Modulating a carrier by a real-valued data sequence results in a sum and a difference frequency, resulting in two symmetrical carrier side-bands.