One more illustration should serve to reinforce these concepts. Figure 3.8
shows a digital bit stream with a data rate of 2000 bits per second. With a bandwidth
of 2500 Hz, or even 1700 Hz, the representation is quite good. Furthermore, we can
generalize these results. If the data rate of the digital signal is W bps, then a very good representation can be achieved with a bandwidth of 2W Hz. However, unless
noise is very severe, the bit pattern can be recovered with less bandwidth than this
(see the discussion of channel capacity in Section 3.4).