Pure carrier vs modulated carrier
This page describes Pure carrier(unmodulated carrier) vs modulated carrier. It mentions difference between pure carrier and modulated carrier.
Figure below is the extracted part of the common physical layer modules of a typical wireless modem.
Figure mentions two cases. In ths case-1; as shown in the figure, if all the 1's or 0's or alternate ones and zeros are fed, which is the known standard pattern. This results in pure carrier i.e. unmodulated carrier, as phase of the modulated carrier does not change. Figure.2 mentions pure carrier in the middle on top of the modulated spectrum.
As mentioned in case-2, PN sequence is fed to the modem; leads to modulated carrier as the output as shown in the figure.