"The useful signal is modulated on a high frequency carrier in order to provide a relative narrow signal bandwidth and the needed communication capacity."
What does the author mean by "relative narrow signal bandwidth"?
For example, for amplitude modulation, the bandwidth of the transmitted signal is twice the message signal. So it is wider, not narrower.
What does the author mean by "relative narrow signal bandwidth"?
For example, for amplitude modulation, the bandwidth of the transmitted signal is twice the message signal. So it is wider, not narrower.