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A most important point to remember is that with either system of
modulation the frequency band occupied depends entirely on the
modulation and not at all on the frequency of the carrier wave.
15.9 Channel Separation
It is now clear that in order to receive a modulated signal completely
the receiver must accept not one frequency but a whole band,
preferably with equal effectiveness throughout. Outside this
frequency band the receiver should ideally have no response, so that
the sidebands of transmissions on nearby carriers are rejected. This
is illustrated for a.m. in Fig. 15.8 in which the dashed line shows an
Fig. 15.8 At (a) is shown