On radiating (sending out) an AM modulated signal, the total radiated power is due to energy carried by ωc, ωc - ωm & ωc + ωm. Suggest ways to minimize cost of radiation without compromising on information.
Note that the frequencies 
and 
are enough to carry all the information; 
is unnecessary. The first two can be added to get two times carrier frequency.
However, we are interested in the message signal. We can subtract the smaller value (
from the larger value (
to get two times the frequency of the message signal.
Hence, we can minimize cost of radiation by only transmitting 
and 
.
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