. D ETECTION OF A MPLITUDE M ODULATED W AVE The transmitted message gets attenuated in propagating through the channel. The receiving antenna is therefore to be followed by an amplifier and a detector. In addition, to facilitate further processing, the carrier frequency is usually changed to a lower frequency by what is called an intermediate frequency (IF) stage preceding the detection.
The detected signal may not be strong enough to be made use of and hence is required