simulation of a superheterodyne receiver using pspice - School of ...

an amplitude of 538mV. The output is fed through a high pass filter as shown in
the second plot. This signal with a 6.83mV amplitude is fed to the audio amplifier
where it is amplified up to 79.35mV. The AM signal generated at the start had an
amplitude of 72mV and now at the output it has a value of 79.35mV.
Fig. 49: AM detection and audio spectrum.
Zooming in on the low frequency components of the AM detector spectrum, as in
Fig. 50 below, a spectral component is present at 5kHz, which has amplitude of
14mV. The reason this component is very important is that 5kHz is the
modulating frequency. This frequency is required to be amplified by the audio
amplifier. This is the case in Fig. 51, where the modulating frequency is amplified
up to 470mV.
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