 Please see the Carrier in modulator (U_1) again. This wave starts from
0 [degree]. (You can expand the scale by choosing "View" ->
"Scale Change" on the menu)
How about the Carrier in demodulator (U_30). This wave starts from 90 [degree].
The reason why we locate a DELAY after this is to adjust the phase error
between these two signals.
The Carrier in AM demodulator needs to be "synchronized" with the carrier in AM modulator. Otherwise the amplitude of demodulated Base Band may decrease a lot.
That's it for this class. If you use multiplier to demodulate AM signals, please take care of the phase of Carrier. You need some effort to decrease the phase error (putting phase-locked loop etc.)
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