A $$1000$$ KHz carrier is simultaneously modulated with $$fm1=300Hz$$ , $$fm2=800Hz$$ and $$fm3=1kHz$$ audio sine waves. What will be the frequencies present in the output?(a) $$fLSB1=999.7kHzfUSB1=1000.3kHz(b)$$ $$fLSB2=999.2kHzfUSB2=1000.8kHz(c)$$ $$fLSB3=999kHzfUSB3=1001kHz(d)$$ $$fLSB3=990kHzfUSB3=1010kHz$$

Question

A $$1000$$ KHz carrier is simultaneously modulated with $$fm1=300Hz$$  ,  $$fm2=800Hz$$ and $$fm3=1kHz$$ audio sine waves. What will be the frequencies present in the output?(a) $$fLSB1=999.7kHzfUSB1=1000.3kHz(b)$$ $$fLSB2=999.2kHzfUSB2=1000.8kHz(c)$$ $$fLSB3=999kHzfUSB3=1001kHz(d)$$ $$fLSB3=990kHzfUSB3=1010kHz$$

Infinity Learn · Accepted Answer

Frequencies present in the output are lower frequency modulation fc−fm  and upper frequency  modulation $$fc+fm$$ .  (a) $$fc=1000kHz$$ $$fm1=300Hz$$ $$=$$ $$0.3$$ kHz $$fLSB1=fc$$−$$fm1=1000kHz$$−$$0.3kHz=999.7kHz$$ $$fUSB1=fc+fm1=1000kHz+0.3kHz=1000.3kHz$$  (b)  $$fc=1000kHz$$ $$fm2=800Hz$$ $$=$$ $$0.8$$ kHz $$fLSB2=fc$$−$$fm2=1000kHz$$−$$0.8kHz=999.2kHz$$ $$fUSB2=fc+fm1=1000kHz+0.8kHz=1000.8kHz$$  (c) $$fc=1000kHz$$ $$fm3=1kHz$$ $$fLSB3=fc$$−$$fm3=1000kHz$$−$$1kHz=999kHz$$ $$fUSB3=fc+fm3=1000kHz+1kHz=1001kHz$$

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A 1000 KHz carrier is simultaneously modulated with fm1=300Hz , fm2=800Hz and fm3=1kHz audio sine waves. What will be the frequencies present in the output?(a) fLSB1=999.7kHzfUSB1=1000.3kHz(b) fLSB2=999.2kHzfUSB2=1000.8kHz(c) fLSB3=999kHzfUSB3=1001kHz(d) fLSB3=990kHzfUSB3=1010kHz

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