Question

When a baseband signal m(t) = cos(1000t)cos(3000t) is AM modulated using a carrier cos(10,000t),

Answer 1

mit) = cos Clooot) Cos (3000t) 2 COSACOS - COSCA+B) +OSCA-B COSA COSB = COSCA+B) +cosca-B Here A-3000 B=1000 -ME+) = { cos C4000+) t4cos(2000t) -0 When The message contains more than one frequency, it is called multitone modulation mct): Am, cos21 fmitt Ama cos 211 mat The time domain equation of AM and si+) = Ac cosenfet + Ac kam coś 2 fete SLE)- Ac fitkamet)] cos 217fct 5 modelated signal, a) Frequency components in the base band signal From the equation 0 W, 22000 radfec Wz = 4000 xad) sec S+)Ac [i+ kamit)] cos amfet .: A Closanft] +te ka[am, cofanfmit + Ame Cofanfirst) . Cosalift : Si+) = Ac fit , losan format tellz cos afirmyt] cosanfet = Ac Cosenfet + Acelli [cos art (fetfimm t + cos an(fe-fromt] the use [cosant (fe +fma)t + cosat (fc-fromy]t? CamScanner Ka Amizliy Ka Amaalle Scanned with

c(t) = COS C10,000t Here Aca! Wc. 210,000 radfsec Sit) = he [1+Ka mlt)] cosuct Carrier frequency sut) = 1 [17* [coscuocot) +cos (2000t)] cs 10,000+ - © of sensitivity the Where ka= Arnolitude modulator Modulation Index Amplitude of The particular message s(t) = COS C10,000+) + COS (19000t) coscuooot) + cos(10,000) cosL2000t)? sct) = cascio, ooot) + f t [cos (1,00ot) +cos(6000+)] ++ [ Los cos C12,000+) +cos (gooot)]] Now the frequency components of modeilated signal are 19 = 10,000 ws=14000, W3 = 6000 Wy = 12,000 & Ws =5000 All are in radfore 1 Sit) The pilly 1 1/4 1/4 Specfum, 11.0 Scanned with CamScanner Wz wg w 6000 8000 10,000 auf Wy Wz 12,000 14000

© power efficiency (n) . If the message contains in frequencies 4² = 4f +42 +4 torr... en n = power ins power in side bands - Total power. PCME 2 2 сце a Xloo - Pc [Itu T stunt Carrier power Pc = 2 = (:' Aczi) 41 242 & M2= k wes= } )} = tutta - Das Yü x100 Ya_x100 - 0-2X100 in = + Yo To - 20% Scanned with CamScanner