Question

4.(30p) A message signal is consisting of voice signal and information code as shown in the figure. This signal modulates an AM carrier signal x(t) defined as x(t) = cos(2 * 11 * 50000 *t) Find and sketch the spectrum of the modulated signal for each AM modulation type below. Explain the advantages and disadvantages of each modulation type. a) DSB-SC b) DSB c) SSB Upper Side Band AMEA)! 2 1 2 5 -5 2-1 f (kHz)

Answer 1

# Solution - → A message signal is consiling of voice signal and information code, this signal modulates an Am Carier signal sects defined as xeta cox(Q17. 5000ot) bez 50000 Hz message signal spectrum bc=50kHz - 2-1 0 -5 ch 2 4 $(kHz) - a) DSB-SC St=xw.mits COAC@50000t, mit SCH)= M($-$c) +MCH+be) M($-50K) + Mebt Sky sbed ett spectrum of modulated signal salg 2 I *(KHà su 46 -54 -so pouser 45 46 Advantage dis Advantage 3 consumption af Low power → Its complex detection as o to obtained enovercoming a wave mod wakion due to the short coming faced by the comien being suppressed other modulation due to which has its product eupauessedweanien in this Proportional to the message nodulationer signal,

B) DSB Sw=xatstat mit) s(6)=sit+ bc) t&lt-bc) mit-bo+mit+bc) + 2 2 AcasokHz $($) 1 10.5 50 -16 url +45 +46 54 -55 -54 55 -50 blkt) dis Advantage more Spectrum of DSB Advantage → DSB Transmitter & are leas complex - DSB receivers are simple, delection is easy DS8 receivers are cost efficient wave can travel a longen distance. Power wastage take place Bandwidth inefficient ystem wave get affected due to Noise, CS Scanned with CamScanner

BARAT ☺ SSB upper side Band SW = zasmets + www.mas) st=[xit.net) mu note] mat → Hilbert Transform signal nu - Hilbert Transform signal spectrum of sss upper eide Band No 54 55 f(KH) -55 -54 dis Advantage Advantage → Brod cast of an → Ereneration & Receiver additional noi of signal of signal is complex, → Power zaved compared to DJ Bf DJB-SC. quality of the signal gets → Nelse present és lear affected unless the SSB > signal loss is legy have an excellent frequency Stabillity, transmitter and receiver CS Scanned with CamScanner