Q2.
(a)
With appropriate block diagram, describe two methods/principles ofdemodulating a Frequency Modulation (FM) signal.
(b)
Consider a frequency modulated signal FM )]sin(cos[)(tttsmcωβω+=where mω is the frequency of a sinusoidal message signal, cω is thecarrier frequency and β is the modulation index.
i)
Using the above equation )(ts, explain the definition of NarrowbandFM and wideband FM.
ii)
Prove that the narrowband FM signal is given by the equation)sin()sin()cos()(ttttsmccωωβω−=.
(c)
An angle modulated signal is given by the expression
??(??)=5??????[??????+40? ????500??? +20? ????1000??? +10?????2000??? ]
i)
Calculate the bandwidth of the angle modulated signal by Carson’srule, if the peak frequency deviation, fΔ= 30 Hz.
ii)
If the modulated signal is a phase modulated signal with phasedeviation constant pk of 5 radians per volt, determine the messagesignal )(tm.
iii)
If the modulated signal is a frequency modulated signal withfrequency deviation constant fkof π000,20radian/sec per volt,determine the message signal )(tm.
