technique. Find the value of the carrier frequency so the bandwidth of th modulated signal is 1% of the carrier frequency. A.17 An FM signal is described by s(t) = 100 cos (2л.10³t + 10-4 cos (1000лt)). Determine the modulating signal m(t). A.18 Consider a communication channel, transfer characteristic of which is def

ii) A single sideband AM signal (SSB-SC) is given by s(t) = 10cos(11000 t). The carrier signal is c(t) = 4cos(10000tt). Determine the modulating signal m(t).

In a Frequency Modulator, the carrier signal, ec=8 sin[27(500k)t] is frequency modulated by em=5cos[2n(1k)t]). The Frequency deviation constant of the modulator is K= - 800 Hz/V. Determine: a. Frequency deviation at t=145µsec b. Frequency deviation at t-360usec c. Maximum frequency deviation d. Modulation index of the FM signal e. Equation of the modulated signal f. Instantaneous frequency of the FM signal at t=283usec g. The percent modulation if the modulated signal is for FM broadcast

A spectrum analyzer with an input impedance of 200 is used to measure the power spectrum of an AM signal at the output of a preamplifier circuit. The AM signal has been modulated with a sine wave. The effective carrier power, Pc, is 750mw, and each sideband, PusB and PLSB, is 120mW. Compute the following: 1- The total effective power Pr. 2- The peak carrier voltage, Vc- 3- The modulation index, m, and the percent modulation index. 4- The modulation voltage,Vm. 5- The lower -and upper - sideband voltages, VLSB and VUB. 6- Sketch the waveform that you would you see with an oscilloscope if it were placed in parallel with the spectrum analyzer.

An FM signal has a maximum frequency deviation of 1500h and a modulating frequency of 500h, its total power is 6500w, applied to a resistive load of 1ohm, the carrier frequency is 400Mhz. Determine the sensitivity of the modulator, and the magnitude spectrum

Q2: A modulating signal is used to modulate a carrier signal(AM modulation). Let Pr , Pc, Psa. PusB, PLSB and u are the total power, carrier power, side band power, upper side band power, lower side band power and modulation index respectively. Prove the following: a. Pc = Pr () c. Pusp = Pasa =) P, 2+m2. b. PsB = Pr %3D 2+m2 2 (2+m2

D E F

Solve C part only.

Q 2 : An audio signal given by 15 sin( 000 pi t)+20 sin(8000 pi t) amplitude modulated DSB-FC) a sinusoidal carrier wave 60 sin(100,000 ) a. Derive an expression for the modulated signal. b. Find the modulation index. c. Find the spectrum of the modulated signal. d. Sketch the spectrum of the modulated signal e. Which type of demodulation method you propose to reconstruct the audio at receiver. Why? Q 2 : A modulating signal is used to modulate a carrier signal(AM modulation). Let P T . P c ,P SB . P USB , P LSB and u are the total power, carrier power, side band power, upper side band power, lower side band power and modulation index respectively, Prove the following: a. P c =P T ( 2 2+m^ 2 ) b. P SB =P T ( m^ 2 2+m^ 2 ) c. P USB =P LSB = 1 2 ( m^ 2 2+m^ 2 )P T

Determine the bandwidth of a narrowband FM signal which is generaled by a 4 KHz audio signal modulating is 125 MHy