6b5b68e90e cos tutorial 3

6b5b68e90e cos tutorial 3

• 1.
  Tutorial 3 1) Findthe efficiency of single tone modulated AM wave if the modulation index is 0.5. 2) Calculate the % power saving when the carrier and one of the sidebands are suppressed in an AM wave modulated to a depth of a) 100% b)50% 3) A sinusoidal carrier voltage of frequency 1 MHz and amplitude 100 Volts is modulated by a sinusoidal voltage of frequency 5 KHz producing 50% modulation. Calculate the frequency and amplitude of upper and lower sidebands. 4) A sinusoidal carrier voltage of frequency 1200 KHz is amplitude modulated by a sinusoidal voltage of frequency 20 KHz resulting in maximum and minimum modulated carrier amplitudes of 100 volts and 90 volts respectively. Calculate a) the frequency of lower and upper sidebands b) the unmodulated carrier amplitude. c) modulation index and amplitude of each sideband. 5) A 75 MHz carrier signal having an amplitude of 50 volts is modulated by a 3 KHz audio signal having an amplitude of 20 volts. a) Sketch the audio signal b) Sketch the carrier signal c) Construct the modulated wave. d) Determine the modulation index and % modulation e) What frequencies would be there in a spectrum analysis of the modulated wave? f) Write trigonometric equation for the carrier and the modulating waves. 6) A sinusoidal carrier voltage frequency 10 MHz and amplitude 200 volts is amplitude modulated by a sinusoidal voltage of frequency 10 KHz producing 40% modulation .Calculate the frequency and amplitude of upper and lower sidebands.
• 2.
  7) Unmodulated RFcarrier power of 2 kW sends a current of 5 amp rms through an antenna. On amplitude modulation by another sinusoidal voltage, the antenna current increases to 5.9 amperes. Calculate a) the modulation index and b) carrier power after modulation. 8) Explain the method of generation of DSB using Ring Modulator. 9) Explain the frequency translation in DSB. 10) Draw the spectrum of AM with all relevant mathematical data.