Communication Electronics — DU B.Sc. (Prog.) Physical Science courses pertaining to Electronics Previous Year Question Papers

Name of the Department Name of the Goursc Department of Physics &nd Astrophysics B.Sc. Prog.-(Physics) NEP: UOCF-2022 Communication Electronics (DSC paper) Question paper Set number Maximum Maries 60 Marks wtroctlom for Candidate,: (a) Why is modulation necessary in communication systems? (b) How many sidebands are· there in FM signal? What is the bandwidth of™ wave? (c)· Write advantages and disadvantage of Pulse Amplitude modulation. (d) What are the three components of PCM explain in brief. (e) Why is mobile phone called cell phone? What are the different types of cells? (t) Explain uplink and downlink in satellite communication? Q2 (a) Derive the expression for total power of AM wave. A 500W, 100 KHz carrier is 60% modulated by a modulatbig signal of frequency 1 KHz: Calculate the total power transmitted. What are the sideband components of AM Wave? (7 .5) (b) What is frequency modulation? Derive expression for modulation index of FM wave. How are FM and PM related? QJ (a) Explain difference between natural sampling 811:d flat top sampling. Draw the circuit diagram of flat top PAM generation and explain i~ working. (7 .5) (b) State sampling theorem. Two signals x1 (t) and x2(t) are band limited to 3 KHz and.4 KHz respectively. Find the Nyquist rate for the following signals. Q4 (a) Explain the working of FDM transmitter and receiver with the help of suitable bloc~ (b) Write mathematical equations for ASK, FSK and PSK. Draw the modulated waves for all these along with message signal arid carrier wave.· (7 .5) Q5 (a) Discuss the role of frequency reuse in mobile communication system. Explain cell sectoring and cell splitting. (7.5) (b) State the advantages of geostationary satellite in communication. Calculate the height of a satellite above sea level orbiting around earth in a geosynchronous orbit. (7 .5)