Page 1 of 2
International Islamic University Chittagong
Department of Electrical and Electronic Engineering
Semester End Assignment of Autumn-2020 Program: B.Sc. Engg. (EEE)Course Code: EEE-3601 Course Title: Communication Theory Time: 5 hours (Writing - 4 hours 30 minutes
+ 30 minutes submission time)
Full Marks: 50 (Written 30 + Viva/Viva-Quiz- 20)
[Answer each of the questions from the followings; Figures in the right margin indicate full marks. Answer script must be submitted through online method within 5 hours from starting
time. Also, write down the Q. Set on the front page of your answer script]
Q. Set-A
1(a). Draw the complete block diagram of the Armstrong frequency modulation system and explain the functions of the mixer and multipliers shown.
CO1 U 03
1(b). An FM wave is given by s(t) = 20 sin (6× 108 t + 7 sin 1250t).
Determine
(i) The carrier and modulating frequencies, the modulation index, and maximum deviation.
(ii) Power dissipated by this FM wave in a 100 ῼ resistor.
CO2 E 03
2(a). A sine wave is sampled at 5 times the Nyquist rate. Sketch the PWM, PAM and PPM wave.
CO1 An 03 2(b). The bandwidth of an input signal to the PCM is restricted to 4 kHz. The
input signal varies in amplitude from -3.8 V to +3.8 V and has the average power of 30 mW. The required signal to noise ratio is given as 20 dB. The PCM modulator produces binary output. Assuming uniform quantization,
(i) Find the number of bits required per sample.
(ii) Outputs of 30 such PCM coders are time multiplexed. What would be the minimum required transmission bandwidth for this multiplexed signal?
CO2 E 03
3(a). Explain the relationship between the minimum bandwidth required for a QPSK system and the bit rate.
CO1 U 03 3(b). For a tribit input of Q = 0, I = 1, and C =1 (011), determine the output
amplitude and phase for the 8-QAM transmitter.
CO3 E 02 3(c). Consider the binary sequence 0100101. Draw the waveforms for the
following signaling formats:
(i) Unipolar NRZ (ii) Polar NRZ
(iii) Polar quaternary NRZ signaling.
CO2 Ap 01
4(a). What is multiplexing? Describe the basic concepts of WDM and also, list the advantages and disadvantages of WDM.
CO1 R,U 02 4(b). Distinguish between baseband transmission and broadband
transmission. We modulate several voice signals and send them through the air. Is this baseband or broadband transmission?
CO1 An 02
4(c). We have 14 sources, each creating 500 8-bit characters per second.
Since only some of these sources are active at any moment, we use
CO2 E 02
Page 2 of 2
statistical TDM to combine these sources using character interleaving.
Each frame carries 6 slots at a time, but we need to add four-bit addresses to each slot. Answer the following questions:
(i) What is the size of an output frame in bits?
(ii) What is the output frame rate?
(iii) What is the duration of an output frame?
(iv) What is the output data rate?
5(a). Classify the communication satellite according to its orbit. Contrast the advantages and disadvantages of geosynchronous satellites.
CO1 R,U 02 5(b). What are the most common multiple-accessing arrangements used with
satellite systems? What is the primary advantage of TDMA as compared with FDMA?
CO1 U 01
5(c). Discuss the reason why there is no buffering of TV broadcasting in the way that internet videos are buffered.
CO1 C 03
6. Viva/Viva-Quiz: The time of viva/viva-quiz will be declared in Google classroom.
CO3 R 20
