Principles of Communication Systems

 

DON BOSCO INSTITUTE OF TECHNOLOGY, BANGALORE-74 DEPARTMENT OF ELECTRONICS & COMMUNICATION ACADEMIC YEAR 2018-2019(EVEN SEM) ASSIGNMENT –  ASSIGNMENT  – 2 SUBJECT : PRINCIPLES OF COMMUNICATION SYSTEM SUB CODE : 17EC44 : IV SEM

Sl

ASSIGNMENT 1

No 

BATCH-1

1

Describe with necessary equations and phasor diagram the generation of Narrow band FM(NBFM)(8M)

CO2

Explain the direct method of generating FM waves(6M)

CO2

A FM signal has sinusoidal modulation with W=15kHz and modulation index β =2. Using Carson's Rule find the transmission bandwid bandwidth th and deviation ratio. Assume ∆f =75KHz =75KHz.(2M) .(2M)

CO1

Show that the spectrum of FM contains infinite number of side bands(8M)

CO1

2 3 4

An angle modulated signal is represented by s(t) = 10cos[2π 10cos[2 πx10^6t + 5 sin2000π sin2000πt+10 CO1 sin 3000π 3000πt]volts find the following following i) frequency deviation ii) Power in modulated modulated signal 5

iii) deviation ratio iv) phase deviation v) Transmission bandwidth. An FM signal with β=1 is transmitted through an ideal BPF with midband frequency fc and BW =5fm where fc is the unmodulated carrier frequency and fm is the frequency if 6

7 8

CO1

the single tone modulating wave. determine the single tone modulating wave. Determine the amplitude spectrum of the filter output. Given J0(1)=0.765, J1(1)=0.44, J2(1)=0.115 Comparison between AM and FM.

CO2

Explain briefly Carson's Rule

CO1

Explain the implementation of phase modulator using frequency modulator and frequency modulator using phase modulator(5M)

CO2

9

BATCH-2 

 

CO2

1

Explain with relevant block diagram and mathematical expression the demodulation of FM signal using non-linear and linear model of the PLL.(1 0M)

CO2

2

Draw the block diagram of a super heterodyne receiver and explain the function of each section Explain the important properties of angle modulated waves.(5M)

CO1

A FM wave is represented by the following equation: equ ation:

CO1

3

4

5

S(t) = 10sin[5x10^8t + 4sin 1250t]. find i) Carrier frequency ii) Modulation Index and frequency deviation iii) Power dissipated by this FM wave across a 5Ω resistor. (4M) resistor. (4M) A 100MHz carrier wave has a peak voltage of 5volts. the carrier is frequency modulated CO1  by a sinusoidal modulating waveform of frequency 2KHz such that the frequency deviation is 75kHz. the modulated wave form passes through zero and is increasing at time t=0. Write the expression for frequency modulated signal. A Carrier wave of frequency 100MHz is frequency modulated by a sinusoidal wave of amplitude 20v and frequency 100kHz. the frequency sensitivity of the modulator is 25K Hz/volt. i) Find the approximate BW of the FM signal using Carson's rule. ii) Find the BW by transmitting only through sideband frequencies whose amplitude exceed 1% of the unmodulated carrier amplitude use universal curve shown below for this calculation.iii) Repeat the calculations assuming that the amplitude of the modulating signal is doubled. iv) repeat the calculations assuming the modulation frequency is doubled.

CO1

An FM wave is defined by s(t) = 10cos[2+ 10co s[2+ sin6πt]. Find the instantaneous frequency of s(t).

CO1

For a wideband frequency modulator if a narrow band carrier f1= 1MHz, second carrier

CO2

6

7

8

f2 = 10MHz,f3= 24MHz output carrier frequency = 200MHz and ∆f = 89KHz calculate

 

the multiplying factors n1 and n2 if NBFM frequency deviation is 45Hz. Draw the suitable block diagram of the modulator. 9

Difference between AM AND FM

CO1

BATCH-3

1 2 3 4

With the help of block diagram explain the working of FM stereo multiplexing.(6M)

CO2

Explain the non linear model of PLL,with relevant block diagram and derivation(5M)

CO2

Explain the working of super heterodyne receiver.(5M)

CO2

Explain the generation of wideband frequency modulated wave by Armstrong method(7M)

CO2

A block diagram of FM transmitter is shown in fig compute the maximum frequency

CO2

deviation, ∆f FM transmitter and= the frequenc y fc. if f1=100kHz, f LO frequency =84MHz =84MHz, ∆f1of=the 34Hz,n1= 76 and n2 98.carrier 98.   

5

6

7

Carrier swing of a frequency modulated signal is 70KHz and the modulating signal is 7KHz sine wave . Determine the modulation index of FM signal and Bandwidth .

CO2

A Carrier wave of frequency 100.2MHz is frequency modulated by a sinusoidal wave of amplitude 20v and frequency 100.23kHz. the frequency sensitivity of the modulator is 25.89K Hz/volt. i) Find the approximate BW of the FM signal using Carson's rule. ii) Find the BW by transmitting only through sideband frequencies whose amplitude exceed 1.5% of the unmodulated carrier amplitude use universal curve shown below for this calculation.iii) Repeat the calculations assuming that the amplitude of the modulating signal is doubled. iv) repeat the calculations assuming the modulation

CO1

frequency is doubled.

 

 

8 9

Explain the important properties of angle modulated waves.(5M)

CO1

Difference between AM AND FM

CO1 BATCH-4 

1 2 3

4

5

With neat circuit diagram explain FM demodulation using balanced slope detector.(6M)

CO2

Explain the linear model of phase locked loop(PLL)(5M)

CO2

The equation for a FM wave w ave is s(t) = 10sin[5.7x10^8t +5sin 12x10^3t].Calculate i) fc ii) fm iii) β iv) ∆f v) Pt for 100Ω (5M) (5 M)

CO1

For a wideband frequency modulator if a narrow band carrier f1= 0.1MHz, second carrier f2 = 9.5MHz, output carrier frequency = 100MHz 1 00MHz and ∆f = 75KHz calculate the multiplying factors n1 and n2 if NBFM frequency deviation d eviation is 20Hz. Draw the suitable  block diagram of the modulator.

CO2

An FM signal with β=2 is transmitted through an ideal BPF with midband frequency fc

CO1

and BW =7fm where fc is the unmodulated u nmodulated carrier frequency and fm is the frequenc frequency y if the single tone modulating wave. determind the single tone modulating wave. Determine the amplitude spectrum of the filter output. Given J 0(2)=2.65, J-1(2)=1.46, J-2(2)= -1.11, J3(2)= 0.5

6

7

WHEN A 50.4MHz carrier is frequency modulated by b y a sinusoidal AF modulating signal, the highest frequency reached is 50.405MHz calculate i)frequency deviation ii) carrier swing of the wave iii) Lowest frequency reached

CO1

A block diagram of FM transmitter is shown in fig compute the maximum frequency deviation ∆f of the FM transmitter and the carrier frequency frequenc y fc. if f1=550kHz, f LLO O

CO2

=96MHz, ∆f1 = 56Hz,n1= 47 and n2 = 89.  89.  

 

  8 9

Explain the important properties of angle modulated waves.(5M)

CO1

Explain the implementation of phase modulator using frequency frequenc y modulator and frequency modulator using phase modulator(5M)

CO2