principles of communications  engineering to b.tech  jntu external question papers 2011

UNIT - I

1.      ***Draw the Block diagram of electrical communication System and explain briefly about each block.[DIAG: 4M+ EXP: 6M]

2.      **What are the Properties of Fourier Series [5 PROP: 10M]

3.      ***What are the Properties of Fourier transform. [5 PROP: 10M]

4.      ***Differentiate Analog ,Pulse &Digital Signals? [ANA:4M+PUL:3M+DIG:3M]

5.      **What is Convolution of signals? Define and prove parietal’s theorem? [CON:4M+DEF:3M+PRO:3M]

6.      **Explain about Correlation and Auto correlation of Signals. [EXP4+AUTO:6M]

7.      *Differentiate Live communication from Radio Communication?[LIVE:5M+RADIO:5M]

8.      **Find the Exponential Fourier series of the Dirac Comb. [FS:4M+DC:6M]

UNIT - II

1.      **What is meant by modulation? What is the need for modulation? [MOD:4M+NEED:6M]

2.      ***Explain about the Generation of DSB – SC Signals briefly. [DIAGRAM:4M+EXP:6M]

3.      ***Classify the Amplitude Modulated signals ad Explain the demodulation of AM waves? [DIAG:4M+EXP:6M]

4.      ***Explain the Generation and Demodulation of SSB-SC signals. [GEN:4M+DEMOD:6M]

5.      **a)List and explain any four advantages of Modulation [A::4M+B:6M]

b)Derive the Expression for Modulation index and Power required for AM & DSBSC

6.      ***With respect to envelop detector derive the following [RDE:5M+RDC:5M]

i)Rate of Decay of Envelope                             ii)Rate of Discharge of capacitor

7.      ***A voltage v= 200 (1+.4sin(w_mt))sinw_ct is applied to a resistor of 100ohms.Find the power dissipated by each of frequency components present in the voltage v. [EQU:4M+ANS:6M]

8.      **An amplitude modulated amplifier has a radio frequency . O/P of 50W at 100% modulation. The internal loss in the modulator is 10W. [I:4M+II:3M+III:3M]

i)What is the modulated carrier power?                                                                                                            

ii)What power O/P is required  from the modulator(base band signal)?

iii)if the %modulation is reduced to 75%,How much O/P s needed from the modulator

UNIT – III

1.      ***Define angle modulation How PM and FM are related?       [ANGLE:4M+REL:6M]

2.      **With the help of block diagram .Explain how narrow band FM is generated. [DIAGRAM:4M+NBFM:6M]

3.      **Explain about the indirect method for Generating FM signals. [DIAG:4M+WAVE:3M+EXP:3M]

4.      ***Explain briefly about the FM demodulation methods? [METH:4M+EXP:6M]

5.      **The linear characteristics derivation in a balanced slope detector is 3B/2, where 2B is the 3dB BW of each resonant circuit. Justify. [EXP:4M+ANS:6M]

6.      ***What is relation between FM & PM? Explain[REL:4M+EXP:6M]

7.      **How do you calculate BW of FM uses Carson’s rule? [BW FM:4M+CARSON:6M]

8.       **List out advantages of FM over AM[FM EXP:4M+AM EXP:6M]

UNIT – IV

1.      ***Classify the pulse modulation Systems. And Explain briefly about them. [PUL:4M+EXP:6M]

2.      **Explain TDM and FDM Systems.? [TDM:5M+FDM:5M]

3.      ***Explain about Generation ad Demodulation of PTM signals. [GEN:5M+DEMOD:5M]

4.      ***Compare TDM and FDM systems. [TDM:5M+FDM:5M]

5.      ***The spectral range of a function extends from 10.0MHz. Find the minimum sampling rate .the maximum sampling time. [EQU:5M+ANS:5M]

6.      **State and prove sampling theorem for band limited signal? [STATE:4M+PROVE:6M]

7.      ***With the help of block diagram explain how PPM is generated. [DIAGRAM:4M+EXP:6M]

8.      **How do you generate PAM signals ?explain. [WAVES:5M+EXP:5M]

UNIT – V

1.      ***Explain the help of block diagram explain the principle of PCM System? [DIA:5M+EXP:5M]

2.      ***What is Quantization?  And Explain about the Quantization process. [DEF:5M+EXP:5M]

3.      *Draw the Block diagram of ADM system and Explain. [DIAG:4M+EXP:6M]

4.      **Compare PCM and DM? [PCM:5M+DM:5M]

5.      **What is Companding? How Companding helps in reducing Quantization error. [DEF:4M+EXP:6M]

6.      **Explain the help of block diagram & waveforms.    explain   how DM System function. [DIAG:4M+WAV:3M+EXP:3M]

7.      ***Explain Quantization error? how does it depends on the step size? [QC:4M+EXP6M:]

8.      **What are the applications of PCM systems give in detail any two applications [PCM:4M+APPLI:6M]

UNIT – VI

1.      ***Explain FSK System in detail? [WAVES:4M+EXP:6M]

2.      ***Explain briefly about QPSK and DPSK Systems. [WAVES:5M+EXP:5M]

3.      ***Explain About ASK System. [WAVES:5M+EXP:5M]

4.      **Compare ASK and FSK?. [WAVES:5M+EXP:5M]

5.      **Derive an expression for error probability of coherent FSK scheme[EQU:5M+DIAG:5M]

6.      **List out advantages of Digital modulation over analog Modulation. [DMADV:5M+AM:5M]

7.      **Explain with neat block diagram &the waveform  generation and recover of QPSK[DIAG:5M+EXP:5M]

8.      ***Explain the Principle of DPSK Demodulator. [DIA:4M+EXP:6M]

UNIT – VII

1.      ***Define and prove Entropy. [DEF:3M+PROV:7M]

2.      **What is the Rate of Information and derive a formula for It.? [DEF:3M+DERIV:7M]

3.      **Derive expression Channel Capacity for infinite bandwidth? [EUQA:3M+DERIVA:7M]

4.      ***Define and Prove Shannon’s Theorem? [DEF:3M+PROV:7M]

5.      **Derive Coding efficiency. Show that the coding efficient s maximum when P(0)=P(1) [DERIV:4M+PROV:6M]

6.      **Explain about Shannon – Fano Coding.? [DEF:4M+DERIV:6M]

7.      **Explain about Huffman Coding. With an example? [EXPM:4M+DERIV:6M]

8.      **What is significance of coding? explain the principles of any one type of source code[CODE:4M+PRIN:6M]

UNIT – VIII

1.      ***Explain Briefly about Block & Cyclic Codes. [BLOCK:5M+CYCLIC:5M]

2.      **What are the differences between block codes and the convolutional codes? Explain[EXP:5M+EXPAMPLE:5M]

3.      **What do you understand by error control coding? Explain the various methods briefly. [ECC:5M+METHODS:5M]

4.      **What are cyclic codes? Explain the algebraic structure of cyclic codes. [CC:5M+EXP:5M]

5.      ***Compare block coder & conventional coder. [CODER:5M+CONVEN:5M]

6.      **Explain various methods for describing convolutional codes? [EXP:6M+EXAMPLE:4M]

7.      **Setch the state diagram .the tree diagram. For convolution encoder of Fig.Below also Find the free distance  of this convolution code[DIAG:5M+EXP:5M]

8.**For a (6,3) systematic linear block code, the three parity check bits C4C5C6  are formed from the following equations C4=d1(d3; C5= d1(d2(d3;C6=d1(d2 

i) write down the generator matrix. [I.EXP:5M+II.EXP:5M] 

ii)construct all possible