Digital Communication- QB

8/12/2019 Digital Communication- QB

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EASWARI ENGINEERING COLLEGE

DEPARTMENT OF ECE

QUESTION BANK

SUBJECT CODE : EC2301 DEGREE/ BRANCH : B.E /ECESUBJECT NAME : DIGITAL COMMUNICATION YEAR/SEMESTER/SEC: III/ V/ A & CSTAFF NAME : B.JESVIN VEANCY

UNIT I

PART A

1. Classify communication channels. [May 2014]

2. State the demerit of digital communication. [May 2014]3. Mention the advantages of digital communication. [Nov 2013]

4. hat is a channel! "ive e#am$les. [Nov 2013]

%. State the advantages and disadvantages of digital communication systems over analogcommunication systems. [May 2013]

&. State the classification of channels. [May 2013]

'. (ra) a ty$ical digital communication system. [Nov 2012]*. +o) can ,- of a system /e im$roved! [Nov 2012]

. "ive an e#am$le for time limited and time unlimited signals. [M 2011]

10. "ive the advantages and disadvantages of digital communication [May 2011]

11. (ra) the /asic /loc diagram of digital communication system. [N5 2011]12. (efine +alf $o)er /and)idth6 [N5 2011]

13. hat is meant /y distortion less transmission! [N5 2010]

14. hich $arameter is called figure of merit of a digital communication systemand )hy! [N5 2010]

1%. (efine ,-

1&. hat are the advantages of 7M!1'. hat is meant /y /asis set!

1*. hat is the condition for orthogonal!

1. (efine noise e8uivalent /and)idth20. State (imensionality theorem

21. hat is "S7!

22. rite the e#$ression for /and)idth of digital signal.

23. rite the e#$ression for 9inear filter channel.

PART-B

1. :i;(ra) the /loc diagram of a digital communication system. -#$lain each /loc :*;.

:ii; (iscuss the advantages of digital communication over analog communication :*;.[May 2014]

2. :i;(efine /asis set. +o) they are useful in re$resenting a signal! :*;


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:ii; ith an e#am$le6 e#$lain ho) the /asis set is determined /y gram Schmidt

$rocedure. :*; [May 2014]

3. :i;-#$lain the various analog $ulse communication system descri/ing their advantages

and dra)/acs.:*;

:ii;(escri/e ho) channels can /e classified and /rief e#$lain each.:*; [Nov 2013]4. :i;(escri/e the elements of a digital communication system.:*;

:ii;-#$lain the mathematical models of various communication channels:*;[Nov 2013]

%. -#$lain any one analog $ulse communication system. [May 2013]

&. (iscuss the characteristics of various discrete communication channels. [May 2013]

'. -#$lain "ram Schmidt orthogonalisation $rocedure. [Nov 2012]

*. :i;-#$lain any three communication channel. :12; [Nov 2012]:ii; State the advantages and disadvantages of a digital communication system :4;

. -#$lain ho) 7M and 77M signals are generated.:1& ; [M 2011]

10. Classify channels. -#$lain the mathematical model of any t)o communication channels

:1&; [M 2011]11. -#$lain in detail "ram Schmidt orthogonalisation $rocedure. [Nov 2011]

12. (iscuss in detail the different mathematical models of communication channel.[Nov 2011]

13. (ra) a neat /loc diagram of a ty$ical digital communication system and

e#$lain the function of the ey signal $rocessing /locs.: 1&; [Nov 2010]14. (istinguish /et)een /ase /and and /and$ass signaling. :&;

1%. -#$lain ,inary symmetric channel and "aussian channel )ith

their mathematical models. :10; [Nov 2010]

1&. (erive "eometrical re$resentation of signal.:*;1'. -#$lain the $rocedure for o/taining from the /asis set.:*;

1*. -#$lain the mathematical models of communication channel.

1. -#$lain the conce$t of 7M and 7M.20. /tain the orthonormal /asis function for the set of )aveforms using "S7.

UNIT-II

PART-A

1. hat is the need for non uniform 8uanti


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*. (ifferentiate the $rinci$les of tem$oral )aveform coding and model /ased coding.

[Nov 2012]

. State sam$ling theorem. [May 2011]10. hat is 8uanti


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%. :i;-#$lain a 7CM system. (erive the e#$ression for 8uantiS;

21. ith neat /loc diagram6 e#$lain in detail a/out delta modulation and the ty$es of8uantiS;

22. ith necessary setches and e#$ressions6 /riefly e#$lain a/out flat to$ sam$ling.

:7@M200%6* M>S;

23. ith su$$orting derivation $rove that if a signal contains no fre8uencies higher than hertS;

24. (erive e#$ressions for the 8uantiS;

2&. (erive the e#$ression for SN in 7CM system and com$are it )ith delta modulation.

-#$lain ho) SN can /e im$roved in a 7CM system.:M@EFN200&610 M>S;


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2'. Sho) that $redication error variance is less than the variance of the $redicator in$ut for

$redictior of order 1 :M@EFN- 200& & M>S;

2*. -#$lain the $rinci$le of delta modulation and derive an e#$ression for average out$utnoise $o)er in delta modulation. :M@EFN200&6* M>S;

2. -#$lain the $rocess of 8uantisation6 encoding and decoding in 7CM! Jn )hat )ay (7CM

is /etter than 7CM! :M @ EFN- 200';

30. -#$lain uniform and non uniform 8uantisation :4 mars= 7@M200*;31. :i; "ive the /loc diagram of differential $ulse Code Modulation Scheme and e#$lain the

$rinci$les in detail :7@M 200* Mars;

a. :ii; /tain an e#$ression for the $rocessing gain of a (7CM system

:7@M 200* 4 M>S;/. :iii; Su$$ose an e#esting standard 7CM system for voice signal is re$laced /y a

(7CM of $rocessing gain &d,6 )hile maintaining the :SN;@ hat )ill /e the

reduction in the /it rate achieved /y (7CM!:7@M 200* 3 M>S;32. :i; Gor a uniform 8uanti


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:3; (etermine the out$ut signal to 8uanti


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2'. rite 4 features of linear /loc codes :7@M200*;

1%.(efine +amming distance of a /loc code. :N5@(-C 200*;

1&.Sho) that the code C?R000610060116111 is not cyclic. :N5@(-C 200*;1'.(efine +amming distance and hamming )eight :M@EFN-200;

1*.hat are the error detection and error correction ca$a/ilities of +amming Code!

:M@EFN- 200;1.hat are the fundamental $ro$erties e#hi/ited /y cyclic codes! :M@EFN-200;

2*. (efine /loc ho$$ing. :M@EFN-200;

2. Mention the $ro$erties of cyclic code. [N5 2011]30. (ra) the O=,i$olar line code format for the information R 10110 . [N5 2011]

PART-B

1. -#$lain the viter/i algorithm assuming a suita/le Convolutional coder and received /it

stream.:1&; [May 2014]

2. :i; ,rief a/out any one decoding $rocedure of linear /loc codes.:*;

:ii; Gind a generator $olynomial for a :'6 4; Cyclic code and hence find the code)ord for [1 0 0 0].:*; [May 2014]

3. (escri/e the ste$s involved in the generation of linear /loc codes. (efine and e#$lainthe $ro$erties of syndrome.:1&; [Nov 2013]

4. :i;-#$lain ho) convolution codes can /e generated. Jllustrate )ith an e#am$le.:*;

:ii;Gor a convolution encoder of contrains length * and rate P o/tain the encoded

out$ut for the in$ut message[1 0 0 1 1] [Nov 2013]%. -#$lain 5iter/i algorithm to decode a convolutionally coded message. [May 2013]

&. (erive and dra) the $o)er s$ectra of a NO6

:i; $olar coded )aveform :ii; ,i$olar coded )aveform. [May 2013]:ii; (erive the e#$ression for $o)er s$ectral density of uni$olar NO line code. +ence

discuss its characteristics. [Nov 2012]'. :i; (esign a /loc code for a message /loc of si


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13. -#$lain ho) encoding is done /y convolutional codes )ith a suita/le e#am$le

[M2010]

14. -#$lain tree diagram6trellis diagram and state transition diagram of convolutional codes1%. rite the generator matri# and $arity chec matri# of :'64; hamming code.

:7@M20046& M>S;

1&. (escri/e a decoding $rocedure for linear /loc code. :7@M20046& M>S;1'. (ra) the /loc diagram of rate P convolutional encoder )ith constraint length 3. hat is

generator $olynomial of the encoder! Gind the encoded se8uence you have dra)n6

corres$onding to the message :10011;. :7@M2004612 M>S;1*. /tain the trellis diagram of the encoder that you have dra)n.:7@M200%64 M>S;

1. (ra) the diagram of the P rate convolutional encoder )ith generator $olynomialQ g:1;

:(;?1I( and g:2;:(;?1I(I(2 . nd com$ute the encoder out$ut for in$ut se8uence

101101. :N5@(-C2004610 M>S;20. hat is meant /y free distance of a convolutional code! +o) does it affect the num/er of

errors that can /e corrected and coding gain! :N5@(-C20046& M>S;

21. ,riefly e#$lain the viter/i=decoding algorithm.

:7@M200%LM@EFN200%67@M200*;22. (escri/e in detail a/out linear /loc codes. :7@M200%L M@EFN200&64 M>S;

23. Consider a rate P 6 non systematic convolutional code )ith6 g:1;? R16061 and g:2;?R16161.(etermine the encoder out$ut corres$onding to the data se8uence R160616061. Jf the first

and the fourth /its of the encoded se8uence are affected during transmission6 demonstrate

the error correcting ca$a/ility of the viter/i algorithm. :N5@(-C200%61& M>S;24. :1%6%; linear cyclic code has a generator $olynomial6 g:(;?1I(I(2I(4I(%I(*I(10

(ra) the /loc diagrams of an encoder and syndrome calculator for this code. Gind the

code $olynomial in the systematic form6 for the message $olynomial m:(;?1I(2I(4.

Js y:(;?1I(4I(&I(*I(146 a code $olynomial! Jf not6 find the syndrome of y:(;.:N5@(-C200%61& M>S;

2%. "enerate the code )ords for :'64; hamming code. :M@EFN200&6 * M>S;

2&. State and $rove the $ro$erties of syndrome decoding.:7@M200%6& M>SL M@EFN200&6* M>S;

2'. -#$lain the features of S code. :7@M200464 M>S;

2*. -#$lain any four characteristics of the follo)ing /loc codes :i; ,C+ codes :ii; CCcodes :iii; ma#imum length codes. :N5@(-C20046 12 M>S;

2. Gind the generator and $arity chec matri# for :%61; re$etition code.

:N5@(-C200464 M>S;

30. -valuate the syndromes for all five $ro/a/le signal error $atterns in :%61; re$etitioncode. :M@EFN200&6& M>S;

31. 9et g:#; /e the generarator $olynomial of a cyclic code C. Gind a scheme for encoding

the data se8uence:d0 6d16 d26 U. d=1 ;into an :n6; systematic code C.:M@EFN-6200'@1&M>S;

32. "ive the details of im$lementation of cyclic encoder and decoder /ased on linear

feed/ac shift registers :N5 @(-C200';

33. (iscuss the convolutional decoder algorithm in detail for the encoder of constraint

length 3 and code rate P. :N5 @(-C200';


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34. 7rove that the minimum distance of a linear /loc code is e8ual to the minimum )eight

of any non


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'. &4 /$s /inary 7CM $olar NO signal is $assed through a communication system

)ith a raised=cosine filter )ith roll=off factor 0.2%. Gind the /and)idth of the filtered

7CM signal. [Nov 2012]*. State any t)o a$$lications of eye $attern. [Nov 2012]

. hat is a matched filter! [M 2011]

10. "ive 2 a$$lication for eye $attern! [M 2011]11. hat is the need for a demodulator in case of /ase/and signaling )hen the received are

already $ulselie )aveforms [N5 2010]

12. +o) does $ulse sha$ing reduce JSJ13. hat does the term e8uali


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3. :i;(escri/e )ith a diagram the functioning of a correlator ty$e receiver:*;.

:ii;-#$lain the e8uivalence /et)een correlator and matched filter receiver. :*; [Nov 2013]

4. (escri/e coherent detection using ma#imum liehood detector:1&; [Nov 2013]

%. (erive the e#$ression for /it error $ro/a/ility of a /inary signal detected )ith amatched filter. [May 2013]

&. (erive and -#$lain the Ny8uist first criterion to minimiS;

1*. hat is meant /y the ideal ny8uist channel! hat are its merits and limitations!

:N5@(-C20046* M>S;1. (ra) the /loc diagram of the duo /inary signaling scheme and derive the overall

fre8uency res$onse of this scheme. :N5@(-C20046 N5 @(-C200';

20. (erive the e8uation for the im$ulse res$onse coefficients of the SL M@EFN200&6* M>S;

23. /tain an e#$ression for ny8uist criterion for distortion less /ase /and transmission for

S;

24. rite /riefly a/out eye $attern and ada$tive e8ualiSL M@EFN200&6* M>S;

2%. hat you understand /y intersym/ol interference :JSJ;! (iscuss in detail the ny8uist

criterion for minimiS;

2&. (iscuss the merits and demerits of duo /inary signaling. :N5@(-C200%6& M>S;

2'. Ahe /inary data :0 1 1 1 0 0 1 0 1; are a$$lied to the in$ut of a duo /inary encoder.Construct the duo /inary encoder out$ut and the corres$onding receiver out$ut6 )ithout

$recoder. Su$$ose due to error during transmission6 the level $roduced /y 3rddigit is

reduced to S;

2*. (iscuss on :i; da$tive e8uali


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i. :ii;,ase /and /inary 7M system. :M@EFN-200';

2. Com$are ,ase /and /inary 7M system )ith ,GS>. :N5 @(-C200';

30. (erive the e#$ression for $ro/a/ility of error for matched filter.:*; :N5 @(-C200';31. (ra) the /loc diaram of ada$tive e8ualisation and e#$lain.:*; :N5 @(-C200';

32. -#$lain Ny8uist solutions to avoid JSJ. :7@M200*;

33. (esign a 3=ta$ e8uali system maes errors at the average rate of 100 errors $er day. (ata rate is 1

/$s. Ahe single=sided noise $o)er s$ectral density is 10=10@+ )aveform for 011011 [M 2011]

10. hat is a non coherent detection system [M 2011]

11. hy is 7S> al)ays $refera/le over S> in coherent detection! [N5 2011]

12. (ifferentiate /et)een coherent and non=coherent detection [N5 2011]


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13. (efine M and dra) its constellation diagram [N5 2010]

14. /inary shift eying system em$loys 2 signalling fre8uencies f1 and f2. the lo)er

fre8uency is 1200h< and signaling rate is %00 /aud calculate f2 [N5 2010]1%. Jn minimum shift eying )hat is the relation /et)een the signal fre8uencies and /it rate!

:7@M2004;

1&. rite the e#$ression for /it error rate for coherent /inary GS>. :N5@(-C2004;1'. ,ring out the difference /et)een coherent and non=coherent /inary modulation schemes.

:7@M200%;

1*. hat is the error $ro/a/ility of MS> and (7S>! :7@M200%;1. +ighlight the maZor difference /et)een 7S> signal and a MS> signal.:N5@(-C200%;

20. Com$are the $ro/a/ility of error of 7S> )ith that of GS>. :M200&6 N5 @(-C200';

21. State the difference /et)een coherent and non=coherent /inary modulation techni8ues.

:M@EFN200&;22. hat do you understand /y continuous $hase fre8uency shift eying! :M@EFN200';

23. "ive the signal s$ace re$resentation of 7S> :N5 @(-C200';

24. hat is a matched filter! :7@M200*;

2%. hat is the need for synchroni6 7S>6 M6 7S> and

GS> signals. [Nov 2012]*. Com$are the $erformance of various coherent and non=coherent digital detection

systems. [Nov 2012]

. (erive the /it error $ro/a/ility due to coherent S>67S> GS> systems. Com$are the

7erformance [M 2011]


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10. (iscuss 7S> Signalling

11. (iscuss /it error $ro/a/ility due to 7S> receiver.Com$are it )ith 7S> receiver.

[M 2011]12. (istinguish coherent and non coherent scheme [N5 2010]

13. (iscuss Noncoherent detection method of ,GS> Signalling [N5 2010]

14. hat do you understand /y coherent detection! :7@M200462 M>S;1%. (iscuss the method of /it synchroniS;

1&. (ra) the /loc diagram of 7S> transmitter and coherent 7S> receiver and e#$lain

their o$eration. :7@M2004610 M>SLM@EFN200&6 N5 @(-C200';1'. Com$are the ,- of coherent 7S>6 coherent 7S> and coherent GS>.

:7@M20046& M>S;

1*. (ra) the /loc diagram of MS> transmitter and e#$lain the function of each /loc.

:N5@(-C20046* M>S;1. -#$lain ho) MS> signal is o/tained from C7S> signal! :N5@(-C20046* M>S;

20. ith necessary e8uations and signal s$ace diagram6 o/tain the $ro/a/ility of error for

coherent /inary GS> systems. :7@M200%612 M>S;

21. (ra) the /loc diagram of a 7S> receiver and e#$lain its )oring. :M200%64M;22. ith neat /loc diagram6 e#$lain /riefly ho) sym/ol synchroniS;23. (iscuss /riefly a/out minimum shift eying for a C7S> signal.

:7@M200%LM@EFN200&6* M>S;

24. -#$lain ,7S> signal transmission and coherent ,7S> rece$tion )ith suita/le diagrams.(erive an e#$ression for the $ro/a/ility of sym/ol error for the scheme.

:N5@(-C200%61& M>S;

2%. ith necessary e8uations and signal s$ace diagram6 e#$lain /riefly a/out GS> system.

:M@EFN200&6 N5 @(-C200'6 7@M200*;2&. /tain $ro/a/ility of error in terms of -/@N0 for 7S>.:M@EFN200&6 7@M200*;

2'. (ra) the /loc diagram of MS> transmitter and e#$lain the function of each /loc)ith

the constellation diagram. :M@EFN-6200'@ 1&M>S;2*. hat are the advantages and disadvantages of MS> as com$ared to 7S> system!:&;

:N5 @(-C200';

2. :1;-#$lain carrier synchroni signal.:&;30. :ii;-#$lain the detection of /inary GS> signal )ith /loc diagram.:';

31. :iii;-#$lain /inary 7S> signal )ith geometrical re$resentation.:3; :N5 @(-C200';

32. -#$lain the )oring of carrier synchroni transmitter and receiver and e#$lain the functions ofeach /loc. (ra) the constellation diagram. (erive $ro/a/ility of error.:N5@(-C 200*;

34. ,inary data are transmitted over a micro)ave lin at the rate of 1 M/$s and the 7S( of the

noise at the receiver in$ut is 10=10@+ and (7S>. :4;

Coherent GS> and non=coherent GS>. :4;

Coherent 7S> and 7S>. :4;


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Coherent GS> and coherent MS>. :4;

:N5@(-C 200*;

3%. -#$lain the generation6 detection6 signal s$ace diagram6 /it error $ro/a/ility and $o)ers$ectra of 7S>. :1&; :M@EFN- 200;

3&. :i; -numerate on carrier and sym/ol synchroni

Digital Communication- QB

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