DIGITAL COMMUNICATION QUESTION BANK | ANNA UNIVERSITY BE ECE QUESTION BANK
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
SUBJECT CODE: EC2301 SEM / YEAR : V / III
SUBJECT NAME : DIGITAL COMMUNICATION


UNIT-1 : DIGITAL COMMUNICATION SYSTEM
Part A ( 2 Marks)
1. Give the mathematical form of sampling process
2. List out uses of sampling theorem
3. Define instantaneous sampling
4. What is anti alising effect
5. What is PWM
6. List out the types of Quantization
7. Define bandwidth.
8. Transfer 01101001 in to Manchester code
9. What is noise consideration in PCM
10. Define processing gain.

Part B
1. Drive the expression for the sampling process in time domain. (16)
2. What are all the types of sampling technique and explain about any two. (16)
3. a. Explain the generation of PPM and PWM with neat circuit diagram. (8)
b. Explain the quantization process with PCM block diagram. (8)
4. Write brief notes on 1) TDM(8 )
2) FDM (8)
5. Compare DM with ADM and explain linear prediction filter. (16)

UNIT -2 : BASEBAND FORMATTING TECHNIQUES
Part A ( 2 Marks)
1. Define matched filter
2. What is decision device
3. Draw the block diagram of base band binary data transmission system
4. What is Nyquist channel
5. Draw the frequency and time response of raised cosine spectrum
6. What you mean by correlative level coding
7. Define LMSA
8. What is DFE
9. List out the use of eye patterns
10.Define zero crossing effect

Part B
1. Derive the expression for the matched filter and prove any one property. (16)
2. Prove the effect ISI using necessary block diagram and design. (16)
3. Write brief notes on Nyquist’s criterion for distortion less base band binary transmission. (16)
4. Explain the six array PAL transmission. (16)
5. Why do we adoptive equalizer and design any one type of adoptive equalizer.

UNIT – 3: BASEBAND CODING TECHNIQUES
Part - A ( 2 Marks)
1. Define FSK
2. Draw the Basic block diagram of FSK
3. Define MFSK
4. Draw the wave form of the MPSK
5. What is MSK
6. Define Non-coherent FSK
7. Differentiate coherent FSK from Non-coherent FSK
8. What do you mean by Probability error.
9. Define Passband transmission.
10 Draw the baseband signal.

Part B
1. Derive the expression for the BPSK technique. (16)
2. Explain the MFSK and derive the pe. (16)
3. Draw the space diagram of MSK and explain about the same. (16)
4. Derive the error probability expression for the MPSK. (16)
5. Compare the all types of Passband transmission. (16)


Unit- 4: BASEBAND RECEPTION TECHNIQUES
Part A ( 2 Marks)
1. Define the Channel coding
2. List out the uses of the Channel Coding
3. Differentiate Sourced coding from the Channel coding.
4. Prove any two properties of Block Codes.
5. What is syndrome?
6. Define Code rate.
7. What is BSC?
8. Draw the channel diagram of the BPSK system
9. What is turbo codes
10. Define CRC.


Part B
1. Explain the channel coding technique used in the Block codes. (16)
2. What are all the message vectors can be extracted from the
code vector that was generated by 1+X+X3. (16)
3. Explain the Viterbi algorithm for the detection of any two
message vectors (One Word) from the code vectors that
were generated by (111), (101) and (011). (16)
4. Explain the construction of Block Code and
Explain how error syndrome is calculated. (16)
5. Explain in detail about Orthogonal codes, Biorthogonal codes and
Transorthogonal codes. (16)


UNIT- 5: BANDPASS SIGNAL TRANSMISSION AND RECEPTION
Part A ( 2 Marks)
1) What are all the types of SSM
2) What is the use of PN sequence
3) List out the prosperities of PN sequence
4) What is the processing gain of SSM.
5) Define jamming margin
6) Define FHSSM
7) Define SFHSS.
8) Define FFHSM.
9) Draw the PN sequence generator for [6,4,2,1]
10) What you mean by runs in PN sequence
11) State the Gold Theorem.

Part B
1. Generate the PN sequence for [5, 4, 3, 1] and prove the all properties of the same. (16)
2. List out and prove the Properties of the PN sequence. (16)
3. Explain the concept of DS/BPSK. (16)
4. List out the uses of the FH. Explain the FH techniques with the frequency spectrum. (16)
5. Write shorts notes on
1. Probability Error. (4)
2. Jamming Margin (4)
3. (S/N) of the DS System. (8