EC2301 Digital Communication B.E Question Bank : dmice.ac.in

Name of the College : DMI College OF Engineering
Department : Electronics & Communication Engineering
Subject Code/ Name : EC2301 –Digital Communication
Degree : B.E
Website : dmice.ac.in
Document Type : Question Bank

Digital Communication : https://www.pdfquestion.in/uploads/dmice.ac.in/1722-EC2301.docx

DMI Digital Communication Question Paper

UNIT – I

PART – A :
** Give an example for time limited and time unlimited signals.
** Give the advantages and disadvantages of digital communication.
** Which parameter is called figure of merit of a digital communication system and why?
** What is meant by distortion less transmission?

Related : DMI College OF Engineering EC2304 Microprocessor And Microcontroller B.E Question Bank : www.pdfquestion.in/1736.html

** Define BER.
** What are the advantages of PAM?
** What is meant by basis set?
** What is the condition for orthogonal?
** Define noise equivalent bandwidth.
** State Dimensionality theorem.

** What is GSOP?
** Write the expression for bandwidth of digital signal.
** Write the expression for Linear filter channel.
** Draw the basic block diagram of digital communication system.
** Define Half power BW.
** Define PWM.
** How is PDM converted into PPM message?
** What the applications of dimensionality theorem?
** Why are the signals represented geometrically?
** How can BER of the system be improved?

PART – B :
** Explain how PWM and PPM signals are generated.
** Classify channels. Explain the mathematical model of any two communication channels.
** Draw a neat block diagram of a typical digital communication system and explain the function of the key signal processing blocks.
** Distinguish between base band and band pass signaling.
** Explain Binary symmetric channel and Gaussian channel with their mathematical models.
** Derive Geometrical representation of signal.
** Explain the procedure for obtaining from the basis set.
** Explain the mathematical models of communication channel.
** Explain the concept of PWM and PAM.
** Obtain the orthonormal basis function for the set of waveforms using GSOP.

UNIT – II

PART – A :
** State sampling theorem.
** What is quantization error.
** Why is prefiltering done before sampling?
** Define quantization noise power.
** State sampling theorem.
** What are the limitations of delta modulation?
** What should be the pass band for anti aliasing and smoothing filters used with pulse modulation / demodulation systems?
** Why compressors are used in PCM?
** Draw the block diagram of transmitter and receiver sections of DPCM.
** What do you understand by the term aliasing?
** A band pass signal has the spectral range that extends from 20 kHz to 82 kHz. Find the acceptable range of sampling frequency fs.
** What is the SNR of PCM system if number of quantization levels is 28?
** Define pulse position modulation scheme with a suitable diagram.
** What is the advantage of delta modulation over PCM.
** What are the two type of quantization error that occurs in delta modulation.
** Define nyquist rate.
** Compare uniform and Non uniform quantization.
** What is meant by temporal wave form encoding.
** What is the difference between DPCM and DM?
** What is the minimum BW required to transmit a PCM signal?

PART – B :
(i)Explain a uniform quantization process.
(ii)Write note on temporal waveform coding.
(i)Explain a spectral waveform encoding process.
(ii)Compare various speeches encoding method.
** Draw the block diagram of differential PCM and explain the function performed by each block.
** What is meant by slope overload distortion in DM? What is the condition to be satisfied to avoid this situation?
** With necessary sketches and expressions, briefly explain about flat top sampling.
** Derive expressions for the quantization noise and signal to noise ratio in a PCM system using uniform quantizer
** Derive the expression for SNR in PCM system and compare it with delta modulation.
** Discuss the principle of Adaptive Delta modulation in detail.
(i)Give an account of the advantages and limitations of PCM.
(ii)Explain about model based encoding.
** Draw the block diagram of adaptive subband coding scheme for speech signal and explain.