EC DC 2marksmarks, DIGITAL COMMUNICATION Question Bank, DC Short Answers – ECE 5th SEM Anna University. 0. By vish on. 2. DIGITAL COMMUNICATION. State sampling theorem. If a finite –energy signal satellite communication two marks question and answers QUESTION BANK. Subject Code: EC Subject Name: Digital Communication Techniques. Year/Sem: III/IV. UNIT I PULSE MODULATION. PART A (2 Marks).

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They need error correction.

EC2301 Digital Communication Question Bank – 16 Mark Questions | 5th Semester ECE Anna University

Adaptive coding is used for speech coding at low bits rates. Code tree indicates flow of the coded signal along the nodes of the tree. Hence a PPM pulse of fixed width is commnuication after falling. The decoding delay is small in convolutional codes since they operate o smaller blocks of data.

There is no analog to digital converter involved in delta modulation. Explain the model of bandpass digital data transmission system? Optical Communication and Networks Question Bank This equation shows that error probability depends only on energy but not on shape of the signal.


What are the advantages of convolutional codes? In mwrks sequence spread spectrum modulation, the pseudo-noise sequence is directly modulated with data sequence.

What is matched filter? The locally generated carrier is in exact phase with the transmitted carrier. This secrecy capability of spread spectrum is used in military as well as in many commercial applications. Free distance is the minimum distance between code vectors.

What is its Fourier Transform? Pseudo noise sequence is a noise like high frequency signal. Write a note on correlative level coding?

These systems bandwidth spreads are very large. Hence quantization error is significantly reduced due to the adaptive quantization. In Ed2301 frequency of the carrier is switched according to input bit sequence. What is nyquist Bandwidth?

This is called quantization. BCH codes are most extensive and powerful error correcting cyclic codes. This operation is equivalent to binary convolution coding.

Application i Multipath access capability. What are the two limitations of delta modulation? Constraint length is the number of shift over which the single digitla bit can influence the encoder output.

EC Digital Communication – Two Marks and 16 Marks with Answers – All Units

The sequence is not completely ex2301, but it is generated by well defined logic. The pseudo-noise sequence and data sequence are applied to a product modulator.


How does Granular noise occurs? What is the value of maximum signal to noise ratio of the matched filter?

PN sequence 2 Effect of distance This system is distance relative Effect of distance is less in this system 3 Acquisition time Acquisition time is long Acquisition time is short Hence the technique is called Differential PSK.

The presence of outputs due to other bits interference with the output of required bit. Define spread spectrum communication Ans: Spread spectrum systems are essentially synchronous. The pseudo noise sequences generated at the receiver and the transmitted must be same and.

What is pseudo noise sequence? Let the PAM signal ak represents kth bit. Code tree is lengthy way of representing coding process.