EC8501 Digital Communication Notes

1. Information rate is represented in average number of bits of information per second.

2. The two code was of the linear code for added by model to arithmetic then it produce 3rd code word in the code.

3. The syndrome depends only on the error pattern and not on the transmitted code word.

4. The number of ones complement are once codeword of the hamming code is called hamming weight.

5. The bandpass digital data transmission system consists of source encoder and modulator in the transmitter.

6. The career synchronization is required in core and detection method to generate component reference at the receiver.

7. The local carrier generated at the receiver is phase locked with the carrier at the transmitter.

8. Eye pattern is used to study the effect of ISI in baseband transmission.

9. The optimum linear receiver is Realised with the help of zero forcing equalizer.

10. Juman ear does not receive the noise in the given frequency band with if it is 15db below the signal level in the band.

EC8501 Digital Communication Notes

11. Adaptive quantizer changes its step size according to variance of the input signal.

12. Delta modulation includes one bit per sample hence Signalling rate is reduced in DM.

13. The sample of Contessa output and prediction error are used to derive estimates of predictor question is called order prediction with backward estimation.

14. Variable length coding is done by source encoder to get higher efficiency.

15. Shannon fano algorithm is used to encode the messages depending upon the probabilities.

16. Slope overload distortion occur mainly due to fixed step size S that cannot follow the rate of rise of input signal.

17. The minimum distance of the linear block code is equal to minimum weight of any non zero in the code.

18. Ninimum variance Huffman code can be obtained by placing combined probabilities as high as possible.

19. The mutual information is defined as the amount of information transferred when Xi it is transmitted and Yi is received.

20. Entropy will be maximum when all the messages have sample probabilities of occurrence.

21. The first as well as amplitude of the quadrature carrier is small letter is called quadrature amplitude phase shift keying QAPSK.

22. The demodulator output is quadrature into more than two level as decoder operates on soft decision made by demodulator.

OVERVIEW SYLLABUS OF EC8501 Digital Communication Notes

 Unit 1

Unit 2 Name is information theory discrete memoryless source important basic problems. what is entropy and its channel capacity the basic concepts related to information contained in this unit. what is memoryless channel, what is mutual information in digital communication all the basic concepts contains in unit 1 this is one of the most important easiest unit in digital communication.

Unit 2

Unit 2 Name is waveform coding and representation. this is all about protecting filter and DPCM data bipolar and unipolar power spectral density this all basic concepts contains in this you need to know, what is waveform coding and representation. what is delta modulation and adaptive delta modulation basic principles contains in this unit 2.

Unit 3

Baseband transmission, what is baseband pulse shaping, coding eye pattern is one of the most important 16 mark in university exam.

Unit 4

Geometrical representation of signals this unit contains basic signal examples its like what is signal, what is error signal, what is continuous signal, what is discrete signal, what is QAM QPSK BFSK DPSK this basic frequency contains in this unit.

Unit 5

Error control coding channel, coding theorem, linear block codes hamming codes cyclic codes conversion cost with the coding decoding is one of the most important 16 mark in in university point of view. this is very basic questions and answers as very important question in University exam point of view if you study that question definitely you will get 10 marks in your digital communication paper this question they will ask in both part b and part C if they ask as compulsory question if you studying this question definitely ask in exam for digital communication subject.