1. Communication Theory (EC ) charjee l Kumar ECE Department Rajalakshmi Engineering College EC COMMUNICATION THEORY Lecture NotesANNA UNIVERSITY ECE 5TH SEMESTER DETAILS: SUBJECT NAME. EC COMMUNICATION THEORY Lecture Notes for ECE – Fourth (4th) Semester posted by han EC Lecture Notes Syllabus.

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Lempel-Ziv coding is performed by parsing the source data into segments that are the shortest subsequences not encountered before.

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The changing value of capacitance causes the oscillator freq to increase and decrease under the control of the information signal. Carrier frequency is directly varied by the message through voltage-controlled oscillator.

One path is direct. When a set has been reduced to one symbol, of course, this means the symbol’s code is complete and will not form the prefix of any other symbol’s code.

A function of one or more independent communicatlon which contain some information. The remainder of this module will focus on FM for mobile radio. Copies of figures from the book in PDF format.

Advantages Disadvantages Better noise immunity Rejection of interfering signals because of capture effect Better transmitter efficiency Excessive use of spectrum More complex and costly circuits. Rate distortion theory can be used for the given below situations: Signals, Capacity, and Coding. Electrical Signal Output Transducer Message. The procedure is repeated until we comunication left with 2 symbols only for which 0 and 1 are assigned. Source Flow of information Destination Figure levture If we neglect the quadrature component of the signal with respect to the noise we have Hence, when carrier-to-noise ratio is small the detector has no component that is strictly proportional to the message signal m t.

Frequency modulation is a special case of angle modulation phase modulation is another special case ledture which the angle of the carrier is varied proportionately to the amplitude of the baseband signal.

### EC COMMUNICATION THEORY Lecture Notes

As long as any sets with more than one member remain, the same process is repeated on those sets, to determine successive digits of their codes. What is a signal? Here it is assumed that Ac is small as compared to r t. A popular method used for FM demodulation is the Frequency discriminator.

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Any circuit that will convert a frequency variation in the carrier back into a proportional voltage variation can be used to demodulate or detect FM signals. Then the Mutual information between the source X and the receiver Y can be expressed as: Ec2252 pre-selector is a broad tuned band-pass filter with adjustable center frequency that is tuned to the desired carrier frequency.

Basically this is achieved by assigning short descriptions to the most frequent outcomes of ontes source output and vice versa.

This is accomplished by passing message signal m tthrough the pre-emphasis filter, denoted Hpe f. This ratio is called figure of merit for the receiver and is defined as.

### Mahalakshmi Engineering College

A signal is said to be periodic, if it exhibits periodicity. This is due to audio signals having the same frequency range and receiver stations cannot distinguish the signals. Transducer — Device that converts one form of energy into another form.

A Two half adders and one OR gate questions and answers pdf, computer organization and nottes multiple choice questions with answers free download. When noise factor is expressed in decibels, it is called noise figure.

The average noise power at the receiver output is Hence we have. The autocorrelation Rw t of white noise is an impulse as shown below. The Conditional probability of an event A given the occurrence of event B is. This loss of information m t at the output of the envelope detector is called the threshold effect. This low freq signal passes nottes the RF choke L1 and is applied across the varactor diode. When low reverse biased voltage is applied, more capacitance is generated and thus decrease the frequency.

It is also separate the information from the received lectuge and sent the information to the destination.

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Data Structures Computer Organization and Architecture:. To offset this undesirable occurrence, pre-emphasis and de-emphasis technique is used.

The functions that relate the rate and distortion are found as the solution of the following minimization problem. The expression for the modulated signal is given as The carrier wave is statistically independent of the message signal.

Create a list oecture the symbols, in decreasing order of probability. It is not possible to digitally encode an analog signal with a finite number of bits without producing some distortion.

For example voice, range of frequency is 0.