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SYLLABUS

UNIT-I

Introduction Elements of communication systems, Information, Messages and signals, Modulation, Modulation methods, Modulation benefits and applications. Amplitude modulation & demodulation Baseband and carrier communication, Amplitude modulation (AM), Rectifier detector, Envelope detector, Double sideband suppressed carrier (DSBSC) modulation and its demodulation, Switching modulators, Ring modulator, Balanced modulator, frequency mixer, Sideband and carrier power of AM, Generation of AM signals, Quadrature Amplitude Modulation (QAM), Single sideband (SSB) transmission, Time domain representation of SSB signals and their demodulation schemes (With carrier, and suppressed carrier), Generation of SSB signals, Vestigial sideband (VSB) modulator and demodulator, Illustrative problems.

UNIT-II

Angle modulation and demodulation Concept of instantaneous frequency, Generalized concept of angle modulation, Bandwidth of angle modulated waves – Narrow Band Frequency Modulation (NBFM), Wide band FM (WBFM) Phase modulation, Verification of frequency modulation bandwidth relationship, Features of angle modulation, Generation of FM waves. Indirect method, Direct generation, Demodulation of FM, Bandpass limiter, Practical frequency demodulators, Small error analysis, Pre-emphasis and de-emphasis filters, FM receiver, FM capture effect, Carrier acquisition - Phased Locked Loop (PLL), Costas loop, Frequency Division Multiplexing (FDM), and super-heterodyne AM receiver, Illustrative problems.

UNIT-III

Noise in communication systems Types of noise, Time domain representation of narrowband noise, Filtered white noise, Quadrature representation of narrowband noise, Envelope of narrowband noise plus sine wave, signal to noise ratio and probability of error, Noise equivalent bandwidth, Effective noise temperature and noise figure, Baseband systems with channel noise, Performance analysis (i.e., finding SNR expression) AM, DSB-SC, SSB-SC, FM, PM in the presence of noise, Illustrative Problems.

UNIT-IV

Analog pulse modulation schemes Pulse amplitude modulation – Natural sampling, Flat top sampling and Pulse Amplitude Modulation (PAM) and demodulation, Pulse time modulation – Pulse duration and pulse position modulation and demodulation schemes, PPM spectral analysis, Illustrative problems. Radio receiver measurements Sensitivity, Selectivity and fidelity.

UNIT-V

Information and channel capacity Introduction, Information content of message, entropy, Entropy of symbols in long independent and dependent sequences, entropy and information rate of markoff sources, Shannon’s encoding algorithm, Discrete communication channels, Rate of information over a discrete channel, Capacity of discrete memoryless channels, Discrete channels with memory, Shannon – Hartley theorem and its implications, Illustrative problems.