Unit I Signals & Spectra Introduction to Communication System, Analog and Digital messages, regenerative repeaters, Signal Bandwidth & Power. Size & classification of signal, exponential Fourier series, concept of negative frequencies. Fourier transform and properties, Frequency shifting, Concept of baseband and bandpass signals, Signal transmission through LTI system. Signal energy & Energy Spectral density. Signal power & Power Spectral Density, Input and output PSD, PSD of modulated signal. (Chapter - 1) Unit IIAM Transmission & Reception for Single Tone Need for frequency translation, Amplitude modulation (DSB-C), Double sideband Suppressed carrier (DSB-SC) modulation, Single sideband modulation (SSB), Vestigial Sideband modulation (VSB),Spectrum and Bandwidth of AM, DSB-SC, SSB & VSB, Calculation of modulation index for AM wave, Modulation index for more than one modulating signals, Power and power efficiency, AM reception. (Chapter - 2) Unit IIIFM Transmission & Reception for Single Tone Phase Modulation (PM) and Frequency Modulation (FM), Relationship between Phase and Frequency Modulation, Modulation Index, Spectrum of FM (single tone): Feature of Bessel Coefficient, Power of FM signal, Bandwidth of tone modulated FM signal, modulation index : AM vs. FM, Spectrum of constant Bandwidth FM, Narrowband and Wideband FM. FM Modulators and Demodulators : FM generation by Armstrong’s Indirect method, frequency multiplication and application to FM, FM demodulator. (Chapter - 3) Unit IVPulse Modulation Need of analog to digital conversion, sampling theorem for low pass signal in time domain, and Nyquist criteria, Types of sampling- natural and flat top. Pulse amplitude modulation & concept of TDM : Channel bandwidth for PAM, equalization, Signal Recovery through holding.(Chapter - 4) Unit V Digital Representation of Analog Signals Unit VI Baseband Digital Transmission
