Introduction, Basic principles, Simplified model of a telecommunication system. Signals and systems. Fourier series and transform. Random signals, Stochastic processes. Frequency domain analysis of signals and systems, Elementary filters, Spectral density. Noise theory, Limitations in communications. Analog modulation systems AM, AM-DSB-SC, AM-SSB. Angle modulation, phase modulation, frequency modulation. Implementation of modulators and applications. Effect of noise on modulation systems. Digital transmission of analog communications, Source coding, Quantization, PCM, DPCM, Delta modulation, Channel models. Digital transmission through the Additive White Gaussian Noise (AWGN) channel, Pulse amplitude modulation, PAM, Digital modulation. Digital transmission through bandlimited AWGN channels, Intersymbol interference and suppression methods, Elements of information theory.