Electronics Engineering

Elements of a communication system [2 hours] * Telecommunication system. Link. User node and central node. Source node, destination node, and channel. Simplex, half-duplex and duplex transmissions. * Signal classes: continuous and time-continuos (analog), continuous and time-discrete, discrete and time-continuous, discrete and time-discrete. *Analog and digital link. Base band and pass band links. * Coder and transmission filter. Transmission speed. Analog and digital modulation. * Ideal and perfect channel. Perfect channel with additive Gaussian noise. * Filter at the receiver. Schemes for analog and digital links. * The case of band pass link. Analog and digital transmissions [6 hours] * Base band digital link. Symbol error probability. * Transmission of an analog signal on a digital link. Sampling and quantization. * Pulse shaper. TDM vs. FDM. ZR and NZR transmission modes. * Nyquist conditions in time and frequency domains. * Multilevel communications * Eye diagram. Time and amplitude measurements: eye opening and width. Circuital schemes for signal transfer over physical transmission media [6 hours] * Linear time-invariant systems [filters]. Transit relationships for base band and pass band signals. * Generator, load, 2-ports (2P) networks and corresponding description models. * Difference between power or energy of a signal (and corresponding spectrum densities), and power or energy absorbed by a load (and corresponding spectrum densities). Long term and short term energy and power absorbed by a resistor and corresponding spectrum distributions. Generalization of the concept of energy and power (and corresponding density spectra) to the case of a generic load. Logarithmic units for power measurement and power ratio measurement. * Connection between generator and load: conditions for impedance matching vs. maximum power transfer. Connection between generator and load through a 2P network: transfer function (absolute value, phase and group delay) and power related aspects (power gain vs. available gain). Noise [6 hours] * Characterization of thermal noise in generators, loads and both active and passive 2P networks. Noise figure. Noise in a chain of 2P networks. Transmission of bandpass analog and digital signals [12 hours] * Baseband and passband signals, analytic signal and complex envelope. Transfer through filters. * Introduction to modulation. Modulation over sinusoidal vs. impulsive carrier. Characterization of a modulated signal by means of its I and Q components. Instantaneous phase and frequency of a signal. Extraction of I and Q components with synchronous demodulation schemes. * Amplitude modulation: DSB-FC, DSB-SC, SSB, RSB, and corresponding power spectrum densities as a function of total signal power. * Angle modulation: phase and frequency modulation. Power spectrum densities of angle modulated signals in the case of a sinusoidal modulating signal and of a modulating signal obtained as a realization of a stationary Gaussian process; Carson formula for RF bandwidth occupation of a FM signal. * Digital modulation: amplitude modulation schemes [ASK, OOK, QAM] and angle modulation schemes [PSK, FSK]. Transmission media [16 hours] * Symmetric and coaxial transmission lines. Equivalent circuital scheme for a transmission line. Impedance matching conditions in the general case and in the special case of long lines. * Propagation characteristics and signal impairments caused by twisted pairs and coaxial cables. * Fiber optics. Path loss and temporal dispersion. * Thermal and quantum noise. * Characteristics of PIN vs. APD photodetectors; signal-to-noise ratio for both thermal and quantum noise as a function of emitted optical power. * Wireless transmissions. * Propagation characteristics of a wireless link under ideal conditions. Antenna gain and free space path loss. Performance evaluation [12 hours] * Performance evaluation for analog transmissions using amplitude and frequency modulation. Performance evaluation for passband digital communications. Bit error probability for a QAM radio link.

Knowledge of signal theory

Comunicazioni Elettriche - Fondamenti, Maria-Gabriella Di Benedetto, Pearson Prentice Hall, ISBN 978-88-7192-332-1, 1a edizione: settembre 2007. Comunicazioni Elettriche - Esercizi e temi d'esame, Maria-Gabriella Di Benedetto, Daniele Domenicali, Luca De Nardis, Pearson Prentice Hall, ISBN 978-88-7192-331-4, 1a edizione: giugno 2007 Lecture slides, scientific articles and practice work material available at http://newyork.ing.uniroma1.it/~lucadn/comel1.php

The course is structured in lectures that treat course topics. Lectures introducing each topic are complemented by lectures in which the topic is analyzed as part of design and dimensioning of a communication link. Depending on the directives provided by Sapienza during the semester, classes are held either in presence or remotely on Zoom at the link https://uniroma1.zoom.us/j/88345130247?pwd=cTViNUtaZGtDTFdBR3FrcmVsMVBiUT09

Course attendace is optional, but strongly recommended.

The exam for Comunicazioni Elettriche I is composed of a written test followed by a discussion. The written test is designed so to allow the instructor to evaluate the skills acquired by the student regarding both system design and theoretical aspects, and typically consists in a link budget problem possibly complemented by a set of questions on selected course topics. Students are not allowed to use textbooks, but they can prepare and bring a "cheating card", that is a paper sheet of size up to 1/4 of an A4 sheet, on which they can write (on both sides) anything they deem useful for the written test. Students can also use a calculator (but not the calculator app on mobile phones). The oral discussion completes the written test, and may consist in a discussion of the result of the written test. Students are required to show a valid ID in order to participate in the exam.

The course is structured in lectures that treat course topics. Lectures introducing each topic are complemented by lectures in which the topic is analyzed as part of design and dimensioning of a communication link. Depending on the directives provided by Sapienza during the semester, classes are held either in presence or remotely on Zoom at the link https://uniroma1.zoom.us/j/88345130247?pwd=cTViNUtaZGtDTFdBR3FrcmVsMVBiUT09