· Introduction. Continuous-time and discrete-time signals. Sequences. Analysis of continuous-time signals in the frequency domain: the Fourier transform. Convolution and correlation. · Digital signals: sampling and quantization. Sampling of continuous-time signals and the sampling theorem. Sampling of periodical signals. Aliasing. Reconstruction of continuous-time signals from samples and interpolation. Quantization. · Analysis of discrete-time signals in the frequency domain. Discrete-time Fourier Transform (DTFT), Discrete Fourier Transform (DFT) and FFT algorithm. Spectral characterization of sampled signals. · Linear time-invariant systems (LTI). Impulse response. Stability and causality. Systems interconnection (series, parallel, feedback). Finite-difference equations as representation of LTI systems. · Zeta transform. Definition and principal properties. Region of convergence. Analysis of LTI systems via Zeta transform. Transfer functions, poles and zeros. Frequency response. Stability condition in the Zeta domain · FIR filters. Linear phase and LTI filter with symmetrical impulse response. FIR filters design with the window method. · IIR filters. Design of digital IIR filters starting from their analog counterparts. Sensitivity to quantization of the filter coefficients.