Experiments on Digital Filtering of Analog Signals: Pulse Amplitude Modulation and Delta Modulation

To boost students' active learning and understanding of abstract scientific concepts, hands-on learning experiences such as experiments are necessary. Computer simulations also allow students to carry out experiments virtually. Analog signals are processed using digital signal processing because of the advantages of digital signal processing over analog signal processing. Numerical experiments, results, and observations on digital band pass filtering of analog signals are presented. Two types of digital modulation are employed: Pulse Amplitude Modulation (PAM) and Delta Modulation (DM). Results demonstrated higher suppression of frequencies in the stopband compared with the transition band. Frequencies in the passband suffer minimum or no attenuation. The phase difference between input and output signals, transient response, and steady state response are observed vividly. PAM is found to add less noise to the system compared with DM. These experiments are recommended as virtual laboratory exercises for undergraduate and postgraduate studies for active learning purposes.