Radio receiver signal processing using hands on hardware experiments

A first course in communications theory requires students to take seriously Fourier theory and spectral analysis. In the laboratory portion of the course the students learn to appreciate the spectrum analyzer as tool for seeing into the frequency domain with real signals. In this paper we explain how the study of radio receiver signal processing can be used to build up a student´s understanding of the Fourier transform frequency translation and modulation theorems and superheterodyne receiver design. Mathematical modeling is the foundation of receiver design, but seeing it really work is very satisfying. The experience of seeing real signal spectra at receiver test points on the spectrum analyzer plus hearing the station is invaluable. The student gets to experiment with frequency translation using both high-side (f_LO above the carrier f_c) and low side (f_LO below the carrier f_c) tuning.