Hands-on software defined radio experiments with the low-cost RTL-SDR dongle

Software defined radio (SDR) is an exciting merger of digital signal processing and wideband radio hardware. The term SDR came into more common usage in 1992 by Dr. Joe Mitola, but actually had its beginnings back in 1984 at E-Systems. The ideal SDR receiver consists of an antenna connected to an analog-to-digital converter (ADC) followed by a digital signal processing system (DSPS) to extract the signal of interest. Low-cost, as in $20, SDR receivers originally designed for digital video broadcasting, have been available for several years. Giving undergraduate students hands-on experience in this area is needed. In this paper we describe the details of an SDR laboratory experiment for students in a first semester communications theory course. Complete open-source SDR receiver software is used to get started, then coding of DSP algorithms is explored to process captured radio signals generated using test equipment and then actual over-the-air broadcasts. Being able to write code to process live signals and then see and hear the results really connects with the students. Both Matlab and Python support code libraries are available.