"Digital Communication Laboratory" Courseware

Digital Communication Laboratory

By Professor Lee C. Potter
Dr. Yang Yang
Electrical and Computer Engineering
The Ohio State University

The laboratory course provides hands-on exploration of physical layer communication. Through a sequence of guided explorations, students design and implement a digital communication system with modulation to an acoustic carrier frequency. The materials are designed to support both a structured laboratory course and self-study; the course is intended for upper-level undergraduates and assumes a prerequisite course in signals and systems. Acoustic operation allows students to hear, see, and wirelessly transmit signals using readily available, low-cost hardware, such as a PC with sound card or a smartphone. Acoustic wireless transmission, while readily accessible, nonetheless presents a student with the channel impairments and synchronization issues encountered in radio frequency systems. An accompanying smartphone app provides an acoustic transmitter for receiver testing and is available for free download. MATLAB files provide code for creating examples and figures found in the text.

Learning Outcomes

• Students master concepts of sampling, aliasing, filtering, and quadrature modulation through implementation of a software-defined acoustic modem.
• Students master signal space representation of digital modulation for phase-shift keying.
• Students design and implement a pulse shape and matched filter to avoid inter-symbol interference and maximize receiver SNR.
• Students implement timing, phase, and frequency recovery for flat-fading channels as examples of combating channel impairments.
• Students advance their skills in creating structured software, debugging, and experimentation. 
• Through supplemental exercises, students may implement: a linear equalizer for inter-symbol interference channels; a block code for forward error correction; orthogonal frequency division multiplexing (OFDM); and, phase tracking.  Additionally, suggestions are provided for low-cost modulation of the acoustic signal to radio frequencies.