Software-Defined Radio
An Activity in LIVE-M Laboratory
Principle Investigator
Professor William Birmingham
Chair, Computer Science Department
Grove City College
wpbirmingham@gcc.edu
724 458 3794
Overview
Software-defined radio (SDR) is an important technology that underlies many modern wireless communications
systems. For example, most cell-phone handsets and wireless routers are based on SDR technology. This
technology is popular among computer scientists, with several interesting software projects underway, such as the
GNU radio and FlexRadio’s SDR 1000 and SDR 5000.
Essentially, SDR replaces much of the electronics in a radio with software. By substituting many hardware
components for software, SDR provides flexibility with baseband waveforms, frequencies, and features. The
software necessary to drive an SDR includes real-time signal processing, a user interface, and other processing
tasks. Therefore, an SDR is a self-contained, embedded software system with real-time deadlines and hardware
interfaces.
Software-defined radios rely on some hardware, minimally a down-converter and A/D for receiving and a D/A and
an up-converter for transmitting. While the hardware circuitry is well defined, it can be challenging to build
because radio operating frequencies are, naturally enough, in the radio frequency (RF) spectrum. While cell phones
are typically in the GHz range, our applications are in the 0.1 MHz – 100 MHz range, specially, the amateur, public
service, and commercial radio bands.
Areas of Ongoing Research
The SDR has become a popular research project with the following applications.
SDR and Public Safety
In this project, we are developing inexpensive, Pocket PC-based SDR systems for public-safety applications.
Creating these “portable” SDRs will allow emergency personnel to use a variety of radio bands during disasters. In
addition, these radios will work on the amateur radio frequencies. Because most communications systems other
than amateur radio go down during disasters, SDR could allow emergency personnel to gain the information they
need in a dependable fashion. Additionally, there were significant communications mismatches between police,
firefighters and other emergency personnel during Hurricane Katrina and the September 11th terrorist attacks. The
flexibility of SDR could help to rectify miscommunication between different branches of public servants.
SDR and “High-Definition” Radio
We are developing additional plug-ins for commercial radio broadcasts of digital AM and FM, commonly called
“high-definition” radio. These new waveforms are intended to give AM radio the quality of current FM stations and
to broadcast FM stations at the quality of CDs.
Based on the SDR library software, we are building decoders for these waveforms. This is a pure software
project using the same down-converting hardware as the other SDR projects.
Mobile Gaming Platforms
Mobile gaming is an important emerging technology. Electronic Arts, Microsoft, and Google, for example,
have made major commitments to mobility. We are interested in developing high-performance computing and
communication platforms specifically to support mobile gaming, communication and computation.
Course Opportunities
Interested students are encouraged to take Computer Science department courses in digital-signal
processing and in SDR. These courses provide the in-depth exposure to the mathematics, software, and system
concepts in SDR.
Research Opportunities
Interested students, from sophomore through senior years, are encouraged to participate in these exciting
projects. Please contact Professor Birmingham.