This paper describes the development of a new Software Defined Communications (SDC) testbed architecture. SDC aims to generalize the area of software defined radio to include propagation media not exclusively limited to radio frequencies (optical, ultrasonic, etc.). This SDC platform leverages existing and custom hardware in combination with reference software applications in order to provide a complete research and development platform. This platform can be used to implement current and future standards that make use of highly demanding communications techniques, including ultrawideband (UWB) radio and free-space optical communications. This paper describes the commercial and custom hardware that is being integrated into the platform, including the baseband hardware and the modular transceiver frontends. Furthermore, the paper describes the software development currently in progress with this platform, including the integration of available open source designs into the platform, and the development of custom IP for scalable OFDM PHY implementations in radio and optical communications. We seek to create a complete research platform for the commercial and academic wireless communities, capable of delivering the highest possible performance and flexibility while providing the necessary development tools and reference designs in order to minimize system learning curve and development cost.