Software Defined Radio Increases Flexibility of Space Hardware

Glenn Research Center is one of the lead NASA centers for software defined radio (SDR) architecture and technology in support of the Space Telecommunication Radio System (STRS). For the past four years, Glenn’s Digital Communication Branch has been defining the STRS Architecture and evaluating SDR technology from various vendors for application in future NASA missions.

The STRS architecture will provide a common framework across different NASA missions and allow the portability of space radio software among small or large platforms, providing a flexible, scalable architecture. The STRS architecture enhances the flexibility of space communication by allowing space radio functions to reside in the software instead of the hardware. SDR converts analog signals to digital data for manipulation and transmission.

In this effort, Glenn has partnered with the Jet Propulsion Lab, Goddard Space Flight Center, Johnson Space Center and NASA Headquarters to form the SDR Architecture Team (SAT). Glenn’s role includes leading the definition of the architecture and technologies and the SDR prototyping. The architecture is then applied to the SDR prototypes for evaluation and refinement of the architecture.

Layered Elements of SDR Open Architecture (Credit: NASA).

A radio runs applications referred to as waveforms, which include all the functions necessary to transmit information from one radio to another. The figure on the right illustrates an example of the software abstraction definition between the waveform application and the radio operating environment. The architecture framework requires that vendors publish a hardware interface definition to provide a physical definition of the hardware interfaces for subsequent module integration.

SDR offers many benefits to the space program. If requirements change prior to a launch, the software can be changed faster and easier than hardware. Changes can be made if a failure occurs on orbit and if the software is able to compensate for unexpected issues elsewhere in the communication system. The software may also be reconfigured to perform multiple processes on the same piece of hardware. Therefore, less hardware is needed, which reduces the total weight and cost of space hardware.

Glenn is planning to test the STRS architecture on a space station experiment, scheduled for launch in 2010. Their efforts will result in an agency-wide standard for the new architecture between 2010-2012. Commercial standards organizations and their member companies are contributing to the STRS architecture through the Objective Management Group (OMG) and the Software Defined Radio Forum.