Space-based Reconfigurable Software Defined Radio Test Bed aboard International Space Station

The National Aeronautical and Space Administration (NASA) recently launched a new software defined radio research test bed to the International Space Station. The test bed, sponsored by the Space Communications and Navigation (SCaN) Office within NASA is referred to as the SCaN Testbed. The SCaN Testbed is a highly capable communications system, composed of three software defined radios, integrated into a flight system, and mounted to the truss of the International Space Station. Software defined radios offer the future promise of in-flight reconfigurability, autonomy, and eventually cognitive operation. The adoption of software defined radios offers space missions a new way to develop and operate space transceivers for communications and navigation. Reconfigurable or software defined radios with communications and navigation functions implemented in software or VHDL (Very High Speed Hardware Description Language) provide the capability to change the functionality of the radio during development or after launch. The ability to change the operating characteristics of a radio through software once deployed to space offers the flexibility to adapt to new science opportunities, recover from anomalies within the science payload or communication system, and potentially reduce development cost and risk by adapting generic space platforms to meet specific mission requirements. The software defined radios on the SCaN Testbed are each compliant to NASA’s Space Telecommunications Radio System (STRS) Architecture. The STRS Architecture is an open, non-proprietary architecture that defines interfaces for the connections between radio components. It provides an operating environment to abstract the communication waveform application from the underlying platform specific hardware such as digital-to-analog converters, analog-to-digital converters, oscillators, RF attenuators, automatic gain control circuits, FPGAs, general-purpose processors, etc. and the interconnections among different radio components. NASA is inviting experimenters from industry, academia, and other agencies to use the SCaN Testbed. On the flight system, the three software defined radios (SDR) and a portion of the flight computer or avionics, is available to experimenters to develop, test, and operate new SDR applications in-orbit. Experiment operations include inflight reconfiguration of the SDR waveform functions, and communications at S-band or Ka-band with NASA’s inspace Tracking and Data Relay Satellite Network, or at Sband direct from the SCaN Tested to any Earth-based compatible ground station. One of the SDRs also receives GPS frequencies at the L1, L2c, and L5 frequencies. Various GPS waveforms are possible using the reconfigurable digital processing of the SDR. Command, control, and experiment operations occur from the Glenn Research Center in Cleveland, Ohio. NASA provides the ground connections between the Experiment Center and the uplink site to the TDRSS Network at White Sands. New Mexico. Experimenters are encouraged to use the SCaN Testbed for a variety of research topics and applications. NASA will provide access and support to both the on-orbit testbed, and ground-based systems for development and verification activities. This paper will provide a description of the SCaN Testbed, the SDR capabilities, and the ground systems available to potential experimenters. Unique aspects of SDR developments, verification, and operations will be discussed.