The Space Communications and Navigation Testbed (SCAN Testbed) consists of a set of reconfigurable software defined radios (SDRs), including newer Ka-band and Global Positioning System (GPS) L5 frequency bands, and uses software based communications and navigation functions capable of being functionally modified once on-orbit. Such reconfigurable software to an existing radio platform allows different radio vendors the ability to demonstrate multiple radio implementations based on the common Space Telecommunications Radio System architecture standard. The goal of providing this facility is to encourage the development and advancement of SDR technologies for common, open space based architectures, in hopes of reducing future developmental risks and costs.Facility Manager(s)
Glenn Research Center, Cleveland, OH, United States
National Aeronautics and Space Administration (NASA)Expeditions Assigned
33/34,35/36,37/38Previous ISS Missions
NASA's Space Communication and Navigation Office is developing the Space Communications and Navigation Testbed (SCAN Testbed) provides radio researchers a platform to investigate the applicability of software defined radios (SDR) to NASA and spaceflight related missions. A part of the investigation is an architecture standard for SDRs used in space-based and ground-based platforms to provide commonality among radio developments in an effort to provide enhanced capability and services while reducing mission and programmatic risk by reducing the need for custom, proprietary radio architectures. This radio architecture standard provides value by employing common waveform software interfaces, and methods for instantiation, operation, and testing among different compliant hardware and software products. Such common interfaces within the architecture mask the underlying hardware through application programming interfaces and other software layers enable independent technology insertion at either the software or hardware layer. This common architecture entitled Space Telecommunications Radio System (STRS) provides the desired software abstraction and flexibility while minimizing developmental and operational resources by tailoring the implementation to functions typically required of NASA radios.
Traditional approaches to radio development have been exemplified by proprietary or custom implementations that only meet a specific set of mission requirements. Presently most requirements can only be satisfied by functions implemented in the hardware (i.e., application-specific integrated circuits (ASIC's)) and thus fixed for a specific mission duration, and historically this was often the only approach, given the available ASIC technology, suitable for space flight. As software defined radios (SDR) begin to infuse deep space, near-Earth, and lunar space applications, a new approach must be considered to best apply the new reprogrammable field programmable gate array (FPGA) technologies for NASA. The advent of software-based radio functionality offers NASA the opportunity to separate the software proliferation and its associated complexities from the underlying and evolving reprogrammable hardware technology by adopting an open architecture standard. Published, well defined interfaces enable different vendors to provide radios that conform to the interface standard, providing commonality among different implementations and enabling interoperability between providers of different hardware and software elements. Standard interfaces provide for software component reuse, and technology insertion through the hardware abstraction. Such a standard also promotes the growth of a large base of domain experts; agency personnel, software and hardware providers, and the user and operations communities, which help reduce the risks of using unique custom architecture implementations.
SCAN Testbed hosts three SDRs based on the STRS Standard. The radios provide different and complimentary capabilities while having the ability to reconfigure their functions based in signal processing hardware (e.g., processors or field programmable gate arrays). The functions performed by the radios include communication with the Tracking and Data Relay Satellite (TDRS) system in both S-Band and Ka-Band, receive Global Positioning Satellite (GPS) signals, and enable proximity communications between the International Space Station (ISS) and approaching vehicles.
The hardware consists of a flight enclosure mounted on a Flight Releasable Attachment Mechanism (FRAM). There are five main components of the payload: the avionics system, the software defined radios, the radio frequency (RF) subsystem, the antenna pointing system, and heaters. Except for the five externally mounted antennas, most of the subsystems are installed on the inside of the enclosure.