Space Communications and Navigation Testbed (SCAN Testbed (Facility)) - 12.03.13
Science Objectives for Everyone
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.
Science Results for Everyone
Glenn Research Center, Cleveland, OH, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)ISS Expedition Duration
September 2012 - March 2014Expeditions Assigned
33/34,35/36,37/38Previous ISS Missions
- The Space Communications and Navigation Testbed (SCAN Testbed) provides researchers access to a set of reconfigurable software defined radios (SDRs) with software based communications and navigation functions, allowing developers the capability to change the functionality of the radio once on-orbit. The ability to change the operating characteristics of the radio?s software after launch allows missions to change the way a radio communicates with ground controllers, and offers the flexibility to adapt to new science opportunities and increased data return. Additionally, this flexibility allows teams to recover from anomalies within the science hardware or communication system, and potentially reduce development cost and risk by using the same hardware platform for different missions while using software to meet specific mission requirements.
- The Space Communications and Navigation Testbed (SCAN Testbed) offers a new operational capability that advances the readiness of SDR technology for adoption by future space missions. The SCAN Testbed enables different radio vendors to provide software to a radio platform and demonstrate multiple radio implementations of the common architecture standard (Space Telecommunications Radio System (STRS: STRS?AR?00001, Space Telecommunications Radio System (STRS) Architecture Standard, Release 1.02.1 NASA TM-2010-216809)), eventually providing multiple industry sources of SDRs for future exploration missions. Each radio within the experiment demonstrates the operation and reconfiguration among different signaling formats (e.g., communications with relay satellites, current and future global positioning satellite signal assessments, etc.) and assesses the performance and procedures for operation.
- This platform provides communications in the S-band, and the Ka-band for newer satellites using these bands. The SCAN Testbed also hosts a Global Positioning System (GPS) L5 frequency (i.e., a new navigation band) space receiver that can be used to study improved orbit determination capabilities using multiple GPS frequencies.
- Currently, Software Designed Radios (SDRs), being a relatively new technology proposed for space missions, are uniquely designed and developed within individual companies. These unique designs only allow the developing company to provide waveform software for the radio and therefore NASA is not able to benefit from lessons learned from one development to another or have the ability to reuse software from one development program to another. These limitations have a tendency to increase NASA's cost and dependence on single vendor solutions for communication and navigation radios.
- The SCAN Testbed provides that ability to advance operational experience with current and emerging reconfigurable radio technologies, and assess radio and software performance to reduce risk in the design of future missions.
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. Operations
- The experiment plan specifies a radio and antenna combination that is required to complete a particular test.
- The payload operations team controls and monitors the SCAN Testbed radio and antenna systems from the Glenn Research Center?s Telescience Support Center (TSC) in Cleveland, OH.
- The flight system is powered on and prepared for the experiment by uploading files and adjusting parameters from the control center.
- Commands and data sent to the radio system include software files that configure and control the radio.
- When commanded from the ground, the radios establish a communication link with the White Sands Complex, through TDRSS and begin to flow data or receive GPS signals (depends on payload configuration).
- Data entails information transmitted from onboard to the ground or from ground to on-board radio, test data files stored on-board or information from a ground or space network transmitted to and from the flight system.
- When the SCAN Testbed achieves loss of signal (LOS), the system is commanded to an idle or powered off state until the next acquisition of signal (AOS) with either the TDRSS or ground station.
- New experiments entails new software uploaded to the software defined radios, each compliant with the STRS standards.
Information PendingResults Publications
Ground Based Results Publications
Ground testing and processing of SCAN Testbed hardware (JPL)
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Schematic overview showing SCAN Testbed hardware and components (JPL)
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External image of ISS showing SCAN Testbed installed on ELC 4 nadir side (NASA)
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