LinkStar-HD -STX3, Third Generation Globalstar Radio Systems For Satellites In LEO - Architecture And Test Results

摘要

LinkStar utilizes the Globalstar satellite radio network, a constellation of 32 satellites in low Earth orbit (LEO) providing global data and voice services for a range of uses including oil rigs, shipping containers, gas pipelines and remote communications - and satellites in LEO. Our research focused on adapting the Globalstar GSP-M20 and updated "HD" modem plus creating the LinkStar radio architecture for use in space. LinkStar-HD is a full duplex radio system (concurrent uplink and downlink) for satellites in LEO providing communications coverage to over 50% of the Earth at data rates of 256kbps, over 26 times faster than current duplex models. LinkStar-HD treats the satellite as a secure node on the internet while it is in orbit and on the ground for testing. Work included marrying the modem with a modified, space rated BeagleBone Black computer which utilizes an embedded Linux based operating system to control the satellite and manage the radio architecture. As part of the radio architecture work also included continued development of QuickSAT/Vehicle Management System (VMS), an open source flight management system. QuickSAT/VMS is flexible and tailored for cubesats and other types of small satellites. The architecture provides for basic satellite command and control, data management, scheduling, event handling and a complete software based radio tool set. The framework allows for users to define custom classes of components (such as radios, magnetometers and other sensors) without modifying the core architecture. The architecture provides a robust data management framework, not only managing the vehicle configuration and schedule, but also logging system messages, errors and events, and storing data as needed into separate recording sessions. QuickSAT/VMS and the BeagleBone Black can serve as both radio and flight computer reducing overall satellite power and mass. The QuickSAT/VMS Communicator APIs allows for the integration of several radios on one satellite. Communicator allows the user to add custom modules to the core architecture, and set parameters to define how the radios will work together. Research also included development and flight testing of the LinkStar-STX3 simplex radio, a low power, low cost simplex radio that beacons data from anywhere in LEO. The LinkStar-STX3 uses 50% less power and is one third the size of the second generation STX2 based radio. LinkStar-STX3 can be used stand alone or with the LinkStar-HD radio. As part of the development FCC testing was conducted, making the LinkStar-STX3 the only FCC Part 25 and Part 15 simplex radio for use in space. In this presentation we will discuss QuickSAT/VMS and how the architecture works with the LinkStar-HD and LinkStar-STX3 radios, and the operation and integration of LinkStar on a satellite. We will present FCC test results plus results from the DARPA near space test flight.