Dynamic frame sizing was added to the existing AOS Packet Service FPGA implementation. This capability provides in-flight system calibration functionality, allowing the spacecraft and ground station the means to optimize a communication link by dynamically adjusting the Advanced Orbiting System (AOS) transfer frame size.
Multiplexing and demultiplexing functions were implemented per CCSDS (Consultative Committee for Space Data Systems) Blue Book 732.0.-B-2, which allows transfer frame muxing and demuxing based on GVCID (Global Virtual Channel ID), which is a combination of the spacecraft ID and virtual channel ID. The AOS Packet Service FPGA implementation was validated via simulation as well as on SCAN Testbed hardware, specifically the Ground Development Unit at Glenn Research Center.
The work described here provides supplemental functionality to the existing AOS transmit and receive implementations required for use by current and future JPL projects such as the LCRD (laser communication relay demonstration) ground station, which is designed to service multiple spacecraft links (i.e., AOS transfer frame streams) requiring multiplexing and demultiplexing services.
Specific examples of JPL instruments that would greatly benefit from a hardware AOS implementation include the Electra and Universal Space Transpond er Software Defined Radios, which both implement Sparc processors that would be significantly relieved from implementing the AOS protocol in software. In addition, combining the AOS protocol with ENCAP and DTN protocols offers a full communication protocol stack in a software defined radio.
The AOS transmit and receive circuits are applicable to any communication subsystem requiring a link layer protocol. This includes software defined radios and optical communication systems.