The Consultative Committee for Space Data Systems (CCSDS) Advanced Orbiting Systems (AOS) space data link protocol provides a framing layer between channel coding such as LDPC (low-density parity-check) and higher-layer link multiplexing protocols such as CCSDS Encapsulation Service, which is described in the following article. Recent advancement in RF modem technology has allowed multi-megabit transmission over space links. With this increase in data rate, the CCSDS AOS protocol implementation needs to be optimized to both reduce energy consumption and operate at a high rate.

CCSDS AOS has been implemented as an intellectual property core so that the aforementioned problems are solved by way of operating the CCSDS AOS inside a field-programmable gate array (FPGA).

The CCSDS AOS in FPGA implementation consists of both framing and deframing features.

Features of the AOS Framer include:

  • Fully customizable with respect to insert zone, virtual channel ID, and trailer fields.
  • 8-bit parallel CCITT CRC16 calculation.
  • First header pointer field calculation based on the data provided from the packet layers such as CCSDS Encapsulation Service or CCSDS Space Packet.
  • Optimized for the Packet Service primitives with M_PDU.
  • Available in byte-based or packet-based egress interface options.
  • Statistical counters at both byte and frame levels to facilitate data product accountability.

Features of the AOS De-Framer include:

  • Ingress buffer implementation to provide ingress processing overflow.
  • 8-bit parallel CCITT CRC16 calculation and frame discard if CRC16 fails.
  • First header pointer field extraction and forwarding to the de-packetizing layers such as CCSDS Encapsulation Service or CCSDS Packet Service.
  • Optimized for the Packet Service primitives with M_PDU.
  • Statistical counters at both byte and frame levels to facilitate data product accountability.

The combination of energy and performance optimization that embodies this design makes the work novel.

This work was done by Loren P. Clare, Jordan L. Torgerson, and Jackson Pang of Caltech for NASA’s Jet Propulsion Laboratory. For more information, contact This email address is being protected from spambots. You need JavaScript enabled to view it..

The software used in this innovation is available for commercial licensing. Please contact Daniel Broderick of the California Institute of Technology at This email address is being protected from spambots. You need JavaScript enabled to view it.. Refer to NPO-47166.


NASA Tech Briefs Magazine

This article first appeared in the September, 2010 issue of NASA Tech Briefs Magazine.

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