Optical Digital Converter - reception and processing of fee-space optical receiver output - Celestia STS

About Optical Digital Converter


The Optical Digital Converter (ODC) provides reception and processing functionality of digital bitstreams output by free-space optical (FSO) receiver modules, capable of receiving data rates of up to 10Gbps.

The ODC is ideal for use in FSO terminals, optical communication ground stations and for use in experimental setups for optical communication.

The ODC provides all required power, TM/TC and digital bitstream interfaces to the FSO receiver. The ODC provides the electrical, data extraction, protocol/data handling (incl. FEC) and status annotation functions. The digital bitstream interface to the FSO receiver is through an industry standard SFP+ interface, which supports both copper and optical fibre connections. The recovered data is offloaded from the ODC using a dedicated 10Gbit TCP/IP streaming interface (SFP+, optical or copper) to a commercial server platform for data storage to local disks (SSD or HDD).

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Key Features


  • Modular Implementation
  • Supports 100Mbps, 1Gbps and 10Gbps FSO Receiver Front-Ends
  • High-Speed Serial or SERDES Interface to FSO Receiver (SFP+)
  • Command and telemetry interface to FSO Receiver (RS-422)
  • DC Power output to FSO Receiver (options: +3V3, +5V or +12V)
  • Support for multiple data processing firmware images
  • Data processing firmware images can be switched run-time
  • Hardware processing of digital bitstream from FSO receiver
  • Bitstream Decoding, FEC Decoding and Data Extraction
  • Hardware Timestamping of Recovered Data
  • PPS output for synchronisation of external equipment
  • External Time/Reference inputs, such as 10MHz, PPS and IRIG
  • Gigabit LAN for Control and Monitoring via TCP/IP (using RJ45)
  • 10Gbit LAN for Data Streaming via TCP/IP (using SFP+)
  • Provided with software to control and archive the data
  • FMEA Report Available

The system consists of a 19″ 2U rack-mountable unit that is controlled and monitored by a software application that allows the system to be used stand-alone or controlled remotely via a Central-Check-Out System (CCS). 

The ODC can be upgraded with custom data processing (such as forward error correction decoding, protocol handling, deciphering, etc.) to support the needs of the program/project. Using the available time synchronisation inputs (PPS and IRIG), the ODC maintains an accurate hardware time (CUC) that is used to timestamp the received data as well a housekeeping telemetry as received from the FSO receiver. The ODC supports multiple data processing images. The data storage interface is implemented using a low-latency TCP/IP stack directly within the hardware, capable of providing near line speed data streaming. This provides back-end independence, allowing commercialservers with standard 10G ethernet cards to be used. The ODC can be delivered with back-end software (Windows Server 2012/2020) for data storage /archiving.

The Optical Digital Converter (ODC) has been released in Q2 2019, while implementing the project of Optical Ground Station in collaboration with TNO (Netherlands Organisation for Applied Scientific Research). During implementation the ODC has been validated with the Hyperion Technologies CubeCAT Lasercom module. Celestia STS continues to develop the next generation ODC in the frame of the same project.