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Objectives
The M3O optical receive only modem project will develop a prototype multi-mission optical modem (M3O), DOG-1 modem, capable of receiving, decoding and buffering CCSDS standardised free space optical waveforms. The DOG-1 modem will be first unit in the DOG suite of products and this project will prototype the DOG-1 modem and allow technology de-risking and functional testing of the technology required for the DOG-1 modem.
Challenges
The most significant challenges in this project are to design and implement an analogue interface to an ultra-high bandwidth optical detector, and implement a soft decision decoder compliant to the CCSDS specification, that is capable of a decode rate of 10 Gbits/s.
System Architecture
Two complementary architectures are proposed to receive and decode high and low intensity laser signals.
High intensity signals can be connected to a low cost detector and fed directly to the Digital-Module (DM) for Reed Solomon (RS) decoding, shown below:
Low intensity signal require a more sensitive treatment. The optical signal is captured using a high-sensitivity detector. The resulting differential analogue electrical signals are fed into the Soft Decision Front End (SDFE) for timing recovery. The re-sampled signals are digitally passed on to the DM, now in “soft decision mode” for LDPC decoding:
Plan
The project will follow a familiar waterfall project process, split across Definition and Technology development phases:
- System Requirements Review, Q1 2022: Technical and customer requirements
- Mid-term Review, Q1 2022: Finalisation of requirements
- Phase Completion review, Q1 2022: Preliminary design, interface specification, LDPC decoder white paper
- Detailed Design Review, Q3 2022: Critical design of Digital and Analog elements, Critical Design of the high performance LDPC decoder
- Test Readiness Review, Q4 2023: Gating milestone to proceed to validation
- Final project review, Q1 2025: Final review and readiness for product realisation
Current Status
The M3O optical receive only modem project activity was completed in March 2025.
The main achievements are:
- Development of COTS based CCSDS O3K receive only modem and Soft-Decision Modem Frontend
- Wide range of symbol rates supported
- Good coverage of mission settings based on practical aspects
- Covers various scenarios/missions for various link budget requirements
- Ranging for positioning
- Storage for safe data reception and delivery
- Versatile platform -> Simple expansion for further versions of the standard and waveforms
- Successful verification in relevant environments
- Space Technology R&D – TRL 6
