A-Series DOG

ScyLight

Status

Completed
Status date

2025-03-20
Activity Code

6C.010

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.

Benefits

DOG-1 is part of the Work Microwave Digital Optical Ground-station (DOG) suite of products designed to receive and decode Free Space Optical communication from space terminals such as CubeLCT, T-Osiris, OPTEL-µ, CAT. The DOG-1 modem offers hard or soft decision decoding, serving both high a low intensity laser signal reception. Its modular design allows the sensitive detection process to be done at the telescope and the remainder of the processing done up to 2km away. DOG-1 also offers the capability to buffer huge amounts of decoded data for later retrieval by the Central Processing Facility.

Features

High and low laser intensity reception
High sensitivity detector interface
CCSDS 142.0-B-1 compliant
Supporting DTE links
Supporting soft-decision O3K decoding
Max decoding rate up to 10Gb/s
High capacity storage up to 1 TB
Modular design
Designed for ARQ, VDR, VCM for future expansion.

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:

System architecture

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:

System architecture

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