Objectives of the SODaH project

What are the steps in the SODaH project necessary to succeed? The project will include a payload architecture concept as well as the maturation of the components necessary to arrive at this concept. The result will be a demonstrator of the Photonic Modulator, Routing and Digitalization Unit (P_MRD Unit) at Technology Readiness Level 5.

Objective 1

Consolidate concepts of LEO broadband constellations using OISL and RF Up/Down links enabling an optical space data highway with:

  • Global coverage (including oceans and low populated areas) with a total capacity of 10 Tbps
  • With a baseline of 300 LEO Satellites with OISL and RF beam steering antennas; leading to
  • Internet access with 100 Mbps/s and latency below 0.03 sec for end users
  • Seamless integration in the 5G ecosystem

To meet these objectives, the consortium designed the following:

  • A combined Walker constellation that provides global coverage with appropriate levels over populous regions compared to the poles.
  • SODaH is 2nd Gen HTS thus performance to be competitive but at medium lifetime.
  • A highly flexible system where phasing of planes can be relatively easily adjusted to optimize link geometries.
  • A system that is competitive with the most advanced HTS systems.

Connecting to Europe’s needs

Objective 1 aims to connect the project to European objectives concerning the 5G ecosystem and (fast) connectivity for its citizens, for unserved and underserved areas elsewhere in the world and for moving terminals like boats and planes.

Objective 2

Demonstrate the feasibility of such a “Software Defined”, “Hybrid Photonic/Digital” payload which is:

  • Able to handle and route 32 Gbps signals from RF user links and 18 Gbps from Gateway through a digital processing unit
  • Able to handle and route signals from four 30 Gbps multiplexed OISL in a fully transparent and regenerative way
  • Compatible with a low-cost access to space
  • Industrially relevant for the production of hundreds of Flight Models per year
  • A miniaturized SWaP (Size < 1 m3, Weight < 200 kg, and Power < 1 kW) compatible with small LEO satellites
To meet these objectives, the consortium designed the following:

  • A system capable of transparently routing optical signals with an aggregate data rate of 30 Gbps.
  • Total mass is compatible with a relatively small payload to be deployed in to a high constellation satellite.
  • Total mass is low enough to enable as many satellites as possible to be packed on to a launcher.

Defining technology and feasibility

Objective 2 is aimed at quantifying what it means to establish a satellite constellation that will serve the goals under objective 1. What is the amount of data a satellite should be able to manage, how will it receive and send signals when its speed and distance to other satellites and end users on the ground are continuously changing? Another major concern in this phase is the SWaP (size, weight, and power) because it will take hundreds of satellites that should be as lean as possible. Also contributing to this leanness is the fact that the payload should be software defined. At this stage, SODaH aims to demonstrate the feasibility of such a concept for the first time.

Objective 3

Develop and qualify to TRL 5 the key technologies necessary for the Photonic, Modulation, Routing and Digitalization Unit of such payloads. These technologies are:

  • An Optical Switch Matrix with 48 ports,
  • Low Noise Amplifiers (LNAs)
  • Receivers
  • Modulators compatible with Dense Wavelength Division Multiplexing (DWDM)
  • Multiplexers (MUX) and De-multiplexers (DEMUX) enabling the use of DWDM

To meet these objectives, the consortium members have focused their efforts on designing and manufacturing breadboards of the 5 key building blocks:

Modulator drive






See the SODaH timeline

Designing the technology and components

Objective 3 takes the context of Objectives 1 and 2 and translates them into the components needed in the satellite. A main point of attention is the conversion between photonic and digital signals, which will enable the connection between end users and gateways on the ground to the fiber in the sky network. Concerning the inter-satellite communication, SODaH focuses on the amplification and repeating of optical signals, as well as clever satellite architecture in terms of redundancy, position, and connection of its elements.

Objective 4

Demonstrate the performances and potential of this payload concept and equipment thought a Photonic Modulation, Routing, and Digitalization Unit (P_MDR)demonstrator by proving:

  • Its performances including aspects such as BER, mass, power consumption, throughput.
  • Its performance under different channel impairments, such as Doppler, pointing error.
  • Its functional requirements (routing, frequency conversion, gain control).
  • Its manufacturability and industrial relevance.
  • Parameters/aspects requiring future work.

These objectives have not been achieved in the time frame of the project duration.

More about the P_MRD

Demonstrating performance excellence

Objective 4 brings everything together in a demonstration model. It takes the components and architecture from Objective 3 and brings it into the practical realm. This step includes performance aspects, testing for various relevant environmental factors like temperature, vacuum and vibrations and regard for manufacturability.