New Avionics for SATCOM SDIU Mk2


In the actual generation of platform the complete avionics for the satellite are provided via two separate units, the PFDIU (PlatForm Distribution Interface Unit) and PLDIU (PayLoad Distribution Interface Unit). The position of these units within the overall satellite architecture is shown in the following figure:

The principal objectives of the ARTES 5.2 Activities can be summarised as follows:

  • Reduction of the risks related to the introduction of
    • DPC’s (Digital Programmable Controller) and their associated firmware in the PFDIU & PLDIU,
    • a CAN bus,
    • new hybrids.
  • Detailed design and analysis of the more risky modules being part of the PFDIU and PLDIU
  • Manufacturing and test of all the SDIU modules (one per type)
  • Test of a Functional Model (FuMo).

All of these activities have been performed with the aim of achieving a cost gain of 30% for the complete avionics subsystem. Indeed it is this indicator that is used to determine the success or not of the programme.


The main challenge for the programme is achieving the significant cost reduction targets. In order to do so we are introducing a proprietary digital programmable controller (DPC), a generic device that, associated with a dedicated firmware to allow it to perform the various different management, command and control functions required in the PxDIU’s. The integration of this DPC and associated firmware represents one of the main technical challenges on the programme.


The main benefits brought by the project are, from a commercial point of view, the increased competitiveness, and from a technical point of view, a potential increased flexibility at system and operational level, with a transfer of certain management elements from the onboard computer to the avionics therefore reducing the tasks to be done centrally.


There are 2 different units, one dedicated to the payload interfacing and control, and the other to the platform, the PLDIU and PFDIU respectively. The architecture is based on two units able to host 14 modules each. The development of the unit implements a number of features to ensure full physical segregation between nominal and redundant chains.

The functions include: the distribution, protection and monitoring of the 100V main bus power to user equipment; distribution, protection, switching and monitoring of heater power; driving and control of solar array deployment and rotation; propulsion command and control; reaction wheel interfacing; Li-Ion monitoring, and control of cell bypass and cell balancing elements; generation and management of an external CAN bus for future payload needs.

The overall dimensions are 451 x 521 x 233 mm3 (L x W x H); in the baseline configuration the mass is estimated at 28.0kg for PFDIU and 31.75kg for PLDIU

System Architecture

The architecture is based on two units able to host 14 modules each.  The modules are stacked and inserted into a backplane that distributes the internal communications bus. The unit is consolidated, from a mechanical point of view, by a baseplate, end plates and top cover. An external Bus Bar distributes the main power bus (100v). The development of the unit implements a number of features to ensure full physical segregation between nominal and redundant chains.

The 2 central modules, called STUB, are very similar and provide: (a) a 1553 interface to the external system; (b) power supplies for all of the internal power needs as well as certain functions such a telecommand generation, motor driver supplies, sensor supplies, etc; (c) management, command and control of the PxDIU through an internal CAN bus. To each side of the nominal and redundant STUB modules there are maximum 7 + 7 functional modules containing all of the necessary functions.


The global Project plan is as follows:

  • ARTES 3-4 study (baseline architecture definition – status: completed)
  • ARTES 5.2 project (risk reduction phase concerning the implementation of digital power control and the introduction of a CAN communications bus, manufacturing and test of a FUMO – subject of the this web page)

ARTES 3-4 project (development model which will be subject to a full qualification campaign to demonstrate that the proposed design is compatible with a 18 year mission in geostationary orbit)

Current status

The ARTES 5.2 project is completed.

ESA Contacts

Status date

Tuesday, May 23, 2017 - 13:58