Skynet 5 Input Beam Selection
Network Firmware

Client: EMS Technologies
Completed in February 2004

The spaceflight firmware for the Skynet 5 IBSN controls the electronic brains of the satellite's beam switching hardware. Simply put, it connects selected input paths to selected outputs. Much of the complexity of the client's system is handled by the firmware in order to reduce part count and cost. To win the IBSN proposal, the client kept costs down by specifying that the firmware run on a legacy part at a very slow speed. This presented a challenge to the firmware due to extremely tight timing requirements and limited input/output capability, combined with the need to address over 150 signals within the timing constraints. The firmware met all the requirements with considerable margin by using a highly multiplexed interface design for the I/O, and optimized assembly code to meet the timing. Janice Bayer wrote most of the code in 8051 assembly due to the timing requirements, with the remainder in C.

Support over multiple project phases: Over a period of six months, Janice completed the feasibility assessment, proof-of-concept code, design, implementation, lab testing using hardware, a 50-page requirements and specifications document, and line-by-line inspection attended by qualified reviewers. All of this work was performed in consultation with other engineers responsible for electronics design and top-level system testing.

High reliability: Skynet 5 is a new constellation of UK military satellites. Reliability is paramount on spaceflight projects. Bugs in the firmware are not acceptable, so the code had to be up to that standard when released. Skynet was Janice's third project with EMS Technologies, and she is proud to have been brought back.