Look to the stars with the University of Oxford
The Department of Physics at the University of Oxford is part of the Square Kilometre Array (SKA) project.
SKA is an ambitious, global radio telescope project. SKA will investigate questions about our universe. The array’s design will enable it to survey the sky up to ten thousand times faster than existing arrays.
How Square Kilometre Array will unlock the secrets of the universe
Within a safety-critical state machine: Feed Package Controller
The Department of Physics has led the hardware and software design for the cryogenic Band 345 Single Pixel Feed (SPF) receiver. This consists of feed horns, OMTs (orthomode transducers) and RF (radio frequency) chain components maintained at cryogenic temperatures (12K and 70K) under vacuum by a Gifford McMahon coldhead.
These components are housed in a cryostat which is monitored and controlled by an attached Feed Package Controller (FPC) module. The FPC consists of a Xilinx System-on-Chip with ADCs (analogue-to-digital converters) and DACs (digital-to-analogue converters) to monitor and control critical temperatures and pressures and control safety critical components such as the main vacuum valve.
In addition, the coldhead motor’s speed can be controlled to match the cryogenic cooling power required to the ambient heat load.
Should the temperature or pressure change too much, it will damage the module. Damage to this is expensive to fix. The array’s intended (remote) locations mean sending someone to make repairs is no easy task.
What the University of Oxford was looking for
The Department of Physics team needed an embedded software supplier who would:
- Speed up development;
- Provide detailed advice on hardware;
- Deliver low-level coding in Verilog for the system’s FPGA;
- Produce further embedded software in C;
- Understand the quality and value of this module;
- Deliver code that any software engineer can work with it.
Challenges Bluefruit Software faced
The project was not without its challenges. The Bluefruit Software team faced:
- Ensuring Verilog only ran low-level features, while C dealt with the rest;
- Making sure software wouldn’t lead to costly system failure;
- Rewriting and refactoring much of the existing code.
Bluefruit addressed all these challenges over the course of the project.
What the University of Oxford gained
- Access to a professional software team with expertise in working on safety-critical systems.
- An increased pace in the module’s software development.
- A Lean-Agile software development process that delivered up-to-date software every two weeks.
- Source code that meets the challenges of an extreme and safety-critical operating environment.
- Software with solid conceptual integrity and unit tests. This means any software engineer could further work on the project as it evolves.
- A time and materials contract that enabled them to put both quality and safety first.
- The project benefitted from emerging knowledge, which Bluefruit used to optimise the software.
- Frequent feedback, communication and support. The Department of Physics team remained a key part of the software development at all stages.
- Hardware support from Bluefruit. This included the team debugging the hardware and initial advice on hardware choices.
- Bluefruit introduced simulation tools to use with the FPC module and its software.
Look to the skies
Bluefruit is continuing to work with The Department of Physics at the University of Oxford to ensure they have the software they need. We’re excited to see what comes from one of the most significant scientific projects of our time.
Are you as fascinated by SKA as we are?
Then check out these resources:
- SKAO (official website)
- The Square Kilometre Array (SKA) research group at the University of Oxford
- MID-Radio Telescope, Single Pixel Feed Packages for the Square Kilometer Array: An Overview (IEEE Journal of Microwaves)
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