Implement Flow Through mode signal processing and product tests according to AA1 Low Use Cases

https://miro.com/app/board/uXjVN7ik-wg=/?moveToWidget=3458764575319872977&cot=14

Who?

• Commissioning scientists; AIV engineers

Why?

• The implementation of the Flow Through mode in the DSP component of PST requires the first major signal processing functionality for the PST product, ahead of deployment at AA1. This mode will be realised by implementing the required pipeline using the DSPSR C++ signal processing library, which will also be used for other PST processing modes.
• DSPSR must be integrated with the PST Flow Through mode software; this first integration will utilise the CPU-based processing functions of DSPSR, providing a reference implementation of the algorithms that supports testing frameworks and compatibility for CI/CD integrations.
• The CPU-based reference implementation will provide critical validation functions for the GPU-based high performance implementation. Additionally, the PST developers will gain familiarity with the architecture of the DSPSR library, developing a solid foundation on which CUDA/GPU code will be implemented in future work.
• Flow Through mode: Typical tied-array beam observations at the full temporal resolution and over the full frequency band generate large amounts of data. The PST 'Flow Through' mode is a useful implementation that allows a commissioning scientist to record only a configurable portion of the band and with reduced bit-depth per sample. The ability to record a compressed version of the data is critical for reducing the turn-around time between obtaining and processing the data of an observation, and shortens the testing–learning–development cycles during telescope commissioning. Early commissioning tests of long-track pulsar observations, drift-scans of bright sources, as well as investigations of low-level RFI in the tied-array beam will benefit from such an implementation.

What?

• Extend the skeleton implementation of the DSP Flow Through mode by implementing the signal processing functionality required using CPU processing
• Ensure the architecture of the signal processing pipeline supports extension to using GPUs via CUDA. 
• Develop the BDD infrastructure for AA1 test cases of the Flow Through mode.

Acceptance Criteria

• C++ API developed that supports CPU based signal processing functionality needed for Flow Through mode.
• C++ API includes provisions for GPU based signal processing in future development work. 
• Jira XRay BDD scenarios/tests for Flow Through added to the PST Internal Integration Plan.