Demonstrate the signal fidelity of Polyphase Filterbank (PFB) inversion according to the L2 Requirements and AA2 Use Cases

https://miro.com/app/board/uXjVKZ900uo=/?moveToWidget=3458764584502767193&cot=14

Beneficiaries (Who)

• AIV engineers; Commissioning scientists

Benefit Hypothesis (Why)

• The ability to invert the channelisation performed in the beamformer to recover a high-fidelity time series with greater time resolution (i.e. PFB inversion) is critical to the high-precision pulsar timing capability of the SKA. The implementation of a real-time PFB inversion of CBF data in PST has not been tested before, so this work aims to retire the risk associated with this critical function, as early as possible.

Description (What?)

• As part of this Feature's deliverables, the PST Complex Voltage Recorder will be used to ingest a pcap file that has been previously captured from the LOW PST beamformer, and to write the unpacked complex voltages to disk (as a DADA archive). The recorded DADA files will then be processed by the MATLAB or dspsr implementation of the PFB inversion, which will invert the filterbank, and then the signal fidelity of the inverted channels, in terms of meeting the L2 requirements for the spectral and temporal performance, will be demonstrated.

Acceptance Criteria

• Configure a CI pipeline that uses test vectors (designed in PI22) to test PFB inversion automatically
• Extend the suite of vectors to include realistic astronomical signals (e.g. dispersed signals). See https://confluence.skatelescope.org/display/SE/Polyphase+Filter+Bank+Inversion%3A+5.+requirements+verification
• Investigate and document the test criteria for the MID & LOW beamformers in order to support testing of different quantisations:
• Extend the work that was done for LOW (see https://confluence.skatelescope.org/display/SE/Polyphase+Filter+Bank+Inversion%3A+3c.+impact+of+fixed-point+precision) to the MID

• Investigate the effects of different integer shifts/offsets between stations/dishes (test the impact on inversion when an integer shift is added between station/dish signal)