Realtime Calibration Library
This package contains the Realtime Calibration Pipeline, a SDP Receive Processors Processor that generates real-time calibration solutions for each visibility payload from the realtime receive pipeline. The solutions are then made available for subsequent real-time processing, in particular for tied-array beamforming in the Correlator & Beamformer (CBF) of the Central Signal Processor.
The payloads are Visibility
datasets that are sent from the Receiver via an Apache Plasma store. Various
corruption factors, such as bandpass matrices, antenna beam matrices and
ionospheric delays, are estimated, combined and inverted to form correction
matrices, which are stored in
GainTable xarray
datasets. A stripped-back version of each dataset is then sent to the Data
Queues using the XARRAY encoding.
Context
At a high level the realtime receive processors lie at the end of the realtime receive pipeline, each working with data written to the plasma store by the Receiver (in the SKA SDP Realtime Receive Modules repository).
The processors are responsible for performing some action on the data, for example writing to a measurement set—and in this case, for performing bandpass calibration. After calibration solving the combined antenna-based correction matrices have spectral sampling that is appropriate for CBF beamforming.
