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meerkat-backend-interface

This repository contains the KATCP Server, Katportal Client and Coordinator components of the diagram below. Together, they extract all the observational metadata required for Breakthrough Listen's automated commensal observing program on MeerKAT. These data include:

  • Addresses of SPEAD packet streams containing raw channelised antenna voltage data, to be subscribed to by our processing nodes for beamforming.
  • Current target information.
  • Information regarding the current stage and historical progress of an observation.
  • Information regarding the current subarray configuration, including:
    • Specific antennas in the subarray
    • All other components in the subarray (e.g. CBF, SDP, other USEs)
    • Information about the band, center frequency, sampling rate, etc.
  • Other comprehensive sensor data including the health of F-engine output streams.

Once acquired, the Coordinator publishes the appropriate commands to the processing nodes via the Hashpipe-Redis gateway.

Other repositories that may be useful:

  • meerkat-reconfig - A tool to resend the most recent observation configuration information to specified hosts (processing nodes). Useful when debugging.

  • CAMcorder - A tool to record and replay Redis commands in sequence; also useful when debugging.

Diagram of the Breakthrough Listen MeerKAT Backend Interface

  • CAM (Control and Monitoring): MeerKAT's control and monitoring system.
  • blpn48 - blpnN: Breakthrough Listen's processing nodes (breakthrough listen processing node)
  • CBF (Correlator-Beamformer): The MeerKAT component from which the F-engine UDP multicast streams are issued.
  • Redis Database: Stores key-value pairs of sensor information, and uses Redis pub/sub channels to disseminate information between components and other processing nodes.
  • The Katportal Client sends requests for additional metadata to CAM.
  • Target Selection and Beam Forming: This system (in a separate repository) selects targets in the current field of view and sends them to the processing nodes.

For redis key formatting and respective value descriptions, please see the Redis Documentation

diagram

Usage

After starting redis, the processes can be started manually as given below. However, the intention is that they be run using circusd or similar.

(venv)$ python katcp_start.py --ip <fixed localhost ip address> --port <port> 

(venv)$ python katportal_start.py --config <config file>

(venv)$ python coordinator.py --config <config file> --triggermode <trigger mode>

Current limitations/considerations:

  • Currently, katportal_start.py does not shut down in a thread-safe way. katcp_start.py manages to do this, but it uses a complex mechanism that I don't understand.

  • Tasks are marked in the code with a TODO keyword.

  • Will this same software be used on the SKA? (approx. 2022?)

References

  1. SETI on MeerKAT Project Proposal, Siemion et al.
  2. katcp-python GitHub repository
  3. katportalclient GitHub repository
  4. MeerKAT ICD
  5. TRAPUM-CAM Interface
  6. Swim Lane Diagram
  7. Katportal Docs.