The ALMA TelCal subsystem Dominique Broguière , Institut de RadioAstronomie Millimétrique (IRAM) TelCal Phasing meeting – Grenoble -10/12/2012
Jan 02, 2016
The ALMA TelCal subsystem
Dominique Broguière , Institut de RadioAstronomie Millimétrique (IRAM)
TelCal Phasing meeting – Grenoble -10/12/2012
TELCAL Phasing meeting - 10 December 2012 2
Presentation layout
• TelCal overview
• ALMA software architecture
• TELCAL software architecture
• Offline mode of TelCal
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TelCal overview (1/3)• TELCAL is the on-line calibration software for the ALMA array.
• On-line calibration groups all the operations needed to maintain the ALMA interferometer optimally tuned to successfully execute the planned observations.
• On-line calibration primarily deals with :– pointing and focus offset computations– delay measurements – solving of antenna positions– measurement of atmospheric absorption and of phase radiometric correction– monitoring of phase and amplitude on an astronomical calibrator source– bandpass and sideband ratio measurements– holography to compute the panel adjustment needed to improve surface rms
and monitor surface quality– pointingModel
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TelCal overview (2/3)
• TELCAL software has been developed since 2003.
• People involved in TELCAL :– Robert Lucas : lead until 31-07-2012 – Dominique Broguiere (IRAM) lead since 01-08-2012– Jean-Christophe Roche (IRAM)
Alexis Tejeda was working in TELCAL until June 2012, currently working in JAO
Juan Pardo was working on ATM library until end of 2011
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TelCal overview (3/3)• Programming languages :
– 70% C++ : calibration code and C++ Corba components– 13% python : offline scripts– 12% fortran90 : holography (gildas)– 5% java : Corba components
• SLOC (Source Lines Of Code) report for TELCAL– Calibration (Engines,TelCalSolvers, tpoint andTools modules) : 40000 lines– CORBA components (TelCalDataManager, TelCalPublisher, TelCalMaster,
and DCsimulator modules) : 10000 lines– Offline scripts (AsdmReader, Tasks and Standalone modules) : 11000 lines– ATM library : 22000 lines– Holography (Gildas) : 260000 lines (~ 15000 lines of fortran90 developed for
ALMA holography and ASDM-PDB filler, rest is frozen code) – Shared Simulator (SharedSimulator and SharedSimLib) : 10000 lines– Others (TelCalScripts module) : 1300 lines
Total : ~ 100000 lines
TelCal and the other subsystems
TELCAL
CONTROL
CORRELATOR
EXECUTIVE
ARCHIVE
Results (ASDM)
Results (ASDM)
Start/stop
Metadata (ASDM)
Correlator data
Totalpower data CONTROL(DataCapturer)
Interfaces of TELCAL with other subsystems
TELCAL architecture : containers and components
Based on ACS (Alma Common Software) infrastructure and tools
• CORBA : enables software components written in several languages (C++, java, python) and running on different machines to work together
• Components are deployed in containers. This simplifies the management of components
• Interface of components described in IDL language • Events used for asynchronous exchanges• AudioVideo streams for binary data transfer (high rates).
New implementation (2012-2013) based on RTI DDS.
TELCAL MASTERCOMPONENT
TELCALPUBLISHER
ARCHIVE
TELCAL TOTALPOWER RECEIVER
(n components)
TELCAL DATAMANAGER(n components)
CORBA components of TELCAL
TOTALPOWER
DISTRIBUTOR
DATACAPTURER
CORRELATOR
DISTRIBUTOR
EXECUTIVE
DATACAPTURER
scripts
TELCALPARAMETER_TUNING
TELCALARRAY
CONTROL
TelCal modules
Architecture :
4 main packages :• TelCalMaster : starting and
stopping the subsytem• TelCalDataManager : receiving,
filtering and organizing all data streams
• TelCalResults : processing the calibration
• TelCalPublisher : publishing the results
ATM package
• Result of research by J. Cernicharo and J. Pardo in Madrid• Agreement to use and extend this for ALMA (TelCal and Offline subsystems).• Predicts atmospheric emission, absorption and path-length for all ALMA bands • Water vapor retrieval algorithms available
Offline mode of TelCal
Goal : Exeute the data reduction off-line using the
science data produced (the asdm dataset)
• Python interface of the C++ modules of TelCal (Engines and AsdmReader)
• Provide tools (plots) to test the validity of the calibration• Default mode for Holography, AntennaPositions and
PointingModel • Also available for the other calibrations: PhaseCal,
PhaseCurve, Pointing, Focus, BandPass, Atmosphere, Skydip
Offline mode : user interface
• TelCal within Casa : Casa tasks– Use the Casa formalism (XML wrapper interface).– Offline tasks
• asdmplot : Plot the data from an ASDM dataset (visibilities,totalpower, WVR data…)
• asdmlist : List the content of an ASDM dataset• tc_antpos : Process an antenna position calibration and plot
the result
– Online tasks• tc_atmosphere, tc_wvr• tc_delay , tc_bandpass, tc_sidebandratio• tc_focus, tc_pointing• tc_amplical, tc_phasecal, tc_phasecurve
Calibration examples
• Examples :– Atmosphere calibration– Pointing, Focus– Delay measurements, Antenna Positions– PhaseCal, Phase Curve– BandPass– Holography
See: Telescope Calibration User Guide from Robert Lucas