AARTFAAC Status Update

Peeyush Prasad

Transcript

1. Algorithm development
   Pipeline Implementation
   ASM Deployment
   AARTFAAC: A Status Update
   Peeyush Prasad∗,†, Stefan Wijnholds∗, Folkert Huizinga†
   ∗ASTRON, †UvA
   January 08, 2014
   LOFAR TKP Meeting, Amsterdam
   TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
   

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2. institution-logo
   Algorithm development
   Pipeline Implementation
   ASM Deployment
   Outline
   Overview
   Algorithm development
   Pipeline Implementation
   Deployment
   Conclusions
   TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
   

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3. institution-logo
   Algorithm development
   Pipeline Implementation
   ASM Deployment
   AARTFAAC ASM
   24/7 Radio Sky Monitor, uses the 6 Superterp LOFAR stations
   Low resolution, low sensitivity, All-sky FoV, all the time (Piggyback)
   Low latency, near real-time response
   TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
   

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4. institution-logo
   Algorithm development
   Pipeline Implementation
   ASM Deployment
   AARTFAAC ASM
   Calibration and Imaging blocks
   24/7 Radio Sky Monitor, uses the 6 Superterp LOFAR stations
   Low resolution, low sensitivity, All-sky FoV, all the time (Piggyback)
   Low latency, near real-time response
   TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
   

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5. institution-logo
   Algorithm development
   Pipeline Implementation
   ASM Deployment
   AARTFAAC ASM
   System level blocks
   TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
   

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6. institution-logo
   Algorithm development
   Pipeline Implementation
   ASM Deployment
   Summary of calibration scheme
   Point src model sky based multisource direction dependent SelfCal.
   Iterative weighted LS estimators for model src flux, and position, antenna
   complex gains, system noise.
   WSF based model source position estimation.
   TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
   

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7. institution-logo
   Algorithm development
   Pipeline Implementation
   ASM Deployment
   Spatial filtering and flux estimation
   Spatial filtering of diffuse and extended emission prior to modeling.
   Leads to overestimation of model source flux with weighted LS estimator.
   Reformulation of Weighting matrix and optimization problem: unbiased
   estimate.
   TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
   

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8. institution-logo
   Algorithm development
   Pipeline Implementation
   ASM Deployment
   Spatial filtering and flux estimation
   Spatial filtering of diffuse and extended emission prior to modeling.
   Leads to overestimation of model source flux with weighted LS estimator.
   Reformulation of Weighting matrix and optimization problem: unbiased
   estimate.
   TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
   

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9. institution-logo
   Algorithm development
   Pipeline Implementation
   ASM Deployment
   Handling Ionospheric Scintillation
   Scintillation can cause model sources to change flux ratios, couples to gain
   TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
   

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10. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Handling Ionospheric Scintillation
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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11. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Handling Ionospheric Position errors
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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12. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Tracking calibration: Bounded latency
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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13. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Tracking calibration: Bounded latency
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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14. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    SelfCal residual phase errors
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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15. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Extracted Light curve stability
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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16. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Difference Imaging beats confusion limit
    IN
    diff
    =
    N
    i=0
    Ii+N
    −
    N
    i=0
    Ii
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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17. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Software Architecture
    Pelican framework for real-time data streaming, with flow management.
    CPU based implementation with low coupling, dedicated core per calibration
    time/freq. unit.
    Service data lane for tracking solution dispersal.
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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18. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Performance
    Eigen3 LinAlg. library for optimized matrix operations.
    Typical latency of ˜250ms for full convergence, ˜2sec on ’difficult’ data.
    Further optimization of the WSF component may be warranted.
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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19. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Control and Monitoring
    Interface with LOFAR via observation parset parsing.
    Universal controller for various subcomponents.
    Cherimoya: python based production mode pipeline monitoring on the network.
    Database of monitor products for history generation.
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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20. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Deployment: Station Hardware
    URI +Uniboards installed at all 6 stations, stress tested with LOFAR hardware
    (˜Nov 2013).
    8bit raw sampling, 7 MHz bandwidth@16bit complex subbands.
    Initial commissioning data over 1Gbps FPGA control links: 1 subband available.
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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21. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Deployment: GPU correlator
    2xXeon-E5 2690 CPU2 corner turner, 2xAMD FirePro S10000 FX engine.
    Hardware installation in progress.
    Expected bandwidth: ∼2.5MHz@16kHz/1sec resolution per GPU (currently
    limited by CPU packet reorder).
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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22. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Deployment: Imaging server
    2xOpteron 6376 dual proc servers, 128 cores.
    16kHz/1sec target resolution, subband collapsed images.
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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23. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    Conclusions
    Basic RFI mitigation via low order statistics seems adequate.
    Pipeline routinely achieves images with a dynamic range of ˜2000:1, limited by
    ionosphere and confusion.
    Difference imaging beats the confusion limit to achieve close to thermal noise
    limited imaging.
    Meeting fundamental latency requirements: Tracking calibration necessary for
    challenging data.
    Single subband pipeline deployment by mid-Feb.
    Future Work
    Interfacing with TraP: Image generation with proper WCS.
    Offline tuning of TraP on AARTFAAC lightcurves.
    Continuous sky monitoring for generation of reference sky.
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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24. institution-logo
    Algorithm development
    Pipeline Implementation
    ASM Deployment
    ‘
    TKP Meeting, Amsterdam Prasad, Wijnholds, Huizinga UvA/AARTFAAC,
    

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