Difference between revisions of "The HFI DPC"

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<span style="font-size:150%">'''Contents of this chapter'''</span>
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; [[HFI_cryogenics | Cryogenics]]: ''[[HFI_cryogenics#Dilution|Dilution]] • [[HFI_cryogenics#4K_J-T_cooler|4K J-T cooler]]
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; [[HFI_cold_optics | Cold optics]]: ''[[HFI_cold_optics #Horns,lenses|Horns,lenses]] • [[HFI_cold_optics #Spectral_Characterization_of_the_HFI_Detector_Focal_Plane|Spectral Characterization of the HFI Detector Focal Plane]]
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; [[HFI_detection_chain | Detection chain]]: ''[[HFI_detection_chain#Bolometers|Bolometers]] • [[HFI_detection_chain#Focal_plane_layout|Focal plane layout]] • [[HFI_detection_chain#Readout|Readout]] • [[HFI_detection_chain#Principles_of_the_readout_electronics|Principles of the readout electronics]] • [[HFI_detection_chain#JFETs|JFETs]] • [[HFI_detection_chain#Data_compression|Data compression]] • [[HFI_detection_chain#Time_response|Time response]] • [[HFI_detection_chain#LFER4_model|LFER4 model]] • [[HFI_detection_chain#Parameters_of_LFER4_model|Parameters of LFER4 model]] • [[HFI_detection_chain#HFI_electronics_filter_sequence|HFI electronics filter sequence]]''
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; [[HFI_operations | Operations]]: ''[[HFI_operations#Overview|Overview]] • [[HFI_operations#Timeline|Timeline]]''
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; [[HFI_summary | Summary]]: here remind worse sytematics and point to DPC. Summary of sucess and limitations. JML. Link to early HFI in flight perf.<span style="color:red">(Lamarre)</span>
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; [[HFI_inst_annexes | Annexes]]
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<span style="font-size:200%">'''Overview'''</span>
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The first stage of HFI data processing is performed on-board in order to generate the telemetry as described in [[HFI_detection_chain#Data_compression | this page]]. On the ground, the HFI DPC has been organized into different "Levels": 1, 2, 3, 4 and "S". In brief, during operations, L1 feeds the database resulting in time-ordered information (TOI) objects. L2 is the core of the processing, which turns TOIs into clean calibrated sky maps. L3 transforms these maps at specific frequencies into more scientific products, like catalogues, maps and spectra of astrophysical components. L3 can rely on simulation provided by the LS, while L4 refers to delivering the DPC products to ESA.  This processing relies on dedicated software and hardware infrastructures developed pre-launch.
 
The first stage of HFI data processing is performed on-board in order to generate the telemetry as described in [[HFI_detection_chain#Data_compression | this page]]. On the ground, the HFI DPC has been organized into different "Levels": 1, 2, 3, 4 and "S". In brief, during operations, L1 feeds the database resulting in time-ordered information (TOI) objects. L2 is the core of the processing, which turns TOIs into clean calibrated sky maps. L3 transforms these maps at specific frequencies into more scientific products, like catalogues, maps and spectra of astrophysical components. L3 can rely on simulation provided by the LS, while L4 refers to delivering the DPC products to ESA.  This processing relies on dedicated software and hardware infrastructures developed pre-launch.
  
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== Level 1: building the reference database during flight operations ==
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<span style="font-size:150%">'''Level 1: building the reference database during flight operations''' </span>
  
 
(L1): consists in receiving the telemetry and ancillary data files and ingesting them into the DPC database.  This involves decompressing, in some cases changing data formats, computing the time of individual data samples from the time of the compression slices, but otherwise no processing proper. Other steps are:
 
(L1): consists in receiving the telemetry and ancillary data files and ingesting them into the DPC database.  This involves decompressing, in some cases changing data formats, computing the time of individual data samples from the time of the compression slices, but otherwise no processing proper. Other steps are:
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This is further described in the [[Pre-processing]] section.
 
This is further described in the [[Pre-processing]] section.
  
== Level 2: converting temporal information into clean calibrated maps ==
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<span style="font-size:150%">'''Level 2: converting temporal information into clean calibrated maps'''</span>
  
 
(L2): this is where the data are processed from timelines into maps. The main processing steps are
 
(L2): this is where the data are processed from timelines into maps. The main processing steps are
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* The resulting data characteristics are given in section [[Summary]].
 
* The resulting data characteristics are given in section [[Summary]].
  
== Level 3: Basic analyses of (Level 2) Frequency maps==
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<span style="font-size:150%">'''Level 3: Basic analyses of (Level 2) Frequency maps'''</span>
  
 
(L3): This is where the data in the form of frequency maps are converted to catalogues and full sky astrophysical component maps. Much of this is done in common with the LFI DPC, and is further described in the [[HL | HFI/LFI common sections ]].
 
(L3): This is where the data in the form of frequency maps are converted to catalogues and full sky astrophysical component maps. Much of this is done in common with the LFI DPC, and is further described in the [[HL | HFI/LFI common sections ]].
  
== Level 4 : Delivering results ==
+
<span style="font-size:150%">'''Level 4 : Delivering results'''</span>
  
 
Level 4 is the "Archive Level". No processing done, but rather exporting, reformating, documenting.  
 
Level 4 is the "Archive Level". No processing done, but rather exporting, reformating, documenting.  
  
== Level S : A common HFI/LFI simulation software ==
+
<span style="font-size:150%">'''Level S : A common HFI/LFI simulation software'''</span>
  
 
Level S is the so-called "Simulation Level"  software suite common to both consortia, which, given a sky model (generated by the Planck sky model, <tt>PSM</tt>), detectors pointing and beams, generates the infalling power on each detector. It can also provide a simplified description of eg. the noise. It is further described in the HFI/LFI [[ HL | common section]]. HFI specific developments (configuration control & MC bench, specific effects like 4K lines, glitches, ADC non-linearity, etc.) are described in [[HFI-Validation | the HFI data validation section]].
 
Level S is the so-called "Simulation Level"  software suite common to both consortia, which, given a sky model (generated by the Planck sky model, <tt>PSM</tt>), detectors pointing and beams, generates the infalling power on each detector. It can also provide a simplified description of eg. the noise. It is further described in the HFI/LFI [[ HL | common section]]. HFI specific developments (configuration control & MC bench, specific effects like 4K lines, glitches, ADC non-linearity, etc.) are described in [[HFI-Validation | the HFI data validation section]].
  
== HFI DPC Infrastructures==
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<span style="font-size:150%">'''HFI DPC Infrastructures'''</span>
 
 
 
The HFI Data Processing Centre can be thought of as a centralized
 
The HFI Data Processing Centre can be thought of as a centralized
 
backbone providing hardware and software infrastructures
 
backbone providing hardware and software infrastructures

Revision as of 11:06, 28 January 2013



Contents of this chapter


Cryogenics
Dilution4K J-T cooler
Cold optics
Horns,lensesSpectral Characterization of the HFI Detector Focal Plane
Detection chain
BolometersFocal plane layoutReadoutPrinciples of the readout electronicsJFETsData compressionTime responseLFER4 modelParameters of LFER4 modelHFI electronics filter sequence
Operations
OverviewTimeline
Summary
here remind worse sytematics and point to DPC. Summary of sucess and limitations. JML. Link to early HFI in flight perf.(Lamarre)
Annexes





Overview

The first stage of HFI data processing is performed on-board in order to generate the telemetry as described in this page. On the ground, the HFI DPC has been organized into different "Levels": 1, 2, 3, 4 and "S". In brief, during operations, L1 feeds the database resulting in time-ordered information (TOI) objects. L2 is the core of the processing, which turns TOIs into clean calibrated sky maps. L3 transforms these maps at specific frequencies into more scientific products, like catalogues, maps and spectra of astrophysical components. L3 can rely on simulation provided by the LS, while L4 refers to delivering the DPC products to ESA. This processing relies on dedicated software and hardware infrastructures developed pre-launch.

The data processing applied for the "Early Planck results" series of publications was described in Planck early paper VI . The Template:REF TO P03 and its co-papers provide the reference for the processing done for the 2013 Data release. An Annex of P03 specifies what had been done (and resulting characteristics) for the "Intermediate Planck results" series of publications.


Level 1: building the reference database during flight operations

(L1): consists in receiving the telemetry and ancillary data files and ingesting them into the DPC database. This involves decompressing, in some cases changing data formats, computing the time of individual data samples from the time of the compression slices, but otherwise no processing proper. Other steps are:

  • data ingestion (science, HK, ancillary, other?)
  • construction of ToS in science data group
  • pointing interpolation
  • construction of other TOI and ROI objects from AHF, ...

This is further described in the Pre-processing section.

Level 2: converting temporal information into clean calibrated maps

(L2): this is where the data are processed from timelines into maps. The main processing steps are

  • Timeline (or Time-Ordered Information = TOI) processing, which includes conversion from ADUs to engineering units (Volts), demodulation, deglitching, conversion from engineering to physical units (Watts), removal of known systematic effects (non-linearities, 4K lines, Jumps, ring flagging), removal of the instrumental signature (time transfer function), temporal noise Estimation. Details here.
  • Pointing and beam of each detector. See section Pointing&Beams.
  • map-making & photomoetric calibration: projecting the TOIs onto all-sky maps, etc. See section Map-making.
  • Characterisation/validation through angular power spectra. See section PowerSpectra.
  • Overal HFI data validation, through difference tests, comparison to detailed simulations, etc., See section HFI-Validation
  • The resulting data characteristics are given in section Summary.

Level 3: Basic analyses of (Level 2) Frequency maps

(L3): This is where the data in the form of frequency maps are converted to catalogues and full sky astrophysical component maps. Much of this is done in common with the LFI DPC, and is further described in the HFI/LFI common sections .

Level 4 : Delivering results

Level 4 is the "Archive Level". No processing done, but rather exporting, reformating, documenting.

Level S : A common HFI/LFI simulation software

Level S is the so-called "Simulation Level" software suite common to both consortia, which, given a sky model (generated by the Planck sky model, PSM), detectors pointing and beams, generates the infalling power on each detector. It can also provide a simplified description of eg. the noise. It is further described in the HFI/LFI common section. HFI specific developments (configuration control & MC bench, specific effects like 4K lines, glitches, ADC non-linearity, etc.) are described in the HFI data validation section.

HFI DPC Infrastructures The HFI Data Processing Centre can be thought of as a centralized backbone providing hardware and software infrastructures to a relatively large number of geographically distributed groups of developers and other R&D groups in the HFI and LFI core teams.

An overview was given in the HFI data processing paper of the "Planck Early Results" series. In particular:


HFI logo H.png

Data Processing Center

(Planck) High Frequency Instrument

European Space Agency

House Keeping

Time of Sample

Ring-Ordered Information (DMC group/object)

Attitude History File

EMI/EMC influence of the 4K cooler mechanical motion on the bolometer readout electronics.

[LFI meaning]: absolute calibration refers to the 0th order calibration for each channel, 1 single number, while the relative calibration refers to the component of the calibration that varies pointing period by pointing period.

(Planck) Low Frequency Instrument

Planck Sky Model

analog to digital converter