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RadioAstron Closed Loop for DiFX

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    Comparing version 15:19, 20 May 2019 by jwagner with version 15:31, 20 May 2019 by jwagner.

    ...

    $ calcif3 --allow-neg-delay rk18cj_1.input
$ raPatchClosedloop.py RA_C_COH.TXT -r 2.4886e-06 RA_C_COH.TXT RA_C_COH_uvw.txt rk18cj_1.im

    ...

    1. scan startthe initial delay (0th order term) is taken from the original .im file)at scan start as predicted by CALC9 based upon V2D & VEXis taken from the .im file
    2. intra-scan poly segment delays (0th order terms) are recomputedsubsequent poly segment intervals have delay (0th order) that is based on (1) and the cumulative sum of delay changes over previous poly segments, this ensures time continuity on polynomial segmentall earlier poly segments, i.e., poly segments are kept time-continuous across poly boundaries
    3. delay rate (1st order termthe initial rate (1th order) and higher-order poly coefficients are taken from the ASC files , rate is adjusted by optional user-provided residual rate (optionnot from VEX or V2D'-r <delta rate usec/sec>')

    To use the new .im.closedloop file infor a DiFX correlation run:

    ...

    If fringe SNR or residual phase behaviour needs to be improved across the duration of scans, the a priori delay polynomial can be refined via fringe fitting in PIMA. After an initial DiFX correlation with just the a priori polynomial data the resulting visibility data can be difx2fits exported (in one band) to a FITS file which then is fringe fitted using PIMA---Iterative improvement of the ASC poly coefficients might be necessary. Currently, we know ASC has a method to do this, but at Bonn we do not have details yet. With PIMA fringe fitting one could determine delay, rate, acceleration residuals. However how higher-order terms could be refined is yet unclear.

    The PIMA config file needs to have "MAX_SCAN_LEN: 60" in order for the fringe fit results to be consistent with Once we settle at a good approach, a mechanism to feed back fringe-fit results into raPatchClosedloop.py will be implemented. TODO: the 60 second interval of CALC9 and ASC delay polynomial segments.1) run PIMA, make fringe fit on scan(s)

    The resultant PIMA .fri file and its delay rate and acceleration residuals can be applied to the ASC a priori polynomial text file to produce a next iteration polynomial text file that can be used in a recorrelation.2) parse PIMA .fri files, patch rate&accel into ASC coeffs producing a new file (2nd gen): need some new script perform the parse and patch

    $ difx2fits --override-version -x -d --clock-merge-mode drop Kband.fits

$ pima_fringe.csh rk18cj K load
$ pima_fringe.csh rk18cj K fine

$ raPatchClosedloop.py -P 3) re-run raPatchClosedloop with the 2nd gen poly file, re-run DiFX
rk18cj_k.fri RA_C_COH.TXT
Wrote RA_C_COH.TXT.rev1

$ raPatchClosedloop.py RA_C_COH.TXT.rev1 rk18cj_2.im
$ mv rk18cj_2.im rk18cj_2.im.openloop ; cp rk18cj_2.im.closedloop rk18cj_2.im
$ startdifx --dont-calc rk18cj_2.input

$ difx2fits 4) run PIMA on the 2nd gen visibility data to check whether residual rate and accel are reduced--override-version -x -d --clock-merge-mode drop final.fits

    Other changes:

    1. /body/p[59]/@style: "margin-left: 40px;" ⇒ nothing

    Version from 15:19, 20 May 2019

    This revision modified by jwagner (Ban)

    ...

    $ calcif3 --allow-neg-delay rk18cj_1.input
$ raPatchClosedloop.py -r 2.4886e-06 RA_C_COH.TXT RA_C_COH_uvw.txt rk18cj_1.im

    ...

    1. the initial delay (0th order) at scan start as predicted by CALC9 is taken from the .im file
    2. subsequent poly segment intervals have delay (0th order) that is based on (1) and the sum of delay changes over all earlier poly segments, i.e., poly segments are kept time-continuous across poly boundaries
    3. the initial rate (1th order) and higher-order poly coefficients are taken from the ASC files
    4. rate is adjusted by optional user-provided residual rate (option '-r <delta rate usec/sec>')

    To use the new .im.closedloop file for a DiFX correlation run:

    ...

    ---Iterative improvement of the ASC poly coefficients might be necessary. Currently, we know ASC has a method to do this, but at Bonn we do not have details yet. With PIMA fringe fitting one could determine delay, rate, acceleration residuals. However how higher-order terms could be refined is yet unclear. Once we settle at a good approach, a mechanism to feed back fringe-fit results into raPatchClosedloop.py will be implemented.

    TODO:

    1) run PIMA, make fringe fit on scan(s)

    2) parse PIMA .fri files, patch rate&accel into ASC coeffs producing a new file (2nd gen): need some new script perform the parse and patch

    3) re-run raPatchClosedloop with the 2nd gen poly file, re-run DiFX

    4) run PIMA on the 2nd gen visibility data to check whether residual rate and accel are reduced

    Version as of 15:31, 20 May 2019

    This revision modified by jwagner (Ban)

    ...

    1. scan start initial delay (0th order term) is taken from the original .im file as predicted by CALC9 based upon V2D & VEX
    2. intra-scan poly segment delays (0th order terms) are recomputed based on (1) and the cumulative sum of delay changes over previous poly segments, this ensures time continuity on polynomial segment boundaries
    3. delay rate (1st order term) and higher-order poly coefficients are taken from the ASC files, not from VEX or V2D

    To use the new .im.closedloop file in a DiFX correlation run:

    ...

    If fringe SNR or residual phase behaviour needs to be improved across the duration of scans, the a priori delay polynomial can be refined via fringe fitting in PIMA. After an initial DiFX correlation with just the a priori polynomial data the resulting visibility data can be difx2fits exported (in one band) to a FITS file which then is fringe fitted using PIMA.

    The PIMA config file needs to have "MAX_SCAN_LEN: 60" in order for the fringe fit results to be consistent with the 60 second interval of CALC9 and ASC delay polynomial segments.

    The resultant PIMA .fri file and its delay rate and acceleration residuals can be applied to the ASC a priori polynomial text file to produce a next iteration polynomial text file that can be used in a recorrelation.

    $ difx2fits --override-version -x -d --clock-merge-mode drop Kband.fits

$ pima_fringe.csh rk18cj K load
$ pima_fringe.csh rk18cj K fine

$ raPatchClosedloop.py -P rk18cj_k.fri RA_C_COH.TXT
Wrote RA_C_COH.TXT.rev1

$ raPatchClosedloop.py RA_C_COH.TXT.rev1 rk18cj_2.im
$ mv rk18cj_2.im rk18cj_2.im.openloop ; cp rk18cj_2.im.closedloop rk18cj_2.im
$ startdifx --dont-calc rk18cj_2.input

$ difx2fits --override-version -x -d --clock-merge-mode drop final.fits