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difx:pcal [2011/03/18 16:27]
walterbrisken
difx:pcal [2015/10/21 10:08] (current)
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 ====== Phase cal Tone Extraction in DiFX ====== ====== Phase cal Tone Extraction in DiFX ======
 **Phase cal tone extraction is currently supported in the trunk of mpifxcorr. The latest versions of difxio (trunk), vex2difx (trunk) and difx2fits (trunk) should also now support pcal extraction.** **Phase cal tone extraction is currently supported in the trunk of mpifxcorr. The latest versions of difxio (trunk), vex2difx (trunk) and difx2fits (trunk) should also now support pcal extraction.**
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 ===Implementation=== ===Implementation===
-Phase cal tones are extracted in DiFX straight after the samples are unpacked to floats. ​ See pcal.cpp for the algorithm and note that the "​Implicit"​ class will be chosen in all but pathological cases. The baseband data are written into the pcal extraction buffer one FFT block at a time. Because a rough delay has already been calculated to align the FFT blocks, the data are derotated by working out the number of samples since the last second tick and calculating the position of the first sample within the pcal buffer based on this. The pcal phase and amplitude is calculated for each tone for each subintegration. These results are then accumulated at the FXManager. An amplitude correction is applied and the results are written out at the same time as the visibilities.+Phase cal tones are extracted in DiFX straight after the samples are unpacked to floats. ​ See pcal.cpp for the algorithm and note that the "​Implicit" or "​Trivial" class will be chosen in all but pathological cases (see [[pcalImplicitAlgorithm]] ​. The baseband data are written into the pcal extraction buffer one FFT block at a time. Because a rough delay has already been calculated to align the FFT blocks, the data are derotated by working out the number of samples since the last second tick and calculating the position of the first sample within the pcal buffer based on this. The pcal phase and amplitude is calculated for each tone for each subintegration. These results are then accumulated at the FXManager. An amplitude correction is applied and the results are written out at the same time as the visibilities.
  
 ==File format== ==File format==
difx/pcal.txt · Last modified: 2015/10/21 10:08 (external edit)