= Changes/atlod = ||atlod || || || || || ||Item || Complexity || Research || Milestone || Time || ||[wiki:Changes/atlod#SYSCALRecordChanges Sampler Statistics] || easy || none || 6 || 1d || ||[wiki:Changes/atlod#SYSCALRecordChanges Storage Of SYSCAL Data] || moderate || some || 6 || 2*5d|| ||ApplyingXYPhaseCorrections|| easy || little || 6 || 5d || ||[wiki:Changes/atlod#DataSizeLimits Data Size Limits] || easy || little || 6 || 2d || ||FlaggingWithinATLOD - basics|| easy || little || 6 || 5d || ||MoreSelectionOptions || easy || little || 6 || 5d || ||IdentifyParentWindow || moderate || some || 8 || 2*5d || ||[wiki:Changes/atlod#FlaggingWithinATLOD Flagging Within ATLOD] - autoflagging || moderate || some || 9 || 4*5d || == SYSCAL Record Changes == The SYSCAL records will change from their current form. SamplerStatistics:: Not present in CABB data; do not execute flagging or "samcorr" code. StorageOfSYSCALData:: AT correlator data format holds 24 scalar values of Tsys (6 antennae * 2 polarizations * 2 IFs) written into every integration, and 12 (6 ant. * 2 IFs) of XYPhase.[[BR]] [[BR]] CABB data will include autocorrelation for both ON and OFF phases of the switched noise diode.[[BR]] ATLOD will calculate[[BR]][[BR]] Tsys(f) = OFF(f) * Tcal(f) / ( ON(f) - OFF(f) )[[BR]] for each of the XX and YY polarization products. In the equation above 'f' is the frequency.[[BR]] Tcal(f) will be included in the RPFITS file once per scan.[[BR]] ATLOD will also calculate[[BR]][[BR]] XYPhase(f) = arg( XYPhase_ON(f) - XYPhase_OFF(f) )[[BR]] ATLOD will record in the Miriad data TsysXX(f), TsysYY(f) and XYPhase(f). Input option 'noauto' will determine whether autocorrelation spectra are kept.[[BR]] Deciding what to do here in terms of data representation requires discussions with WarwickWilson. Making changes here has flow on effects to other tasks that use Tsys or XYPhase. ApplyingXYPhaseCorrections:: ATLOD applies the XYPhase correction, but retains the XYPhase(f) spectrum in the output. A few tasks (eg [http://www.atnf.csiro.au/computing/software/miriad/doc/atxy.html atxy] and [http://www.atnf.csiro.au/computing/software/miriad/doc/varplt.html varplt] ) use these data.[[BR]] [[BR]] Research needed: The phase values computed on a per channel basis will be noisy, and applying them will just introduce noise. We need to understand how much smoothing across frequency will be needed. Need to do some experiments to understand the sequence of events in reading in a file.[[BR]] Research needed: Does ATLOD work in a streaming mode? == Data Size Limits == Research needed: check for size limits on the data dimensions - number of windows, channels, etc == Identify Parent Window == Each spectral window output by the correlator can have some [wiki:Glossary/ZoomBands ZoomBands] defined. Miriad will keep track of each window's parent window. There will be 0 or 1 parents. Research needed: Determine whether it is necessary to keep track of the children of a particular band. == Flagging Within ATLOD == [http://www.atnf.csiro.au/computing/software/miriad/doc/atlod.html atlod] does not copy bad data to its output. This makes flagging in ATLOD qualitatively different to other parts of Miriad. Other editing tasks in Miriad set flags in a flag table to mask out bad data. For CABB data, ATLOD's [wiki:Glossary/Birdies birdie] flagging will change: * a different set of birdie frequencies (to be determined) * removal of every second frequency channel will not be needed. Research needed * What are the birdie frequencies in the new system? * Can data be flagged automatically by ATLOD using [Glossary/AutoCorrelations autocorrelations]? (Could we use algorithms from 'pieflag'?) == More Selection Options == Miriad will need the capability to inspect an RPFITS file in order to determine the identity of the various spectral windows in the file. Research needed: How are zoom bands to be represented in the RPFITS data format? [wiki:Changes Changes Home][[BR]] [/trac/miriad4cabb Wiki Home]