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calibrater.setsolvegainspline  Function
2.2.1 Specialization of setsolve for cubic spline G (timedependent gain)
solving
Description
This function is a specialization of the setsolve method which should be used
when cubic spline G solutions are desired, e.g., when SNR on calibrators is
very low. Currently, this solving mode treats dual polarization data on a
perpolarization basis. The option to obtain a joint solution (a la ’T’) will be
provided in the future.
The visibility data are averaged in frequency (for multichannel data) prior to the solution.
This method uses many of the basic parameters as the generic setsolve. Parameters unique to the spline solver are:
 mode
 For phase solutions only, use mode=’PHAS’. For amplitude solutions only, use mode=’AMP’. If both are desired, use mode=’PHASAMP’, and both will be solved for using the same spline timescale (this mode also assumes that all calibrators have the correct relative flux densities). If solving for phase and amplitude separately (usually in this order), it is usually desirable to apply the first one when solving for the second one. Spline solution so obtained will be stored in separate calibration tables. In the near future, the mode parameter will be consolidated with the generic apmode parameter.
 splinetime
 The spline timescale (time between knots) is specified here. The default is 10800 seconds (3 hours). In future this parameter will be consolidated with the generic t parameter. The preavg parameter should be set to a value at least 4X shorter than the spline time (an error will occur if there is insufficient sampling within the splinetime timescale), and consistent with the expected coherence. Consistent with these constraints, use the largest possible value for preavg to optimize the SNR of the presolve phasetracking algorithm.
 npointaver and phasewrap
 These parameters tune the phaseunwrapping algorithm when mode = ’PHAS’. Cycle slips are detected (and removed before the spline solve) when the median phase a sequence of length npointaver (in integrations) differs by more than phasewrap degrees from the previous sequence.
Pending improvements:
 Consolidate more parameters with the generic setsolve
 Introduce the generic combine options
 Improve phasetracking algorithm
Arguments
Inputs 
 
table 
 Output calibration table name
 
 allowed:  string 

 Default: 
 
append 
 Append to existing table?
 
 allowed:  bool  
 Default:  false 

mode 
 Phase or Amplitude mode?
 
 allowed:  string 

 Default:  AMP PHASAMP PHAS 

splinetime 
 Spline timescale (sec)
 
 allowed:  double 

 Default:  10800 

preavg 
 Preaveraging interval (in sec)
 
 allowed:  double 

 Default:  0.0 

npointaver 
 
 allowed:  int 

 Default:  10 

phasewrap 
 
 allowed:  double 

 Default:  250 

refant 
 Reference antenna. Default is none.
 
 allowed:  any 

 Default:  variant


bool
Example
cb.open(’ngc5921.ms’)
cb.selectvis(field=’1445*’)
cb.setsolvegainspline (table=’gcalph’,mode=’PHAS’,splinetime=3600.0,preavg=60.0)cb.solve()
cb.setsolvegainspline (table=’gcalamp’,mode=’AMP’,splinetime=10800.0);
cb.solve();
cb.close();
In this example, a spline solution is first found for phase on a hourly timescale, then for amplitude on a threehour timescale.
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