Calibration::StandardData Class Reference

Computes the normalized Stokes parameters in each phase bin. More...

#include <StandardData.h>

Inheritance diagram for Calibration::StandardData:

Public Member Functions
	StandardData (const Pulsar::PolnProfile *select=0)
	Default constructor.
void	select_profile (const Pulsar::PolnProfile *)
	Select the baseline and on-pulse regions from profile.
void	set_profile (const Pulsar::PolnProfile *)
	Set the profile from which estimates will be derived.
void	set_normalize (bool)
	Normalize estimates by the average determinant.
Stokes< Estimate< double > >	get_stokes (unsigned ibin)
	Get the Stokes parameters of the specified phase bin.
Pulsar::PolnProfileStats *	get_poln_stats ()
	Get the algorithm used to compute the profile statistics.
Estimate< double >	get_total_squared_invariant ()
	Get the total squared invariant used to normalize the Stokes parameters.
Public Member Functions inherited from Reference::Able
	Able (const Able &)
Able &	operator= (const Able &)
unsigned	get_reference_count () const
Public Member Functions inherited from Reference::HeapTracked
	HeapTracked (const HeapTracked &)
HeapTracked &	operator= (const HeapTracked &)
bool	__is_on_heap () const

Protected Attributes
Reference::To< Pulsar::PolnProfileStats >	stats
Reference::To< MEAL::NormalizeStokes >	normalize
Estimate< double >	total_squared_invariant
	The square of the invariant, integrated over all onpulse-phase bins,.

Additional Inherited Members
Static Public Member Functions inherited from Reference::Able
static size_t	get_instance_count ()
Static Public Member Functions inherited from Reference::HeapTracked
static void *	operator new (size_t size, void *ptr=0)
static void	operator delete (void *location, void *ptr)
static void	operator delete (void *location)
static size_t	get_heap_queue_size ()
Protected Member Functions inherited from Reference::Able
Handle *	__reference (bool active) const
void	__dereference (bool auto_delete=true) const

Detailed Description

Computes the normalized Stokes parameters in each phase bin.

The apparent pulsar flux varies with time, and it is necessary to normalize the observed Stokes parameters when modelling. Because the total intensity is distorted by polarimetric tranformations, it is necessary to estimate the apparent gain variations using the polarimetic invariant interval.

Before this class was written, the NormalizeStokes class was used to normalize each set of Stokes parameters by their invariant. However, when the signal-to-noise ratio is low, the invariant can be less than or equal to zero and as a result many points had to be discarded.

This problem is overcome by normalizing each set of Stokes parameters by the mean of the invariant interval over all on-pulse phase bins. This approach has the following benefits:

1) even when the Stokes parameters in a single phase bin are highly polarized, the other less polarized on-pulse phase bins will produce a mean invariant greater than zero

2) the mean invariant interval has sqrt(onpulse_nbin) greater S/N

3) the mean invariant is chi distributed with onpulse_nbin * 4 degrees of freedom (much more like normally distributed than 4 d.o.f)

Constructor & Destructor Documentation

StandardData()

Calibration::StandardData::StandardData

(

const Pulsar::PolnProfile *

select = 0

)

Default constructor.

If specified, baseline and on-pulse regions are defined by select

References select_profile().

Member Data Documentation

total_squared_invariant

Estimate<double> Calibration::StandardData::total_squared_invariant

protected

The square of the invariant, integrated over all onpulse-phase bins,.

This is proportional to the gain squared, so it's sqrt is taken as a normalization factor.

Referenced by get_stokes(), get_total_squared_invariant(), select_profile(), and set_profile().

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The documentation for this class was generated from the following files:

• StandardData.h
• StandardData.C