Pulsar::NoiseStatistics Class Reference

Computes the noise to Fourier noise ratio. More...

#include <NoiseStatistics.h>

Inheritance diagram for Pulsar::NoiseStatistics:

Public Member Functions
	NoiseStatistics ()
	Default constructor.
void	set_baseline_fourier (float width)
	Set the fractional number of high frequencies used to calculate noise.
void	set_baseline_time (float width)
	Set the fractional number of phase bins used to calculate noise. More...
float	get_nfnr (const Profile *profile)
	Return the noise to Fourier noise ratio.
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
float	baseline_fourier
float	baseline_time

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 noise to Fourier noise ratio.

By Parseval's Theorem, the energy in the noise of the off-pulse baseline in the phase domain should be equal to the energy in the noise of the post-Nyquist harmonics in the frequency domain.

However, if the profile baseline is corrupted by some periodic structure, then the r.m.s. computed in the phase domain will be larger than that in the frequency domain, where the periodic corruption is likely isolated in some low harmonic.

Likewise, if the profile is unresolved, then the r.m.s. computed in the frequency domain will be larger than that in the phase domain because there are no post-Nyquist harmonics.

The noise to Fourier noise ratio is a way to detect either of these problems. If it is much greater than unity, then there is likely some low frequency structure in the profile baseline. If it is much less than unity, then it is likely that the profile contains unresolved structure. In either case, there is likely a good reason to discard the data.

Member Function Documentation

set_baseline_time()

void Pulsar::NoiseStatistics::set_baseline_time

(

float

width

)

Set the fractional number of phase bins used to calculate noise.

Set the fractional number of high frequencies used to calculate noise.

Referenced by Pulsar::Statistics::get_nfnr().

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

• NoiseStatistics.h
• NoiseStatistics.C