GSTLALWhiten

GSTLALWhiten — Whiten coloured Gaussian noise.

Synopsis

struct              GSTLALWhiten;
struct              GSTLALWhitenClass;
#define             GSTLAL_PSDMODE_TYPE
#define             GSTLAL_WHITEN_TYPE
GstMessage *        gstlal_whiten_message_psd_new       (GSTLALWhiten *element,
                                                         const gchar *instrument,
                                                         const REAL8FrequencySeries *psd);
REAL8FrequencySeries * gstlal_whiten_message_psd_parse  (GstMessage *m);

Object Hierarchy

  GObject
   +----GstObject
         +----GstElement
               +----GstBaseTransform
                     +----GSTLALWhiten

Properties

  "average-samples"          guint                 : Read / Write / Construct
  "delta-f"                  gdouble               : Read
  "expand-gaps"              gboolean              : Read / Write / Construct
  "f-nyquist"                gdouble               : Read
  "fft-length"               gdouble               : Read / Write / Construct
  "mean-psd"                 GValueArray*          : Read / Write
  "median-samples"           guint                 : Read / Write / Construct
  "n-samples"                guint                 : Read
  "psd-mode"                 GSTLAL_PSDMODE        : Read / Write / Construct
  "sigma-squared"            gdouble               : Read
  "spectral-correlation"     GValueArray*          : Read
  "zero-pad"                 gdouble               : Read / Write / Construct

Description

This element constructs a whitening filter from a power spectral density function, which it uses to transform coloured Gaussian noise into white Gaussian noise. The power spectral density function can be provided externally or the element can measure it from the time series data using the LALPSDRegressor machinery. When measuring the spectrum internally, the element will track changes in the spectrum. The "average-samples" and "n-samples" parameters control the time scales of the averaging.

The power spectral density function measured by the element is available to external code via three communication channels. The PSD and its physical parameters can be retrieved through the "delta-f", "f-nyquist", and "psd" properites. Use GObject's notify mechanism to be informed of changes in these values. When a new PSD is measured, the element posts a GstMessage to the pipeline's message bus containing the PSD and its properites (see #gstlal_whiten_message_psd_parse() for parsing the message). Finally, a request pad named "mean-psd" is available. If the pad is present, each PSD is packed into a GstBuffer and pushed out that GstPad.

To set a PSD, the "f-nyquist" property should be consulted. This property gives the Nyquist frequency (in Hertz) of the PSD data that must be provided and is determined by the sample rate of the time series. The "fft-length" property sets the length of the FFT blocks that will be used for filtering the data, and thus determines the value of the "delta-f" property.

Reviewed: cf799de0ed55bf454fcd7fd8bc88dcaa8c4bd97e 2014-08-10 K. Cannon, J. Creighton, B. Sathyaprakash.

Details

struct GSTLALWhiten

struct GSTLALWhiten;

struct GSTLALWhitenClass

struct GSTLALWhitenClass {
	GstBaseTransformClass parent_class;
};

GstBaseTransformClass parent_class;

 the parent class

GSTLAL_PSDMODE_TYPE

#define             GSTLAL_PSDMODE_TYPE

GSTLAL_WHITEN_TYPE

#define             GSTLAL_WHITEN_TYPE

gstlal_whiten_message_psd_new ()

GstMessage *        gstlal_whiten_message_psd_new       (GSTLALWhiten *element,
                                                         const gchar *instrument,
                                                         const REAL8FrequencySeries *psd);

gstlal_whiten_message_psd_parse ()

REAL8FrequencySeries * gstlal_whiten_message_psd_parse  (GstMessage *m);

Property Details

The "average-samples" property

  "average-samples"          guint                 : Read / Write / Construct

Number of FFTs to be used in PSD average.

Allowed values: >= 1

Default value: 32

The "delta-f" property

  "delta-f"                  gdouble               : Read

PSD frequency resolution in Hertz.

Allowed values: >= 0

Default value: 0

The "expand-gaps" property

  "expand-gaps"              gboolean              : Read / Write / Construct

expand gaps to fill entire fft length.

Default value: FALSE

The "f-nyquist" property

  "f-nyquist"                gdouble               : Read

Nyquist frequency in Hertz.

Allowed values: >= 0

Default value: 0

The "fft-length" property

  "fft-length"               gdouble               : Read / Write / Construct

Total length of the FFT convolution (including zero padding) in seconds.

Allowed values: >= 0

Default value: 8

The "mean-psd" property

  "mean-psd"                 GValueArray*          : Read / Write

Mean power spectral density being used to whiten the data. First bin is at 0 Hz, last bin is at f-nyquist, bin spacing is delta-f.

The "median-samples" property

  "median-samples"           guint                 : Read / Write / Construct

Number of FFTs to be used in PSD median history.

Allowed values: >= 1

Default value: 9

The "n-samples" property

  "n-samples"                guint                 : Read

Number of FFTs used for PSD average. Stops increasing after the number of FFTs equals average-samples.

Default value: 0

The "psd-mode" property

  "psd-mode"                 GSTLAL_PSDMODE        : Read / Write / Construct

PSD estimation mode.

Default value: GSTLAL_PSDMODE_RUNNING_AVERAGE

The "sigma-squared" property

  "sigma-squared"            gdouble               : Read

FFT window mean square.

Allowed values: >= 0

Default value: 0

The "spectral-correlation" property

  "spectral-correlation"     GValueArray*          : Read

Two-point spectral correlation function for output stream. Bin index is |k - k'|.

The "zero-pad" property

  "zero-pad"                 gdouble               : Read / Write / Construct

Length of the zero-padding to include on both sides of the FFT in seconds.

Allowed values: >= 0

Default value: 2

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