sensor.cc File Reference

Functions related to sensor modelling. More...

#include <cmath>
#include <list>
#include <stdexcept>
#include "arts.h"
#include "logic.h"
#include "matpackI.h"
#include "matpackII.h"
#include "messages.h"
#include "sorting.h"
#include "sensor.h"

Go to the source code of this file.

Functions
void	antenna1d_matrix (Sparse &H, const Index &antenna_dim, ConstMatrixView antenna_los, const GriddedField4 &antenna_response, ConstVectorView za_grid, ConstVectorView f_grid, const Index n_pol, const Index do_norm)
	antenna1d_matrix More...
void	antenna2d_simplified (Sparse &H, const Index &antenna_dim, ConstMatrixView antenna_los, const GriddedField4 &antenna_response, ConstVectorView za_grid, ConstVectorView aa_grid, ConstVectorView f_grid, const Index n_pol, const Index do_norm)
	antenna2d_simplified More...
void	gaussian_response (Vector &x, Vector &y, const Numeric &x0, const Numeric &fwhm, const Numeric &xwidth_si, const Numeric &dx_si)
	gaussian_response More...
void	mixer_matrix (Sparse &H, Vector &f_mixer, const Numeric &lo, const GriddedField1 &filter, ConstVectorView f_grid, const Index &n_pol, const Index &n_sp, const Index &do_norm)
	mixer_matrix More...
void	sensor_aux_vectors (Vector &sensor_response_f, ArrayOfIndex &sensor_response_pol, Vector &sensor_response_za, Vector &sensor_response_aa, ConstVectorView sensor_response_f_grid, const ArrayOfIndex &sensor_response_pol_grid, ConstVectorView sensor_response_za_grid, ConstVectorView sensor_response_aa_grid, const Index za_aa_independent)
	sensor_aux_vectors More...
void	sensor_integration_vector (VectorView h, ConstVectorView f, ConstVectorView x_f_in, ConstVectorView x_g_in)
	sensor_integration_vector More...
void	sensor_summation_vector (VectorView h, ConstVectorView f, ConstVectorView x_f, ConstVectorView x_g, const Numeric x1, const Numeric x2)
	sensor_summation_vector More...
void	spectrometer_matrix (Sparse &H, ConstVectorView ch_f, const ArrayOfGriddedField1 &ch_response, ConstVectorView sensor_f, const Index &n_pol, const Index &n_sp, const Index &do_norm)
	spectrometer_matrix More...
bool	test_and_merge_two_channels (Vector &fmin, Vector &fmax, Index i, Index j)
	Test if two instrument channels overlap, and if so, merge them. More...
void	find_effective_channel_boundaries (Vector &fmin, Vector &fmax, const Vector &f_backend, const ArrayOfGriddedField1 &backend_channel_response, const Numeric &delta, const Verbosity &verbosity)
	Calculate channel boundaries from instrument response functions. More...

Variables
const Numeric	PI
const Numeric	NAT_LOG_2
const Index	GFIELD1_F_GRID
const Index	GFIELD4_FIELD_NAMES
const Index	GFIELD4_F_GRID
const Index	GFIELD4_ZA_GRID
const Index	GFIELD4_AA_GRID

Detailed Description

Functions related to sensor modelling.

Author

Mattias Ekström ekstr.nosp@m.om@r.nosp@m.ss.ch.nosp@m.alme.nosp@m.rs.se

Date

2003-02-27

Functions to model sensor behaviour and integration calculated as vector multiplication.

Definition in file sensor.cc.

Function Documentation

antenna1d_matrix()

void antenna1d_matrix	(	Sparse &	H,
		const Index &	antenna_dim,
		ConstMatrixView	antenna_los,
		const GriddedField4 &	antenna_response,
		ConstVectorView	za_grid,
		ConstVectorView	f_grid,
		const Index	n_pol,
		const Index	do_norm
	)

antenna1d_matrix

Core function for setting up the response matrix for 1D antenna cases.

Main task is to extract correct antenna pattern, including frequency interpolation. Actual weights are calculated in sensor_integration_vector.

Parameters

H	The antenna transfer matrix
antenna_dim	As the WSV with the same name
antenna_los	As the WSV with the same name
antenna_response	As the WSV with the same name
za_grid	Zenith angle grid for pencil beam calculations
f_grid	Frequency grid for monochromatic calculations
n_pol	Number of polarisation states
do_norm	Flag whether response should be normalised

Author

Mattias Ekström / Patrick Eriksson

Date

2003-05-27 / 2008-06-17

Definition at line 78 of file sensor.cc.

References GriddedField4::data, DEBUG_ONLY, GriddedField::get_numeric_grid(), GriddedField::get_string_grid(), GFIELD4_AA_GRID, GFIELD4_F_GRID, GFIELD4_FIELD_NAMES, GFIELD4_ZA_GRID, gridpos(), Sparse::insert_row(), interp(), interpweights(), joker, Sparse::ncols(), Array< base >::nelem(), ConstVectorView::nelem(), Sparse::resize(), sensor_integration_vector(), and ConstVectorView::sum().

Referenced by antenna2d_simplified(), and sensor_responseAntenna().

antenna2d_simplified()

void antenna2d_simplified	(	Sparse &	H,
		const Index &	antenna_dim,
		ConstMatrixView	antenna_los,
		const GriddedField4 &	antenna_response,
		ConstVectorView	za_grid,
		ConstVectorView	aa_grid,
		ConstVectorView	f_grid,
		const Index	n_pol,
		const Index	do_norm
	)

antenna2d_simplified

A first function for setting up the response matrix for 2D antenna cases.

Following the ARTS definitions, a bi-linear variation (in za and aa dimensions) for both antenna pattern and pencil beam radiances should be assumed here. This function does not handle this. It performs instead a series of 1D antenna calculations and "sums up" the results. In this summation, both antenna pattern and radiances are assumed to constant in the azimuthal direction around each point in aa_grid (corresponding to mblock_aa_grid). That is, for azimuth, a step-wise function is used instead of a piecewise linear one.

Parameters

H	The antenna transfer matrix
antenna_dim	As the WSV with the same name
antenna_los	As the WSV with the same name
antenna_response	As the WSV with the same name
za_grid	Zenith angle grid for pencil beam calculations
aa_grid	Azimuth angle grid for pencil beam calculations
f_grid	Frequency grid for monochromatic calculations
n_pol	Number of polarisation states
do_norm	Flag whether response should be normalised

Author

Patrick Eriksson

Date

2009-09-16

Definition at line 246 of file sensor.cc.

References antenna1d_matrix(), GriddedField4::data, GriddedField::get_numeric_grid(), GFIELD4_AA_GRID, gridpos(), Sparse::insert_row(), last(), ConstTensor4View::nbooks(), ConstVectorView::nelem(), ConstTensor4View::npages(), ConstTensor4View::nrows(), GriddedField4::resize(), Sparse::resize(), and GriddedField::set_grid().

Referenced by sensor_responseAntenna().

find_effective_channel_boundaries()

void find_effective_channel_boundaries	(	Vector &	fmin,
		Vector &	fmax,
		const Vector &	f_backend,
		const ArrayOfGriddedField1 &	backend_channel_response,
		const Numeric &	delta,
		const Verbosity &	verbosity
	)

Calculate channel boundaries from instrument response functions.

This function finds out the unique channel boundaries from f_backend and backend_channel_response. This is not a trivial task, since channels may overlap, or may be sorted in a strange way. The function tries to take care of all that. If channels overlap, they are combined to one continuous frequency region. therefore the number of elements in the output vectors fmin and fmax can be lower than the number of elements in f_backend and backend_channel_response.

The function also does consistency checking on the two input variables.

The output vectors fmin and fmax will be monotonically increasing.

Author

Stefan Buehler

Parameters

[out]	fmin	Vector of lower boundaries of instrument channels.
[out]	fmax	Vector of upper boundaries of instrument channels.
[in]	f_backend	Nominal backend frequencies.
[in]	backend_channel_response	Channel response, relative to nominal frequencies.
[in]	delta	Extra margin on both sides of each band. Has a default value of 0.

Definition at line 1076 of file sensor.cc.

References CREATE_OUT2, get_sorted_indexes(), is_increasing(), Array< base >::nelem(), ConstVectorView::nelem(), Vector::resize(), and test_and_merge_two_channels().

Referenced by f_gridFromSensorAMSU(), and f_gridFromSensorHIRS().

gaussian_response()

void gaussian_response	(	Vector &	x,
		Vector &	y,
		const Numeric &	x0,
		const Numeric &	fwhm,
		const Numeric &	xwidth_si,
		const Numeric &	dx_si
	)

gaussian_response

Returns a 1D gaussian response

First a grid is generated. The grid is si*[-xwidth_si:dx_si:xwidth_si], where si is the "standard deviation" corresponding to the FWHM. That is, width and spacing of the grid is specified in terms of number of standard deviations. If xwidth_si is set to 2, the response will cover about 95% the complete response. For xwidth_si=3, about 99% is covered.

y is the response matching x.

Parameters

x	Grid generated.
y	Calculated response.
x0	The x-position of response centre/max.
fwhm	The full width at half-maximum of the response
xwidth_si	The one-sided width of x. See above.
dx_si	The grid step size of x. See above.

Author

Patrick Eriksson

Date

2009-09-20

Definition at line 408 of file sensor.cc.

References linspace(), NAT_LOG_2, ConstVectorView::nelem(), PI, and Vector::resize().

Referenced by antenna_responseGaussian(), and backend_channel_responseGaussian().

mixer_matrix()

void mixer_matrix	(	Sparse &	H,
		Vector &	f_mixer,
		const Numeric &	lo,
		const GriddedField1 &	filter,
		ConstVectorView	f_grid,
		const Index &	n_pol,
		const Index &	n_sp,
		const Index &	do_norm
	)

mixer_matrix

Sets up the sparse matrix that models the response from sideband filtering and the mixer.

The size of the transfer matrix is changed in the function as follows: nrows = f_mixer.nelem() ncols = f_grid.nelem()

The returned frequencies are given in IF, so both primary and mirror band is converted down.

Parameters

H	The mixer/sideband filter transfer matrix
f_mixer	The frequency grid of the mixer
lo	The local oscillator frequency
filter	The sideband filter data. See sideband_response for format and constraints.
f_grid	The original frequency grid of the spectrum
n_pol	The number of polarisations to consider
n_sp	The number of spectra (viewing directions)
do_norm	Flag whether rows should be normalised

Author

Mattias Ekström / Patrick Eriksson

Date

2003-05-27 / 2008-06-17

Definition at line 455 of file sensor.cc.

References GriddedField1::data, DEBUG_ONLY, GriddedField::get_numeric_grid(), GFIELD1_F_GRID, Sparse::insert_row(), last(), ConstVectorView::nelem(), Vector::resize(), Sparse::resize(), sensor_summation_vector(), and ConstVectorView::sum().

Referenced by sensor_responseMixer().

sensor_aux_vectors()

void sensor_aux_vectors	(	Vector &	sensor_response_f,
		ArrayOfIndex &	sensor_response_pol,
		Vector &	sensor_response_za,
		Vector &	sensor_response_aa,
		ConstVectorView	sensor_response_f_grid,
		const ArrayOfIndex &	sensor_response_pol_grid,
		ConstVectorView	sensor_response_za_grid,
		ConstVectorView	sensor_response_aa_grid,
		const Index	za_aa_independent
	)

sensor_aux_vectors

Sets up the the auxiliary vectors for sensor_response.

The function assumes that all grids are common, and the aux vectors are just the grids repeated.

Parameters

sensor_response_f	As the WSV with same name
sensor_response_pol	As the WSV with same name
sensor_response_za	As the WSV with same name
sensor_response_aa	As the WSV with same name
sensor_response_f_grid	As the WSV with same name
sensor_response_pol_grid	As the WSV with same name
sensor_response_za_grid	As the WSV with same name
sensor_response_aa_grid	As the WSV with same name
za_aa_independent	Flag to indicate that za and aa dimensions are "perpendicular". This is only valid before the antenna response has been considered.

Author

Patrick Eriksson

Date

2008-06-09

Definition at line 586 of file sensor.cc.

References Array< base >::nelem(), ConstVectorView::nelem(), and Vector::resize().

Referenced by sensor_responseAntenna(), sensor_responseBackend(), sensor_responseBackendFrequencySwitching(), sensor_responseBeamSwitching(), sensor_responseFillFgrid(), sensor_responseFrequencySwitching(), sensor_responseInit(), sensor_responseMixer(), sensor_responseMultiMixerBackend(), sensor_responsePolarisation(), and sensor_responseWMRF().

sensor_integration_vector()

void sensor_integration_vector	(	VectorView	h,
		ConstVectorView	f,
		ConstVectorView	x_f_in,
		ConstVectorView	x_g_in
	)

sensor_integration_vector

Calculates the (row) vector that multiplied with an unknown (column) vector approximates the integral of the product between the functions represented by the two vectors.

E.g. h*g = integral( f(x)*g(x) dx )

See Eriksson et al., Efficient forward modelling by matrix representation of sensor responses, Int. J. Remote Sensing, 27, 1793-1808, 2006, for details.

The grids are internally normalised to cover the range [0,1] for increased numerical stability.

Parameters

h	The multiplication (row) vector.
f	The values of function f(x).
x_f_in	The grid points of function f(x). Must be increasing.
x_g_in	The grid points of function g(x). Can be increasing or decreasing. Must cover a wider range than x_ft (in both ends).

Author

Mattias Ekström and Patrick Eriksson

Date

2003-02-13 / 2008-06-12

Definition at line 683 of file sensor.cc.

References b0, dx, is_decreasing(), is_increasing(), and ConstVectorView::nelem().

Referenced by antenna1d_matrix(), and spectrometer_matrix().

sensor_summation_vector()

void sensor_summation_vector	(	VectorView	h,
		ConstVectorView	f,
		ConstVectorView	x_f,
		ConstVectorView	x_g,
		const Numeric	x1,
		const Numeric	x2
	)

sensor_summation_vector

Calculates the (row) vector that multiplied with an unknown (column) vector approximates the sum of the product between the functions at two points.

E.g. h*g = f(x1)*g(x1) + f(x2)*g(x2)

The typical application is to set up the combined response matrix for mixer and sideband filter.

See Eriksson et al., Efficient forward modelling by matrix representation of sensor responses, Int. J. Remote Sensing, 27, 1793-1808, 2006, for details.

No normalisation of the response is made.

Parameters

h	The summation (row) vector.
f	Sideband response.
x_f	The grid points of function f(x).
x_g	The grid for spectral values (normally equal to f_grid)
x1	Point 1
x2	Point 2

Author

Mattias Ekström / Patrick Eriksson

Date

2003-05-26 / 2008-06-17

Definition at line 831 of file sensor.cc.

References gridpos(), interp(), interpweights(), last(), and ConstVectorView::nelem().

Referenced by mixer_matrix().

spectrometer_matrix()

void spectrometer_matrix	(	Sparse &	H,
		ConstVectorView	ch_f,
		const ArrayOfGriddedField1 &	ch_response,
		ConstVectorView	sensor_f,
		const Index &	n_pol,
		const Index &	n_sp,
		const Index &	do_norm
	)

spectrometer_matrix

Constructs the sparse matrix that multiplied with the spectral values gives the spectra from the spectrometer.

The input to the function corresponds mainly to WSVs. See f_backend and backend_channel_response for how the backend response is specified.

Parameters

H	The response matrix.
ch_f	Corresponds directly to WSV f_backend.
ch_response	Corresponds directly to WSV backend_channel_response.
sensor_f	Corresponds directly to WSV sensor_response_f_grid.
n_pol	The number of polarisations.
n_sp	The number of spectra (viewing directions).
do_norm	Corresponds directly to WSV sensor_norm.

Author

Mattias Ekström and Patrick Eriksson

Date

2003-08-26 / 2008-06-10

Definition at line 897 of file sensor.cc.

References GFIELD1_F_GRID, Sparse::insert_row(), Array< base >::nelem(), ConstVectorView::nelem(), Sparse::resize(), sensor_integration_vector(), and ConstVectorView::sum().

Referenced by sensor_responseBackend().

test_and_merge_two_channels()

bool test_and_merge_two_channels	(	Vector &	fmin,
		Vector &	fmax,
		Index	i,
		Index	j
	)

Test if two instrument channels overlap, and if so, merge them.

The channels boundaries are specified in two separate vectors, fmin and fmax. These vectors are both input and output. If merging has happened, they will each be one element shorter.

The positions of the channels to compare is given by the input parameters i and j. It is assumed that the minimum frequency of i is lower than or equal to that of j.

Furthermore, it is assumed that i itself is lower than j.

The range of the first channel (i) will have been extended to accomodate the second channel (j). The second channel will have been removed.

The function also handles the updating of index j: If the two channels do not overlap, j is increased by one.

Function returns true if merging has happened.

Author

Stefan Buehler

Returns

True if channels were merged, otherwise false.

Return values

fmin	Lower channel boundaries.
fmax	Upper channel boundaries.

Parameters

i	Index of first channel.
j	Index of second channel.

Definition at line 1000 of file sensor.cc.

References ConstVectorView::nelem(), and Vector::resize().

Referenced by find_effective_channel_boundaries().

Variable Documentation

GFIELD1_F_GRID

const Index GFIELD1_F_GRID

extern

Referenced by mixer_matrix(), and spectrometer_matrix().

GFIELD4_AA_GRID

const Index GFIELD4_AA_GRID

extern

Referenced by antenna1d_matrix(), and antenna2d_simplified().

GFIELD4_F_GRID

const Index GFIELD4_F_GRID

extern

Referenced by antenna1d_matrix().

GFIELD4_FIELD_NAMES

const Index GFIELD4_FIELD_NAMES

extern

Referenced by antenna1d_matrix().

GFIELD4_ZA_GRID

const Index GFIELD4_ZA_GRID

extern

Referenced by antenna1d_matrix().

NAT_LOG_2

const Numeric NAT_LOG_2

extern

Referenced by gaussian_response().

PI

const Numeric PI

extern

Referenced by gaussian_response().