ElNullAnalyses.h File Reference

A collection of functions for EL Null analysis in range direction. More...

#include <complex>
#include <optional>
#include <vector>
#include <Eigen/Dense>
#include <isce3/core/EMatrix.h>
#include <isce3/core/Linspace.h>
#include "detail/BinarySearchFunc.h"

Go to the source code of this file.

Namespaces
namespace	isce3
	base interpolator is an abstract base class

Typedefs
using	isce3::antenna::RowMatrixXcf = isce3::core::EMatrix2D<std::complex<float>>
using	isce3::antenna::Linspace_t = isce3::core::Linspace<double>
using	isce3::antenna::tuple_ant = std::tuple<Eigen::ArrayXcd, Eigen::ArrayXcd, Eigen::ArrayXd>
using	isce3::antenna::tuple_echo = std::tuple<Eigen::ArrayXd, Eigen::ArrayXd, detail::ArrayXui>

Functions
Eigen::ArrayXcd	isce3::antenna::linearInterpComplex1d (const Eigen::Ref< const Eigen::ArrayXd > &x0, const Linspace_t &x, const Eigen::Ref< const Eigen::ArrayXcd > &y)
	1-D linear interpolation of a complex array of uniformly-sampled y(x) at new array of points x0.
tuple_ant	isce3::antenna::genAntennaPairCoefs (const Eigen::Ref< const Eigen::ArrayXcd > &el_cut_left, const Eigen::Ref< const Eigen::ArrayXcd > &el_cut_right, double el_ang_start, double el_ang_step, std::optional< double > el_res_max={})
	Generate weighting coefficients used in digital beamforming (DBF) and null formation for a pair of adjacent, partially overlapping beams.
std::tuple< double, Eigen::Index, double, Eigen::ArrayXd >	isce3::antenna::locateAntennaNull (const Eigen::Ref< const Eigen::ArrayXcd > &coef_left, const Eigen::Ref< const Eigen::ArrayXcd > &coef_right, const Eigen::Ref< const Eigen::ArrayXd > &el_ang_vec)
	Locate antenna null by forming antenna null and get its min location in EL direction from a pair of EL antenna pattern or its equivalent complex conjugate coeffs.
tuple_echo	isce3::antenna::formEchoNull (const std::vector< std::complex< float > > &chirp_ref, const Eigen::Ref< const RowMatrixXcf > &echo_left, const Eigen::Ref< const RowMatrixXcf > &echo_right, double sr_start, double sr_spacing, const Eigen::Ref< const Eigen::ArrayXcd > &coef_left, const Eigen::Ref< const Eigen::ArrayXcd > &coef_right, const Eigen::Ref< const Eigen::ArrayXd > &sr_coef)
	Form x-track echo null power (linear) averaged over range lines and formed from a pair of echoes and a pair of weighting coefs as a function of both EL angles (rad) and slant ranges (m).

Detailed Description

A collection of functions for EL Null analysis in range direction.

Function Documentation

formEchoNull()

tuple_echo isce3::antenna::formEchoNull	(	const std::vector< std::complex< float > > &	chirp_ref,
		const Eigen::Ref< const RowMatrixXcf > &	echo_left,
		const Eigen::Ref< const RowMatrixXcf > &	echo_right,
		double	sr_start,
		double	sr_spacing,
		const Eigen::Ref< const Eigen::ArrayXcd > &	coef_left,
		const Eigen::Ref< const Eigen::ArrayXcd > &	coef_right,
		const Eigen::Ref< const Eigen::ArrayXd > &	sr_coef )

Form x-track echo null power (linear) averaged over range lines and formed from a pair of echoes and a pair of weighting coefs as a function of both EL angles (rad) and slant ranges (m).

Parameters

[in]	chirp_ref	is complex chirp ref samples used in range compression.
[in]	echo_left	is complex 2-D array of raw echo samples (pulse by range) for the left RX channel corresponding to the left beam.
[in]	echo_right	is complex 2-D array of raw echo samples (pulse by range) for the right RX channel corresponding to the right beam.
[in]	sr_start	is start slant range (m) for both uniformly-sampled echoes in range.
[in]	sr_spacing	is slant range spacing (m) for both uniformly-sampled echoes in range.
[in]	coef_left	is complex array of coef for the left beam.
[in]	coef_right	is complex array of coef for the right beam.
[in]	sr_coef	array of slant ranges (m) for both left/right coeffs

Returns

array of echo null power pattern in (linear).

array of slant range values related to the null power pattern.

array of indices used for mapping null slant ranges to antenna EL angles.

Exceptions

RuntimeError

genAntennaPairCoefs()

tuple_ant isce3::antenna::genAntennaPairCoefs	(	const Eigen::Ref< const Eigen::ArrayXcd > &	el_cut_left,
		const Eigen::Ref< const Eigen::ArrayXcd > &	el_cut_right,
		double	el_ang_start,
		double	el_ang_step,
		std::optional< double >	el_res_max = {} )

Generate weighting coefficients used in digital beamforming (DBF) and null formation for a pair of adjacent, partially overlapping beams.

Computes DBF coefficients by forming the complex conjugate of each input antenna elevation pattern within the inner peak-to-peak region between the two beams. The resulting coefficients may be resampled to finer resolution than the input spacing, if desired. The function returns a vector of coefficients for each beam, as well as a vector of the corresponding elevation angle positions.

Parameters

[in]	el_cut_left	is complex array of uniformly-sampled relative or absolute EL-cut antenna pattern on the left side.
[in]	el_cut_right	is complex array of uniformly-sampled relative or absolute EL-cut antenna pattern on the right side. It must have the same size as left one!
[in]	el_ang_start	elevation angle of the first sample in the left/right patterns, in (rad)
[in]	el_ang_step	elevation angular spacing for left/right patterns in (rad)
[in]	el_res_max	(optional) max EL angle resolution in (rad). If this value is smaller than the input spacing, el_ang_step, then the outputs will be resampled via linear interpolation to either this finer resolution or a value close to that depending on whether ratio el_ang_step/el_res_max is an integer or not.

Returns

array of complex coeff for the left beam

array of complex coeff for the right beam

array of uniformly-sampled EL angles in (rad)

Exceptions

InvalidArgument,RuntimeError

linearInterpComplex1d()

Eigen::ArrayXcd isce3::antenna::linearInterpComplex1d	(	const Eigen::Ref< const Eigen::ArrayXd > &	x0,
		const Linspace_t &	x,
		const Eigen::Ref< const Eigen::ArrayXcd > &	y )

1-D linear interpolation of a complex array of uniformly-sampled y(x) at new array of points x0.

Parameters

[in]	x0	is array of values to be interpolated
[in]	x	is isce3 Linspace object for uniformly sampled input "x"
[in]	y	is array of function value "y(x)".

Returns

array of interpolated complex values at samples "x0".

Exceptions

InvalidArgument

locateAntennaNull()

std::tuple< double, Eigen::Index, double, Eigen::ArrayXd > isce3::antenna::locateAntennaNull	(	const Eigen::Ref< const Eigen::ArrayXcd > &	coef_left,
		const Eigen::Ref< const Eigen::ArrayXcd > &	coef_right,
		const Eigen::Ref< const Eigen::ArrayXd > &	el_ang_vec )

Locate antenna null by forming antenna null and get its min location in EL direction from a pair of EL antenna pattern or its equivalent complex conjugate coeffs.

Parameters

[in]	coef_left	is complex array of coef for the left beam
[in]	coef_right	is complex array of coef for the right beam
[in]	el_ang_vec	is array of EL angles in (rad)

Returns

el angle of the null location in (rad)

index of null location

peak-normalized null magnitude in (linear)

1-D peak-normalized antenna null power pattern (linear) with the same size as el_ang_vec.

Exceptions

RuntimeError