A class for forming Null power patterns in EL direction from both a pair of adjacent El-cut antenna patterns as well as the respective raw echoes of two adjacent RX channels. More...

#include <ElNullRangeEst.h>

Public Types
using	RowMatrixXcf = isce3::core::EMatrix2D<std::complex<float>>

Public Member Functions
	ElNullRangeEst (double wavelength, double sr_spacing, double chirp_rate, double chirp_dur, const isce3::core::Orbit &orbit, const isce3::core::Attitude &attitude, const isce3::geometry::DEMInterpolator &dem_interp={}, const Frame &ant_frame={}, const isce3::core::Ellipsoid &ellips={}, double el_res=8.726646259971648e-06, double abs_tol_dem=1.0, int max_iter_dem=20, int polyfit_deg=6)
	A constructor.

std::tuple< isce3::core::DateTime, NullProduct, NullProduct, NullConvergenceFlags, NullPowPatterns >	genNullRangeDoppler (const Eigen::Ref< const RowMatrixXcf > &echo_left, const Eigen::Ref< const RowMatrixXcf > &echo_right, const Eigen::Ref< const Eigen::ArrayXcd > &el_cut_left, const Eigen::Ref< const Eigen::ArrayXcd > &el_cut_right, double sr_start, double el_ang_start, double el_ang_step, double az_ang, std::optional< double > az_time={}) const
	Generate null products from echo (measured) and antenna (nominal/expected).

double	waveLength () const

double	slantRangeSpacing () const

std::string	gridTypeName () const

Eigen::ArrayXcf	chirpSampleRef () const

std::string	refEpoch () const

double	demRefHeight () const

double	midTimeOrbit () const

double	maxElSpacing () const

double	atolDEM () const

int	maxIterDEM () const

double	atolNull () const

int	maxIterNull () const

int	polyfitDeg () const

Protected Types
using	Linspace_t = isce3::core::Linspace<double>

using	tuple_null

Protected Attributes
double	_wavelength

double	_sr_spacing

isce3::core::Orbit	_orbit

isce3::core::Attitude	_attitude

isce3::geometry::DEMInterpolator	_dem_interp

Frame	_ant_frame

isce3::core::Ellipsoid	_ellips

double	_el_res_max

double	_abs_tol_dem

int	_max_iter_dem

int	_polyfit_deg

std::vector< std::complex< float > >	_chirp_ref

double	_az_time_mid

isce3::core::DateTime	_ref_epoch

const double	_ftol_newton {1e-5}

const int	_max_iter_newton {25}

Detailed Description

A class for forming Null power patterns in EL direction from both a pair of adjacent El-cut antenna patterns as well as the respective raw echoes of two adjacent RX channels.

The location of null in both antenna and echo domain will be estimated and their respective values in EL angle, slant range, and Doppler will be reported at a specific azimuth time in orbit. See the following citation and its references for algorithm, simulation and analyses, [NullPatternElPointDoc]

Member Typedef Documentation

◆ tuple_null

using isce3::antenna::ElNullRangeEst::tuple_null

protected

Initial value:

std::tuple<isce3::core::DateTime, NullProduct,

NullProduct, NullConvergenceFlags, NullPowPatterns>

isce3::core::DateTime

Data structure to store date time to nano-sec precision.

Definition DateTime.h:18

isce3::antenna::NullConvergenceFlags

A set of flags indicating convergence of iterative operations used in EL null product formation.

Definition ElNullRangeEst.h:41

isce3::antenna::NullPowPatterns

EL Null Power Patterns for both echo and antenna as a function of EL angles.

Definition ElNullRangeEst.h:52

isce3::antenna::NullProduct

EL null product.

Definition ElNullRangeEst.h:26

Constructor & Destructor Documentation

◆ ElNullRangeEst()

isce3::antenna::ElNullRangeEst::ElNullRangeEst	(	double	wavelength,
		double	sr_spacing,
		double	chirp_rate,
		double	chirp_dur,
		const isce3::core::Orbit &	orbit,
		const isce3::core::Attitude &	attitude,
		const isce3::geometry::DEMInterpolator &	dem_interp = {},
		const Frame &	ant_frame = {},
		const isce3::core::Ellipsoid &	ellips = {},
		double	el_res = 8.726646259971648e-06,
		double	abs_tol_dem = 1.0,
		int	max_iter_dem = 20,
		int	polyfit_deg = 6 )

A constructor.

Parameters

[in]	wavelength	wavelength in (m)
[in]	sr_spacing	slant range spacing in (m)
[in]	chirp_rate	chirp rate in (Hz/sec)
[in]	chirp_dur	chirp duration in (sec)
[in]	orbit	isce3 Orbit object
[in]	attitude	isce3 Attitude object for quaternions from antenna to ECEF
[in]	dem_interp	(optional) isce3 DEMInterpolator object. Default is 0.0 (m) or reference ellipsoid.
[in]	ant_frame	(optional) isce3 antenna Frame object. Default is "EL_AND_AZ" antenna coordinate system.
[in]	ellips	(optional) isce3 Ellipsoid object. Default is WGS84 ellipsoid.
[in]	el_res	(optional) max EL angle resolution in (rad) used for all EL angles. Default is 8.726646259971648e-06 (rad) equivalent to 0.5 (mdeg). Note that if antenna patterns have finer EL angle step then this value will be ignored!
[in]	abs_tol_dem	(optional) absolute DEM height tolerance in (m). Default is 1. This is used in a recursive process of transformation from antenna angle to slant range in the presence of topography/DEM data.
[in]	max_iter_dem	(optional) max number of iteration in meeting above DEM height tolerance. Default is 20.
[in]	polyfit_deg	(optional) degree of polyfit used for smoothing of echo null power pattern and locating its null/min location. Default is 6. The even orders equal or larger than 2 is required.

Exceptions

InvalidArgument

Member Function Documentation

◆ atolDEM()

double isce3::antenna::ElNullRangeEst::atolDEM ( ) const

inline

Returns: Absolute tolerance (m) in DEM height estimation used in geometry transformation

◆ atolNull()

double isce3::antenna::ElNullRangeEst::atolNull ( ) const

inline

Returns: Absolute tolerance (-) in Newton method used in estimating null location from echo null pattern

◆ chirpSampleRef()

Eigen::ArrayXcf isce3::antenna::ElNullRangeEst::chirpSampleRef ( ) const

inline

Returns: complex Hann-windowed chirp samples used as chirp ref in rangecomp

◆ demRefHeight()

double isce3::antenna::ElNullRangeEst::demRefHeight ( ) const

inline

Returns: reference DEM height in (m)

◆ genNullRangeDoppler()

ElNullRangeEst::tuple_null isce3::antenna::ElNullRangeEst::genNullRangeDoppler	(	const Eigen::Ref< const RowMatrixXcf > &	echo_left,
		const Eigen::Ref< const RowMatrixXcf > &	echo_right,
		const Eigen::Ref< const Eigen::ArrayXcd > &	el_cut_left,
		const Eigen::Ref< const Eigen::ArrayXcd > &	el_cut_right,
		double	sr_start,
		double	el_ang_start,
		double	el_ang_step,
		double	az_ang,
		std::optional< double >	az_time = {} ) const

Generate null products from echo (measured) and antenna (nominal/expected).

The null product consists of azimuth time tag, null relative magnitude and its location in EL and slant range, plus its Doppler value given azimuth (antenna geometry)/squint(Radar geometry) angle.

Parameters

[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. Must have the same shape as of that of left one!
[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]	sr_start	is start slant range (m) for both uniformly-sampled echoes in range.
[in]	el_ang_start	is start elevation angle for left/right EL patterns in (rad)
[in]	el_ang_step	is step elevation angle for left/right EL patterns in (rad)
[in]	az_ang	azimuth angle in antenna frame (similar to squint angle in radar geometry) in (rad). This angle determines the final Doppler centroid on top of slant range value for both echo and antenna nulls.
[in]	az_time	(optional) azimuth time of echoes in (sec) w.r.t reference epoch of orbit. If not specified, the mid azimuth time of orbit will be used instead.

Returns: isce3 DateTime object representing the azimuth time tag of the null.; isce3::antenna::NullProduct with members: slant_range (m), el_angle (rad), doppler (Hz), and magnitude(linear) for measured/estimated null product from a pair of raw echoes.; isce3::antenna::NullProduct with members: slant_range (m), el_angle (rad), doppler (Hz), and magnitude(linear) for expected/nomial null product from a pair of EL antenna patterns.; isce3::antenna::NullConvergenceFlags with members: newton-solver, geometry_echo and geometry_antenna related to ant2rgdop convergence flag.; isce3::antenna::NullPowPatterns with members: ant, echo, and el representing null power patterns (linear) for both antenna and echo as a function of EL angles (radians).

Exceptions

InvalidArgument,RuntimeError

◆ gridTypeName()

std::string isce3::antenna::ElNullRangeEst::gridTypeName ( ) const

inline

Returns: name of antenna spherical grid type

◆ maxElSpacing()

double isce3::antenna::ElNullRangeEst::maxElSpacing ( ) const

inline

Returns: Max EL angle spacing or resolution (rad)

◆ maxIterDEM()

int isce3::antenna::ElNullRangeEst::maxIterDEM ( ) const

inline

Returns: Max iteration in DEM height estimation used in geometry transformation

◆ maxIterNull()

int isce3::antenna::ElNullRangeEst::maxIterNull ( ) const

inline

Returns: Max iteration in Newton method used in estimating null location from echo null pattern

◆ midTimeOrbit()

double isce3::antenna::ElNullRangeEst::midTimeOrbit ( ) const

inline

Returns: mid azimuth time of the orbit in (sec)

◆ polyfitDeg()

int isce3::antenna::ElNullRangeEst::polyfitDeg ( ) const

inline

Returns: poly-fit degree used in polyfitting echo null pattern

◆ refEpoch()

std::string isce3::antenna::ElNullRangeEst::refEpoch ( ) const

inline

Returns: reference epoch UTC time in ISO8601 format

◆ slantRangeSpacing()

double isce3::antenna::ElNullRangeEst::slantRangeSpacing ( ) const

inline

Returns: slant range spacing in (m)

◆ waveLength()

double isce3::antenna::ElNullRangeEst::waveLength ( ) const

inline

Returns: wavelength in (m)

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

/home/runner/work/isce3/isce3/cxx/isce3/antenna/ElNullRangeEst.h
/home/runner/work/isce3/isce3/cxx/isce3/antenna/ElNullRangeEst.cpp

Public Types

Public Member Functions

Protected Types

Protected Attributes

Detailed Description

Member Typedef Documentation

◆ tuple_null

Constructor & Destructor Documentation

◆ ElNullRangeEst()

Member Function Documentation

◆ atolDEM()

◆ atolNull()

◆ chirpSampleRef()

◆ demRefHeight()

◆ genNullRangeDoppler()

◆ gridTypeName()

◆ maxElSpacing()

◆ maxIterDEM()

◆ maxIterNull()

◆ midTimeOrbit()

◆ polyfitDeg()

◆ refEpoch()

◆ slantRangeSpacing()

◆ waveLength()