dspastemat.m

阵列信号处理的工具箱

function A = dspastemat(antenna, doas, lambda, ranges)

%DSPASTEMAT Calculation of the derivative of the spatial steering matrix.
%
%--------
%Synopsis:
%  a = dspastemat(antenna, doas, lambda, ranges)
%
%Description:
%  Calculates the derivative of the ideal spatial steering matrix with
%  respect to the DOA:s for specified DOA:s for a particular distance.
%
%  For the antenna type 'aimtEx', there is an implementation of a special
%  analytic solution of the derivative, which is evaluated at the desired
%  DOA:s.
%  For all other antenna antenna types the derivative is calculated with
%  numerical methods using the function "spastemat". This should work for
%  all present and future antenna types if "spastemat" can handle these antenna
%  types as long as one angle only of the DOA:s (theta) is used.
%
%  Note! That the numerical methods are not as robust as analytical ones.
%
%Output and Input:
%  A (CxMatrix): The calculated derivative of the spatial steering matrix.
%    Size (noCh x noDoa),
%    where noCh is the number of channels and noDoa is the number of
%    directions.
%  antenna (AntDefT): The definition of the receiving antenna to use.
%  doas  (Vector of DoaT): Directions to calculate the steering vectors at.
%  lambda (RealScalarT): Wavelength of the carrier.
%  ranges [D](RealVectorT): Focus distance [m].
%
%
%--------
%AIMT Application Example ('aimtEx').
%Synopsis:
%
%Description:
%  For a description, see reference [].
%
%Output and Input:
%
%Algoritm:
%
%--------
%Notations:
%  Data type names are shown in parentheses and they start with a capital
%  letter and end with a capital T. Data type definitions can be found in [1]
%  or by "help dbtdata".
%  [D] = This parameter can be omitted and then a default value is used.
%  When the [D]-input parameter is not the last used in the call, it must be
%  given the value [], i.e. an empty matrix.
%  ... = There can be more parameters. They are explained under respective
%  metod or choice.
%
%Examples:
%
%Software Quality:
%  (About what is done to ascertain software quality. What tests are done.)
%
%Known Bugs:
%  Not all possible input parameters of the function "spastemat" is used;
%  pointing directions of subarray and antenna errors are not specified.
%  Only one angle of the DOA:s (theta) can be used.
%
%References:
%  [1]: Bj鰎klund S.: "DBT, A MATLAB Toolbox for Radar Signal Processing.
%    Reference Guide", FOA-D--9x-00xxx-408--SE, To be published.
%
%See Also:
%  spastemat


%   *  DBT, A Matlab Toolbox for Radar Signal Processing  *
% (c) FOA 1994-2000. See the file dbtright.m for copyright notice.
%
%  Start        : 961120 Svante Bj鰎klund (svabj).
%  Latest change: $Date: 2000/10/16 15:20:48 $ $Author: svabj $.
%  $Revision: 1.4 $
% *****************************************************************************

global thSign
  % Defines the reference direction for the theta angle in DOA:s.
  % Defined in "defant".

% ----------------------------------------------------------------------- %
% Handle input parameters.
% ----------------------------------------------------------------------- %

antennaType = antenna.antennaType;
if ~(strcmp(antennaType,'isotropULA') | strcmp(antennaType,'ULA')...
     | strcmp(antennaType,'LA'))
  error('DBT-Error: Not implemented for the desired antenna type.')
end
if (nargin < 4)
  ranges = Inf*ones(size(doas,1));
end
if (any(ranges ~= Inf))
   error('DBT-Error: Only focus on infinity is implemented.')
end


% ----------------------------------------------------------------------- %
% Antenna types.
% ----------------------------------------------------------------------- %

if isfield(antenna,'name')

% ----------------------------------------------------------------------- %
% Short cuts for special antenna types.
% ----------------------------------------------------------------------- %

  % --------------------------------------------------------------------- %
  % AIMT Application Example.
  %
  % Start: 9xxxxx David Rejdemyhr (davrej).
  % --------------------------------------------------------------------- %
  if (strcmp(antenna.name,'aimtEx'))
    dElem = 0.05;       % Distance between elements in a
               %   subarray
    dSubArray = 0.1;       % Distance between subarray centers
    K1 = 3;          % No of elements in an SubArray
    K2 = 25;            % No of Subarray in an antenna
    k1 = (0:K1-1)';        % Vector of elements in one subarray
    k2 = (0:K2-1)';        % Vector of subarrays in one antenna
%    l1 = -j*2*pi/lambda*dElem;     % Temp variable
%    l2 = -j*2*pi/lambda*dSubArray; % Temp variable
    l1 = thSign*j*2*pi/lambda*dElem;      % Temp variable
    l2 = thSign*j*2*pi/lambda*dSubArray;  % Temp variable
    w = antenna.element.beamSpaceTrans;
      % Tapering weights vector
    theta = doas(1,:)';       % Vector of target angles
    aSub = exp(l1*k1*sin(theta'));  % Steering vector for the subarrays
    aAnt = exp(l2*k2*sin(theta'));  % Steering vector for the main array

    aSubDer = l1*k1*cos(theta').*exp(l1*k1*sin(theta'));
      % Diff of the above aAnt
    aAntDer = l2*k2*cos(theta').*exp(l2*k2*sin(theta'));
      % Diff of the above aSub

    A = (aAntDer*diag(w'*aSub)+aAnt*diag(w'*aSubDer))* ...
    diag(sqrt(cos(theta)))+aAnt*diag(w'*aSub)* ...
    diag(((-sin(theta))./(2*sqrt(cos(theta)))));

% ----------------------------------------------------------------------- %
% General antenna types.
% ----------------------------------------------------------------------- %
  elseif (strcmp(antennaType,'ULA') | strcmp(antennaType,'LA'))
    element = antenna.element;
    eType = element.antennaType;
    if (strcmp(eType,'elem'))
      pType = element.patternType;
      if (strcmp(pType,'isotrop'))
        noSrc = size(doas,2);
        noElem   = antenna.noElem;
        A = zeros(noElem, noSrc);
        for m=1:noSrc
          A(:,m) = dspastevec(antenna, doas(:,m), lambda, ranges);
        end%for m
      end%if
    else % Generalized ULA
      delta_theta = 1E-7;
      th1 = doas(1,:) - delta_theta;
      th2 = doas(1,:) + delta_theta;
      A = (spastemat(antenna,th2,lambda,ranges) - ...
        spastemat(antenna,th1,lambda,ranges))./(2*delta_theta);
    end%if
  else
    error('DBT-Error: Not implemented for desired antenna type.')
  end%if
else
  error('DBT-Error: Antenna definition too old. Contact programmers.')
end%if exist name