spastemat.m

阵列信号处理的工具箱

function A = spastemat(antenna, doas, lambda, focusDist, pointSubDoa, steVecFlag)

%SPASTEMAT Calculation of spatial steering matrix.
%
%--------
%Synopsis:
%  A = spastemat(antenna, doas, lambda, focusDist, pointSubDoa)
%
%Description:
%  Calculates the spatial steering matrix for specified angles for a particular
%  focus distance. This function is normally not called by the end user but
%  by the extension programmer that extends the toolbox DBT with new signal
%  processing methods etc.
%
%  Possible antenna types are currently Isotropical ULA ('isotropULA'),
%  AIMT Application Example ('aimtEx'), AIMT Experimental Antenna ('expAnt'),
%  Uniform Linear Array ('ULA'), Non-Uniform Linear Array ('LA') and
%  Antenna elements (one channel antennas) with isotropical or arbitrary
%  antenna patterns. See the function "defant" for more information.
%
%Output and Input:
%  A (CxMatrix): The calculated spatial steering matrix. Size (noChan, noDoa),
%    where noChan is the number of antenna 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 [m].
%  focusDist [D](RealVectorT): Focusing distance [m].
%  pointSubDoa [D](DoaT): Pointing direction of subarrays. The same direction
%    is used for all subarrays.
%  steVecFlag [D](StringT): Whether steering vectors (default) or beamforming 
%    weights are to be calculated. There is a difference only when correcting 
%    for calibration on the steering vectors and beamforming weights. See []
%    p. 15-18 for more information.
%
%--------
%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.)
%  The 'expAnt' antenna type was used in the work done by A. Heydarkhan [5].
%
%
%Known Bugs:
%  Only one angle of the DOA:s (theta) can be used.
%  Focusing distance by the input parameter "focusDist" does not work. The
%  distance is allways infinity.
%
%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.
%  [2]: Athley F.:"Till鋗pningsexempel f鰎 studie av modellbaserad
%    lobformning", Ericsson Microwave Systems 1996, No FY/XU-96:299.
%  [3]: Pettersson L., Danestig M., Sj鰏tr鰉 U.: "An Experimental S-Band
%    Digital Beamforming Antenna", IEEE AES Systems Magazine, November 1997,
%    p.19-26.
%  [4]: Bj鰎klund S.:"A MATLAB Toolbox for Radar Signal Processing",
%    Proceedings of Nordic MATLAB Conference `97,Stockholm 27-28 October 1997.
%  [5]: Heydarkhan A.: "Model Based Direction of Arrival Estimation Methods
%    Applied to Experimental Antenna Data", Master's Thesis, Chalmers
%    University of Technology 1997. FOA-R--97-00631-408--SE,FOA November 1997.
%  [6]: Stutzman W.L., Thiele G.A.: "Antenna Theory and Design", Wiley 1981,
%    ISBN 0-471-04458-X.
%  [7]: Pettersson L.: "講ersiktlig beskrivning av m鋞dataanalysprogram f鰎 
%    digital gruppantenn", FOA februari 1996, FOA-D--96-00226-3.2--SE.
%  []: Danestig M., Pettersson L., Sj鰏tr鰉 U.: "An Experimental S-Band
%    Digital Beamforming Antenna", IEEE International Symposium on Phased
%    Array Antennas, Boston, 15-18 October 1996.
%
%See Also:
%  dspastemat, The code of: doaspc1, doapar1, compsim2, pantpat3

%   *  DBT, A Matlab Toolbox for Radar Signal Processing  *
% (c) FOA 1994-2000. See the file dbtright.m for copyright notice.
%
%  Start        : 961120 Svante Bjvrklund (svabj).
%  Latest change: $Date: 2000/10/21 14:06:14 $ (17:08) $Author: svabj $.
%  $Revision: 1.12 $
% *****************************************************************************

if (0)
  global thSign
  % Defines the reference direction for the theta angle in DOA:s.
  % Defined in "defant".
else
  thSign = 1;
end%if

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

% ****************** Add missing input parameters ******************

% Here should be some code also.

% ****************** Default values ******************

doas1 = zeros(2,size(doas,2)); 	% If phi is missing, extend "doas" with
				% a zero row
doas1(1:size(doas,1),:) = doas;
doas = doas1;

if (nargin < 4)
  focusDist = [];
end
if (nargin < 5)
  pointSubDoa = [];
end

if (isempty(focusDist))
  focusDist = Inf;
  %focusDist = Inf*ones(1,size(doas,2));
    % If there can be different focusing distances to the
    % different sources.
else
  focusDist = Inf;
    % Only if the focusing distance always is the same to all sources.
end%if

if (isempty(pointSubDoa))
  pointSubDoa = [0;0];
end%if


% ****************** Error check input parameters ******************

if (any(focusDist ~= Inf))
  error('DBT-Error: Only focus on infinity is implemented.')
end

% ----------------------------------------------------------------------- %
% Cell array of antenna definitions.
% ----------------------------------------------------------------------- %
if iscell(antenna)
  % In this code the input parameter "antenna" is a cell array with
  % antenna definitions. spastemat is called for each of the antennas.
  % The result is stacked in A with new rows for each new antenna.
  nDoas = size(doas,2);		% Number of DOA:s.
  nAnt=length(antenna);		% Number of antennas.
  nChan = 0;			% Total number of channels in all antennas.
  ixChanEnd = zeros(nAnt,1);	% End channel index in A for all antennas.
  for n = 1:nAnt
    nChan = nChan + antenna{n}.noElem;
    ixChanEnd(n) = nChan;
  end%for n
  A = zeros(nChan,nDoas);

if (0)	% If different pointing directions for different subarrays.
  if (size(pointSubDoa,2) > 1)	% If not the same definition of all elements.
    %Do nothing.
  else 	% Identical elements.
    pointSubDoa = repmat(pointSubDoa,1,nAnt);
  end%if
end%if (0)

  ixChanStart = 1;
  for n = 1:nAnt
    A(ixChanStart:ixChanEnd(n),:) = spastemat(antenna{n}, doas, lambda, ...
      focusDist, pointSubDoa);
    %A(ixChanStart:ixChanEnd(n),:) = spastemat(antenna{n}, doas, lambda, ...
    %  focusDist, pointSubDoa(n));
      % If different pointing directions for different subarrays.
    ixChanStart = ixChanEnd(n) + 1;
    %A = [A; spastemat(antenna{n}, doas, lambda, focusDist, pointSubDoa)]
  end%for

else % Not iscell(antenna)


% ----------------------------------------------------------------------- %
% Code common to all antenna types.
% ----------------------------------------------------------------------- %

  % ****************** Pick out fields from input parameters. ******************

  antennaType = antenna.antennaType;


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

% ----------------------------------------------------------------------- %
% Short cuts for special antenna types.
% ----------------------------------------------------------------------- %
  % --------------------------------------------------------------------- %
  % Isotropical ULA.
  %
  % Start: 980107 Svante Bj鰎klund (svabj).
  % --------------------------------------------------------------------- %
  if (strcmp(antenna.name,'isotropULA'))

    % Not implemented yet.

  % --------------------------------------------------------------------- %
  % AIMT Application Example.
  %
  % Start: 9xxxxx Fredrik Athley (freath).
  % --------------------------------------------------------------------- %
  elseif (strcmp(antenna.name,'aimtEx'))
    if (nargin < 5)
       pointSubDoa = [];
    end
    if (isempty(pointSubDoa))
      pointSubDoa = 0;
    else
      pointSubDoa = pointSubDoa(1,:);
    end%if
    poserr = 0;
    %lambda = antenna.lambda;
    d = antenna.distElem;
    K = antenna.noElem;
    k = 0:K-1;
    dmek = k*d + poserr;
    theta = doas(1,:);
    elementFactor = subpat(antenna,theta,pointSubDoa,poserr,[0.5 1 0.5],lambda);
    % The position errors in "poserr" will be the same for all subarrays.