basecorrm.m

阵列信号处理的工具箱

function Rout  = basecorrm(snapshots, rxRadarSig)

%BASECORRM Gives a base estimates of the antenna signal correlation matrix.
%
%--------
%Synopsis:
%  Rout  = basecorrm(snapshots, rxRadarSig)
%
%Description:
%  Gives a base estimates of the antenna signal correlation matrix.
%  The estimate can be used as input to spectral (e.g MUSIC) and parametric
%  DOA estimation methods (e.g WSF). basecorrm allows you to choose whatever
%  snapshots you want, e.g. special pulse or range bins, to use for the
%  estimate. basecorrm i suitable both when taking snapshots from the same
%  signal (e.g. from different range bins, pulses) and from more than one
%  signal. A "snapshot" is a column vector with antenna channel signals.
%  You have to collect all snapshots to a comnplex matrix (CxMatrixT)
%  yourself. See the examples below.
%
%  The estimate is a maximum likelihood (ML) estimate
%
%Output and Input:
%  Rout (RxCorrMatT): The estimated antenna signal correlation matrix.
%  snapshots (CxMatrixT): Snapshots of the antenna signal. This means
%    that different rows are signals from different antenna channels
%    and different columns come from different pulses, ranges, trials etc.
%  rxRadarSig (RxRadarSigT): An antenna signal, from which parameters
%    are extracted that are stored in Rout (needed by some processing
%    functions).
%
%--------
%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:
%  Example 1:
%    ant = defant('isotropULA',[12, 0.45*lambda]);
%    sig = compsim5(ant, lambda, noPulses, noRangeBins, 'const', ...
%      [theta, phi, SNR, alpha, dalpha,dist], 'nonoise');
%    sigsize(sig);
%    figure,sigplot2(sig,1,':',':'),title('Before beamforming')
%    snapshots = [getm3(sig.signals,3,[],':',1,':'), ...
%      getm3(sig.signals,3,[],':',2,':')];
%    R = basecorrm(snapshots,sig);
%    s = sdoaspc('music',R)
%    figure,splot2(s)
%
%  Example 2:
%    ant = defant('expAnt');
%      % Define the antenna.
%    setcal1('wctab','m1065.dbc')
%      % Set calibration compensation to use with sdoaspc, sdoapar1 etc.
%    sig = expsig1(ant,'m1065..dbs');
%    sig = sigsubix(sig,1:127,':',':');
%      % Read the received antenna signals.
%    sigsize(sig);
%    figure,sigplot2(sig,1,':',':'),title('Before beamforming')
%    snapshots = [...
%      getm3(sig.signals,3,[],':',15,':'), ...
%      getm3(sig.signals,3,[],':',16,':'), ...
%      getm3(sig.signals,3,[],':',17,':'), ...
%      getm3(sig.signals,3,[],':',18,':')
%      ];
%      % Get snapshots from range bins 15,16,17,18 from all pulses.
%    R = basecorrm(snapshots,sig);
%    s = sdoaspc('music',R)
%    figure,splot2(s)
%      % Plot a Music spectrum.
%
%Algoritm:
%
%Software Quality:
%  (About what is done to ascertain software quality. What tests are done.
%   Known bugs.)
%
%Known Bugs:
%
%
%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:
%  ecorrm


%   *  DBT, A Matlab Toolbox for Radar Signal Processing  *
% (c) FOA 1994-2000. See the file dbtright.m for copyright notice.
%
% Start        : 980602 Svante Bj鰎klund (svabj).
% Latest change: $Date: 2000/10/16 15:19:59 $ $Author: svabj $.
% $Revision: 1.8 $
% *****************************************************************************

RxCorrMatTVersion = 3;

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

if (nargin < 2)
  error('DBT-Error: To few input parameters.')
end

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



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

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

chkdtype(snapshots, 'CxMatrixT')
chkdtype(rxRadarSig, 'RxRadarSigT')


% ----------------------------------------------------------------------- %
% Get a base estimate of the correlation matrix
% ----------------------------------------------------------------------- %

  % ****************** Maximum Likelihood estimate ******************
  L = size(snapshots,2);
  Rxx = 1/L * snapshots*snapshots';

  % ****************** Create an output variable. ******************
  old = 0;
  if (old)
    Rout = rxRadarSig;
    Rout = rmfield(Rout,'signals');
    Rout.dataType = 'RxCorrMatT';
    Rout.version = RxCorrMatTVersion;
    Rout.corrMat = Rxx;
    Rout.noSamples = L;
  else
    Rout = RxCorrMatT(Rxx, L, rxRadarSig);

  end%if