dbtex70.m

阵列信号处理的工具箱

%DBTEX70 An example of performing radar signal processing on and plotting of measured radar signals from FOA experimental antenna.
%
% Radar-like measurements in anechoic chamber with FOA's experimental 
% digital array antenna.
% This file is a changed copy of m1078a.m and m1078aplot.m.
% The resulting graphs of this main program were puplished in:
%   Bj鰎klund S., Grahn P., Pettersson L.: "Radar-Like Measurements with
%   an Experimental Digital Beamforming Array Antenna", Proceedings of the 
%   International Radar Symposium IRS 98, Munich, Germany, 15-17 September
%   1998, pp. 993-1002.

% Sampling frequency before down conversion fs1 = 25.8e6 Hz.
% Sampling frequency after down conversion (in DBT) fs = 25.8e6/4 Hz
%   = 6.45e6 Hz.
% Period time (after down conversion) T = 1/6.45e6 s (about 0.155e-6 s)

%   *  DBT, A Matlab Toolbox for Radar Signal Processing  *
% (c) FOA 1994-2000. See the file dbtright.m for copyright notice.
%  Start        : 980520 Svante Bj鰎klund (svabj).
%  Latest change: $Date: 2001/08/31 14:49:36 $ $Author: svabj $.
%  $Revision: 1.3 $
% *****************************************************************************
%

% ----------------------------------------------------------------------- %
% Read measured signals.
% ----------------------------------------------------------------------- %

%----  Define the antenna.  ----

ant = defant('expAnt');


%----  .dbs- and .dbc-files to use.  ----

expFileNamePath =  '';
expFileName = 'm1078';
expFileName = [expFileNamePath,expFileName]
  % File names.


%----  Set calibration compensation to use.  ----

setcal1('wctab',[expFileName, '.dbc'])


%----  Read the received antenna signals.  ----

load code1079a	% Fetch the pulscode in the variable X.
  % Pulscode taken from measured signal (without calibration compensation).
pModulation = X;

sig = expsig1(ant,[expFileName, '.dbs'],[],[],[],[],pModulation);


%----  Calibration compensation of the signals.  ----

sig10 = sigcomp2(sig,[expFileName, '.dbc'], 'Ccmp',[],'nearfldcomp',0);



% ----------------------------------------------------------------------- %
% Processing.
% ----------------------------------------------------------------------- %

%---- Processing parameters  ----

PRF        = 8.0625e+03;
doaPos     = d2r(-50:2:50);	% Do conventional beamforming in these
				%  directions.
doaPosDOA     = d2r(-50:0.2:50);% Estimate DOA spectra in these directions.
noDopChan = 128;		% Number of doppler channels.


%----  Pulse compression ----

sig3 = pulscomp(sig,pModulation);


%----  Doppler filtering  ----

sig4 = dfb2(sig3,[],noDopChan);


%----  Spacial processing:  ----

%----  Conventional beamforming  ----

  sig2 = dbf(sig4,doaPos);


%----  High resolution direction estimation  ----

  spect20 = doaspc1('music',sig4,[],doaPos,[],1:256);
  doaPos = spect20.doaPos;
  sig20 = doaspc2sig(spect20);


% ----  DOA estimation for a single range.  ----

  spectCBF74 = doaspc1('cbf',sig4,[],doaPosDOA,[],74);
  spectMUSIC74 = doaspc1('music',sig4,[],doaPosDOA,[],74);

  spectCBF97 = doaspc1('cbf',sig4,[],doaPosDOA,[],97);
  spectMUSIC97 = doaspc1('music',sig4,[],doaPosDOA,[],97);


% ----------------------------------------------------------------------- %
% Plotting.
% ----------------------------------------------------------------------- %

% The first target probably starts in range bin 11 and ends in range bin 64.
% Thesecond target probably starts in range bin



% ----  Some system parameters  ----

global c0;		% Speed of light.
fs = 25.8e6/4;		% Sampling frequency after down conversion.
T = 1/fs;		% Period time (after down conversion).
Kfore = 1;		% with 3.225 MHz. This means twice as many samples
			% with 6.45 Mhz.

% ----  Plot parameters.  ----

printFlag = 0		% 1 = print to eps-files. 0 = do not print.
set(0,'DefaultAxesFontSize',8)
set(0,'DefaultAxesFontAngle','italic')
colMap = hot;


pulseIx = 96;
  % Doppler channel 96 has the largest value for direction 0 degrees.
  %  Two smaller peaks are located at 88 and 90.
  % For direction -14 degrees (beam 19 when doaPos == d2r(-50:2:50)),
  %  the peaks are in the same doppler channels.
rangeIxRange = 1:200; % Plot for these range bins plotting several range bins.
rangeIx = 15;         % Plot for this range bin when plotting only one bin.
scaleType = 'lin';    %
pulAxis = [];
ranAxis = [];
%ranAxis = (rangeIxRange + 2*Kfore) * T * c0;
spaAxis = r2d(doaPos);
pulAxis = linspace(-PRF/2, PRF/2, noDopChan);
fprintf('Study signal for doppler frequency %g Hz.\n',pulAxis(pulseIx));


% ----------------------------------------------------------------------- %
% Esimate SNR.
% ----------------------------------------------------------------------- %

pulse = 20;
channel = 6;
noisePower = mean(abs(sig.signals(pulse,107:256,channel)).^2);
tgt1Power = mean(abs(sig.signals(pulse,11:32,channel)).^2);
tgt2Power = mean(abs(sig.signals(pulse,78:96,channel)).^2);
SNR1 = 10*log10(tgt1Power/noisePower)
SNR2 = 10*log10(tgt2Power/noisePower)


% ----------------------------------------------------------------------- %
% Plot Direction - Range slice.
% ----------------------------------------------------------------------- %


%figure
sigplot2(sig2,pulseIx,rangeIxRange,':', ...
  {'scaleType','lin',  ...
   'ranAxis',ranAxis, ...
   'spaAxis',spaAxis, ...
   'normType', 'max'})
shading flat
title('Direction-range slice.')
xlabel('Direction [degrees]')
%ylabel('Range [m]')
xlim(r2d([doaPos(1),  doaPos(length(doaPos))]))
ylim([rangeIxRange(1) rangeIxRange(length(rangeIxRange))])
plotaline([-13 0],'a',0.02)
plotaline('a',[74 96.5],0.03)
colormap(colMap)
if (printFlag)
  printfm('m1078aplot2.eps',[],8)
end%if

% This plot seems strangely enough be the same for doppler channels 1 and 96.
%  But can the the signal be present in all doppler channels?


% ----------------------------------------------------------------------- %
% Plot DOA spectra for all ranges.
% ----------------------------------------------------------------------- %


figure
[d1,d2,d3,d4,d5,h] = sigplot2(sig20,1,rangeIxRange,':', ...
  {'scaleType','lin',  ...
   'plotType','surfl',...
   'ranAxis',ranAxis, ...
   'spaAxis',spaAxis, ...
   'normType', 'max'});
shading flat
%title('After beamforming.')
title('DOA spectrum')
xlabel('Direction [degrees]')
%ylabel('Range [m]')
xlim(r2d([doaPos(1),  doaPos(length(doaPos))]))
ylim([rangeIxRange(1) rangeIxRange(length(rangeIxRange))])
plotaline([-13 0],'a',0.01)
plotaline('a',[74 96.5],0.01)
colormap(colMap)
if (printFlag)
  printfm('m1078aplot3.eps',[],8)
end%if



% ----------------------------------------------------------------------- %
% Plot DOA spectra for the target ranges (74 and 97) only.
% ----------------------------------------------------------------------- %

sigMUSIC74 = doaspc2sig(spectMUSIC74);
sigCBF74 = doaspc2sig(spectCBF74);
figure
hold on
sigsize(sigMUSIC74)
sigplot2(sigMUSIC74,1,1,':', ...
  {'scaleType','log',  ...
   'normType', 'max',  ...
   'normMaxLevel', 1,  ...
   'spaAxis',r2d(doaPosDOA),  ...
   'lineSpec' ,'b'})
sigplot2(sigCBF74,1,1,':', ...
  {'scaleType','log', ...
   'normType', 'max',  ...
   'normMaxLevel', 1,   ...
   'spaAxis',r2d(doaPosDOA),  ...
   'lineSpec' ,'r--'})
ylim([-35 5])
plotxline([-13 0],[],'-.')
hold off
grid
legend('MUSIC','Conv. beamform.')
xlabel('Direction [degrees]')
title('Range bin 74')
if (printFlag)
  printfm('m1078aplot4.eps',[],8)
end%if


sigMUSIC97 = doaspc2sig(spectMUSIC97);
sigCBF97 = doaspc2sig(spectCBF97);
figure
hold on
sigplot2(sigMUSIC97,1,1,':', ...
  {'scaleType','log',  ...
   'normType', 'max',  ...
   'normMaxLevel', 1,  ...
   'spaAxis',r2d(doaPosDOA),  ...
   'lineSpec' ,'b'})
sigplot2(sigCBF97,1,1,':', ...
  {'scaleType','log', ...
   'normType', 'max',  ...
   'normMaxLevel', 1,   ...
   'spaAxis',r2d(doaPosDOA),  ...
   'lineSpec' ,'r--'})
ylim([-35 5])
plotxline([-13 0],[],'-.')
hold off
grid
legend('MUSIC','Conv. beamform.')
xlabel('Direction [degrees]')
title('Range bin 97')
if (printFlag)
  printfm('m1078aplot5.eps',[],8)
end%if