How to eliminate this error, Array indices must be positive integers or logical values?

Question

Basmah Ahmad 2024-1-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2073751-how-to-eliminate-this-error-array-indices-must-be-positive-integers-or-logical-values

回答： Steven Lord 2024-1-24

采纳的回答： Steven Lord

在 MATLAB Online 中打开

Hi, I am getting this error

Array indices must be positive integers or logical values.

Error in untitled11 (line 43)

bwrmss = bandwidth(h)/sqrt(12);

Please resolve it. Following is my code

c = physconst('LightSpeed');
fc = 2.4e9;
pri = 2e-05;
fs = 100e+06;
Numtgts = 3;
tgtpos = zeros(Numtgts);
tgtpos(1,:) = [500 530 750];
tgtvel = zeros(3,Numtgts);
tgtvel(1,:) = [-60 20 40];
tgtrcs = db2pow(10)*[1 1 1];
tgtmotion = phased.Platform(tgtpos,tgtvel);
target = phased.RadarTarget('PropagationSpeed',c,'OperatingFrequency',fc, ...
    'MeanRCS',tgtrcs);
radarpos = [0;0;0];
radarvel = [0;0;0];
radarmotion = phased.Platform(radarpos,radarvel);
txantenna = phased.IsotropicAntennaElement;
rxantenna = clone(txantenna);
code2 = comm.GoldSequence('FirstPolynomial','x^6+x+1', 'FirstInitialConditions',[ 0 0 0 0 0 1], 'SecondPolynomial','x^6 + x^5 + x^4 + x^3 + x^2 + x + 1', 'SecondInitialConditions',[0 0 0 0 0 1], 'Index',2, 'SamplesPerFrame',63);
gold_code = code2();
PRF = 50000; % Pulse repetition frequency in Hz
pulseWidth = 2e-8; % Pulse width in seconds
rangeRes = 3e8 * pulseWidth; % Range resolution in meters
h = zeros(length(gold_code ), length(tgtpos(1,:))); % Preallocate matrix for transmitted pulses
for i = 1:length(targets)
    h(:,i) = [gold_code ; zeros(1, round(pulseWidth/code2.SamplesPerFrame*PRF)-length(gold_code ))];
end
sig = h()
disp(size(h));
bwrmss = mean(abs(h(:)))/sqrt(12);
Nr = length(sig);
bwrmss = bandwidth(h)/sqrt(12);
rngrms = c/bwrmss;
peakpower = 11e+03;
txgain = 20.0;
transmitter = phased.Transmitter( ...
    'PeakPower',peakpower, ...
    'Gain',txgain, ...
    'InUseOutputPort',true);
radiator = phased.Radiator( ...
    'Sensor',txantenna,...
    'PropagationSpeed',c,...
    'OperatingFrequency',fc);
channel = phased.FreeSpace( ...
    'SampleRate',fs, ...    
    'PropagationSpeed',c, ...
    'OperatingFrequency',fc, ...
    'TwoWayPropagation',true);
collector = phased.Collector( ...
    'Sensor',rxantenna, ...
    'PropagationSpeed',c, ...
    'OperatingFrequency',fc);
rxgain = 42.0;
noisefig = 1;
receiver = phased.ReceiverPreamp( ...
    'SampleRate',fs, ...
    'Gain',rxgain, ...
    'NoiseFigure',noisefig);
Np = 128;
dt = pri;
cube = zeros(Nr,Np);
for n = 1:Np
    [sensorpos,sensorvel] = radarmotion(dt);
    [tgtpos,tgtvel] = tgtmotion(dt);
    [tgtrng,tgtang] = rangeangle(tgtpos,sensorpos);
     % Calculate Doppler frequency shift for each target
    fd = (2 * tgtvel(1, :) * fc) / c;
    sig = h();
    [txsig,txstatus] = transmitter(sig);
    txsig = radiator(txsig,tgtang);
    txsig = channel(txsig,sensorpos,tgtpos,sensorvel,tgtvel);    
    tgtsig = target(txsig);   
    rxcol = collector(tgtsig,tgtang);
    rxsig = receiver(rxcol);
    cube(:,n) = rxsig;
end
imagesc([0:(Np-1)]*pri*1e6,[0:(Nr-1)]/fs*1e6,abs(cube))
xlabel('Slow Time {\mu}s')
ylabel('Fast Time {\mu}s')
axis xy
ndop = 128;
rangedopresp = phased.RangeDopplerResponse('SampleRate',fs, ...
    'PropagationSpeed',c,'DopplerFFTLengthSource','Property', ...
    'DopplerFFTLength',ndop,'DopplerOutput','Speed', ...
    'OperatingFrequency',fc);
matchingcoeff = getMatchedFilter(h);
[rngdopresp,rnggrid,dopgrid] = rangedopresp(cube,matchingcoeff);
imagesc(dopgrid,rnggrid,10*log10(abs(rngdopresp)))
title('Barker Code Range Doppler Map')
xlabel('Closing Speed (m/s)')
ylabel('Range (m)')
axis xy
mfgain = matchingcoeff'*matchingcoeff;
dopgain = Np;
noisebw = fs;
noisepower = noisepow(noisebw,receiver.NoiseFigure,receiver.ReferenceTemperature);
noisepowerprc = mfgain*dopgain*noisepower;
noise = noisepowerprc*ones(size(rngdopresp));
rangeestimator = phased.RangeEstimator('NumEstimatesSource','Auto', ...
    'VarianceOutputPort',true,'NoisePowerSource','Input port', ...
    'RMSResolution',rngrms);
dopestimator = phased.DopplerEstimator('VarianceOutputPort',true, ...
    'NoisePowerSource','Input port','NumPulses',Np);
detidx = NaN(2,Numtgts);
tgtrng = rangeangle(tgtpos,radarpos);
tgtspd = radialspeed(tgtpos,tgtvel,radarpos,radarvel);
tgtdop = 2*speed2dop(tgtspd,c/fc);
for m = 1:numel(tgtrng)
    [~,iMin] = min(abs(rnggrid-tgtrng(m)));
    detidx(1,m) = iMin;
    [~,iMin] = min(abs(dopgrid-tgtspd(m)));
    detidx(2,m) = iMin;
end
%Find the noise power at the detection locations.
ind = sub2ind(size(noise),detidx(1,:),detidx(2,:))
%Estimate the range and range variance at the detection locations. The estimated ranges agree with the postulated ranges.
[rngest,rngvar] = rangeestimator(rngdopresp,rnggrid,detidx,noise(ind))
%Estimate the speed and speed variance at the detection locations. The estimated speeds agree with the predicted speeds.
[spdest,spdvar] = dopestimator(rngdopresp,dopgrid,detidx,noise(ind))

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Answer 1

Steven Lord 2024-1-24

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2073751-how-to-eliminate-this-error-array-indices-must-be-positive-integers-or-logical-values#answer_1396576

在 MATLAB Online 中打开

You likely have a variable named bandwidth in your workspace. You may intend that line of code to call the bandwidth function (I think I selected the documentation for the correct object's method to link to) but if there is a variable and a function with the same names available the variable takes precedence. Rename the variable and clear it from your workspace.

To check my suspicion, run this line of code:

which -all bandwidth
built-in (/MATLAB/toolbox/matlab/matfun/bandwidth)
built-in                                                         % gpuArray method
/MATLAB/toolbox/control/ctrlanalysis/@DynamicSystem/bandwidth.m  % DynamicSystem method
/MATLAB/toolbox/parallel/gpu/@gpuArray/bandwidth.m               % gpuArray method
/MATLAB/toolbox/parallel/parallel/@codistributed/bandwidth.m     % codistributed method

Watch how that changes if I create a variable. Note the new first line.

bandwidth = 42;
which -all bandwidth
bandwidth is a variable.
built-in                                                         % Shadowed gpuArray method
/MATLAB/toolbox/control/ctrlanalysis/@DynamicSystem/bandwidth.m  % Shadowed DynamicSystem method
/MATLAB/toolbox/parallel/gpu/@gpuArray/bandwidth.m               % Shadowed gpuArray method
/MATLAB/toolbox/parallel/parallel/@codistributed/bandwidth.m     % Shadowed codistributed method
built-in (/MATLAB/toolbox/matlab/matfun/bandwidth)               % Shadowed