Plot RangeAngleResponse of ACC Example

I'm dealing with the ACC example.

https://www.mathworks.com/help/phased/examples/automotive-adaptive-cruise-control-using-fmcw-technology.html?fbclid=IwAR0s4h2OmG5PZEkB5DO7iWGXtGenqb0Tz845v3k4pFXNob7ERub17qV-EIE

Code below is almost similar to original code from ACC example.

clear;close all;clc;


fc          = 77e9;
c           = physconst('LightSpeed');
lambda      = c/fc;
range_max   = 80;
tm          = 5.5*range2time(range_max,c);
range_res   = 1;
bw          = range2bw(range_res,c);
sweep_slope = bw/tm;
fr_max      = range2beat(range_max,sweep_slope,c);
fb_max      = fr_max; %+fdoppler
fs          = max(2*fb_max,bw);

waveform    = phased.FMCWWaveform('SweepTime',tm,'SweepBandwidth',bw,'SampleRate',fs);

sig = waveform();

% figure(1);
% subplot(211); plot(0:1/fs:tm-1/fs,real(sig));
% xlabel('Time (s)'); ylabel('Amplitude (v)');
% title('FMCW signal'); axis tight;
% subplot(212); spectrogram(sig,32,16,32,fs,'yaxis');
% title('FMCW signal spectrogram');

%% Target Setting
car_dist = 20;
car_speed = 0;%96*1000/3600;
car_rcs = db2pow(min(10*log10(car_dist)+5,20));

cartarget = phased.RadarTarget('MeanRCS',car_rcs,'PropagationSpeed',c,...
    'OperatingFrequency',fc);
carmotion = phased.Platform('InitialPosition',[car_dist;0;0],...
    'Velocity',[car_speed;0;0]);

channel = phased.FreeSpace('PropagationSpeed',c,...
    'OperatingFrequency',fc,'SampleRate',fs,'TwoWayPropagation',true);  %The propagation model is assumed to be free space.


%% Radar System Setup
ant_aperture = 6.06e-4;                         % in square meter
ant_gain = aperture2gain(ant_aperture,lambda);  % in dB

tx_ppower = db2pow(5)*1e-3;                     % in watts
tx_gain = 9+ant_gain;                           % in dB

rx_gain = 15+ant_gain;                          % in dB
rx_nf = 4.5;                                    % in dB

transmitter = phased.Transmitter('PeakPower',tx_ppower,'Gain',tx_gain);
receiver = phased.ReceiverPreamp('Gain',rx_gain,'NoiseFigure',rx_nf,'SampleRate',fs);

radar_speed = 0;
radarmotion = phased.Platform('InitialPosition',[0;0;0],'Velocity',[radar_speed;0;0]);


%% Radar Signal Simulation
% specanalyzer = dsp.SpectrumAnalyzer('SampleRate',fs,...
%     'PlotAsTwoSidedSpectrum',true,...
%     'Title','Spectrum for received and dechirped signal',...
%     'ShowLegend',true);

rng(2012);
Nsweep = 64;
xr = complex(zeros(waveform.SampleRate*waveform.SweepTime,Nsweep));

for m = 1:Nsweep
    % Update radar and target positions
    [radar_pos,radar_vel] = radarmotion(waveform.SweepTime);
    [tgt_pos,tgt_vel] = carmotion(waveform.SweepTime);

    % Transmit FMCW waveform
    sig = waveform();
    txsig = transmitter(sig);

    % Propagate the signal and reflect off the target
    txsig = channel(txsig,radar_pos,tgt_pos,radar_vel,tgt_vel);
    txsig = cartarget(txsig);

    % Dechirp the received radar return
    txsig = receiver(txsig);
    dechirpsig = dechirp(txsig,sig);

    % Visualize the spectrum
%     specanalyzer([txsig dechirpsig]);

    xr(:,m) = dechirpsig;
    m
end


rngdopresp = phased.RangeDopplerResponse('PropagationSpeed',c,...
    'DopplerOutput','Speed','OperatingFrequency',fc,'SampleRate',fs,...
    'RangeMethod','FFT','SweepSlope',sweep_slope,...
    'RangeFFTLengthSource','Property','RangeFFTLength',2048,...
    'DopplerFFTLengthSource','Property','DopplerFFTLength',256);

clf;
plotResponse(rngdopresp,xr);                     % Plot range Doppler map
axis([-100 100 0 range_max])
clim = caxis;

What I want to do now is plotting RangeAngleResponse of the example, so I added code at the end.

sULA = phased.ULA('NumElements',4,'ElementSpacing',lambda/2);

rngangresp = phased.RangeAngleResponse('SensorArray',sULA,...
    'RangeMethod','FFT','SweepSlope',sweep_slope,'OperatingFrequency',fc,...
    'SampleRate',fs,'PropagationSpeed',c,...
    'RangeFFTLengthSource','Property','RangeFFTLength',2048);

plotResponse(rngangresp,xr);                     % Plot range angle map
axis([-100 100 0 range_max])

But I got a lot of errors.

Can you tell me what's going on?

Thanks!

[Honglei Chen]

Could you list the errors you got? Thanks.

[Wei-Min Chen]

Error using  * 
Incorrect dimensions for matrix multiplication. Check that the number of columns in the first matrix matches the
number of rows in the second matrix. To perform elementwise multiplication, use '.*'.

Error in phased.RangeAngleResponse/stepImpl (line 901)
                raresp = rresp*conj(ang_stv);

Error in phased.RangeAngleResponse/plotResponse (line 591)
                    [resp,rng_grid,ang_grid] = step(haresp,x);

Error in ACC (line 110)
plotResponse(rngangresp,xr);                     % Plot range Doppler map

Answer 1

[Honglei Chen]

It looks like you are using the first part of your code to generate xr and then the second part to do range-angle processing? If that's the case, it won't work because the simulated xr assumes a single element so the spatial domain infromatin is not there and the dimension of the signal is incorrect. You will have to update your signal simulation part to use your ULA too then you can process the signal in the angular domain.

HTH

[Wei-Min Chen]

Thanks for your help.

But I still have no idea where should I add phased.ULA to this ACC example.

Is there any example code?