Error using mfsk waveform for multiple target detection

Question

LeGeND 2020-9-10

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/591901-error-using-mfsk-waveform-for-multiple-target-detection

Hi I am trying to simulate mfsk waveform for multiple targets and I am getting "Array exceeds maximum array size preference" error. The thing is, before I didnot use to get this error while working with mfsk waveform for 5 targets. There is something wrong in input parameters of mfsk waveform. Can someone tell me what bandwidth, sample rate, frequency offset should be fine?

clear all;
rng(2015);
%[fmcwwaveform,target,tgtmotion,channel,transmitter,receiver,...
%    sensormotion,c,fc,lambda,fs,maxbeatfreq] = helperMFSKSystemSetup;
% System parameter
fc = 24e9;      % operating frequency
c = 3e8;        % propagation speed
lambda = c/fc;  % wavelength
tm = 0.001;     % sweep time
bw = 240e6;              % range resolution
range_res = bw2range(bw,c); % bandwidth
sweep_slope = bw/tm;        % sweep slope
range_max = 100;
fr_max = range2beat(range_max,sweep_slope,c);
v_max = 75;
fd_max = speed2dop(2*v_max,lambda);
fb_max = fr_max+fd_max;
fs = max(2*fb_max,bw);
% fmcwwaveform = phased.FMCWWaveform('SweepTime',tm,'SweepBandwidth',bw,...
%     'SampleRate',fs,'SweepDirection','Triangle');
car1_dist = 10;
car1_speed = 10;
car1_rcs = db2pow(min(10*log10(car1_dist)+5,20));
car2_dist = 25;
car2_speed = 20;
car2_rcs = db2pow(min(10*log10(car2_dist)+5,20));
car3_dist = 40;
car3_speed = 30;
car3_rcs = db2pow(min(10*log10(car3_dist)+5,20));
car4_dist = 60;
car4_speed = 40;
car4_rcs = db2pow(min(10*log10(car4_dist)+5,20));
car5_dist = 80;
car5_speed = 50;
car5_rcs = db2pow(min(10*log10(car5_dist)+5,20));
% truck_dist = 85;
% truck_speed = 25;
% truck_rcs = db2pow(min(10*log10(truck_dist)+5,20));
tgtpos = [[car1_dist;0;0],[car2_dist;0;0],[car3_dist;0;0],[car4_dist;0;0],[car5_dist;0;0]];%,[truck_dist;0;0]];
tgtvel = [[car1_speed;0;0],[car2_speed;0;0],[car3_speed;0;0],[car4_speed;0;0],[car5_speed;0;0]];%,[truck_speed;0;0]];
tgtmotion = phased.Platform('InitialPosition',tgtpos,'Velocity',tgtvel);
tgtrcs = [car1_rcs,car2_rcs,car3_rcs,car4_rcs,car5_rcs];%,truck_rcs];
target = phased.RadarTarget('MeanRCS',tgtrcs,'PropagationSpeed',c,...
    'OperatingFrequency',fc);
channel = phased.FreeSpace('PropagationSpeed',c,...
    'OperatingFrequency',fc,'SampleRate',fs,'TwoWayPropagation',true);
ant_aperture = 6.06e-4;                         % in square meter
ant_gain = aperture2gain(ant_aperture,lambda);  % in dB
tx_ppower = 100*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;
sensormotion = phased.Platform('Velocity',[radar_speed;0;0]);
mfskwaveform = phased.MFSKWaveform(...  %bw=240e6;fs=150e6;tm=0.001
    'SampleRate',5*fs,...
    'SweepBandwidth',bw,...
    'StepTime',tm,...
    'StepsPerSweep',512,...
    'FrequencyOffset',-468750,...
    'OutputFormat','Sweeps',...
    'NumSweeps',1);
show(mfskwaveform())
%%spectrograph%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
numsamp_step = round(mfskwaveform.SampleRate*mfskwaveform.StepTime);
sig_display = mfskwaveform();
spectrogram(sig_display(1:8192),kaiser(3*numsamp_step,100),...
    ceil(2*numsamp_step),linspace(0,4e6,2048),mfskwaveform.SampleRate,...
    'yaxis','reassigned','minthreshold',-60) 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Nsweep = 1;
%release(channel);
channel.SampleRate = mfskwaveform.SampleRate;
%release(receiver);
receiver.SampleRate = mfskwaveform.SampleRate;
xr = helperFMCWSimulate(Nsweep,mfskwaveform,sensormotion,tgtmotion,...
    transmitter,channel,target,receiver);
x_dechirp = reshape(xr(numsamp_step:numsamp_step:end),2,[]).';
fs_dechirp = 1/(2*mfskwaveform.StepTime);
xf_dechirp = fft(x_dechirp);
num_xf_samp = size(xf_dechirp,1);
beatfreq_vec = (0:num_xf_samp-1).'/num_xf_samp*fs_dechirp;
%clf;
subplot(211),plot(beatfreq_vec/1e3,abs(xf_dechirp(:,1)));grid on;
ylabel('Magnitude');
title('Frequency spectrum for sweep 1');
subplot(212),plot(beatfreq_vec/1e3,abs(xf_dechirp(:,2)));grid on;
ylabel('Magnitude');
title('Frequency spectrum for sweep 2');
xlabel('Frequency (kHz)')
cfar = phased.CFARDetector('ProbabilityFalseAlarm',1e-2,...
    'NumTrainingCells',8);
peakidx = cfar(abs(xf_dechirp(:,1)),1:num_xf_samp);
Fbeat = beatfreq_vec(peakidx);
phi = angle(xf_dechirp(peakidx,2))-angle(xf_dechirp(peakidx,1));
sweep_slope = mfskwaveform.SweepBandwidth/...
    (mfskwaveform.StepsPerSweep*mfskwaveform.StepTime);
temp = ...
    [1 sweep_slope;mfskwaveform.StepTime mfskwaveform.FrequencyOffset]\...
    [Fbeat phi/(2*pi)].';
r_est = c*temp(2,:)/2
v_est = lambda*temp(1,:)/(-2)