Problem Matched Filtering in Matlab.

I got the source code for simulation Mached Filtering in Matlab :

clear; clc

hsensor = phased.IsotropicAntennaElement(...
   'FrequencyRange',[5e9 15e9]);

htx = phased.Transmitter('Gain',20,'InUseOutputPort',true);

fc = 10e9;

htgt = phased.RadarTarget('Model','Nonfluctuating',...
   'MeanRCS',1,'OperatingFrequency',fc);

txloc = [0;0;0];

tgtloc = [5000;5000;10];

htxloc = phased.Platform('InitialPosition',txloc);

htgtloc = phased.Platform('InitialPosition',tgtloc);

[tgtrng,tgtang] = rangeangle(htgtloc.InitialPosition,...
   htxloc.InitialPosition);

hwav = phased.RectangularWaveform('PulseWidth',25e-6,...
   'OutputFormat','Pulses','PRF',1e4,'NumPulses',1);

c = physconst('LightSpeed');

maxrange = c/(2*hwav.PRF);

SNR = npwgnthresh(1e-6,1,'noncoherent');

Pt = radareqpow(c/fc,maxrange,SNR,...
   hwav.PulseWidth,'RCS',htgt.MeanRCS,'Gain',htx.Gain);

htx.PeakPower = Pt;

hrad = phased.Radiator('PropagationSpeed',c,...
   'OperatingFrequency',fc,'Sensor',hsensor);

hspace = phased.FreeSpace('PropagationSpeed',c,...
    'OperatingFrequency',fc,'TwoWayPropagation',false);

hcol = phased.Collector('PropagationSpeed',c,...
   'OperatingFrequency',fc,'Sensor',hsensor);

hrec = phased.ReceiverPreamp('NoiseFigure',0,...
   'EnableInputPort',true,'SeedSource','Property','Seed',2e3);

hmf = phased.MatchedFilter(...
   'Coefficients',getMatchedFilter(hwav),...
   'GainOutputPort',true);

% Generate waveform

wf = step(hwav);

% Transmit waveform

[wf,txstatus] = step(htx,wf);

% Radiate pulse toward the target

wf = step(hrad,wf,tgtang);

% Propagate pulse toward the target

wf = step(hspace,wf,txloc,tgtloc,[0;0;0],[0;0;0]);

% Reflect it off the target

wf = step(htgt,wf);

% Propagate the pulse back to transmitter

wf = step(hspace,wf,tgtloc,txloc,[0;0;0],[0;0;0]);

% Collect the echo

wf = step(hcol,wf,tgtang);

% Receive target echo

rx_puls = step(hrec,wf,~txstatus);

[mf_puls,mfgain] = step(hmf,rx_puls);

% Get group delay of matched filter

Gd = length(hmf.Coefficients)-1;

% The group delay is constant

% Shift the matched filter output

mf_puls=[mf_puls(Gd+1:end); mf_puls(1:Gd)];

subplot(2,1,1);

t = unigrid(0,1e-6,1e-4,'[)');

rangegates = c.*t;

rangegates = rangegates/2;

plot(rangegates,abs(rx_puls)); title('Received Pulse');

ylabel('Amplitude'); hold on;

plot([tgtrng, tgtrng], [0 max(abs(rx_puls))],'r');

subplot(2,1,2)

plot(rangegates,abs(mf_puls)); title('With Matched Filtering');

xlabel('Meters'); ylabel('Amplitude'); hold on;

plot([tgtrng, tgtrng], [0 max(abs(mf_puls))],'r');

[Mail Abos]

But, after i run this source code on Matlab, its can not run, there is error appears :

Error using phased.FreeSpace/step Too many input arguments; expected 3 (in addition to the object handle), got 5.

Please help to solve this problem, so this code can run on Matlab. Thank you very much.

Answer 1

[Honglei Chen]

This is because you are using an older version of Phased Array System Toolbox. Technically, you just need to replace the following lines

wf = step(hspace,wf,txloc,tgtloc,[0;0;0],[0;0;0]);

with

wf = step(hspace,wf,txloc,tgtloc);

and it should run. However, you may want to find the corresponding example in your version to make sure other things are matched too.

The additional arguments are added in a later release so the Doppler effect within a pulse can be modeled. This is important for modeling range-Doppler coupling effect.

HTH