Error: Unrecognized function or variable 'getMatchedFilter'.

I am facing with some problems when I try to apply matched filter to my waveform. What is the problem? The error is

Unrecognized function or variable 'getMatchedFilter'.

Error in Untitled10 (line 53)

'Coefficients',getMatchedFilter(waveform),...

Here is my code block.

close all
clc
clear

fs = 5e9;                      % sample freq
D = [0:100]'*2e-7;             % pulse delay times
t = 0 : 1/fs : 7500/fs;        % signal evaluation time
w = 1e-7;                      % width of each pulse
yp = pulstran(t,D+w/2,@rectpuls,w);            
ylin = chirp(t,0,1e-9,50e6);
waveform = yp.*ylin
figure
subplot(3,1,1)
plot(t,yp);
subplot(3,1,2)
plot(t,ylin);
subplot(3,1,3)
plot(t,waveform)

antenna = phased.IsotropicAntennaElement('FrequencyRange',[5e9 15e9]);
transmitter = phased.Transmitter('Gain',20,'InUseOutputPort',true);
fc = 10e9;
target = phased.RadarTarget('Model','Nonfluctuating',...
    'MeanRCS',5,'OperatingFrequency',fc);
txloc = [0;0;0];
tgtloc = [5000;5000;10];
transmitterplatform = phased.Platform('InitialPosition',txloc);
targetplatform = phased.Platform('InitialPosition',tgtloc);
[tgtrng,tgtang] = rangeangle(targetplatform.InitialPosition,...
    transmitterplatform.InitialPosition);

c = physconst('LightSpeed');
maxrange = c/(2*2e-7);
SNR = npwgnthresh(1e-6,1,'noncoherent');
lambda = physconst('LightSpeed')/target.OperatingFrequency;
Ts = 290;
dbterms = db2pow(SNR - 2*transmitter.Gain);
Pt = (4*pi)^3*physconst('Boltzmann')*Ts/2e-7/target.MeanRCS/(lambda^2)*maxrange^4*dbterms;

transmitter.PeakPower = Pt

radiator = phased.Radiator('PropagationSpeed',c,...
    'OperatingFrequency',fc,'Sensor',antenna);
channel = phased.FreeSpace('PropagationSpeed',c,...
    'OperatingFrequency',fc,'TwoWayPropagation',false);
collector = phased.Collector('PropagationSpeed',c,...
    'OperatingFrequency',fc,'Sensor',antenna);
receiver = phased.ReceiverPreamp('NoiseFigure',0,...
    'EnableInputPort',true,'SeedSource','Property','Seed',2e3);

filter = phased.MatchedFilter(...
    'Coefficients',getMatchedFilter(waveform),...
    'GainOutputPort',true);

[Christopher McCausland]

Hi Goktug,

The error message points to a problem with line;

yp = pulstran(t,D+w/2,@rectpuls,w);

I suspect that the input is unexpected, and the waveform does not add up correctly. Can you incluce an image of the rectangular waveform you are trying to produce?

Christopher

[tinkyminky93]

Hello dear Christopher,

I am trying to produce a pulse train LFM signal. It is something like that

Answer 1

[Walter Roberson]

The input to getMatchedFilter must be a phased-encoded waveform object, but instead you are just passing in double precision array.

See for example https://www.mathworks.com/help/phased/ug/matched-filtering.html where they show

waveform = phased.RectangularWaveform('PulseWidth',25e-6,...
   'OutputFormat','Pulses','PRF',10e3,'NumPulses',1);

filter = phased.MatchedFilter(...
   'Coefficients',getMatchedFilter(waveform),...
   'GainOutputPort',true);

[tinkyminky93]

I don't want to filter a rectangular waveform, instead I need pulse train LFM waveform. What should I do?

[Walter Roberson]

Your pulse train has a finite series of rectangular pulses of known width and delay. It looks to me as if you can construct the specifications for the same kind of object by using phased.RectangularWaveform with 'NumPulses' set as appropriate to fill the needed time.