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step

System object: phased.StretchProcessor
Package: phased

Perform stretch processing for linear FM waveform

Syntax

Y = step(H,X)

Description

Y = step(H,X) applies stretch processing along the first dimension of X. Each column of X represents one receiving pulse.

Input Arguments

H

Stretch processor object.

X

Input signal. Each column represents one receiving pulse.

Output Arguments

Y

Result of stretch processing. The dimensions of Y match the dimensions of X.

Examples

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Detection of Target Using Stretch Processing

Use stretch processing to locate a target at a range of 4950 m.

Simulate the signal.

hwav = phased.LinearFMWaveform;
x = step(hwav);
c = 3e8; r = 4950;
num_sample = r/(c/(2*hwav.SampleRate));
x = circshift(x,num_sample);

Perform stretch processing.

hs = getStretchProcessor(hwav,5000,200,c);
y = step(hs,x);

Plot the spectrum of the resulting signal.

[Pxx,F] = periodogram(y,[],2048,hs.SampleRate,'centered');
plot(F/1000,10*log10(Pxx)); grid;
xlabel('Frequency (kHz)');
ylabel('Power/Frequency (dB/Hz)');
title('Periodogram Power Spectrum Density Estimate');

Detect the range.

[~,rngidx] = findpeaks(pow2db(Pxx/max(Pxx)),...
    'MinPeakHeight',-5);
rngfreq = F(rngidx);
re = stretchfreq2rng(rngfreq,hs.SweepSlope,...
    hs.ReferenceRange,c);

See Also

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