getStretchProcessor
System object: phased.LinearFMWaveform
Package: phased
Create stretch processor for waveform
Syntax
HS = getStretchProcessor(H)
HS = getStretchProcessor(H,refrng)
HS = getStretchProcessor(H,refrng,rngspan)
HS = getStretchProcessor(H,refrng,rngspan,v)
Description
HS = getStretchProcessor(H)H. HS is
set up so the reference range corresponds to 1/4 of the maximum unambiguous
range of a pulse. The range span corresponds to 1/10 of the distance
traveled by the wave within the pulse width. The propagation speed
is the speed of light.
HS = getStretchProcessor(H,refrng)
HS = getStretchProcessor(H,refrng,rngspan)refrng.
HS = getStretchProcessor(H,refrng,rngspan,v)
Input Arguments
|
Linear FM pulse waveform object. |
|
Reference range, in meters, as a positive scalar. Default: 1/4 of the maximum unambiguous range of a pulse |
|
Length of the interval of ranges of interest, in meters, as
a positive scalar. The center of the interval is the range value specified
in the Default: 1/10 of the distance traveled by the wave within the pulse width |
|
Propagation speed, in meters per second, as a positive scalar. Default: Speed of light |
Output Arguments
|
Stretch processor as a |
Examples
Detect a Target Using Stretch Processing
Use stretch processing to locate a target at a range of 4950 m.
Note: This example runs only in R2016b or later. If you are using an earlier release, replace each call to the function with the equivalent step syntax. For example, replace myObject(x) with step(myObject,x).
Simulate the signal.
waveform = phased.LinearFMWaveform;
x = waveform();
c = physconst('LightSpeed');
rng = 4950.0;
num_samples = round(rng/(c/(2*waveform.SampleRate)));
x = circshift(x,num_samples);Perform stretch processing.
stretchproc = getStretchProcessor(waveform,5000,200,c); y = stretchproc(x);
Plot the spectrum of the resulting signal.
[Pxx,F] = periodogram(y,[],2048,stretchproc.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);
rng = stretchfreq2rng(rngfreq,stretchproc.SweepSlope,stretchproc.ReferenceRange,c)rng = 4.9634e+03