dsp.Chirp
R2026bGenerate swept-frequency cosine (chirp) signal
Description
The dsp.Chirp
System object™ generates a swept-frequency cosine (chirp) signal. The chirp function also generates a swept-frequency cosine (chirp) signal. However,
the object can process large streams of real-time data and handle system states automatically.
The function performs one-time computations on data that is readily available and cannot
handle system states. For a comparison between the two, see System Objects vs MATLAB Functions.
To generate the chirp signal:
Create the
dsp.Chirpobject and set its properties.Call the object with arguments, as if it were a function.
To learn more about how System objects work, see What Are System Objects?
Creation
Description
chirp = dsp.Chirpchirp, with unity amplitude.
chirp = dsp.Chirp(PropertyName=Value)Type to
"Logarithmic".
Properties
Usage
Syntax
Output Arguments
Object Functions
To use an object function, specify the
System object as the first input argument. For
example, to release system resources of a System object named obj, use
this syntax:
release(obj)
Examples
Generate a bidirectional chirp signal with these settings:
Target frequency of 25 Hz
Initial frequency of 0 Hz
Sweep time of 1 second
Target time of 1 second
400 samples per frame
Sample rate of 400 Hz
Inherit Target Time From Sweep Time
Construct a dsp.Chirp object. Set the InheritTargetTime property to true to inherit the target time from the sweep time.
chirp = dsp.Chirp(... SweepDirection="Bidirectional", ... TargetFrequency=25, ... InitialFrequency=0,... InheritTargetTime=true, ... SweepTime=1, ... SamplesPerFrame=400, ... SampleRate=400)
chirp =
dsp.Chirp with properties:
Type: 'Linear'
SweepDirection: 'Bidirectional'
InitialFrequency: 0
TargetFrequency: 25
SweepTime: 1
InheritTargetTime: true
InitialPhase: 0
SamplesPerFrame: 400
SampleRate: 400
OutputDataType: 'double'
Plot the chirp signal.
plot(chirp());
Initialize the spectrumAnalyzer object to show the spectrogram.
specAna = spectrumAnalyzer(ViewType="spectrogram",... Method="welch",... FrequencyResolutionMethod="window-length",... WindowLength=128,... FFTLengthSource="auto",... SpectrumUnits="dBm",... TimeSpanSource="property",... TimeSpan=6,... FrequencySpan="start-and-stop-frequencies",... StartFrequency=0,... StopFrequency=40,... Window="hamming",... OverlapPercent=80,... SampleRate=400,... FrequencyOffset=0,... Colormap="parula",... AveragingMethod="exponential",... ForgettingFactor=0,... PlotAsTwoSidedSpectrum=true)
specAna =
spectrumAnalyzer handle with properties:
InputDomain: 'time'
SpectrumType: 'power'
ViewType: 'spectrogram'
SampleRate: 400
Method: 'welch'
PlotAsTwoSidedSpectrum: 1
FrequencyScale: 'linear'
AxesScaling: 'auto'
Show all properties
Stream in the chirp signal and view its spectrogram in the spectrum analyzer.
for i = 1:1000 input = chirp(); specAna(input); end
Manually Specify Target Time
Set the InheritTargetTime property to false. Specify a target time of 0.5 seconds. The sweep time is 1 second.
release(chirp) chirp.InheritTargetTime = false; chirp.TargetTime = 0.5;
Plot the chirp signal.
plot(chirp())
Stream in the chirp signal and view its spectrogram in spectrum analyzer.
for i = 1:1000 input = chirp(); specAna(input); end
Algorithms
This object implements the algorithm, inputs, and outputs described on the Chirp block reference page. The object properties correspond to the block parameters.
