dspopts (Signal Processing Toolbox)

Spectral estimation parameter information

Syntax

```
Hopts = dspopts.optsobj
```

Description

Hopts = dspopts.optsobj returns a DSP options object Hopts of type optsobj. This DSP options object contains optional parameter information for the specified type of optsobj.

You create options objects via methods on other objects. For example,

```
Hopts = psdopts(Hs,X) 
```

returns a spectrum object Hs options object. You can change the values of the Hopts object and then use this modified options object as an input to the psd method of a spectrum object Hs:

```
Hpsd = psd(Hs,X,psdopts)
```

Note You must use an optsobj with dspopts.

Options Objects

An options object (optsobj) for dspopts contain optional parameter values for the particular optsobj. Available optsobjs for dspopts are as follows:

spectrum -- Spectrum options for any spectrum estimation method object. The spectrum object method to create this options object is psdopts and msspectrumopts. See spectrum for more information.

Properties and valid values of a dspopts.spectrum object are as follows:
- 'NFFT'-- integer number of FFT points
- 'NormalizedFrequency'-- whether frequency is normalized (true) or not (false)
- 'Fs'-- sampling frequency, used only when 'NormalizedFrequency' is false. If 'NormalizedFrequency' is true, the value of Fs is 'Normalized'.
- 'SpectrumType'-- 'Onesided' for half the Nyquist interval or 'Twosided' for the whole Nyquist interval.

pseudospectrum -- Pseudospectrum options for spectrum.music and spectrum.eigenvector objects. The spectrum object method to create this options object is pseudospectrumopts. See spectrum for more information.

Properties and valid values of a dspopts.pseudospectrum object are as follows:
- 'NFFT' -- integer number of FFT points
- 'NormalizedFreqeuncy'--whether frequency is normalized (true) or not (false)
- 'Fs' -- sampling frequency, used only when 'NormalizedFrequency' is false. If 'NormalizedFrequency' is true, the value of Fs is 'Normalized'.
- 'SpectrumRange' -- 'Half' for half the Nyquist interval or 'Whole' for the whole Nyquist interval.

Modifying a DSPOPTS Object

To set specific properties, use

set(Hopts,'property1',value, 'property2',value,...)

or use the dot method

```
Hopts.property = value
```

where 'property1', 'property2', and property are the specific property names.

To view the options for a property use set without specifying a value

```
set(Hopts,'property')
```

Note that you must use single quotation marks around the property name if you are not using the dot method.

Another way to change an object's properties is by using the inspect command, which opens the Property Inspector window where you can edit any property, except dynamic properties.

```
inspect(Hopts)
```

Examples

Define a fourth order auto-regressive model and view its power spectral density using the Burg algorithm. Use dspopts to specify the FFT length and sampling frequency.

randn('state',1);
x=randn(100,1);
x=filter(1,[1 1/2 1/3 1/4 1/5],x);%Fourth order AR filter
Hs=spectrum.burg;                 %Fourth order AR model
Hopts = dspopts.spectrum;
set(Hs,'FFTLength','UserDefined');
set(Hopts,'NFFT',512);
set(Hopts,'Fs',1000);
psd(Hs,x,Hopts)

dspfwiz ellip