Signal Processing Toolbox Release Notes

Chapter 3
Signal Processing Toolbox 6.2 Release Notes

New Features

This section summarizes the new features and enhancements introduced in the Signal Processing Toolbox 6.2.

This section is organized into the following subsections:

• Spectrum Objects
• Dspdata Objects
• Options Objects
• Filter States Objects
• Enhancements to Discrete-time Filter Objects
• Enhancements to Window Objects
• Enhancement to Spectral Estimation Functions
• FDATool Enhancements
• FVTool Enhancement

Spectrum Objects

The Signal Processing Toolbox 6.2 adds a new spectrum object. Spectrum objects contain parameter information for a particular spectral estimation method (e.g., spectrum.welch). This object provides an improved way to view and manipulate spectral estimation parameters. See the spectrum reference page and the associated estimation method reference pages for more information.

Dspdata Objects

A new data object dspdata has been added. These data objects contain parameter information for spectral data. Available types of data objects are dspdata.msspectrum, dspdata.psd, and dspdata.pseudospectrum. These objects contain the mean-square spectrum data, the power spectral density data, and the pseudospectrum data, respectively. With these objects, you can apply methods that calculate certain values or modify the data, such as computing the average power, centering the DC value, converting the spectrum between one-sided and two-sided, and normalizing the frequency. You can plot the data in a new Spectral Analysis plot. See dspdata for information.

Options Objects

A new options object dspopts has been added. This object contains optional parameter information for spectrum objects. You create options objects via methods on other objects. See dspopts for information.

Filter States Objects

A new filter states object filtstates with two properties--Numerator and Denominator, that contain the filter states for an IIR Direct-form I filter, has been added. The states property of a dfilt.df1, dfilt.df1t, dfilt.df1sos, or dfilt.df1tsos filter now contains a filtstates.dfiir object, instead of a double vector. See filtstates for more information.

Note that you cannot change the values in the Numerator or Denominator using this syntax:

• Hd.states.numerator = [<data>]
  

Note    The sign of the Denominator states for dfilt.df1t and dfilt.df1tsos is negated from what it was in previous versions. Refer to the structure diagrams shown on the reference pages. If you use the double command on a filter states object to get a vector of double-precision values of the numerator and denominator, the numerator values are listed first, followed by the denominator values. In previous versions, the denominator values were listed first. States saved for SOS objects in previous versions cannot be loaded into the current version.

Enhancements to Discrete-time Filter Objects

• The leading coefficient of the denominator (a0) can not be set to zero.
• New methods have been added to dfilt objects:
• fcfwrite--writes an ASCII filter coefficient file.
• info--displays filter structure, order, stability and linear phase information.
• The terminology used for multistage and second-order sections (SOS) filters has been clarified and some dfilt method names have been changed. SOS filters have sections, where sections compose a single filter. Cascade and parallel filters have stages, where each stage is a separate filter. See the "Methods" section of the dfilt reference page for information on methods related to sections and stages. The new or renamed methods are
• addstage--adds a stage to a parallel or cascade filter object.
• nstages--returns the number of stages in the filter.
• removestage--removes a stage from a parallel or cascade filter object.
• setstage--overwrites a stage of a parallel or cascade filter object.

Enhancements to Window Objects

Two new methods have been added to sigwin objects:

• winwrite--writes an ASCII file containing window weights
• info--displays information about the window object

Note    To obtain command line help for Signal Toolbox objects, type help objectname or help objectname/classname or help objectname/methodname. For example, to display help on the psd class of dspdata, type help dspdata/psd and for help on the average power method, type help dspdata/avgpower.

Enhancement to Spectral Estimation Functions

All of the spectral estimation functions (pburg, pcov, peig, periodogram, pmcov, pmtm, pmusic, pwelch, and pyulear) now use the new Spectral Analysis plot when no output arguments are specified. For an example of this plot, see the spectrum reference page.

FDATool Enhancements

• A new graphical Pole/Zero Editor panel has been added. You can graphically edit the filter (move, add, and delete poles/zeros) and see the resulting effect on your filter design.
• File->Export changes include adding the ability to export the filter directly to SPTool, exporting an ASCII coefficient file instead of a text file, exporting cascades and parallel structures, and general improvements to the dialog box.
• FIR Constrained Least Squares (fircls) and complex and nonlinear-phase equiripple FIR (cfirpm) filters have been added as design methods.
• A Filter Manager has been added. You can use the Filter Manager to store and recall multiple filters in a single FDATool session. You can also use it to cascade filters easily.
• The Analysis Parameters dialog box has been reorganized and simplified. The Frequency Units field has been removed and a Normalized Frequency checkbox has been added. (This also applies to FVTool.)

FVTool Enhancement

From the command line, you can change the sampling frequency (Fs) for the filter(s) in FVTool. See the Controlling FVTool from the MATLAB Command Line section of fvtool for more information.

New Demos

Two new demos have been added:

• Waveform Generation -- generates common waveforms, such as pulse trains.
• DTMF -- generates telephone pad tones.

Upgrading from an Earlier Release

Major Bug Fixes

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