Mathworks FILTER DESIGN TOOLBOX RELEASE NOTES

Filter Design Toolbox™ Release Notes

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Filter Design Toolbox™ Release Notes

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Summary by Version ............................... 1

Contents

Version 4.7 (R2010a) Filter Design Toolbox

Version 4.6 (R2009b) Filter Design Toolbox

Version 4.5 (R2009a) Filter Design Toolbox

Version 4.4 (R2008b) Filter Design Toolbox

Version 4.3 (R2008a) Filter Design Toolbox

Version 4.2 (R2007b) Filter Design Toolbox

Version 4.1 (R2007a) Filter Design Toolbox

Version 4.0 (R2006b) Filter Design Toolbox

Version 3.4 (R2006a) Filter Design Toolbox

Version 3.3 (R14SP3) Filter Design Toolbox

........... 4

.......... 9

........... 12

.......... 17

........... 18

.......... 20

........... 22

.......... 24

........... 27

.......... 36

Version 3.2 (R14SP2) Filter Design Toolbox

Compatibility Summary for the Filter Design Toolbox

Product

......................................... 54

.......... 48

iii

iv Contents

SummarybyVersion

This table provides quick access to what’s new in each version. For clarification, see “Using Release Notes ” on page 1 below.

Filter Design Toolbox™ Release Notes

Version (Release)

Latest Versi V4.7 (R2010a

V4.6 (R2009

V 4.5 (R2009a)

V4.4 (R2008b)

V4.3 (R2

V4.2 (R2007b)

V4.1 (R2007a)

V4.0 (

V3.4 (R2006a)

008a)

R2006b)

New Features and Changes

Yes

)

Details

Yes Details

Yes

Detai

Yes Details

Version Compatibilit Consideratio

Yes Summary

No Bug Reports No

Yes Summary

No Bug Report

Yes Summary

No Bug Rep

No Bug Reports No

Yes Summary

Fixed Bugs

and Known

Problems

Bug Reports No

orts

Bug Reports No

Related Documentation at Web Site

V3.3 (R14SP3)

2(R14SP2)

V3.

Reports

Yes

ails

Det

Yes Details

ing Release Notes

se release notes when upgrading to a newer version to learn about:

Yes

mary

Sum

Yes Summary

Bug

Bug Reports No

Filter Design Toolbox™ Release Notes

• New features

• Changes

• Potential impact on your existing files and practices

Review the release notes for other MathWorks™ products required for this product (for example, MATLAB

or Simulink®). Determine if enhancements,

bugs, or compatibility considerations in other products impact you.

If you are upgrading from a software version other than the m ost recent one, review the current release notes and all interim versions. For example, when you upg rade from V1.0 to V1.2, review the release notes for V1.1 and V1.2.

What Is in the Release Notes

New Features and Changes

• New functionality

• Changes to existing functionality

Version Compatibility Con si derations

When a new feature or change introduces a reported incompatibility between versions, the Compatibility Considerations subsection explains the impact.

Compatibility issues reported after the product release appear under Bug Reports at The MathWorks™ Web site. Bug fixes can sometimes result in incompatibilities, so review the fixed bugs in Bug Reports for any compatibility impact.

Fixed Bugs and Known Problems

The MathWorks offers a user-searchable Bug Reports database so you can view Bug Reports. The development team updates this database at release time and as more information becomes available. Bug Reports include provisions for any known workarounds or file replacem ents. Information is available for bugs existing in or fixed in Release 14SP2 or later. Information is not avail able for all bugs in earlier releases.

Access Bug Reports using y our MathWorks Account.

SummarybyVersion

Filter Design Toolbox™ Release Notes

Version 4.7 (R2010a) Filter Design Toolbox

This table summarizes what is new and changed in Version 4.7 (R2010a)

New Features and Changes

Yes Details belo

• “Audio Wei

• “Functio

Removed”

New feat version

Audio W

In R201

ting filters model the frequency and level-dependent perceptual

weigh

ts of the human auditory system. The filter specification object

weigh

gn.audioweighting

fdesi

and IT

ghting Filters” on page 4

ns,Objects,ObjectMethods,andObjectPropertiesBeing

on page 5

ures and changes with compatibility impact introduced in this

eighting Filters

0a,youcandesignseveraltypesof audio weighting filters. Audio

U-R 468-4 weighting filters.

Version Compatibility Consideratio

Yes — Details labeled as

Compatibility Considerations

below. See also Summary.

providessupportforA,C,C-message,ITU-T0.41,

Fixed Bugs and Known

Problems

Bug R eports

Related Documentation at Web Site

Printable Release Notes: PDF

Current product documentation

Version 4.7 (R2010a) Filter Design Toolbox™

Name

adaptlms (Object)

adaptnl

adaptrls (Object)

adaptsd (Object)

ptse

ada

adaptss (Object)

fdesign.decim

(Object)

Functions, Obje Properties Bein

What Happens When you Use the Function, Object, Object Method, or Object Property

Errors

rors

Errors

Use Instead Compatibility

adaptfilt.lms

adaptfi

adaptfilt.rls

adaptfilt.sd

ptfilt.se

ada

adaptfilt.ss

fdesign.decimator

cts, Object Methods, and Object

g Removed

Considerations

lexisting

sof

adaptlms

tfilt.lms

adaptnlms

adaptrls

ace all existing

adaptsd with

tfilt.sd

adaptse with

adaptss with

lt.nlms

Replace al instance with adap

Replace all existing instances of with a daptfilt.nlms.

Replace all existing instances of with adaptfilt.rls.

Repl

ances of

inst

adap

Replace all existing instances of

adaptfilt.se.

Replace all existing instances of

adaptfilt.ss.

Replace all exi s tin g instances of

fdesign.decim with

fdesign.decimator.

Filter Design Toolbox™ Release Notes

Name

fdesign.interp

(Object)

fdesign.src (Object)

farrow.fd (Object)

farrow.linearfd

(Object)

filtmsb (Method)

initlms (Object)

initnlms (Object)

What Happens When you Use the Function, Object, Object Method, or Object Property

Errors

Use Instead Compatibility

Considerations

fdesign.interpolator

fdesign.rsrc

dfilt.farrowfd

Replace all exi s tin g instances of

fdesign.interp with

fdesign.interpolator.

Replace all exi s tin g instances of

fdesign.src with

fdesign.rsrc.

Replace all existing instances of

farrow.fd

with d filt.farrowfd.

dfilt.farrowfd

FilterInternals property

mfilt.cicdecim and

mfilt.cicinterp objects

adaptfilt.lms

adaptfilt.nlms

Replace all exi s tin g instances of

farrow.linearfd with

dfilt.farrowfd.

Replace all exi s tin g instances of

filtmsb by setting the

FilterInternals property

mfilt.cicdecim and mfilt.cicinterp objects to 'FullPrecision'.

Replace all existing instances of

adaptfilt.lms.

initlms with

Replace all existing instances of

initnlms

with a daptfilt.nlms.

Version 4.7 (R2010a) Filter Design Toolbox™

Name

initrls (Object)

initsd (Object)

initse (Object)

initss (Object)

legacyfixptfir

SectionWordLengthMode

(Property of

mfilt.cicdecim and mfilt.cicinterp

objects)

What Happens When you Use the Function, Object, Object Method, or Object Property

Errors

Warns

Errors

Use Instead Compatibility

Considerations

adaptfilt.rls

adaptfilt.sd

adaptfilt.se

adaptfilt.ss

Replace all existing instances of

adaptfilt.rls.

initrls with

Replace all existing instances of

adaptfilt.sd.

initsd with

Replace all existing instances of

adaptfilt.se.

initse with

Replace all existing instances of

adaptfilt.ss.

initss with

Replace all pre-R14SP2 fixed-point FIR filters with post-R14SP2 fixed-point FIR filters.

FilterInternals property

mfilt.cicdecim and

mfilt.cicinterp objects

Replace all exi s tin g instances of

SectionWordLengthMode

by setting the

FilterInternals property

mfilt.cicdecim and

mfilt.cicinterp objects

'MinWordLengths',or 'SpecifyWordLengths'.

Filter Design Toolbox™ Release Notes

Name

StageInputAutoScale

(Property of fixed-point

dfilt.df1tsos, dfilt.df2sos,and dfilt.df2tsos

objects)

StageOutputAutoScale

(Property of fixed-point

dfilt.df1tsos, dfilt.df2sos,and dfilt.df2tsos

objects)

StageInputWordLength

(Property of fixed-point

dfilt.df1tsos, dfilt.df2sos,and dfilt.df2tsos

objects)

StageOutputWordLength

(Property of fixed-point

dfilt.df1tsos, dfilt.df2sos,and dfilt.df2tsos

objects)

What Happens When you Use the Function, Object, Object Method, or Object Property

Warns

Use Instead Compatibility

Considerations

SectionInputAutoScale

Replace all existing instances of

StageInputAutoScale with SectionInputAutoScale.

SectionOutputAutoScale

Replace all existing instances of

StageOutputAutoScale with SectionOutputAutoScale.

SectionInputWordLength

Replace all existing instances of

StageInputWordLength with SectionInputWordLength.

SectionOutputWordLength

Replace all exi s tin g instances of

StageOutputWordLength

with

SectionOutputWordLength.

Version 4.6 (R2009b) Filter Design Toolbox™

Version 4.6 (R2009b) Filter Design Toolbox

This table summarizes what is new and changed in Version 4.6 (R2009b):

New Features and Changes

Yes Details below

New featur

• “Optimal F

• “Quality a

Filters”

• “Multira

and Rati

• “Zero-P

• “filter

page 11

• “Abili

es and changes introduced in this version:

on page 10

te Pulse-Shaping Filter Support Added for Decimator, Interpolator,

onal Sample-Rate Converter Designs” on page 10

hase Option Added for Equiripple Nyquist Filters” on page 10

builder Support for Peaking and Notching IIR Comb Filters” on

ty to Export Filter Coefficients Added to realizemdl” on page 11

Version Compatibility Consideration

No Bug R eports

inite W ordlength FIR Filter Designs” on page 9

nd Shelving Factor Support Added for Parametric Equalizer

Fixed Bugs and Known

Problems

Related Documentation at Web Site

Printable Release Notes: PDF

Current product documentation

Optim

Relea finit that the c For m

min

Too

al Finite Wordlength FIR Filter Designs

se R2009b introduces three new

e wordlength FIR filter designs. Yo u can construct fixed-point filters

meet the floating-point specifications while minimizing or constraining oefficient wordlength, or maximizing the stopband attenuation.

ore information, see

imizecoeffwl

lbox™ software.

. Construction of fixed-point filters requires the Fixed-Point

constraincoeffwl, maximizestopband,and

dfilt and mfilt methods for optimizing

Filter Design Toolbox™ Release Notes

Quality and Shelving Factor Support Added for Parametric Equalizer Filters

This release introduces support for the specification of a quality factor or shelving slope in parametric equalizer filters. You can specify parametric equalizer filters using the quality factor or shelving slope parameter in both

fdesign.parameq and filterbuilder. Access the parametric equalizer filter

design pane in

filterbuilder('parameq')

at the MATLAB command prompt. Set Order mode to specify to enable the quality factor or shelving slope specifications.

Multirate Pulse-Shaping Filter Support Added for Decimator, Interpolator, and Rational Sample-Rate Converter Designs

R2009b introduces support for polyphase pulse-shaping filter designs using

fdesign.decimator, fdesign.interpolator, fdesign.rsrc,and

filterbuilder. The supported pulse-shaping filters include: Gaussian,

raised cosine, and square root raised cosine filters. Access the des ign pane for multirate pulse shaping filters in

filterbuilder by entering:

filterbuilder('pulseshaping')

at the MATLAB command prompt. Specify the type of multirate filter with

Filter Type.

Zero-Phase Option Added for Equiripple Nyquist Filters

Filter Design Toolbox™ Version 4.6 software now supports zero-phase equiripple Nyquist filter designs. The zero-phase option is available in

fdesign.nyquist, fdesign.halfband,andfilterbuilder using the 'N,TW'

specification string. Setting 'ZeroPhase' to true returns a nonnegative amplitude, or zero phase response. following exam ple demonstrates how todesignanequirippleNyquistfilter with a nonnegative zero phase response:

f=fdesign.nyquist(4,'N,TW');

'ZeroPhase' defaults to false.The

Version 4.6 (R2009b) Filter Design Toolbox™

d=design(f,'equiripple','ZeroPhase',true); % Plot the zero-phase response zerophase(d)

In filterbuilder,setOrder mode to Specify and then set Frequency

constraints

zero phase response option under

to Transition width. These settings enable the nonnegative

Design options.

filterbuilder Support for Peaking and Notching IIR Comb Filters

In R2009b, filterbuilder supports peaking and notching IIR comb filters. Access the comb filter design pane by entering:

filterbuilder

at the MATLAB command prompt and choosing co mb from filter response menu, or by entering:

filterbuilder('comb')

For help on using filterbuilder, see “Designing a Filter in the Filterbuilder GUI”.

Ability to Export Filter Coefficients Added to realizemdl

If you use Simulink, you can now use the new MapCoeffstoPorts property with

realizemdl to map filter coefficients from dfilt and mfilt objects to

constant blocks. The coefficients also appear in the MATLAB workspace providing tunability to the realized Simulink m odel. See a list of supported filter structures and any restrictions.

dfilt an d mfilt for

Filter Design Toolbox™ Release Notes

Version 4.5 (R2009a) Filter Design Toolbox

This table summarizes what is new and changed in Version 4.5 (R2009a):

New Features and Changes

Yes Details belo

New featur

• “Fdesign S

• “Maximum

• “Changes

• “Change

• “New Qua

Filterb

Fdesig

fdesi

comb f

t a series of harmonically-related frequencies.

data a

es and changes introduced in this version are described here.

upport for Comb Filters” on page 12

in SOS IIR Design Defaults” on page 13

s in FIR Equiripple Design Defaults” on page 14

ntization Rounding Modes Added for Realizemdl, Block, and

uilder” on page 16

n Support for Comb Filters

now supports IIR peaking and notching comb filters. You can use

ilters to enhance (peaking) or eliminate (notching) energy in the input

Version Compatibility Consideratio

Yes Summary

Phase Option Added for Equiripple Designs” on page 12

Fixed Bugs and Known Problems

Bug R eports

Related Documentation at Web Site

Printable Release Notes: PDF

Current product documentation

nstruct comb filters use the

To co

type

Comb

Max Des

Equ

nstruct maximum-phase equiripple filter using the

esign.bandpass

property as 'notch' or 'peak'.

imum Phase Option Added for Equiripple

igns

iripple filter designs now include a maximum phase option. You can

,andfdesign.bandstop filter designers.

fdesign.comb function and specify the

fdesign.lowpass,

Version 4.5 (R2009a) Filter Design Toolbox™

The impulse response of a maximum-phase filter builds more slowly than any other filter of equal length and magnitude response. All the zeros of a maximum-phase filter lie on or outside the unit circle. Maximum-phase filters are useful in a number of applications including channel equalization. The following example demonstrates how to construct a maximum-phase equiripple filter using the lowpass filter designer:

d=fdesign.lowpass; %Construct a lowpass filter object using the defaults.

Hd=design(d,'equiripple','maxphase',true); %Implement the filter.

zplane(Hd) %Note all th e zeros are on or outside the unit circle.

fvtool(Hd,'analysis','impulse') %Plot the impulse response.

Changes in SOS IIR Design Defaults

Changes have been made to the default specifications invoked by fdesign when constructing second-order sections (SOS) IIR filters.

Previous to the R2009a release, lowpass, highpass, bandpass, or bandstop SOS IIR filters used peak magnitude response scaling (

Linf)bydefault.

In R2009a no scaling is applied by default to lowpass, highpass, bandpass, or bandstop SOS IIR filters.

Compatibility Considerations

Section-order sections IIR filters generated in R2009a will be scaled differently than in previous releases. Users can recreate their pre-R2009a default designs by setting the following example illustrates a lowpass B utterworth filter design in R2008b and its equivalent in R2009a.

Code in R2008b:

d=fdesign.lowpass; %lowpass filter designer

Hd=design(d,'butter'); %Butterworth filter with default (Linf) scaling

Equivalent code in R2009a:

d=fdesign.lowpass; %lowpass filter designer

Hd=design(d,'butter','sosscalenorm','linf');

'SOSScaleNorm' property to 'Linf'.The

Filter Design Toolbox™ Release Notes

Note You must consider scaling carefully when you design fixed-point filters to guard against overflow. See the “Floating-Point to Fixed-Point Conversion of IIR Filters” demo for overflow analyses, both with and without scaling.

Changes in FIR Equiripple Design Defaults

In R2009a, the firpm function is used by default to construct the following FIR equiripple filters:

fdesign.lowpass('Fp,Fst,Ap,Ast')

fdesign.lowpass('N,Fp,Fst')

fdesign.highpass('Fst,Fp,Ast,Ap')

fdesign.highpass('N,Fst,Fp')

fdesign.bandpass('Fst1,Fp1,Fp2,Fst2,Ast1,Ap,Ast2')

fdesign.bandpass('N,Fst1,Fp1,Fp2,Fst2')

fdesign.bandstop('Fp1,Fst1,Fst2,Fp2,Ap1,Ast,Ap2')

fdesign.bandstop('N,Fp1,Fst1,Fst2,Fp2')

fdesign.arbmag('N,F,A')

fdesign.arbmag('N,B,F,A')

fdesign.differentiator(`N')

fdesign.differentiator('N,Fp,Fst')

fdesign.hilbert('N,TW')

In pre-R2009a releases, the firgr function was used to construct the FIR equiripple filters in the previous code samples.

Beginning with R2009a, users of the Signal Processing Toolbox™ can use

fdesign and design to specify and design filters. However, only concurrent

users of the Filter Design Toolbox have access to the enhanced capabilities of

firgr.

The change in the default algorithm for the specified FIR equiripple filter designs facilitates code sharing between Signal Processing Toolbox users and concurrent users of the Filter Design Toolbox.

Filter Design Toolbox users can access a new allows them to design equiripple filters with either the

UniformGrid property, which

firpm or firgr

functions. Setting the Unifor mGrid property to false calls the firgr function

Version 4.5 (R2009a) Filter Design Toolbox™

to construct the filter. Leaving the UniformGrid property unspecified, or setting it to

true,callsthefirpm function.

Note In general, both firpm and firgr filter designs will meet user specifications. H owever, increasing the number of frequency points near filter transition regions by using a nonuniform grid may improve the equiripple property and frequency response approximation of the filter. Using a nonuniform grid may also produce lower-order filters in minimum-order designs.

Compatibility Considerations

Code used to generate FIR equiripple filters in pre-R2009a releases may produce filters with different orders or coefficients in R2009a. Users can recreate their pre-R2009a default designs in the current release by explicitly setting the equivalent filter designs in R2008b and R2009a using the property.

UniformGrid property to false. The following examples illustrate

UniformGrid

Code in R2008b:

d=fdesign.lowpass;

Hd=design(d,'equiripple');

Equivalent code in R2009a:

d=fdesign.lowpass;

Hd=design(d,'equiripple','UniformGrid',false);

Therearetwoexceptionsinequiripple filter design where fdesign sets the

UniformGrid property internally:

• If you create arbitrary magnitude designs that result in complex-valued

filter co efficients, the

• If you create a design in which you set the

StopbandShape properties to nondefault values, the UniformGrid property

defaults to

False.

UniformGrid property defaults to true.

MinPhase, MaxPhase,or

Filter Design Toolbox™ Release Notes

If you attempt to override the internal settings to these exceptions, you will get a warning message.

New Quantization Rounding Modes Added for Realizemdl, Block, and Filterbuilder

The rounding modes for the realizemdl method, the block method, and

filterbuilder GUI-basedwizardnowincluderoundandconvergentmodes.

The rounding mode determines how the filter quantizes numeric values that lie between representable values for the data format (word and fraction lengths).

When you set the rounding mode to representable integer, and ties round to the nearest even stored integer. This approach is the least biased of the methods available in the toolbox.

When the rounding mode is set to representable integer, negative ties round toward negative infinity, and positive ties round toward positive infinity.

convergent, values round to the closest

round, values round to the closest

Version 4.4 (R2008b) Filter Design Toolbox™

Version 4.4 (R2008b) Filter Design Toolbox

This table summarizes what’s new and changed in Version 4.4 (R2008b):

New Features and Changes

Yes Details belo

New featur

• “Fdesign

• “Optimiz

Object” o

Fdesign

fdesign

• Raised

• Maxfl

es and changes introduced in this version are described here.

Support for Additional Filter Types” on page 17

eScaleValues Property A dded to npage17

Support for Additional Filter Types

now supports the following filter types:

-cosine and square-root raised-cosine

atFIRandIIRlowpass

at FIR highpass

Version Compatibility Consideratio

No Bug Reports

Fixed Bugs and Known

Problems

Related Documentation at Web Site

Printable Release Notes: PDF

Current product documentation

dfilt Second-order Sections

• Const

Opti Seco

Opt all of F

1. S mu

rained least-squares FIR lowpass, highpass, bandpass, bandstop

mizeScaleValues Property Added to

dfilt

nd-order Sections Object

imizeScaleValues property added to

ows the user to control skipping multiplication-by-1. Previous versions

ilter Design Toolbox software always optimized scale values eq ual to

tarting in R2008b, users can configure the software so it does not skip

ltiplication-by-1 between sections.

dfilt second-order sections object,

Filter Design Toolbox™ Release Notes

Version 4.3 (R2008a) Filter Design Toolbox

This table summarizes what’s new and changed in Version 4.3 (R2008a):

New Features and Changes

Yes Details belo

New featur

• “Realize

on page 18

• “Fdesign

• “Expand

Factors

• “Fdesi

• “Input

on page

Reali Sampl

an now create Simulink models of Polyphase and Farrow Sample Rate

You c

erters from the command line using the realizemdl command with

Conv

t.firsrc and mfilt.farrowsrc.

mfil

es and changes introduced in this version are described here.

mdl Support for Polyphase and Farrow Sample Rate Converters”

Support for Farrow Sample Rate Converters” on page 18

ed Demo: Efficient Sample Rate Conversion Between Arbitrary

”onpage19

gn Support for Highpass Halfband Filters” on page 19

Quantization Added to Models Generated by the Block Method”

zemdl Support for Polyphase and Farrow

e Rate Converters

Version Compatibility Consideratio

Yes Summary

Fixed Bugs and Known

Problems

Bug Reports

Related Documentation at Web Site

Printable Release Notes: PDF

Current product documentation

sign Support for Farrow S ample Rate Converters

Fde

tirate Farrow filters can efficiently implement arbitrary (including

Mul

rational) rate change factors. You can design Farrow sample rate converters

ing the new fdesign function fdesign.polysrc.

Version 4.3 (R2008a) Filter Design Toolbox™

Expanded Demo: Efficient Sample Rate Conversion Between Arbitrary Factors

The expanded Efficient S ample Rate Conversion Between Arbitrary Factors demo now shows you how to design Farrow sample rate converters using the new fdesign.polysrc function.

Fdesign Support for Highpass Halfband Filters

The fdesign design class, fdesign.halfband, has a new property, type,that youcanusetocreatea

lowpass or highpass halfband filter.

Input Quantization Added to Models Generated by the Block Method

Models generated by the block method now include a new input quantization feature.

Compatibility Considerations

The new input quantization feature does not work with models generated using previous versions of the software. To restore the previous behavior, open the generated subsystem block, remove the Convert block, and reconnect the remaining block to the subsystem input.

Filter Design Toolbox™ Release Notes

Version 4.2 (R2007b) Filter Design Toolbox

This table summarizes what’s new and changed in Version 4.2(R2007b):

New Features and Changes

Yes Details belo

New featur

• “Farrow C

• “All Mult

• “New Mul

page 21

• “Update

• “Compa

• “Funct

Farro

The tw

dfilt

es and changes introduced in this version are described here.

irate F il ter Structures Sup port Com plex C oefficients” on page 20

tirate Farrow Filter Capable of Sample Rate Conversion” on

d Getting Started and User’s Guide” on page 21

tibility Considerations” on pa ge 21

ions Being Removed” o n page 21

w Classes Moved into DFILT package

oclasses

.farrowfd

Version Compatibility Consideratio

Yes Bug Reports

lasses Moved into DFILT package” on page 20

farrow.fd and farrow.linearfd have been moved into

and d filt .farrowlinearfd,respectively.

Fixed Bugs and Known

Problems

Related Documentation at Web Site

Printable Release Notes: PDF

Current product documentation

All M Coe

All

ultirate Filter Structures Support Complex

fficients

structures for

mfilt multirate filters can use complex coefficients.

Version 4.2 (R2007b) Filter Design Toolbox™

New Multirate Farrow Filter Capable of Sample Rate Conversion

A ne w multirate filter, mfilt.farrowsrc, has been added to mfilts, allowing for Farrow decimators and interpolators, and fractional decimators and fractional interpolators where the resulting interpolation or decimation facto r is not an integer.

Updated Getting Started and User’s Guide

Updates to structure of User’s Guide and Getting started include sections about using FIR filters

filterbuilder and a new chapter about using integers with

Compatibility Considerations

• The farrow.fd and farrow.linearfd functions have been removed. For

more information about the removal of these functions, see “Functions Being Removed” on page 21.

Function Being Removed

farrow.fd

farrow.linearfd

Functions Being Removed

What Happens When You Run the Function?

Still runs

Use this Function Instead

dfilt.farrowfd

dfilt.farrowlinearfd

Compatibility Considerations

Farrow filters are now constructed using the dfilt (discrete-time filter) structure. Instead of using farrow.fd, use dfilt.farrowfd. See the reference page for dfilt for more information.

As noted above Farrow filters are now created using the dfilt constructor.

Filter Design Toolbox™ Release Notes

Version 4.1 (R2007a) Filter Design Toolbox

This table summarizes what’s new and changed in Version 4.1(R2007a):

New Features and Changes

Yes Details belo

New featur

• “Fdesign

Filters”

• “Fdesign

• “Fdesig

• “Arbitr

• “Suppo

Toolbo

Fdesi Fract

e-band and fractional-octave-band filters are commonly used in

Octav

stics, for e xample, in noise control to perform spectral analysis. You

acou

esign o ctave band and fractional octave band filters using the fdesign

can d

tion

func

hical approach, try the

grap

es and changes introduced in this version are described here.

Support Added for Octave Band and Fractional Octave Band

on page 22

Support Added for Parametric Equalizer Filters” on page 23

n Support Added for Notch and Peak Filters” on page 23

ary Magnitude and Phase Added to Multirate Filters” on page 23

rt for Fixed-point Inputs and Tunable Parameters in Filter Design

xBlocks”onpage23

gn Support Added for Octave Band and

ional Octave Band Filters

fdesign.octave. If you prefer to design these filters using a

Version Compatibility Consideratio

No Bug Reports

filterbuilder function.

Fixed Bugs and Known

Problems

Related Documentation at Web Site

Printable Release Notes: PDF

Current product documentation

Version 4.1 (R2007a) Filter Design Toolbox™

Fdesign Support Added for Parametric Equalizer Filters

Parametric equalizers are digital filters used in audio for adjusting the frequency content of a sound signal. The Filter Design Toolbox provides the capability to design high-order IIR parametric equalizers. Such high-order designs provide much more control over the shape of each filter. You can design parametric equalizer filters using the fdesign function

fdesign.parameq. The same functionality can be achieved through the GUI

function

filterbuilder.

Fdesign Support Added for Notch and Peak Filters

Filters that peak or notch at a certain frequency are useful to retain or eliminate a particular frequency component of a signal. You can design these peak or notch filters using the new functions

fdesign.notch. The same functionality can be achieved through the GUI

function

filterbuilder.

fdesign.peak and

Arbitrary Magnitude and Phase Added to Multirate Filters

When designing a multirate filter, you can specify the response o f the resulting filter. Arbitrary magnitude as well as arbitrary magnitude and phase are two responses that have been added to an already extensive list. To understand how to use these responses when designing multirate filters, see

fdesign.rsrc, fdesign.decimator,andfdesign.interpolator.

Support for Fixed-point Inputs and Tunable Parameters in Filter Design Toolbox Blocks

The blocks in the Filter Design Toolbox library of Signal Processing Blockset™ now support fixed-point and integer data types on their input and output ports. In addition, parameters of these blocks that do not change filter order or structure are now tunable. This feature is fully described in the "Signal Processing Blockset User’s Gu ide".

Filter Design Toolbox™ Release Notes

Version 4.0 (R2006b) Filter Design Toolbox

This table summarizes what’s new and changed in Version 4.0 (R2006b):

New Features and Changes

Yes Details belo

New featur

• “Blocks fo

Design To

• “Support

Based on I

• “New fil

• “Fixed-

• “Fract

• “New fr

Frequ

• “Para

es and changes introduced in this version are described here.

r Designing Filters Added to Signal Processing Blockset (Filter

for Automatically Converting Floating-Point Filters to Fixed-Point

terbuilder Function for Interactive Filter Design” on page 26

Point Farrow Filter Support” on page 26

ional D elay Filter D es ig n with fdesign.fracdelay” on page 26

eqrespest Function for Using Filtering to Estimate the Filter

ency Response from Measured Data” on page 26

llel Filter Objects Support Multirate filters” on pag e 26

Version Compatibility Consideratio

No Bug Reports

olbox Required)” on page 25

nput Data” on page 25

Fixed Bugs and Known Problems

Related Documentation at Web Site

Printable Release Notes: PDF

Current product documentation

• “Coup

led-Allpass Designs Available for All fdesign Objects” on page 26

Version 4.0 (R2006b) Filter Design Toolbox™

Blocks for Designing Filters Added to Signal Processing Blockset (Filter Design Toolbox Required)

This release adds a block library to the Signal Processing Blockset product. The new library contains blocks that design single- and multirate filters using the new Filter Design Toolbox, you can use the new blocks to design and implement filters in simulations. Users who do not have Fixed-Point Toolbox licenses can run models that contain the new blocks, but they cannot change the filter designs in the blocks.

filterbuilder filter design dialog boxes. If you have a license for

Support for Automatically Converting Floating-Point Filters to Fixed-Point Based on Input Data

Twonewaspectsofanalysisallowyoutoconvert filters from floating-point tofixed-pointformatautomatically:

• Scaled doubles logging

mfilt and dfilt objects now support the scaled double data type. Scaled

doubles data types ac t like fixed-point data types, allowing you to work with both fixed-point and scaled doubles in the same calculation. Allowing this overcomes the limitation that math is permitted only between the same data types. The value property of the numerictype object. The following values have also been added to the

DataTypeMode property of the numerictype object:

ScaledDouble has been added to the DataType

- Scaled double: binary point scaling

- Scaled double: slope and bias scaling

- Scaled double: unspecified scaling

• Anewmethod,autoscale, automatically converts an input filter from

floating-point format to fixed-point format based on the results of filtering a set of data. autoscale attempts to scale the filter to prevent overflows in all filter computations.

The combination of these new capabilities provides the conversion support.

Filter Design Toolbox™ Release Notes

New filterbuilder Function for Interactive Filter Design

A new function, filterbuilder, provides a graphical tool for designing singleandmultiratefiltersinbothfloating-point and fixed-point forms. For more information, refer to

Fixed-Point Farrow Filter Support

We upgraded the Farrow filters to provide fix ed-point support. Similar to the fixed point for all other

Fractional Delay Filter Design with fdesign.fracdelay

Add the new method fdesign.fracdelay for designing filters that offer fractional delays. To support designing filters with we added a

New freqrespest Function for Using Filtering to Estimate the Filter Frequency Response from Measured Data

Use this new method to estimate the frequency response of a dfilt or mfilt object. freqrespest uses filtering to estimate the filter response. To support this new method, we added parameters for

filterbuilder.

dfilt objects.

fdesign.fracdelay,

lagrange design method.

freqrespopts,anobjectthatcontainsthe

freqrespest.

Parallel Filter Objects Support Multirate filters

With the addition of this feature, you can create parallel structures composed of multirate filters. This extends the parallel filter capability using

dfilt.parallel by letting you use multirate filters as the input filters. To

create parallel filter objects from two or more multirate filters, the individual filters must have the same rate change factors.

Coupled-Allpass Designs Available for All fdesign Objects

All specification objects now support coupled-allpass filter designs as structures.

Version 3.4 (R2006a) Filter Design Toolbox™

Version 3.4 (R2006a) Filter Design Toolbox

This table summarizes what’s new and changed in Version 3.4 (R2006a):

New Features and Changes

Yes Details belo

New feature

• “Farrow Fi

• “IIR Polyp

• “Single-

• “iirlinp

• “Arbitr

• “iirlin

• “CIC Fi

• “Neare

• “Cost

• “New O

s and changes introduced in this version are described here.

Rate Allpass Discrete-time and Multirate Filters” on page 28

hase Method for Designing Linear Phase IIR Filters” on page 28

ary Magnitude and Phase Filter Specification Object” on page 29

phase/elliptic Design for Hilbert Transformers” on page 29

lters Provide Full Precision and Specify All Options” on page 29

st Round Mode for dfilt and mfilt O bjects” on page 31

Method” on page 31

nline H elp for fdesign.structure” on page 31

Version Compatibility Consideratio

Yes

lters” on page 27

hase D ecimators and Interpolators” on page 28

Summary

Fixed Bugs and Known

Problems

Bug Reports

Related Documentation at Web Site

Printable Release Notes: PDF

• “Info

• “Mea

• “rea

• “Fi

Far

Th yo

Method Updated to Include Filter Measurements” on page 34

surement Display Changes” on page 34

lizemdl Creates Additional Multirate Polyphase Filters” on page 34

lter Design Object Now Called Filter Specification Object in the

umentation” on page 35

Doc

row Filters

e too lbox now provides Farrow filter capability with farrow. Using

u create filters based on the structure and a few options. After you create

farrow

Filter Design Toolbox™ Release Notes

your filter, various analysis functions, like cost and fvtool, help you determine your filter’s fitness. produce blocks for Sim ulink models as well.

IIR Polyphase Decimators and Interpolators

Now the toolbox provides design tools for IIR polyphase decimators and interpolators using

Single-Rate Allpass Discrete-time and Multirate Filters

Eight new filter function enable you to design both single-rate and multirate allpass filters, including w ave digital f il ters.

•

dfilt.allpass

• dfilt.wdfallpass

• dfilt.cascadeallpass

• dfilt.cascadewdfallpass

realizemdl works with Farrow filters to

fdesign.decimator and fdesign.interpolator.

• mfilt.iirdecim

• mfilt.iirwdfdecim

• mfilt.iirinterp

• mfilt.iirwdfinterp

iirlinphase Method for Designing Linear Phase IIR Filters

Thenewiirlinphasemethodaddedinthis release designs quasi-linear phase IIR f ilters from a halfband filter specification objects. Use the form

hd = design(d,'iirlinphase');

when d is a halfband specification object. Returned filter object hd is an IIR filter with linear phase in the passband.

Version 3.4 (R2006a) Filter Design Toolbox™

Arbitrary Magnitude and Phase Filter Specification Object

The new arbmagnphase specification object added in this release designs filters where you define the filter magnitude response and the phase response explicitly. Use the form

d = fdesign.arbmagnphase();

is a filter specification object where the magnitude and phase responses are

specified as a complex frequency response you provide.

iirlinphase/elliptic Design for Hilbert Transformers

When you use fdesign.hilbert to create a Hilbert transformer specification object, the toolbox provides new implement the filter from the specification object as an elliptic filter or as a quasilinear phase IIR filter.

ellip and iirlinphase design methods to

CIC Filters Provide Full Precision and Specify All Options

CIC filters, such as those created by fdesign.decimator and

fdesign.interpolator, now supports full precision and three word and

fraction length modes for the property

•

FullPrecision mode automatically sets the CIC filter word lengths

and fraction lengths to maintain the maximum precision in the filtering process. (new)

•

MinWordLengths mode lets you set the output word length for the filter.

SpecifyWordLengths mode lets you specify the word lengths for all sections

•

of the filter and for the output. But you cannot set the fraction lengths.

•

SpecifyPrecision mode lets you set all fraction lengths and word lengths

for the filter sections and for the output. (new)

For more information, refer to the reference pages for and fdesign. inte rpolator in the Filter Design Toolbox documentation.

FilterInternals.

fdesign.decimator

Filter Design Toolbox™ Release Notes

ThefollowingexampleusestheSpecifyPrecision mode. Use a decimation factor of 5 and differential delay equal to 1.

d=fdesign.decimator(5,'cic',1) % M=5, D=1.

NormalizedFrequency: true

hm=design(d) % Use the default multisection desig n method.

hm =

MultirateType: 'Decimator'

DecimationFactor: 5

Response: 'CIC'

Specification: 'Fp,Ast'

Description: {'Passband Frequency';'Aliasing Attenuation(dB)'}

DifferentialDelay: 1

Fpass: 0.01

Astop: 60

FilterStructure: 'Cascaded Integrator-Comb Decimator'

Arithmetic: 'fixed'

DifferentialDelay: 1

NumberOfSections: 2

DecimationFactor: 5

PersistentMemory: false

InputWordLength: 16

InputFracLength: 15

FilterInternals: 'FullPrecision'

hm.FilterInternals='specifyPrecision'

hm =

FilterStructure: 'Cascaded Integrator-Comb Decimator'

Arithmetic: 'fixed'

DifferentialDelay: 1

Version 3.4 (R2006a) Filter Design Toolbox™

NumberOfSections: 2

DecimationFactor: 5

PersistentMemory: false

InputWordLength: 16

InputFracLength: 15

FilterInternals: 'SpecifyPrecision'

SectionWordLengths: [21 21 21 21]

SectionFracLengths: [15 15 15 15]

OutputWordLength: 21

OutputFracLength: 15

Nearest Round Mode for dfilt and mfilt Objects

dfilt and mfilt objects include an additional mode for rounding the results

of calculations — in the chosen format. Changing this behavior makes

mfilt objects consistent with round in Simulink.

nearest. Results round to the nearest representable value

round for dfilt and

For more information about rounding, refer to fi in the Fixed Point Toolbox documentation, since the new rounding modes derive from the

fi obje ct used

by fixed-point filters.

Compatibility Considerations

The new round mode behavior is now matches MATLAB round as well.

Cost Method

After you create a filter, you can use cost to determine the arithmetic cost when you filter data.

cost returns estimates of the add, multiplies, and other

operations that occur when you use the filter.

New Online Help for fdesign.structure

With the addition of more fdesign methods and specification objects, t h e toolbox changes the way you get help about a specific design method—the command-line h elp is now adaptive, recognizing the object and the design method in the help syntax.

Filter Design Toolbox™ Release Notes

The command-line help adapts to the filter specification object you have and the design method you inte nd to use, and provides help specifically for that combination o f specification and method. For example, if you are designing a highpass filter and plan to use the way to get help:

d = fdesign.highpass('fst,fp,ast,ap',0.45,0.55,1,60))

designmethods(d)

Design Methods for clas s fdesign.highpass (Fst,Fp,Ast,Ap):

butter

cheby1

cheby2

ellip

equiripple

ifir

kaiserwin

butter design method, here is the new

help(d,'butter') % New help command syntax with object and method.

DESIGN Design a Butterw orth IIR filter.

HD = DESIGN(D, 'butter' ) designs a Butterworth filter specified by the

FDESIGN object D.

HD = DESIGN(..., 'Filte rStructure', STRUCTURE) returns a filter with the

structure STRUCTURE. STRUCTURE is 'df2sos' by default and can be any of

the following.

'df1sos'

'df2sos'

'df1tsos'

'df2tsos'

HD = DESIGN(..., 'Match Exactly', MATCH) designs a Butterworth filter

and matches the frequen cy and magnitude specification for the band

MATCH exactly. The other band will exceed the specification. MATCH

Version 3.4 (R2006a) Filter Design Toolbox™

can be 'stopband' or 'passband' and is 'stopband' by default.

% Example #1 - Compare passband and stopband MatchExactly.

h = fdesign.highpass('Fst,Fp,Ast,Ap', .7, .9, 60, 1);

Hd = design(h, 'butter', 'Ma tchExactly', 'passband');

Hd(2) = design(h, 'butt er', 'MatchExactly', 'stopband');

% Compare the passband edges in FVTool.

fvtool(Hd);

axis([.89 .91 -2 0]);

Suppose you decide to use an equiripple design method instead. Again, the

help command with the specification object d and the method equiripple

provides help for that combination.

help (d,'equiripple') % New help command syntax with object and method.

DESIGN Design a Equirip ple FIR filter.

HD = DESIGN(D, 'equirip ple') designs a Equiripple filter specified by the

FDESIGN object D.

HD = DESIGN(..., 'Filte rStructure', STRUCTURE) returns a filter with the

structure STRUCTURE. STRUCTURE is 'dffir' by default and can be any of

the following.

'dffir'

'dffirt'

'dfsymfir'

'dfasymfir'

'fftfir'

HD = DESIGN(..., 'Densi tyFactor', DENS) specifies the grid density DENS

used in the optimizatio n. DENS is 16 by default.

HD = DESIGN(..., 'MinPh ase', MPHASE) designs a minimum-phase filter

when MPHASE is TRUE. MPHASE is FALSE by default.

HD = DESIGN(..., 'MinOr der', 'any') designs a minimum-order filter.

The order of the filter can be even or odd. This is the default.

Filter Design Toolbox™ Release Notes

HD = DESIGN(..., 'MinOr der', 'even') designs an minimum-even-order

filter.

HD = DESIGN(..., 'MinOr der', 'odd') designs an minimum-odd-order filter.

% Example #1 - Design a lowpass Equiripple filter in a transposed

structure.

Notice that the content is different for the different methods. This makes it easier for you to know the options that apply to any combination of specification object and desi gn method.

Info Method Updated to Include Filter Measurements

When you request information about a filter, the information now includes measurements of the filter characteristics based on the filter s pe cif ications. Thesearethesameresultsthatmeasureprovides.

h = fdesign.highpass('Fst,Fp,Ast,Ap');

Hd = design(h, 'equiripp le', 'FilterStructure', 'dffirt');

Measurement Display Changes

measure now shows more information and more specific information for

any referred object. Now the display provides full text descriptions of the measured values, such as Sampling Frequency (instead of Edge instead of

Fstop. You should find this a more clear presentation of

Fs) and Stopband

the filter information.

realizemdl Creates Additional Multirate Polyphase Filters

From the command line, you can use realizemdl to create realizations for

firdecim, firtdecim, firinterp,andlinearinterp filters. You can also

apply

realizemdl to the new IIR single-rate and multirate filters:

•

dfilt.allpass

• dfilt.wdfallpass

• dfilt.cascadeallpass

Version 3.4 (R2006a) Filter Design Toolbox™

• dfilt.cascadewdfallpass

• mfilt.iirdecim

• mfilt.iirwdfdecim

• mfilt.iirinterp

• mfilt.iirwdfinterp

Filter Design Object Now Called Filter Specification Object in the Documentation

When you use fdesign.response, MATLAB returns an object, usually called

d, that contains the specifications for a filter design. In the documentation,

the returned object is now called a specification object.

Forclarity,werenamedthefilterdesignobjecttofilterspecification object, because the object specifies the filter specifications, such as the magnitude response parameters. The specification object is not a filter, but an intermediate step in the filter design process that uses and design.

fdesign.response

Filter Design Toolbox™ Release Notes

Version 3.3 (R14SP3) Filter Design Toolbox

This table summarizes what’s new in Version 3.3 (R14SP3):

New Features and Changes

Yes Details belo

New feature

• “New Appro

• “New Way to

• “New Demo

page 42

• “Fdesig

page 42

• “Fdesig

on page

• “Fdesi

page 4

• “butt

on pag

s a nd changes introduced in this version are

n Now Provides Arbitrary Magnitude Filter Response Design” on

n Now Provides Hilbert and Differentiator Filter Response Design”

gn Objects Now Use a Default Design Method When Available” on

er and ellip Half-Band Design Methods Added for IIR Fdesign Objects”

e43

Version Compatibility Consideratio

Yes Summary

ach and Methods for Designing Filters” on page 37

Get Help for Filter Desig ns” on page 40

Programs to Introduce fdesign Filter Design Approach” on

Fixed Bugs and Known

Problems

Bug Reports

Related Documentation at Web Site

Printable Release Notes:

PDF

• “Add

• “lim

• “nor

• “Ne

• “Wi

• “W

ed multistage Filter Design Method” on page 43

itcycle Method Restored to the Toolbox” on page 43

malizefreq Method Added to the Toolbox” on page 44

w measure Method for Filters” on page 44

th Fdesign Objects, N ew Passband Z oo m View Optio n” on page 44

ith Fdesign Objects, New Filter Specification Mask View Option” on

ge 44

Version 3.3 (R14SP3) Filter Design Toolbox™

• “Fdesign Object Display No Longer Shows Fs When the Design Object U ses

Normalized Frequency” on page 45

• “For cicinterp Objects, Changed the Order of the Properties in the Display”

on page 45

• “For IIR Design Objects, Property Fcutoff is Now Called F3dB” on page 46

• “Changes to the Displays in MATLAB for Filters” on page 46

• “Obsolete Functions and Methods in This Release” on page 46

• “block Method for mfilt.firfracdecim Filter Objects No Longer Works” on

page 47

New Approach and Methods for Designing Filters

To unify and take advantage of the object-based nature of the filters in the toolbox, this release introduces a new design approach for filters using filter design objects and new design methods. In the new process, your filter design tasks begin with identifying the filter response you need for your application.

Here is the new process.

1 Determine the response typeforyourfilter.

2 Choose the appropriate fdesign.response method to create a filter

specifications object.

3 Select the specifications to use to define your filter object. Here you can

select minimum order designs, IIR or FIR designs, o r designs that specify the filter order as well as the frequency and magnitude specifications, among many choices.

4 Use designmethods to find out which design algorithms apply to your

specifications object. Select the design method to use.

5 Use designopts with your design object to review the input arguments for

your specifications object and your selected design method.

6 Now design your filter using your filter design object, the design method

you chose, and the input arguments you require.

Filter Design Toolbox™ Release Notes

The result of this p roces s is a filter object that meets your requirements in response shape or form and designed by the method you selecte d.

Based on three design methods and a new help method, you now d esign filters starting w ith the desired response and moving to the final filter. These new methods are:

Method Description

design

designmethods

designopts

Here is a short example that demonstrates the new design flow. This

fdesign.lowpass syntax uses the default response specification

’

Fp,Fst,Ap,Ast’, where Fp is the passband edge, Fst is the stopband edge,

Ap specifies the ripple in the passband, and Ast de fines the desired stopband

attenuation.

Design a filter from the specifications using either a default method or a specified method.

Find out which design methods apply to your current design object, including dependence on the specifications.

Find out which input arguments apply to your design method and desig n object.

d = fdesign.lowpass % Select the response.

designmethods(d) % Determine the design methods a vailable.

hd = design(d) % Design the filter using the default method (equiripple).

Response: 'Lowpass'

Specification: 'Fp,Fst,Ap,Ast'

Description: {4x1 cell}

NormalizedFrequency: true

Fpass: 0.45

Fstop: 0.55

Apass: 1

Astop: 60

Version 3.3 (R14SP3) Filter Design Toolbox™

Design Methods for clas s fdesign.lowpass (Fp,Fst,Ap,Ast):

butter

cheby1

cheby2

ellip

equiripple

ifir

kaiserwin

multistage

hd =

FilterStructure: 'Direct-Form FIR'

Arithmetic: 'double'

Numerator: [1x43 double]

PersistentMemory: false

For more information about a particular design method, use the new help capability with your specification object and the design method as input arguments to

This help example gets more information about using the

help.

equiripple method

to design a lowpass filter.

help(d,'equiripple') % Get help on using equirip ple with your lowpass filter.

DESIGN Design a Equiri pple FIR filter.

HD = DESIGN(D, 'eq uiripple') designs a Equiripple filter specified by the

FDESIGN object H.

HD = DESIGN(..., ' FilterStructure', STRUCTURE) returns a filter with the

structure STRUCTURE. STRUCTURE is 'dffir' by default and can be any of

the following.

'dffir'

'dffirt'

Filter Design Toolbox™ Release Notes

'dfsymfir'

'fftfir'

HD = DESIGN(..., ' DensityFactor', DENS) specifies the grid density DENS

used in the optimi zation. DENS is 16 by default.

HD = DESIGN(..., ' MinPhase', MPHASE) designs a minimum-phase filter

when MPHASE is TRU E. MPHASE is FALSE by default.

HD = DESIGN(..., ' MinOrder', 'any') designs a minimum-order filter.

The order of the filter can be even or odd. This is the default.

HD = DESIGN(..., ' MinOrder', 'even') designs an minimum-even-order filter.

HD = DESIGN(..., ' MinOrder', 'odd') designs an minimum-odd-order filter.

HD = DESIGN(..., ' StopbandShape', SHAPE) designs a filter whose stopband

has the shape defi ned by SHAPE. SHAPE can be 'flat', '1/f', or 'line ar'.

SHAPE is 'flat' by default.

HD = DESIGN(..., ' StopbandDecay', DECAY) specifies the decay to use when

'StopbandShape' is not set to 'flat'. When the shape is '1/f' this

specifies the power that 1/f is raised. When shaped is 'linear' this

specifies the slope of the stopband in dB/rad/s.

% Example #1 - Design a lowpass Equiripple filter in a transposed structure.

h = fdesign.lowpass('Fp,Fst,Ap,Ast');

Hd = design(h, 'equiripp le', 'FilterStructure', 'dffirt');

New Way to Get Help for Filter Designs

Getting help about filter design and filterdesignmethodsisnowdynamic and depends on the design object and method. When you want help about designing a filter, use method to use to d esig n the filter. Here is an example.

d = fdesign.bandpass(0.25,0.35,0.55,0.65,50,0.05,50)

designmethods(d)

help with both the filter specification object and the

Version 3.3 (R14SP3) Filter Design Toolbox™

Response: 'Bandpass'

Specification: 'Fst1,Fp1,Fp2,Fst2,Ast1,Ap,Ast2'

Description: {7x1 cell}

NormalizedFrequency: true

Fstop1: 0.25

Fpass1: 0.35

Fpass2: 0.55

Fstop2: 0.65

Astop1: 50

Apass: 0.05

Astop2: 50

Design Methods for clas s fdesign.bandpass (Fst1,Fp1,Fp2,Fst2,Ast1,Ap,Ast2):

butter

cheby1

cheby2

ellip

equiripple

kaiserwin

help(d,'kaiserwin')

DESIGN Design a Kaiser Windowed FIR filter.

HD = DESIGN(D, 'ka iserwin') designs a Kaiser Windowed filter

specified by the F DESIGN object H.

HD = DESIGN(..., ' FilterStructure', STRUCTURE) returns a filter with the

structure STRUCTURE. STRUCTURE is 'dffir' by default and can be any of

the following.

'dffir'

'dffirt'

'dfsymfir'

'dfasymfir'

'fftfir'

HD = DESIGN(..., ' ScalePassband', SCALE) scales the first passband so

that it has a magnitude of 0 dB after windowing when SCALE is TRUE.

Filter Design Toolbox™ Release Notes

SCALE is TRUE by default.

% Example #1 - Design a bandpass Kaiser Windowed FIR filter.

New Demo Programs to Introduce fdesign Filter Design Approach

This release adds many new tutorial demos that introduce you to using

fdesign foryourfilterdesigntasks. Toaccessthenewdemos,enter

demos

at the Command prompt. W hen the Help system opens, select Filter

Design > Tutorial Demos

h = fdesign.bandpass('Fst1,Fp1,Fp2,Fst2,Ast1,Ap,Ast2');

Hd = design(h, 'kaiserwi n', 'ScalePassband', false);

from the Help Navigator tree in the left pane.

Alternatively, use the

demo('toolbox','filter design')

to ope n the D emos folder showing the Filter Design Toolbox demos.

demo command with input arguments:

Fdesign Now Provides Arbitrary Magnitude Filter Response Design

The designs available for fdesign now include arbitrary magnitude response filters. You use of frequency points and response values at those points to define a custom filter response curve.

fdesign.arbmag with input arguments to specify a vector

Fdesign Now Provides Hilbert and Differentiator Filter Response Design

The designs available for fdesign now include differentiator and Hilbert magnitude response filters. You use

fdesign.hilbert with input arguments to specify a differentiator or Hilbert

filter design object.

fdesign.differentiator or

Version 3.3 (R14SP3) Filter Design Toolbox™

Fdesign Objects Now Use a Default Design Method When Available

design now applies a default design method if you do not provide the design

method as an input. Usually the default method is and

ellip for IIR filters.

equiripple for FIR filters

butter and ellip Half-Band Design Methods Added for IIR Fdesign Objects

For designing IIR halfban d filters with fdesign and design, we added both butter and ellip to the available design methods.

Added multistage Filter Design Method

In addition to single-stage filters, you can now design multistage filters from lowpass filter design objects by applying the the object.

multistage design method to

For example, after you create a lowpass filter object, use the filter as a multistage filter.

d=fdesign.lowpass(0.25,0.35,0.05,50); hd = design(d,'multistage')

hd =

FilterStructure: Cascade

Stage(1): Direct-Form FIR P olyphase Decimator Stage(2): Direct-Form FIR P olyphase Decimator Stage(3): Direct-Form FIR P olyphase Interpolator Stage(4): Direct-Form FIR P olyphase Interpolator

PersistentMemory: false

multistage to create

limitcycle Method Restored to the Toolbox

The function limitcycle is now available to test your fixed-point IIR filters for the limit cycle behavior.

Filter Design Toolbox™ Release Notes

normalizefreq Method Added to the Toolbox

To let you convert your filters to use normalized frequency specifications, rather than absolute frequency, the toolbox adds objects.

New measure Method for Filters

A new method, measure, lets you measure the response of filters after you design them. in the filter magnitude response.

With Fdesign Objects, New Passband Zoom View Option

Selecting the View > Passband option from the m enu bar automatically zooms the display to focus on the passband for the filter shown. Using an

fdesign object to design your filter enables the Passband Zoom option in

FVTool.

normalizefreq for filter

measure returns the response values at a variety of frequencies

With Fdesign Objects, New Filter Specification Mask View Option

When you use FVTool or FDATool to display a filter response for a filter you design with an passband, stopband, and transition regions as specified by your filter object.

The following graphic shows the mask for a lowpass filter. To display the specification mask, use a filter design o bject to con stru c t your filter, and then display the filter in FVTool. Select View > Specification Mask from the menubarinFVTooltoseethespecificationmask.

fdesign object, you see new masks that outline the filter

Version 3.3 (R14SP3) Filter Design Toolbox™

Fdesign Object Display No Longer Shows Fs When the Design Object Uses Normalized Frequency

In this release, the default filter display no longer shows the sampling frequency of absolute frequency.

Fs when you specify the filter to use normalized frequency instead

For cicinterp Objects, Changed the Order of the Properties in the Display

Reordered the listing of the filter properties in the default display of CIC filters. The new arrangement better matches the display organization for single rate filters.

Filter Design Toolbox™ Release Notes

For IIR Design Objects, Property Fcutoff is Now Called F3dB

The f ilter property Fcutoff is now called F3dB to be more descriptive.

Changes to the Displays in MATLAB for Filters

Some of the displays for filter objects, showing the properties and values, are different in this release. Some property names have changed, and some properties reordered to make the displays more logically grouped and consistent across the various objects. Among the changed displays are the CIC object property arrangements and the names of some properties for bandpass, bandstop, and general IIR filter objects.

Compatibility Considerations

If y ou depend on the displays in your code or scripts or programs, be sure to modify your work to accommodate the new display names and arrangements.

Obsolete Functions and Methods in This Release

The following methods are now obsolete.

Compatibility Considerations

As you see in the table, new methods replace them, providing the same or expanded design capability.

Obsolete Method Replacement Method

fdesign.decim fdesign.decimator

fdesign.interp fdesign.interpolator

fdesign.src fdesign.rsrc

The obsolete m ethods continue to work, but they may be removed in the future.

Version 3.3 (R14SP3) Filter Design Toolbox™

block Method for mfilt.firfracdecim Filter Objects No Longer Works

Changes in the FIR Sample Rate Change block in the Signal Processing Blockset software required that the be made obsolete. You cannot use

firfracdecim filter object. To create a block from the firfracdecim object,

convert the object to an

hm = mfilt.firfracdecim(4,7); convert(hm,'firsrc') block(hm)

firsrc object, and then use block.

Compatibility Considerations

Programs that use the block method for firfracdecim require that you convert your

convert method.

mfilt.firfracdecim multirate filter to firsrc form using the

block method for firfracdecim filters

block to create a Simulink block from an

Filter Design Toolbox™ Release Notes

Version 3.2 (R14SP2) Filter Design Toolbox

This table summarizes what’s new in Version 3.2 (R14SP2):

New Features and Changes

Yes Details belo

New feature

• “Improved

• “Fixed-Po

• “realize

• “Context

• “Second

Line” on

• “Funct

page 51

Impro

Four F

ributes and methods (mostly) that the fixed-point multirate filters use.

or att

s a nd changes introduced in this version are

Fixed-Point Support for FIR Filters” on page 48

int Linear and Hold Interpolators” on pag e 49

mdl Creates CIC Filters” on page 49

-Sensitive Help for FDATool Returns” on page 50

-Order Section Filter View Options Available from t h e Command page 50

ion fdesign Specif ies Filter Response with Specifie d Structure” on

ved Fixed-Point Support for FIR Filters

IR filters now support fixed-point processing using the same properties

Version Compatibility Consideratio

Yes Summary

Fixed Bugs and Known

Problems

Bug Reports

Related Documentation at Web Site

Printable Release Notes:

PDF

•

• dfil

• dfi

Wit no wo

t.dfasymfir

dfil

t.dffir

lt.dffirt

lt.dfsymfir

h the improved filter objects, the properties for your discrete-time filters

w look the same as your multirate filters. Unifying the look and feel makes

rking with the full range of filters in the toolbox easier and more clear.

Version 3.2 (R14SP2) Filter Design Toolbox™

Additionally, making the switch from floating-point to fixed-point by setting

Arithmetic to fixed creates a fixed-point version of your floating-point filter

that uses full precision arithmetic internally. The result—a fixed-point filter that most closely matches to your floating-point prototype. If your design cannot support the resources for this fixed-point implementation, you can start to adjust the fixed-point properties as you need.

To continue to use your existing fixed-point FIR filters, you have to upgrade them to the new format. The toolbox includes a new utility for making the transition— Design Toolbox documentation. You can g et help by entering

help legacyfixptfir

at the M ATLAB prompt.

For information about converting your existing fixed-point FIR filters to the new objects, refer to “Upgrading Your Existing Fixed-Point FIR Filters to the New Properties” on page 51.

legacyfixptfir. Note that this utility is not covered in the Filter

Fixed-Point Linear and Hold Interpolators

Both mfilt .ho ldinterp and mfilt.linearinterp let you use fixed-point arithmetic. After you create the interpolator object, you can switch the setting for the

Both also support single-precision floating-point arithmetic.

Arithmetic property to fixed to use fixed-point interpolation.

realizemdl Creates CIC Filters

You can use realizemdl to construct CIC filters from basic blocks for processing signals. If you construct a C IC decimator filter, as shown in this example, Simulink product for you.

hm=mfilt.cicdecim(4); realizemdl(hm)

A new Simulink model window opens and you see a filter block. Double-clicking on the new block shows you the CIC filter subsystem.

realizemdl can make an atomic subsystem CIC fil ter b lock in the

Filter Design Toolbox™ Release Notes

Note You must have the Signal Processing Blockset to use realizemdl to implement CIC filters.

Context-Sensitive Help for FDATool Returns

FDATool now provides help for options on the quantization, multirate filter design, and frequency transformation panels. Acces s the new help feature either by right-clicking on an option and selecting What’s This from the context menu, or clicking the What’s This help icon on the tool bar.

Second-Order Section Filter View Options Available from the Command Line

In Filter Visualization Tool (FVTool), you can view secon d -ord er section filters as “individual sections,” “cumulative sections,” or as sections that you define. Now this functionality is available from the MATLAB command line, by using the

sosViewSettings property of the FVTool object. In previous releases

these view options were available only as options in the SOS View Settings dialog box in FVTool.

Access the FVTool object properties by launching FVTool with a filter object and including a left-hand side output argument:

handle = fvtool(hd)

handle

you u se

now contains the FVTool properties, similar to the following listing —

set and get to manipulate the property values.

handle=fvtool(hd)

handle =

Version 3.2 (R14SP2) Filter Design Toolbox™

set(handle.sosviewsettings,'view')

ans =

'Complete' 'Individual' 'Cumulative' 'UserDefined'

set(handle.sosviewsettings,'view','individual')

In SOSV iewSettings, the options are the same, with the same meaning, that you find in View > SOS View Settings in FDATool.

For more information about the Signal Processing Toolbox documentation or in the online Help system.

fvtool properties, refer to fvtool in the

Function fdesign Specifies Filter Response with Specified Structure

You can use fdesign.response to specify a filter response and specify the filter structure to use during construction.

Upgrading Your Existing Fixed-Point FIR Filters to the New Properties

There is a utility named legacyfixptfir to ensure backw ard compatibility of your existing scripts and a function new FIR filters. between pre- and post-Filter Design Toolbox 3.2 FIR filters.

Here is an example of the process of converting your o ld FIR filters to the new form in this version of the toolbox.

Beginwithanexistingdirect-formFIRfilter

h = dfilt.dffir

legacyfixptfir switches the preferences for your session

update to help you migrate to the

h that you constructed with

in an earlier version of the toolbox. First, use legacyfixptfir to retrieve h in the old format. Then convert

h to the new form.

Filter Design Toolbox™ Release Notes

legacyfixptfir(true) % To get the old form of h. h.Arithmetic='fixed'

FilterStructure: 'Direct-Form FIR'

Arithmetic: 'fixed'

Numerator: 1

PersistentMemory: false

CoeffWordLength: 16

CoeffAutoScale: true

Signed: true

InputWordLength: 16 InputFracLength: 15

OutputWordLength: 16

OutputMode: 'AvoidOverflow'

ProductMode: 'FullPrecision'

AccumMode: 'KeepMSB'

AccumWordLength: 40

CastBeforeSum: true

RoundMode: 'convergent'

OverflowMode: 'wrap'

update(h) % Convert h to the new properties. h

FilterStructure: 'Direct-Form FIR'

Arithmetic: 'fixed'

Numerator: 1

PersistentMemory: false

CoeffWordLength: 16

CoeffAutoScale: true

Signed: true

InputWordLength: 16 InputFracLength: 15

FilterInternals: 'SpecifyPrecision'

OutputWordLength: 16 OutputFracLength: 13

ProductWordLength: 32 ProductFracLength: 29

AccumWordLength: 40 AccumFracLength: 29

RoundMode: 'convergent'

OverflowMode: 'wrap'

Version 3.2 (R14SP2) Filter Design Toolbox™

Note the changes in properties. The filter performs the same way but the attributes are now updated to the newest form.

Filter Weights Have Been Removed from the Specifications in fdesign

Theweightsappliedtothefiltermagnituderesponsearenowdesignoptions. Theyarenolongerpropertiesofthe them as property name/property value (PV) pairs to the appropriate filter design method, as shown in this example.

h = fdesign.lowpass('N,Fp,Fst',30) % Was 'N,Fp,Fst,Wp,Wst'.

hd = equiripple(h, 'Wpass', 3, 'Wstop ', 25); % Specify the

hd(2) = equiripple(h, 'Wpass', 3, 'Ws top' , 1); fvtool(hd)

fdesign.typeobject. To set them, pass

% Removed Wp and Wst.

% weights here.

Filter Design Toolbox™ Release Notes

Compatibility Summary for the Filter Design Toolbox Product

This table summarizes new features and changes that might cause incompatibilities when you upgrade from an earlier version, or wh en you use files on multiple versions of the product. Details about the compatibility effects appear with the description of the new feature or change in the New Features and Changes sections for the product.

Version (Release ) New Features and Cha nges with Version

Compatibility Impact

Latest Release V4.7 (R2010a)

V 4.6 (R2009b)

V 4 .5 (R2009a) See the Compatibility Considerations

V4.4 (R2008b)

V4.3 (R2008a) See the Compatibility Considerations

V4.2 (R2007b) See the Compatibility Considerations

V4.1 (R2007a)

V4.0 (R2006b)

See the Compatibility Considerations subheading for each of these new features or changes:

• “Functions, Objects, Object Methods, and Object

Properties Being Removed” on page 5

None

subheading for each of these changes:

• “Changes in SOS IIR Design Defaults” on page 13

• “Changes in FIR Equiripple Design Defaults” on

page 14

None

subheading for “Input Quantization Added to Models Generated by the Block Method” on page 19.

subheading for “Functions Being Removed” on page

21.

None

Compatibility Summary for the Fi lter Design Toolbox™ Product

Version (Release ) New Features and Cha nges with Version

Compatibility Impact

V3.4 (R2006a) See the Compatibility Considerations

subheading for “Nearest Round Mode for dfilt and mfiltObjects”onpage31

V3.3 (R14SP3) See the Compatibility Considerations subheading

for each of these new features or changes:

• “Fdesign Object Display No Longer Show s

Fs When the Design Object Uses Normalized Frequency” on page 45

• “Changes to the Displays in MATLAB for Filters”

on page 46

• “Obsolete F unctions and Methods in This Release”

on page 46

• “block Method for mfilt.firfracdecim Filter Objects

No Longer Works” on page 47

V3.2 (R14SP2) See the Compatibility Considerations subheading

for each of these new features or changes:

• “Upgrading Your Existing Fixed-Point FIR Filters

to the New Properties” on page 51

• “Filter Weights Have Been Removed from the

Specifications in fdesign” on page 53

Mathworks FILTER DESIGN TOOLBOX RELEASE NOTES

Specifications and Main Features

Frequently Asked Questions

User Manual