Note: This page has been translated by MathWorks. Click here to see

To view all translated materials including this page, select Country from the country navigator on the bottom of this page.

To view all translated materials including this page, select Country from the country navigator on the bottom of this page.

Bandstop filter specification object

`D = fdesign.bandstop`

D = fdesign.bandstop(SPEC)

D = fdesign.bandstop(SPEC,specvalue1,specvalue2,...)

D = fdesign.bandstop(specvalue1,specvalue2,specvalue3,specvalue4,...

specvalue5,specvalue6,specvalue7)

D = fdesign.bandstop(...,Fs)

D = fdesign.bandstop(...,MAGUNITS)

`D = fdesign.bandstop`

constructs
a bandstop filter specification object `D`

, applying
default values for the properties `Fpass1`

, `Fstop1`

, `Fstop2`

, `Fpass2`

, `Apass1`

, `Astop1`

and `Apass2`

.

`D = fdesign.bandstop(SPEC)`

constructs
object `D`

and sets the `Specification`

property
to `SPEC`

. Entries in `SPEC`

represent
various filter response features, such as the filter order, that govern
the filter design. Valid entries for `SPEC`

are shown
below. These entries are not case sensitive.

Specification options marked with an asterisk require the DSP System Toolbox™ software.

`'Fp1,Fst1,Fst2,Fp2,Ap1,Ast,Ap2'`

(default spec)`'N,F3dB1,F3dB2'`

`'N,F3dB1,F3dB2,Ap'`

*`'N,F3dB1,F3dB2,Ap,Ast'`

*`'N,F3dB1,F3dB2,Ast'`

*`'N,F3dB1,F3dB2,BWp'`

*`'N,F3dB1,F3dB2,BWst'`

*`'N,Fc1,Fc2'`

`'N,Fc1,Fc2,Ap1,Ast,Ap2'`

`'N,Fp1,Fp2,Ap'`

`'N,Fp1,Fp2,Ap,Ast'`

`'N,Fp1,Fst1,Fst2,Fp2'`

`'N,Fp1,Fst1,Fst2,Fp2,C'`

*`'N,Fp1,Fst1,Fst2,Fp2,Ap'`

*`'N,Fst1,Fst2,Ast'`

`'Nb,Na,Fp1,Fst1,Fst2,Fp2'`

*

The filter specifications are defined as follows:

`Ap`

— amount of ripple allowed in the passband in decibels (the default units). Also called Apass.`Ap1`

— amount of ripple allowed in the pass band in decibels (the default units). Also called Apass1.`Ap2`

— amount of ripple allowed in the pass band in decibels (the default units). Also called Apass2.`Ast`

— attenuation in the first stopband in decibels (the default units). Also called Astop1.`BWp`

— bandwidth of the filter passband. Specified in normalized frequency units.`BWst`

— bandwidth of the filter stopband. Specified in normalized frequency units.`C`

— Constrained band flag. This enables you to specify passband ripple or stopband attenuation for fixed-order designs in one or two of the three bands.In the specification

`'N,Fp1,Fst1,Fst2,Fp2,C'`

, you cannot specify constraints simultaneously in both passbands and the stopband. You can specify constraints in any one or two bands.`F3dB1`

— cutoff frequency for the point 3 dB point below the passband value for the first cutoff.`F3dB2`

— cutoff frequency for the point 3 dB point below the passband value for the second cutoff.`Fc1`

— cutoff frequency for the point 6 dB point below the passband value for the first cutoff. (FIR filters)`Fc2`

— cutoff frequency for the point 6 dB point below the passband value for the second cutoff. (FIR filters)`Fp1`

— frequency at the start of the pass band. Also called Fpass1.`Fp2`

— frequency at the end of the pass band. Also called Fpass2.`Fst1`

— frequency at the end of the first stop band. Also called Fstop1.`Fst2`

— frequency at the start of the second stop band. Also called Fstop2.`N`

— filter order.`Na`

— denominator order for IIR filters.`Nb`

— numerator order for IIR filters.

Graphically, the filter specifications look similar to those shown in the following figure.

Regions between specification values like `Fp1`

and `Fst1`

are
transition regions where the filter response is not explicitly defined.

The filter design methods that apply to a bandstop filter specification
object change depending on the `Specification`

. Use `designmethods`

to determine which design
methods apply to an object and the `Specification`

property
value.

Use `designopts`

to determine
the design options for a given design method. Enter `help(D,METHOD)`

at
the MATLAB^{®} command line to obtain detailed help on the design
options for a given design method, `METHOD`

.

`D = fdesign.bandstop(SPEC,specvalue1,specvalue2,...)`

constructs
an object `D`

and sets its specifications at construction
time.

`D = fdesign.bandstop(specvalue1,specvalue2,specvalue3,specvalue4,...`

constructs
an object

specvalue5,specvalue6,specvalue7)`D`

with the default `Specification`

property,
using the values you provide in ```
specvalue1,specvalue2,specvalue3,specvalue4,specvalue5,
specvalue6
```

and `specvalue7`

.

`D = fdesign.bandstop(...,Fs)`

adds
the argument `Fs`

, specified in Hz to define the
sampling frequency. If you specify the sampling frequency as a trailing
scalar, all frequencies in the specifications are in Hz as well.

`D = fdesign.bandstop(...,MAGUNITS)`

specifies
the units for any magnitude specification you provide in the input
arguments. `MAGUNITS`

can be one of

`'linear'`

— specify the magnitude in linear units`'dB'`

— specify the magnitude in dB (decibels)`'squared'`

— specify the magnitude in power units

When you omit the `MAGUNITS`

argument, `fdesign`

assumes
that all magnitudes are in decibels. Note that `fdesign`

stores
all magnitude specifications in decibels (converting to decibels when
necessary) regardless of how you specify the magnitudes.

`fdesign`

| `fdesign.bandpass`

| `fdesign.highpass`

| `fdesign.lowpass`