Note: This page has been translated by MathWorks. Please click here

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

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

Bandpass filter specification object

`D = fdesign.bandpass`

D = fdesign.bandpass(SPEC)

D = fdesign.bandpass(spec,specvalue1,specvalue2,...)

D = fdesign.bandpass(specvalue1,specvalue2,specvalue3,

specvalue4,...specvalue4,specvalue5,specvalue6)

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

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

`D = fdesign.bandpass`

constructs
a bandpass filter specification object `D`

, applying
default values for the properties `Fstop1`

, `Fpass1`

, `Fpass2`

, `Fstop2`

, `Astop1`

, `Apass`

,
and `Astop2`

— one possible set of values
you use to specify a bandpass filter.

`D = fdesign.bandpass(SPEC)`

constructs
object `D`

and sets its `Specification`

property
to `SPEC`

. Entries in the `SPEC`

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

are shown
below and used to define the bandpass filter. These entries are not
case sensitive.

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

`'Fst1,Fp1,Fp2,Fst2,Ast1,Ap,Ast2'`

(default`spec`

)`'N,F3dB1,F3dB2'`

`"N,F3dB1,F3dB2,Ap'`

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

*`'N,F3dB1,F3dB2,Ast1,Ap,Ast2'`

*`'N,F3dB1,F3dB2,BWp`

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

*`'N,Fc1,Fc2'`

`'N,Fc1,Fc2,Ast1,Ap,Ast2'`

`'N,Fp1,Fp2,Ap'`

`'N,Fp1,Fp2,Ast1,Ap,Ast2'`

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

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

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

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

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

*

The filter specifications are defined as follows:

`Ap`

— amount of ripple allowed in the pass band. Also called Apass.`Ast1`

— attenuation in the first stop band in decibels (the default units). Also called Astop1.`Ast2`

— attenuation in the second stop band in decibels (the default units). Also called Astop2.`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,Fst1,Fp1,Fp2,Fst2,C'`

, you cannot specify constraints in both stopbands and the passband simultaneously. 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. Specified in normalized frequency units. (IIR filters)`F3dB2`

— cutoff frequency for the point 3 dB point below the passband value for the second cutoff. Specified in normalized frequency units. (IIR filters)`Fc1`

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

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

— frequency at the edge of the start of the pass band. Specified in normalized frequency units. Also called Fpass1.`Fp2`

— frequency at the edge of the end of the pass band. Specified in normalized frequency units. Also called Fpass2.`Fst1`

— frequency at the edge of the start of the first stop band. Specified in normalized frequency units. Also called Fstop1.`Fst2`

— frequency at the edge of the start of the second stop band. Specified in normalized frequency units. Also called Fstop2.`N`

— filter order for FIR filters. Or both the numerator and denominator orders for IIR filters when na and nb are not provided.`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 `Fst1`

and `Fp1`

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

The filter design methods that apply to a bandpass 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.bandpass(spec,specvalue1,specvalue2,...)`

constructs
an object `D`

and sets its specifications at construction
time.

`D = fdesign.bandpass(specvalue1,specvalue2,specvalue3,`

constructs

specvalue4,...specvalue4,specvalue5,specvalue6)`D`

with
the default `Specification`

property, using the values
you provide as input arguments for ```
specvalue1,specvalue2,specvalue3,specvalue4,specvalue4,specvalue5,
specvalue6
```

and `specvalue7`

.

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

adds
the argument `Fs`

, specified in Hz to define the
sampling frequency to use. In this case, all frequencies in the specifications
are in Hz as well.

`D = fdesign.bandpass(...,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.bandstop`

| `fdesign.highpass`

| `fdesign.lowpass`

Was this topic helpful?