Arbitrary response magnitude filter specification object
D= fdesign.arbmag
D= fdesign.arbmag(SPEC)
D = fdesign.arbmag(SPEC,specvalue1,specvalue2,...)
D = fdesign.arbmag(specvalue1,specvalue2,specvalue3)
D = fdesign.arbmag(...,Fs)
D= fdesign.arbmag
constructs
an arbitrary magnitude filter specification object D
.
D= fdesign.arbmag(SPEC)
initializes
the Specification
property to SPEC
.
The input argument SPEC
must be one of the entries
shown in the following table. Specification entries are not case sensitive.
Note: Specification entries marked with an asterisk require the DSP System Toolbox™ software. |
'N,F,A'
— Single band design
(default)
'F,A,R'
— Single band minimum
order design *
'N,B,F,A'
— Multiband design
'N,B,F,A,C'
— Constrained
multiband design *
'B,F,A,R'
— Multiband minimum
order design *
'Nb,Na,F,A'
— Single band
design *
'Nb,Na,B,F,A'
— Multiband
design *
The SPEC
entries are defined as follows:
A
— Amplitude vector. Values
in A
define the filter amplitude at frequency points
you specify in f
, the frequency vector. If you
use A
, you must use F
as well.
Amplitude values must be real. For complex values designs, use fdesign.arbmagnphase
.
B
— Number of bands in the
multiband filter
C
— Constrained band flag.
This enables you to constrain the passband ripple in your multiband
design. You cannot constrain the passband ripple in all bands simultaneously.
F
— Frequency vector. Frequency
values in specified in F
indicate locations where
you provide specific filter response amplitudes. When you provide F
,
you must also provide A
.
N
— Filter order for FIR
filters and the numerator and denominator orders for IIR filters.
Nb
— Numerator order for
IIR filters
Na
— Denominator order for
IIR filter designs
R
— Ripple
By default, this method assumes that all frequency specifications are supplied in normalized frequency.
F
and A
are the input
arguments you use to define the filter response desired. Each frequency
value you specify in F
must have a corresponding
response value in A
. The following table shows
how F
and A
are related.
Define the frequency vector F
as [0
0.25 0.3 0.4 0.5 0.6 0.7 0.75 1.0]
Define the response vector A
as [1
1 0 0 0 0 0 1 1]
These specifications connect F
and A
as
shown here:
F (Normalized Frequency) | A (Response Desired at F) |
---|---|
0 | 1 |
0.25 | 1 |
0.3 | 0 |
0.4 | 0 |
0.5 | 0 |
0.6 | 0 |
0.7 | 0 |
0.75 | 1 |
1.0 | 1 |
Different specifications can have different design methods available.
Use designmethods
to get a
list of design methods available for a given specification and filter
specification object.
Use designopts
to get
a list of design options available for a filter specification object
and a given design method. Enter help(D,METHOD)
to
get detailed help on the available design options for a given design
method.
D = fdesign.arbmag(SPEC,specvalue1,specvalue2,...)
initializes
the specifications with specvalue1
, specvalue2
.
Use get(D,'Description')
for descriptions of the
various specifications specvalue1
, specvalue2
,
... specvalueN
.
D = fdesign.arbmag(specvalue1,specvalue2,specvalue3)
uses
the default specification 'N,F,A'
, setting the
filter order, filter frequency vector, and the amplitude vector to
the values specvalue1
, specvalue2
,
and specvalue3
.
D = fdesign.arbmag(...,Fs)
specifies
the sampling frequency in Hz. All other frequency specifications are
also assumed to be in Hz when you specify Fs
.