fdesign.decimator
Decimator filter specification object
Note
The 'Raised Cosine'
and 'Square Root Raised Cosine'
response methods in the fdesign.decimator
object will be removed in a
future release. Use rcosdesign
and comm.RaisedCosineReceiveFilter
(Communications Toolbox) instead.
Note
Support for designing an mfilt.firdecim
object using the fdesign.decimator
and the design
functions will be removed in a future release. Use the
design
function with the
SystemObject
=true
flag to design an FIR decimator
System object™.
Note
Support for multistage filter design using the fdesign.decimator
object will be removed in a future release. Use the designMultistageDecimator
function instead.
For more information, see Compatibility Considerations.
Syntax
D = fdesign.decimator(M)
D = fdesign.decimator(M, RESPONSE)
D = fdesign.decimator(M, CICRESPONSE,
D)
D = fdesign.decimator(M,
RESPONSE, SPEC)
D = fdesign.decimator(...,SPEC,specvalue1,specvalue2,...)
D = fdesign.decimator(...,Fs)
D = fdesign.decimator(...,MAGUNITS)
Description
D = fdesign.decimator(M)
constructs
a decimator filter specification object D
with
the DecimationFactor
property equal to the positive
integer M
and the Response
property
set to 'Nyquist'
. The default values for the transition
width and stopband attenuation in the Nyquist design are 0.1π
radians/sample and 80 dB. If M
is unspecified, M
defaults
to 2.
D = fdesign.decimator(M, RESPONSE)
constructs
a decimator specification object with the decimation factor M
and the 'Response'
property.
D = fdesign.decimator(M, CICRESPONSE,
D)
constructs a CIC or CIC compensator decimator specification
object with the decimation factor, M
, 'Response'
property
equal to 'CIC'
or 'CICCOMP'
,
and D
equal to the differential delay. The differential
delay, D
, must precede any specification option.
Because you are designing multirate filters, the specification
options available are not the same as the specifications for designing
single-rate filters. The decimation factor M
is
not included in the specification options. Different filter responses
support different specifications. The following table lists the supported
response types and specification options. The options are not case
sensitive.
Design Method | Valid Specification Options |
---|---|
| See
|
| See
|
| See
|
| See
|
|
To specify a CIC decimator, include
the differential delay after |
| See
To specify a CIC compensator decimator,
include the differential delay after |
|
|
'Gaussian' |
The specification must be preceded by an
integer-valued |
| See
If you use the quasi-linear IIR design
method, |
| See
|
| See
|
| See
|
| See
|
| See
|
| See
|
D = fdesign.decimator(M,
RESPONSE, SPEC)
constructs object D
and
sets the Specification
property to SPEC
for
the response type, RESPONSE
. Entries in the SPEC
represent
various filter response features, such as the filter order, that govern
the filter design. Valid entries for SPEC
depend
on the RESPONSE
type.
Because you are designing multirate filters, the specification
options available are not the same as the specifications for designing
single-rate filters with such response types as fdesign.lowpass
.
The options are not case sensitive.
The decimation factor M
is not in the specification
options.
D = fdesign.decimator(...,SPEC,specvalue1,specvalue2,...)
constructs
an object D
and sets its specifications at construction
time.
D = fdesign.decimator(...,Fs)
provides the sampling frequency of the signal to be filtered. Fs
must
be specified as a scalar trailing the other numerical values provided. Fs
is
assumed to be in Hz as are all other frequency values provided.
D = fdesign.decimator(...,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.
Examples
Version History
Introduced in R2011aSee Also
fdesign
| fdesign.arbmagnphase
| fdesign.interpolator
| fdesign.rsrc