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classdef (CaseInsensitiveProperties=true, TruncatedProperties=true) comb < fdesign.abstracttypewspecs & dynamicprops
%COMB Construct a comb filter designer.
% D = FDESIGN.COMB(COMBTYPE,SPECSTRING,VALUE1,VALUE2,...) constructs a
% comb filter designer D. Note that D is not the design itself, it only
% contains the design specifications. In order to design the filter, one
% needs to invoke the DESIGN method on D. For example (more examples
% below):
% D = fdesign.comb('notch','N,BW',8,.01);
% H = design(D); % H is a DFILT
%
% SPECSTRING is a string that determines what design specifications will
% be used. There are several possible specifications, a complete list is
% given below.
%
% Different specification types may have different design methods
% available. Use DESIGNMETHODS to get a list of design methods
% available for a given SPEC: designmethods(D).
%
% VALUE1, VALUE2, etc. are scalars that provide the value of the
% corresponding specification. Use get(D,'description') for a description
% of VALUE1, VALUE2, etc.
%
% By default, all frequency specifications are assumed to be in
% normalized frequency units. Moreover, all magnitude specifications are
% assumed to be in dB.
%
% COMBTYPE is a string that determines whether the design will correspond
% to a notching or peaking comb filter. To obtain a notching comb filter
% design let COMBTYPE = 'notch'. To obtain a peaking comb filter design
% let COMBTYPE = 'peak'.
%
% D = FDESIGN.COMB(...,Fs) provides the sampling frequency of the signal
% to be filtered. Fs must be specified as a scalar trailing all other
% provided values. For this case, Fs is assumed to be in Hz as are all
% other frequency values provided. Note that you don't change the
% specification string in this case. In the example above, if the input
% signal is sampled at 8 kHz, we can obtain the same filter by specifying
% the bandwidth in Hz as: D = fdesign.comb('notch','N,BW',8,40,8e3); H =
% design(D);
%
% The full list of possible values for SPECSTRING (not case sensitive) is:
%
% 'N,Q' (default)
% 'N,BW'
% 'L,BW,GBW,Nsh'
%
% where
% N - Filter Order
% Q - Peak or Notch Quality Factor
% BW - Peak or Notch Bandwidth
% GBW - Gain at which Bandwidth (BW) is measured (dB)
% L - Number of Peaks or Notches in the entire [-1 1] normalized
% frequency interval
% Nsh - Shelving Filter Bandwidth
%
% Specification GBW must always be in dB.
%
% The comb filter is designed by up-sampling a shelving lowpass (for
% peaking combs) or highpass (for notching combs) filter design by a
% factor of L, or N (depending on the SPECSTRING value). The resulting
% transfer function corresponds to a peak/notch comb filter with L, or N
% peaks/notches in the Nyquist frequency interval. Designs based on
% 'N,Q', and 'N,BW' specifications use a default unity order shelving
% filter and a quality factor or bandwidth referenced to a -3 dB
% gain. Designs based on the 'L,BW,GBW,Nsh' specification allow the
% choice of an arbitrary value for the shelving filter order Nsh (the
% default still being unity) as well as an arbitrary gain reference GBW
% for the peak/notch bandwidth BW (the default value is -3 dB). In this
% scenario, the number of peaks/notches is chosen by parameter L and the
% overall comb filter order is equal to Nsh*L. Design parameter Nsh
% allows the sharpening of the response of the peaks/notches of the comb
% design.
%
% D = FDESIGN.COMB uses the default SPECSTRING ('N,Q') and sets the
% corresponding values to N, and Q.
%
% % Example #1 - Design a notching comb filter with 8 notches, and a
% % notch bandwidth of 0.02 referenced to a -3dB level.
% d = fdesign.comb('notch','N,BW',8,0.02)
% Hd = design(d);
% fvtool(Hd)
%
% % Example #2 - Design a notching comb filter with 8 notches, a notch
% % bandwidth of 0.02 referenced to a -5dB level, and a shelving filter
% % order of 1.
% d = fdesign.comb('notch','L,BW,GBW,Nsh',8,0.02,-5,1);
% Hd = design(d);
% fvtool(Hd)
%
% % Example #3 - Design a notching comb filter with 10 notches, a notch
% % bandwidth of 5 Hz referenced to a -4dB level, a shelving filter
% % order of 4, and a sampling frequency of 600 Hz.
% d = fdesign.comb('notch','L,BW,GBW,Nsh',10,5,-4,4,600);
% Hd = design(d);
% fvtool(Hd)
%
% % Example #4 - Design a peaking comb filter with 5 peaks, and a peak
% % quality factor of 25.
% d = fdesign.comb('peak','N,Q',5,25);
% Hd = design(d);
% fvtool(Hd)
%
% See also FDESIGN, FDESIGN/SETSPECS, FDESIGN/DESIGN, FDESIGN/DESIGNOPTS.
% Copyright 2004-2015 The MathWorks, Inc.
%fdesign.comb class
% fdesign.comb extends fdesign.abstracttypewspecs.
%
% fdesign.comb properties:
% Response - Property is of type 'ustring' (read only)
% Description - Property is of type 'string vector' (read only)
% CombType - Property is of type 'CombTypeType enumeration: {'Peak','Notch'}'
% NotchFrequencies - Property is of type 'double_vector user-defined' (read only)
% PeakFrequencies - Property is of type 'double_vector user-defined' (read only)
% Specification - Property is of type 'combSpecTypes enumeration: {'N,Q','N,BW','L,BW,GBW,Nsh'}'
%
% fdesign.comb methods:
% disp - Display the design object.
% get_notchfrequencies - PreGet function for the 'NotchFrequencies'
% get_peakfrequencies - PreGet function for the 'PeakFrequencies'
% getconstructor - Return the constructor for the specification type.
% getmask - Get the mask.
% getmeasureconstructor - Get the measureconstructor.
% propstocopy - Returns the properties to copy that are not part of the specs.
% set_combtype - PreSet function for the 'CombType' property
% setspecs - Set the specs
% this_setspecs - Set all the specs.
% thisloadobj - Load this object.
properties (AbortSet, SetObservable, GetObservable)
%COMBTYPE Property is of type 'CombTypeType enumeration: {'Peak','Notch'}'
CombType = 'Notch';
end
properties (SetAccess=protected, AbortSet, SetObservable, GetObservable)
%NOTCHFREQUENCIES Property is of type 'double_vector user-defined' (read only)
NotchFrequencies = [ ];
%PEAKFREQUENCIES Property is of type 'double_vector user-defined' (read only)
PeakFrequencies = [ ];
end
properties (SetObservable, GetObservable)
%SPECIFICATION Property is of type 'combSpecTypes enumeration: {'N,Q','N,BW','L,BW,GBW,Nsh'}'
Specification
end
methods % constructor block
function this = comb(varargin)
% this = fdesign.comb;
this.Response = 'Comb Filter';
this.Specification = 'N,Q';
this.setspecs(varargin{:});
capture(this);
end % comb
end % constructor block
methods
function set.CombType(obj,value)
% Enumerated DataType = 'CombTypeType enumeration: {'Peak','Notch'}'
value = validatestring(value,getAllowedStringValues(obj,'CombType'),'','CombType');
obj.CombType = set_combtype(obj,value);
end
%------------------------------------------------------------------------
function value = get.NotchFrequencies(obj)
value = get_notchfrequencies(obj,obj.NotchFrequencies);
end
%------------------------------------------------------------------------
function set.NotchFrequencies(obj,value)
% User-defined DataType = 'double_vector user-defined'
obj.NotchFrequencies = value;
end
%------------------------------------------------------------------------
function value = get.PeakFrequencies(obj)
value = get_peakfrequencies(obj,obj.PeakFrequencies);
end
%------------------------------------------------------------------------
function set.PeakFrequencies(obj,value)
% User-defined DataType = 'double_vector user-defined'
obj.PeakFrequencies = value;
end
%------------------------------------------------------------------------
function value = get.Specification(obj)
value = get_specification(obj,obj.Specification);
end
%------------------------------------------------------------------------
function set.Specification(obj,value)
value = validatestring(value,getAllowedStringValues(obj,'Specification'),'','Specification');
obj.Specification = set_specification(obj,value);
end
end % set and get functions
methods
function vals = getAllowedStringValues(obj,prop)
if strcmp(prop,'Specification')
vals = { 'N,Q',...
'N,BW',...
'L,BW,GBW,Nsh'}';
elseif strcmp(prop,'CombType')
vals = {'Peak','Notch'}';
else
vals = {};
end
end
end
methods (Access = protected)
%This function defines the display behavior for the class
%using matlab.mixin.util.CustomDisplay
function propgrp = getPropertyGroups(obj)
propList = get(obj);
cpropList = propstoadd(obj.CurrentSpecs);
propList = reorderstructure(propList,'Response', 'CombType', 'Specification', ...
'Description', 'NormalizedFrequency','PeakFrequencies','NotchFrequencies',cpropList{:});
if propList.NormalizedFrequency
propList = rmfield(propList, 'Fs');
end
if isequal(lower(obj.CombType),'notch')
propList = rmfield(propList,'PeakFrequencies');
else
propList = rmfield(propList,'NotchFrequencies');
end
propgrp = matlab.mixin.util.PropertyGroup(propList);
end
end
methods % public methods
freqs = get_notchfrequencies(this,freqs)
freqs = get_peakfrequencies(this,freqs)
cSpecCon = getconstructor(this,stype)
[F,A] = getmask(this,fcns,rcf,specs)
measureconstructor = getmeasureconstructor(this)
p = propstocopy(this)
combtype = set_combtype(this,combtype)
setspecs(this,combtype,varargin)
this_setspecs(this,varargin)
thisloadobj(this,s)
end % public methods
end % classdef
% [EOF]