www.gusucode.com > signal 工具箱matlab源码程序 > signal/+fdesign/@nyquist/nyquist.m
classdef (CaseInsensitiveProperties=true, TruncatedProperties=true) nyquist < fdesign.abstracttypewband & dynamicprops
%NYQUIST Construct a nyquist filter designer.
% D = FDESIGN.NYQUIST(L) constructs a Lth band Nyquist filter designer D.
%
% The band of a Nyquist filter is the inverse of the cutoff frequency in
% terms of normalized units. For instance, a 4th-band filter has a cutoff
% of 1/4. The case L=2 is referred to as a halfband filter. Use
% FDESIGN.HALFBAND for more options with halfband filter design.
%
% D = FDESIGN.NYQUIST(L,SPEC) initializes the filter designer
% 'Specification' property to SPEC. SPEC is one of the following
% strings and is not case sensitive:
%
% 'TW,Ast' - (minimum order, default)
% 'N'
% 'N,Ast'
% 'N,TW'
%
% where
% Ast - Stopband Attenuation (dB)
% N - Filter Order
% TW - Transition Width
%
% By default, all frequency specifications are assumed to be in
% normalized frequency units. Moreover, all magnitude specifications are
% assumed to be in dB.
%
% Different specification types may have different design methods
% available. Use DESIGNMETHODS(D) to get a list of design methods
% available for a given SPEC.
%
% D = FDESIGN.NYQUIST(L, SPEC, SPEC1, SPEC2, ...) initializes the filter
% designer specifications with SPEC1, SPEC2, etc...
% Use GET(D, 'DESCRIPTION') for a description of SPEC1, SPEC2, etc.
%
% D = FDESIGN.NYQUIST(L, TransitionWidth, Astop) uses the default
% SPEC ('TW,Ast') and sets the transition width and stopband
% attenuation.
%
% D = FDESIGN.NYQUIST(...,Fs) specifies the sampling frequency (in
% Hz). In this case, the transition width, if specified, is also in Hz.
%
% D = FDESIGN.NYQUIST(...,MAGUNITS) specifies the units for any
% magnitude specification given in the constructor. MAGUNITS can be one
% of the following: 'linear', 'dB', or 'squared'. If this argument is
% omitted, 'dB' is assumed. Note that the magnitude specifications are
% always converted and stored in dB regardless of how they were
% specified.
%
% % Example #1 - Design a minimum order, 4th band Nyquist filter.
% d = fdesign.nyquist(4,'TW,Ast',.01, 80);
% designmethods(d);
% Hd = design(d, 'kaiserwin');
% fvtool(Hd)
%
% % Example #2 - Design a 42nd order, 5th band Nyquist filter.
% d = fdesign.nyquist(5,'N,Ast', 42, 80)
% design(d)
%
% % Example #3 - Control the transition width.
% d = fdesign.nyquist(5,'N,TW', 42, .1)
% design(d)
%
% % Example #4 - Design a 2nd band (halfband) Nyquist filter. Compare FIR
% % equiripple and IIR elliptic designs
% d = fdesign.nyquist(2,'TW,Ast',.1,80);
% H(1) = design(d,'equiripple');
% H(2) = design(d,'ellip');
% hfvt = fvtool(H); legend(hfvt,'Equiripple','Elliptic')
%
% See also FDESIGN, FDESIGN/SETSPECS, FDESIGN/DESIGN.
% Copyright 2004-2015 The MathWorks, Inc.
%fdesign.nyquist class
% fdesign.nyquist extends fdesign.abstracttypewband.
%
% fdesign.nyquist properties:
% Response - Property is of type 'ustring' (read only)
% Description - Property is of type 'string vector' (read only)
% Band - Property is of type 'posint user-defined'
% Specification - Property is of type 'nyquistSpecsTypes enumeration: {'TW,Ast','N','N,Ast','N,TW'}'
%
% fdesign.nyquist methods:
% getconstructor - Return the constructor for the specification type.
% getdefaultmethod - Get the defaultmethod.
% getmask - Get the mask.
% getmeasureconstructor - Get the measureconstructor.
% getnoiseshapefilter - Get the noiseshapefilter.
% noiseshape - Noise-shape the FIR filter Hd
% noiseshapeparetobands - Returns the band where to measure the frequency
% passbandspecmet - Check whether passband response is within spec.
% propstoadd - Return the properties to add to the parent object.
% setspecs - Set the specs.
properties (SetObservable, GetObservable)
%SPECIFICATION Property is of type 'nyquistSpecsTypes enumeration: {'TW,Ast','N','N,Ast','N,TW'}'
Specification
end
methods % constructor block
function this = nyquist(varargin)
% this = fdesign.nyquist;
this.Response = 'Nyquist';
this.Specification = 'TW,Ast';
if nargin>0,
defaulttw(this,varargin{1})
end
this.setspecs(varargin{:});
capture(this);
end % nyquist
end % constructor block
methods
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 = {'TW,Ast',...
'N',...
'N,Ast',...
'N,TW'}';
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','Specification','Description',cpropList{:});
if propList.NormalizedFrequency
propList = rmfield(propList, 'Fs');
end
propgrp = matlab.mixin.util.PropertyGroup(propList);
end
end
methods % public methods
cSpecCon = getconstructor(this,stype)
defaultmethod = getdefaultmethod(this)
[F,A] = getmask(this,fcns,rcf,specs)
measureconstructor = getmeasureconstructor(this)
nsf = getnoiseshapefilter(this,nnsf,cb)
Hns = noiseshape(this,Hd,WL,args)
bands = noiseshapeparetobands(this)
flag = passbandspecmet(Hf,Hd,ng)
p = propstoadd(this)
setspecs(this,B,varargin)
end % public methods
methods (Hidden) % possibly private or hidden
varargout = currentfdesigndesignmethods(this,varargin)
defaulttw(this,band)
multiratedefaults(this,maxfactor)
[xlim,ylim] = thispassbandzoom(this,fcns,Hd,hfm)
end % possibly private or hidden
end % classdef