fdhelpstr.m

matlabDigitalSigalProcess内有文件若干

function str = fdhelpstr(tag,fig,h)
%FDHELPSTR Help for Filter Designer.
% Inputs:
%   tag - string identifying the object clicked on
%   fig - figure handle of GUI
%   h - handle of the clicked object

%   Copyright (c) 1988-98 by The MathWorks, Inc.
%   $Revision: 1.10 $

    str{1,1} = 'Filter Designer';
    str{1,2} = {['No help for this object (' tag ')']};

% ****                       WARNING!                       ****
% ****                                                      ****
% ****  All help text between the SWITCH TAG and OTHERWISE  ****
% ****  statements is automatically generated.  To change   ****
% ****  the help text, edit FDHELP.HLP and use HWHELPER to  ****
% ****  insert the changes into this file.                  ****

switch tag
case {'help','filtdes','axFrame','tb2Frame'}
str{1,1} = 'FILTER DESIGNER';
str{1,2} = {
'This window is a Filter Designer.  It allows you to create FIR and IIR '
'digital filters of various lengths and types using design functions in the '
'Signal Processing Toolbox.'
' '
'To create a new filter, click the "New Design" button in the SPTool.  To '
'edit an existing filter, click on it in the SPTool and click the "Edit '
'Design" button.'
' '
'The main axes displays the frequency response of the current filter.  '
'The current type of filter is determined by the "Algorithm" popup-menu'
'in the center of the window, just above the main axes.  This menu'
'decides the type of filter (FIR or IIR) and the error minimization'
'scheme employed to design the filter, as well as characteristics'
'of each filter type.  For details about any of the algorithms, click'
'on the Help Button again and then click on the Algorithm menu itself.'
' '
'The toolbar across the top of the window allows you to select different '
'filters, zoom into and out of the frequency response, and obtain help on '
'any of the tool''s components.  A second toolbar just above the main axes '
'allows you to change the filter''s algorithm and sampling frequency, overlay a '
'spectrum, or change the way the Filter Designer responds to your changes '
'via the "Auto Design" check box.'
' '
'The rest of the Filter Designer is made up of three areas: SPECIFICATIONS, '
'MAIN AXES, and MEASUREMENTS.  Select any of these under "Topics"'
'for more information.'
};

str{2,1} = 'SPECIFICATIONS';
str{2,2} = {
'On the left of the window are filter "Specifications".  Modify these'
'parameters to change the filter band configuration (lowpass, highpass,'
'bandpass, bandstop), whether you desire a minimum order filter, and other'
'band edges or parameters depending on the algorithm.  If "AutoDesign"'
'is checked, then every time you change a specification, the filter '
'redesigns.  If "AutoDesign" is not checked, changing a specification will'
'not design the filter until you hit the "Apply Button".'
' '
'To get help on a specification, click the help button and then click on the '
'specification.'
};

str{3,1} = 'MAIN AXES';
str{3,2} = {
'The main axes area consists of a display of the current filter''s frequency'
'response, and other lines which are used to either manipulate or measure'
'the filter.  When moving the mouse over these lines, you will see the mouse'
'pointer change to indicate you can perform some action by clicking and'
'dragging the line, usually up and down or back and forth.'
' '
'GREEN LINES are specification lines, and dragging them causes the filter'
'to be redesigned.  If "AutoDesign" is checked, the filter will redesign'
'as you drag the mouse - this is recommended only for the fastest machines.'
'If "AutoDesign" is not checked, the filter will be designed when you'
'release the mouse button (after you are done dragging the line to its'
'desired location).  The Filter Designer will do its best to meet the '
'specifications, but in the case of REMEZ and KAISER, the response will'
'sometimes exceed the green lines.'
' '
'RED LINES are measurement lines, and dragging them does not cause the'
'filter to be redesigned.  As you drag these lines, some measurements on'
'the right will change to reflect the changed position of the line.'
' '
'You can also drag the FREQUENCY RESPONSE LINE.  In this case, when you'
'are zoomed-in, dragging this line allows you to see other parts of the'
'response which are off the screen.  When you release the mouse button, the'
'only thing that changes are the axes limits.'
' '
'To get help on a line (to see what it represents and how to drag it), click the '
'help button and then click on the line.'
};

str{4,1} = 'MEASUREMENTS';
str{4,2} = {
'The right side of the window contains some labelled numeric quantities '
'called "Measurements".'
' '
'Most measurements are read-only quantities.  They reflect some quantity of '
'interest about the current filter.  Some measurements are interactive, for '
'example, they let you ask questions such as "what is the value of the '
'stopband ripple at x Hz?" or "at what frequency do I attain a passband '
'ripple of .1 dB or less?".'
' '
'To get help on a measurement, click the help button and then click on the '
'measurement.'
};

str{5,1} = 'MORE HELP';
str{5,2} = {
'To get help at any time, click once on the ''Help'' button.  The mouse '
'pointer becomes an arrow with a Question Mark symbol.  You can then click '
'on anything in the Filter Designer (or select a menu) to find out what it '
'is and how to use it.'
};

case 'fdremez'
str{1,1} = 'Remez';
str{1,2} = {
'Equiripple FIR'
' '
'FIR filter design using the Chebyshev error criterion and the Remez '
'exchange algorithm.  The maximum error between the desired frequency '
'response and the actual filter response over the desired bands is minimized '
'(hence the name "minimax" which is sometimes used for these filters as '
'well).  Filter exhibits the "equiripple" property in which the response '
'oscillates a fixed amount above and below the ideal "brickwall" response in '
'the passband and stopband.'
' '
'MINIMUM ORDER MODE'
'The minimum order for an Equiripple FIR is an approximation based on'
'heuristic measurements (see the function REMEZORD).  The actual'
'filter may not meet the desired specifications.  If this is the case,'
'just change to non-minimum order mode, and increase the order'
'until you achieve the desired specifications.'
' '
'DESIGN PARAMETERS IN NON-MINIMUM ORDER MODE'
'The filter parameters for this type of filter are the filter order,'
'the frequency band edges, and the passband and stopband error'
'weights (w1 and w2).  The error in the passband will be '
'w2/w1 times the error in the stopband. '
' '
'Uses REMEZ.M.'
};

case 'fdfirls'
str{1,1} = 'Firls';
str{1,2} = {
'Least Squares FIR'
' '
'FIR filter design using the weighted least squares (L_2) error criterion '
'with transition band(s).  The square of the integral of the error between '
'the desired frequency response and the actual filter response over the '
'desired bands is minimized (hence the name "least squares").  Filter '
'exhibits smaller ripple over most of the band than that of the equiripple '
'filter, but near the band edges the error is worse.'
' '
'MINIMUM ORDER MODE'
'There is no minimum order mode for a FIR least-squares filters as there is'
'no formula to estimate the order.'
' '
'DESIGN PARAMETERS IN NON-MINIMUM ORDER MODE'
'The filter parameters for this type of filter are the same as that of the '
'equiripple filter: filter order, the frequency band edges, and the passband '
'and stopband error weights (w1 and w2).  '
' '
'Uses FIRLS.M.'
' '
};

case 'fdkaiser'
str{1,1} = 'Kaiser';
str{1,2} = {
'Kaiser Window FIR'
' '
'FIR filter design using a least squares error criterion without transition '
'band, along with a Kaiser Window to provide a smoother truncation of the '
'ideal impulse response.  Specifically, the impulse response is obtained as '
'the inverse Fourier Transform of the ideal brickwall filter with cut-off '
'frequency Fc (or Fc1 and Fc2), and then pointwise multiplied by the Kaiser '
'window.'
' '
'MINIMUM ORDER MODE'
'The minimum order for the Kaiser window FIR is an approximation based on'
'heuristic measurements (see the function KAISERORD).  The actual'
'filter may not meet the desired specifications.  If this is the case,'
'just change to non-minimum order mode, and increase the order'
'until you achieve the desired specifications.'
' '
'DESIGN PARAMETERS IN NON-MINIMUM ORDER MODE'
'The filter parameters for this type of filter are the filter order, the '
'transition frequency (or frequencies for bandpass and bandstop) of the '
'brickwall filter, and the Beta parameter for the Kaiser window.'
' '
'Uses KAISER.M and FIR1.M.'
};

case 'fdbutter'
str{1,1} = 'Butterworth';
str{1,2} = {
'Butterworth'
' '
'IIR filter design using a maximally flat (Taylor series) approximation to '
'the desired frequency response at 0 and Fs/2, where Fs is the sampling '
'frequency.  The response is smoothly varying in both the pass and '
'stopbands (no ripples).'
' '
'Compared with Chebyshev types 1 and 2 and Elliptic IIR filters, to achieve '
'a given set of specifications, Butterworth requires the largest filter '
'order.'
' '
'DESIGN PARAMETERS IN NON-MINIMUM ORDER MODE'
'The filter parameters for this type of filter are the filter order and the '
'3dB frequency (or frequencies for bandpass and bandstop filters).  The 3dB '
'frequency is that frequency where the filter''s magnitude response is -3dB.'
' '
'Uses BUTTER.M.'
};

case 'fdcheby1'
str{1,1} = 'Chebyshev I';
str{1,2} = {
'Chebyshev Type 1'
' '
'IIR filter design using a Chebyshev (equiripple) approximation to the '
'desired frequency response in the passband and a maximally flat '
'approximation at Fs/2.  The response has ripples in the passband, but not '
'the stopband. '
' '
'Compared with Butterworth, Chebyshev type 2 and Elliptic IIR filters, to '
'achieve a given set of specifications, Chebyshev type 1 and 2 require an '
'intermediate filter order, less than Butterworth but more than Elliptic.'
' '
'DESIGN PARAMETERS IN NON-MINIMUM ORDER MODE'
'The filter parameters for this type of filter are the filter order, the '
'passband ripple Rp, and the passband frequency (or frequencies for bandpass '
'and bandstop filters).  The passband frequency is that frequency where the '
'filter''s magnitude response is -Rp dB.'
' '
'Uses CHEBY1.M.'
};

case 'fdcheby2'
str{1,1} = 'Chebyshev 2';
str{1,2} = {
'Chebyshev Type 2 (inverse Chebyshev)'
' '
'IIR filter design using a maximally flat approximation to the desired '
'frequency response at 0 and a Chebyshev (equiripple) approximation in the '
'stopband.  The response has ripples in the stopband, but not the passband.'
' '
'Compared with Butterworth, Chebyshev type 1 and Elliptic IIR filters, to '
'achieve a given set of specifications, Chebyshev type 2 and 1 require an '
'intermediate filter order, less than Butterworth but more than Elliptic.'
' '
'DESIGN PARAMETERS IN NON-MINIMUM ORDER MODE'
'The filter parameters for this type of filter are the filter order, the '
'stopband ripple Rs, and the stopband frequency (or frequencies for bandpass '
'and bandstop filters).  The stopband frequency is that frequency where the '
'filter''s magnitude response is -Rs dB.'
' '
'Uses CHEBY2.M.'
};

case 'fdellip'
str{1,1} = 'Elliptic';
str{1,2} = {
'Elliptic'
' '
'IIR filter design using a Chebyshev error criterion in both the passband '
'and stopband.  The response has ripples in both the pass and stop bands.'
' '
'Compared with Butterworth, Chebyshev type 1 and 2 IIR filters, to '
'achieve a given set of specifications, Elliptic filters require the '
'smallest filter order.'
' '
'DESIGN PARAMETERS IN NON-MINIMUM ORDER MODE'
'The filter parameters for this type of filter are the filter order, the '
'passband and stopband ripples Rp and Rs, and the passband frequency (or '
'frequencies for bandpass and bandstop filters).  The passband frequency is '
'that frequency where the filter''s magnitude response is -Rp dB.'
' '
'Uses ELLIP.M.'
' '
};

case 'AutoDesign'
str{1,1} = 'AutoDesign';
str{1,2} = {
' '
'AutoDesign Checkbox'
' '
'This checkbox allows you to control how often the filter is redesigned '
'based on your inputs.  It has two different effects based on changes to '
'Specifications controls on the left, and based on dragging Specifications '
'Lines in the main axes area.  Basically, if you have a slower machine, or '
'your filter order is very large, you will want to leave AutoDesign '
'unchecked.'
' '
'When AutoDesign is checked, every time you change a Specification and every '
'time the mouse moves while dragging a Specification Line, the filter is '
'designed.'
' '
'When AutoDesign is not checked, the filter is designed only when you press '
'the "Apply" button, or when you release the mouse after dragging a '
'Specification Line.'
' '
};

case 'specFrame'
str{1,1} = 'SPECIFICATIONS';
str{1,2} = {
' '
'On the left of the window are filter "Specifications".  Modify these'
'parameters to change the filter band configuration (lowpass, highpass,'
'bandpass, bandstop), whether you desire a minimum order filter, and other'
'band edges or parameters depending on the algorithm.  If "AutoDesign"'
'is checked, then every time you change a specification, the filter '
'redesigns.  If "AutoDesign" is not checked, changing a specification will'
'not design the filter until you hit the "Apply Button".'
' '
'To get help on a specification, click the help button and then click on the '