normalize(hq) normalizes the filter numerator coefficients for a quantized filter to have values between -1 and 1. The coefficients of hq change — normalize does not copy hq and return the copy. To restore the coefficients of hq to the original values, use denormalize.

Note that for lattice filters, the feed-forward coefficients stored in the property lattice are normalized.

g = normalize(hd) normalizes the numerator coefficients for the filter hq to between -1 and 1 and returns the gain g due to the normalization operation. Calling normalize again does not change the coefficients. g always returns the gain returned by the first call to normalize the filter.

Examples

Create a direct form II quantized filter that uses second-order sections. Then use normalize to maximize the use of the range of representable coefficients.

d=fdesign.lowpass('n,fp,ap,ast',8,.5,2,40);
 
hd=design(d,'ellip');
 
hd
 
hd =
 
         FilterStructure: 'Direct-Form II, Second-Order Sections'                                    
              Arithmetic: 'double'                                                                   
               sosMatrix: [4x6 double]                                                               
             ScaleValues: [0.116791640438469;0.647874293162077;0.912408909495157;0.979110139688082;1]
     OptimizeScaleValues: true                                                                       
        PersistentMemory: false    
hd.arithmetic='fixed'
 hd =
 
         FilterStructure: 'Direct-Form II, Second-Order Sections'                                  
              Arithmetic: 'fixed'                                                                  
               sosMatrix: [4x6 double]                                                             
             ScaleValues: [0.116790771484375;0.64788818359375;0.91241455078125;0.979095458984375;1]
     OptimizeScaleValues: true                                                                     
        PersistentMemory: false                                                                    
                                                                                                   
         CoeffWordLength: 16             
          CoeffAutoScale: true           
                  Signed: true           
                                         
         InputWordLength: 16             
         InputFracLength: 15             
                                         
  SectionInputWordLength: 16             
   SectionInputAutoScale: true           
                                         
 SectionOutputWordLength: 16             
  SectionOutputAutoScale: true           
                                         
        OutputWordLength: 16             
              OutputMode: 'AvoidOverflow'
                                         
         StateWordLength: 16             
         StateFracLength: 15             
                                         
             ProductMode: 'FullPrecision'
                                         
               AccumMode: 'KeepMSB'      
         AccumWordLength: 40             
           CastBeforeSum: true           
                                         
               RoundMode: 'convergent'   
            OverflowMode: 'wrap'

Check the filter coefficients. Note that hd.sosMatrix(1,2)>1

hd.sosMatrix

ans =

    1.0000    1.5132    1.0000    1.0000   -0.9207    0.4373
    1.0000    0.3867    1.0000    1.0000   -0.2779    0.8242
    1.0000    0.0929    1.0000    1.0000   -0.0514    0.9610
    1.0000    0.0339    1.0000    1.0000   -0.0020    0.9934

Use normalize to modify the coefficients into the range between -1 and 1. The output g contains the gains applied to each section of the SOS filter.

g = normalize(hd)

g =

    1.5132
    1.0000
    1.0000
    1.0000

hd.sosMatrix

ans =

    0.6608    1.0000    0.6608    1.0000   -0.9207    0.4373
    1.0000    0.3867    1.0000    1.0000   -0.2779    0.8242
    1.0000    0.0929    1.0000    1.0000   -0.0514    0.9610
    1.0000    0.0339    1.0000    1.0000   -0.0020    0.9934

None of the numerator coefficients exceed -1 or 1.

normalize - Normalize filter numerator or feed-forward coefficients

Syntax

Description

Examples

See Also