Filter Design Toolbox

Copying Filters to Inherit Properties

If you already have a quantized filter Hq with the property values set the way you want them, you can create a new quantized filter Hq2 with the same property values as Hq by typing

• Hq2 = copyobj(Hq)
  

This function is convenient to use when you are changing a small number of properties on a set of filters.

For example, create a 16-bit precision filter Hq from an FIR reference filter with

• b = fir1(80,0.5,kaiser(81,8)); % Reference filter
  Hq = qfilt('fir',{b})
  

Except for the filter coefficients provided by {b}, Hq inherits the default property values for a quantized filter.

Changing Filter Property Values After Construction

Now suppose you want to analyze the response of this same reference filter b when you:

• Change all of the data format property values using setbits
• Change the ScaleValues property value to [0.5 0.5]

You can do this by first copying Hq, and then changing only those properties you want to change.

• Hq2 = copyobj(Hq);
  setbits(Hq2,[16,14])
  Hq2.ScaleValues = [0.5 0.5];
  Hq2.scale
  
  ans =
      0.5000    0.5000
  

For more information on setting filter properties, see Setting Property Values with the set Command and Direct Property Referencing to Set and Get Values.

Constructing a Quantized Filter from a Reference

Quantized Filter Properties