| Filter Design Toolbox Release Notes | |
Enhanced Quantized Filter Structures
To improve the scaling performance and reliability of quantized filters in the toolbox, the quantized filter structures no longer include the input and output scale values s(1) and s(2) in the default structures. This eliminates two quantization error sources when you quantize your filter without input and output scaling.
Also, the df1, df1t, df2, and df2t structures do not include the leading denominator coefficient, a(1), when the coefficient is equal to one. When a(1) 
1, the structures include the coefficients. Thus, when you quantize a filter with a(1) = 1, the quantization skips the multiplication operation and does not quantize a(1).
To see both these changes, and for more information, refer to Quantized Filter Property Reference in your Filter Design Toolbox documentation or the Help browser. For an example, the next figures show the original df2t structure and the newer version.
Figure 1-1: Original dft2 Structure Including s(1) and s(2)
Figure 1-2: New df2t Structure Without Scale Values and with Coefficient a(1) = 1
New Graphic Showing the Quantizers in a Filter
To help you understand where and how the quantizers in a filter structure work, your toolbox documentation provides a figure detailing the quantizers in a df2 quantized filter structure. Refer to Filter Structure with Quantizers in Place" in your Filter Design Toolbox documentation.
New and Enhanced Filter Demonstration Programs
Version 2.2 adds to and enhances the existing set of demos for the toolbox. We've added:
firceqripdemo--demonstrates the filter design function firceqrip for designing constrained equiripple FIR filters
firtransdemo--demonstrates frequency transformations for linear-phase FIR filters
freqtransdemo--demonstrates frequency transformations for IIR filters
noisepowerdemo--demonstrates the noise power spectrum for filters
numbercircledemo--demonstrates and defines fixed-point numbers
qerrordemo--demonstrates the new quantizer statistics functions
And we substantially enhanced these existing demos:
| | New Transformations Pane Added to FDATool | Major Bug Fixes | |