Filter Design Toolbox Release Notes

New Frequency Transformation Functions Added

The Filter Design Toolbox 2.2 includes new filter transformation functions. Every transformation maintains the overall ripple characteristics of your prototype or original filter while transforming to your target filter specification.

All of the new transformation functions return the coefficients of your target filter and the coefficients of the allpass mapping filter used to transform your prototype filter to the new filter. In the following lists, transformation functions appear grouped by

• Allpass transformation filters
• Format of the prototype filter specification you supply
• IIR transfer function
• Zero-pole-gain

Allpass Filter Transformations

Use an allpass filter to map a prototype filter to a new frequency specification:

• allpasslp2lp--design an allpass filter to transform a lowpass filter to a lowpass filter
• allpasslp2hp--design an allpass filter to transform a lowpass filter to a highpass filter
• allpasslp2bp--design an allpass filter to transform a lowpass filter to a bandpass filter
• allpasslp2bs--design an allpass filter to transform a lowpass filter to a bandstop filter
• allpassshift--design an allpass filter to perform a real frequency shift transformation
• allpaslp2mb--design an allpass filter to transform a lowpass filter to an M-band frequency filter
• allpasslp2xn--design an allpass filter to transform a lowpass filter to N-point frequency specification
• allpasslp2bpc--design an allpass filter for lowpass to complex bandpass frequency transformation
• allpasslp2bsc--design an allpass filter for lowpass to complex bandstop frequency transformation
• allpassshiftc--design an allpass filter for complex shift frequency transformation
• allpasslp2mbc--design an allpass filter for lowpass to complex M-band frequency transformation
• allpasslp2xc--design an allpass filter for lowpass to complex N-point frequency transformation
• allpassbpc2bpc--design an allpass filter for complex bandpass frequency transformation
• allpassrateup--design an allpass filter for integer upsampling frequency transformation

IIR Filter Transformations

Use the allpass filter described in the allpass filter transformations to transform a prototype IIR filter to a new frequency response specification:

• iirlp2mb--transform an IIR filter from lowpass to M-band frequency response
• iirlp2cn--transform an IIR filter from lowpass to N-point frequency response
• iirlp2bpc--transform an IIR filter from lowpass to complex bandpass frequency response
• iirlp2bsc--transform an IIR filter from lowpass to complex bandstop frequency response
• iirshiftc--perform an IIR complex shift frequency transformation
• iirlp2mbc--transform an IIR filter from lowpass to complex M-band frequency response
• iirlp2xc--transform an IIR filter from lowpass to complex N-point frequency response
• iirbpc2bpc--transform an IIR filter from complex bandpass to complex bandpass frequency response
• iirrateup--perform an IIR interger upsample frequency transformation
• iirftransf--apply an IIR mapping filter to a prototype filter

Zero-Pole-Gain Filter Transformations

Use the allpass filter described in the allpass filter transformations to transform a prototype filter in zero-pole-gain format to a new frequency response specification:

• zpklp2lp--transform a filter specified by its zero-pole-gain form from lowpass to lowpass frequency response
• zpklp2hp--transform a filter specified by its zero-pole-gain form from lowpass to highpass frequency response
• zpklp2bp--transform a filter specified by its zero-pole-gain form from lowpass to bandpass frequency response
• zpklp2bs--transform a filter specified by its zero-pole-gain form from lowpass to bandstop frequency response
• zpkshift--use a filter in zero-pole-gain format to perform a real shift frequency transformation
• zpklp2mb--transform a filter specified by its zero-pole-gain form from lowpass to M-band frequency response
• zpklp2xn--transform a filter specified by its zero-pole-gain form from lowpass to N-point frequency response
• zpklp2bpc--transform a filter specified by its zero-pole-gain form from lowpass to complex bandpass frequency response
• zpklp2bsc--transform a filter specified by its zero-pole-gain form from lowpass to complex bandstop frequency response
• zpkshiftc--use a filter in zero-pole-gain format to perform a complex shift frequency transformation
• zpklp2mbc--transform a filter specified by its zero-pole-gain form from lowpass to complex M-band frequency response
• zpklp2xc--transform a filter specified by its zero-pole-gain form from lowpass to complex N-point frequency response
• zpkbpc2bpc--transform a filter specified by its zero-pole-gain form from complex bandpass to complex bandpass frequency response
• zpkrateup--use a filter in zero-pole-gain format to perform a complex bandpass frequency transformation
• zpkftransf--use a filter specified in zero-pole-gain format to transform an IIR lowpass filter to a new IIR lowpass filter

You use these from the MATLAB command line or from the new Transformations panel provided in FDATool. To read about using these new transformations, refer to Digital Frequency Transformations in the online help.

Filter Design Toolbox 2.2 Release Notes

New Transformations Pane Added to FDATool