DSP Blockset

Filter Designs

Because the chief purpose of a filter is to alter the frequency content of a signal, it is natural to describe filter characteristics in the frequency domain. The blocks in the Filter Designs library let you specify the characteristics of a filter using convenient frequency-domain criteria. You enter the desired filter response characteristics, such as cutoff frequency and bandwidth, and the block automatically computes the filter coefficients that approximate the desired response. The filter is applied to the input signal using a direct-form II transpose filter structure, which yields the same results as the filter function in MATLAB. (For other architectures, see Filter Structures.)

The Filter Designs library contains the following seven blocks. The icon of each block displays the frequency response of the filter that is currently specified in the block's dialog box:

• Analog Filter Design
• Digital FIR Filter Design
• Digital FIR Raised Cosine Filter Design
• Digital IIR Filter Design
• Least Squares FIR Filter Design
• Remez FIR Filter Design
• Yule-Walker IIR Filter Design

The following sections provide further information about the capabilities of these blocks:

• Filter Design Categorization
• Designing Discrete-Time Classical IIR and FIR Filters
• Designing Continuous-Time Classical IIR Filters
• Designing Discrete-Time Special IIR and FIR Filters

All of the blocks in the Filter Designs library are built on the filter design capabilities of the Signal Processing Toolbox. For further details on any of the filter design topics discussed in the following sections, see the Filter Designs section of the Signal Processing Toolbox documentation.

Adaptive Filters

Filter Design Categorization