The lattice filter implementation

Direct implementation of the IIR filter can lead to instabilities if is quantised. The filter is stable provided - hence can be quantised and the result is guaranteed to be stable.

Can either convert back from to or implement the IIR filter as a lattice and use the values directly - useful if working on a limited precision DSP chip (e.g. a GSM phone).

  
Figure 40: The lattice filter

This is analogous with the lossless tube model:

• each filter section is one section of the tube
• The forward wave is partially reflected backwards
• The backward wave is partially reflected forwards

Hence the terminology of .