A non-uniform filter bank is created by joining sections of oversampled uniform
filter bands that are based on complex exponential modulation (as opposed to cosine
modulation). Each filter bank handles a given, non-overlapping frequency band.
The bands are not of uniform bandwidth, and the filters of different banks have
different bandwidths. The frequency bands of the different filter banks cover the
frequency of interest with gaps in the neighborhoods of the filter band edges.
A set of transition filters fills those gaps.