User`s guide

Dyadic Synthesis Filter Bank

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Applications

The primary application for asymmetric dyadic synthesis filter banks is coding

for compression using wavelets.

At the transmitting end, the output of a dyadic analysis filter bank is fed to a

lossy compression scheme, which typically assigns the number of bits for each

filter bank output in proportion to the relative energy in that frequency band.

This represents the more powerful signal components by a greater number of

bits than the less powerful signal components.

At the receiving end, the transmission is decoded and fed to the dyadic

synthesis filter bank to reconstruct the original signal. The filter coefficients of

the complementary analysis and synthesis stages are designed to cancel

aliasing introduced by the filtering and resampling.

Latency

Zero Latency. The Dyadic Synthesis Filter Bank block has no tasking latency for

frame-based operation, which is always single-rate. The block therefore uses

the first input samples (received at t=0) to synthesize the first output sample.

Nonzero Latency. The Dyadic Synthesis Filter Bank block has tasking latency

only for sample-based operation, which is always multirate. As shown in the

table below, the amount of latency, D, depends on the structure (symmetric or

asymmetric) of the n-level tree used by the block.

In the above cases, the block repeats a zero initial condition in each channel for

the first D output samples. For example, in single-tasking mode the

Multirate... Symmetric Tree Asymmetric Tree

Single-tasking

None 2

-2 samples

Multitasking

samples 2

samples

lossy

coding

decoding