Transposed Tapped Delay Line (TTDL)

$\epsfig{file=eps/tdl.eps,width=\textwidth }$
Tapped Delay Line (TDL)

$\epsfig{file=eps/ttdl.eps,width=\textwidth }$
Transposed Tapped Delay Line (TTDL)

A flow-graph is transposed (or ``reversed'') by reversing all signal paths:

Branchpoints become sums
Sums become branchpoints
Input/output exchanged
Transfer function identical for SISO systems
- Derives from Mason's gain formula
Transposition converts direct-form I & II digital filters to two more direct forms