Soft decoding algorithms evaluated in this work. (A) The trellis architecture and connections of states used by the Beam Trellis algorithm (Chandak et al.). (B) Edge scoring mechanism of the Beam Trellis algorithm to account for CTC-encodings of candidate messages. (C) State merging required by the Beam Trellis algorithm to account for duplicate state messages. (D) Architecture and scoring methodology used by our novel alignment matrix algorithm. Arrows in the alignment matrix represent data used to calculate newly added rows for both the new blank and base symbols.