The PR4 Viterbi Detector performs maximum-likelihood (ML) sequence estimation on the equalized sample values. The output of the Viterbi detector is the allowed (ideal) PR4 sampled waveform sequence which minimizes the sum-of-squared errors between itself and the sample sequence from the equalized readback signal. This is determined by considering exhaustively all allowed PR4 sampled sequences during the data field.

Features:

• performs maximum-likelihood (ML) sequence estimation on the equalized sample values.
• the output of the Viterbi detector is the allowed (ideal) PR4 sampled waveform;
• implementation of the ML detector is based on the block diagram of Figure 1; all operations shown in this figure are applied to the trellis diagram in Figure 2.
• the best sequence is selected by suitably comparing all candidate sequences using recursive computations based on the ADD-COMPARE- SELECT (ACS) units;
• small complexity, every even/odd sample being used independently( odd/even path), system equation being .
• programmable targets
• path memory of 30 samples per interleave

figure 1.Block Diagram

Figure 2.Trellis Diagram