New code design methods and Viterbi detector architectures are present
ed for high-rate trellis-coded partial-response (TCPR) systems. The me
thods, which extend the matched-spectral-null (MSN) coding technique,
use novel code constraints and time-varying detector trellis structure
s to reduce path memory requirements by as much as a factor of two, re
lative to previously reported codes, while retaining the other attract
ive features of MSN codes. The design methods and corresponding time-v
arying trellis structures are illustrated with several examples.