Simplified signal space detector for optical recording

A signal space detector is a low-complexity approximation of fixed-delay tree search with decision feedback (FDTS/DF). This paper proposes the simplest version possible of a τ = 2 FDTS/DF for a minimum run-length constraint of d = 2. The hardware needs only two multiplications and additions, facilitating high data-rate/low-complexity implementations. Simulation results show that the performance of the proposed detector equals that of the τ = 2 FDTS/DF even when jitter noise is present. It is shown that for d = 2, a partial response maximum-likelihood detector with the target response Σ_k=0³ D^k outperforms one with (1 + D)³ because of good spectral matching at normalized density S ⩾ 4.6