Parity check codes for partial response channels

The use of turbo coding and decoding techniques in digital magnetic recording is now being given serious consideration. Major technical concerns are implementation complexity and decoding delay. In this paper, we present and analyze the performance of a simple, serial concatenation scheme comprising an outer parity check code, interleaver, and a precoded partial response channel. We apply an iterative decoding procedure incorporating separate a posteriori probability (APP) detectors for the code and precoded channel. Simulation results for a dicode channel show a bit-error-rate (BER) of 10/sup -5/ at rate-normalized signal-to-noise ratio SNR=6.7 dB for a rate 8/9 code, representing a gain of about 3.5 dB over the uncoded channel. We also present simulation results for higher-rate codes and other partial response channels, confirming the performance benefits of the new scheme.