Channel model and GPRML detections for a single-layered perpendicular magnetic recording with a modified ring-head

We present an asymmetric linear channel model for a perpendicular magnetic recording with a single-layered medium and a modified ring-head. The waveforms and their spectra of the modeled signals are in good agreement with those of the real readback signals. The GPRML detections without DC-free coding get SNR gains more than 1 dB compared to conventional PRML systems at 10-5 BER, and DC-free coded GPRML detections get gains about 0.5 and 1.0 dB compared with the case of no DC-free coding at the normalized density of 2.8 and 3.0, respectively