Bit error rate in digital azimuth recording

Azimuth recording can reduce the side reading and thus allow a playback head wider than the track pitch to obtain a large tracking margin. Since the azimuth rejection is usually poor at long wavelength, it is preferred to employ a dc-free code to roll-off the long wavelength spectrum. We have investigated the bit error rate of azimuth recording with a Miller squared (M²) code channel. The single bit error increases due to the finite azimuth rejection. Additionally this increase is weakly dependent on the spectral content of the adjacent tracks. Our work indicates that the side reading in azimuth recording is dominated by the signal of adjacent tracks at long wavelength, and by modulation noise at short wavelength. Proper design of the playback head trackwidth can achieve low bit error rate as well as improved playback tracking margin.