A study on modulation noise reduction in digital recording

In digital recording, modulation noise is one of causes of degradation of the signal-to-noise ratio. A new mathematical model of reproduced digital signals including modulation noise is derived by considering that the major element of modulation noise in short-wave recording is head-to-media spacing variations. The total noise calculated from the mathematical model coincides with the noise extracted from reproduced digital signals of VCRs. A modulation noise reduction method which utilizes the mathematical model is proposed, and a simulation of reducing the modulation noise is shown. The improvement in the signal-to-noise ratio as a result of removing the modulation noise is approximately 2 dB.