Relations between magnetostatics and analog audio storage performance: a theoretical analysis

Analog recording on a magnetic medium requires system linearity, which is achieved in an anhysteretic magnetization process. A large high-frequency AC field (bias field) is superimposed on the actual signal field. The linearity and slope of the anhysteretic remanence curve depends on the amplitude of the bias field. With increasing signal strength, deviations in the linearity occur that produce harmonics in the reproduction signal, so analog recording is only carried out up to the remanence at which the harmonics reach a certain proportion of the total reproduction level, called the maximum output level (MOL). Recently it was demonstrated that consideration of the coercivity distribution in the magnetic medium alone is sufficient to obtain an accurate description of the recording process, so that for the first time the harmonics and recording level curves can be calculated from the system data. The author deals with quantifying the importance of magnetostatics for the MOL at long wavelengths on the basis of this new model