Theory of linear superposition in tape recording

The conditions under which linear superposition (LSP) of isolated pulses is valid for the synthesis of multibit waveforms are examined theoretically. LSP is found to be valid subject to three conditions; first, that all the processes following the write process be linear operations on the tape magnetization; second, that the write field rise time be less than the bit interval; and third, that each change in magnetization, occurring during the write process, be a function only of the field causing that change. Additionally, the validity of LSP at 15 000 bit/in is demonstrated for a high resolution tape recorder using standard γ-Fe
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tape.