Compact spectrum recording, a new binary process maximizing the use of a recording channel

Studies of the interaction between very short recording gaps and isotropic particulate media [l] have shown vanishing transition length and good phase cohesiveness at short wavelengths. A systematic search for a binary signalling scheme capable of materializing the largest possible fraction of the information carrying capacity intrinsic to such a recording channel led to the identification of a modulation-detection pair which performs remarkably well. In contrast with modulation codes, which are constructed to maximize the use of a discrete model of the recording channel, this new process was developed by the use of a continuous model. This unusual modulation-detection pair is linear and signals in the amplitude dimension. To reflect the fact that it is both bandwidth efficient and bandpass in character, it is referred to as "Compact spectrum recording". The synergism between this signal process and the recording channel, which is also bandpass in character, brings to system designers a new measure of recording density and reproduce reliability.