Hilbert-transformer side-chain phase equaliser for analogue magnetic recording

A substantial amount of phase distortion occurring in analogue magnetic recording can be eliminated by using a simple equalisation scheme which removes the Hilbert-transformed portion of the signal that is added in a normal record/reproduce process. In the phase equaliser, the performance of an ideal Hilbert transformer can be approximated by using a quadrature-phase-shift circuit. The methods of phase equalisation is explained theoretically and oscilloscope photographs of experimental results are presented.