A System of Double Noise Reduction for Variable-Area Recording for Direct-Playback Purposes

In variable-area recordings made for direct-playback purposes, the density of the “opaque” part of the track is established by distortion criteria and is usually so low that the signal-to-noise ratio is adversely affected. A system of “double noise reduction” is proposed which does not require the use of auxiliary lamps, slits or galvanometers. By this means, not only is the clear area of the track reduced during periods of low modulation, but also the density of the exposed area of the track outside the modulation envelope is increased in order to reduce the noise contributed by this part of the track. Tests indicate that a reduction in noise of 3 to 4 db can be expected.

Print ISSN

0898-042X

Published

1951-10

Content type

Original Research

DOI

10.5594/J06282