A study of tracking-angle errors in stereodisk recording

Lateral tracking-angle errors are easily controlled in stereodisk systems and present no serious problems. Vertical tracking-angle errors are much less easily controlled and frequently are the cause of serious harmonic and inter-modulation distortion in playback. The mechanisms producing vertical tracking-angle distortion are outlined. Among other things it is shown that IM products due to frequency-modulation effects in a multi-component signal are particularly serious. It is shown, also, that the effective tilt angle in a recorder while cutting a groove may be considerably different from the nominal tilt angle determined by the internal geometrical configuration of the cutter. This difference can be attributed to bending of the recording stylus as a result of the drag force of the record material being removed from the groove. With present understanding it should be possible to reduce the distortion due to vertical-tracking-angle errors to negligibly-low values in stereodisk systems.