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 intermodulation 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 multicomponent 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.