Crystal sync

EN: Crystal sync

Cinematografie

Specifically, a way of recording Sync Sound where the camera runs at correct speed with a quartz crystal-governed motor, and tape recorder records its pilottone using a built-in quartz crystal pilottone generator. The crystal is much like the kind used in a quartz watch. Unlike cable sync, the camera and tape recorder are not attached.
The Pollio Folio - Glossary of Cinematography Terms