High-Speed Inspection of Magnetic-Striped Release Prints

Abstract

A low-frequency (30-cycle) sine wave is recorded along with the audio when making the release print. This signal may then be picked up during high-speed (400 ft/min) examination of other physical defects. Thyratron-actuated relays stop the machine in the event of a dropout, splice or reduction in signal output level indicating an alteration in the soundtrack. The operator may then start up again at 24 frame/sec and listen for any objectionable erasure or re-recording.