60 Frames/Second Film and Continuous-Motion Projector for Picturephone® System Testing

A series of 60 frames/s, 35mm black-and-white sound films has recently been made for use in a PICTUREPHONE® visual telephone system test and evaluation program. In such a subjective test program, a prime requisite is a source of invariant test material for use by imaging on the vidicon target of the visual telephone set. The film production program using a Mitchell high-speed camera modified for synchronous operation at 60 frames/s, included the design and fabrication of a continuous-motion film projector and the solving of several electronic problems in maintaining projection synchronism and in recording double-system sound. The film speed of 60 frames/s was chosen to have a 1:1 correspondence to the vidicon scanning rate. Sound has been recorded synchronously at 18.75 in./s, using a 150-Hz recorded pilot tone locked to the 60-Hz power line. The tape, when played back at 7.5 in./s, provided the requisite 60-Hz pilot tone to synchronize the optical soundtrack processing equipment.

Print ISSN

0361-4573

Published

1967-04

Content type

Original Research

DOI

10.5594/J09164