| 摘要 |
Correct exposure of photographic sound records for motion pictures and the like is insured by processing as part of each record a conventional test signal, scanning the completed test signal record, and producing a cathode ray tube display that shows both the magnitude and the direction of the change in printing exposure that is required to correct any distortion. The test signal typically comprises a high frequency tone that is amplitude modulated at a low frequency. The test record is preferably scanned by oscillating it back and forth, typically by hand, approximating one-tenth normal speed. An effectively continuous signal output is thereby obtainable from only 1 or 2 inches of record. High and low frequency components, corresponding to the test tone and the modulation frequency, are isolated from the scanner output and are applied after suitable respective amplification to the x and y deflection circuits of the cathode ray tube. The tube is preferably blanked under control of the high frequency component to eliminate spurious signals during turnaround of the oscillating film.
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