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Proposed American Standard
16mm Motion Picture Projector
For Use With Monochrome Television Film
Chains Operating on Full-Storage Basis
(Fourth Draft)
PH22.91
1 8.2 Output Level.
18.2.1 Standard. The output level shall be -lOdbm.
1 8.2.2 Method of measurement. This level shall be produced using level test film complying with the requirements of American Standard Z22.45-1946.
18.2.3 A gain normalization control shall be provided having sufficient range to insure compliance with the above standard for any normal combination of exciter lamp, photocell and amplifier tubes.
18.3 Frequency Response.
1 8.3.1 If the frequency response from film to output is fixed, it shall be flat within ± 1 db from 50 to 6000 cycles per second. If tone controls are provided in the preamplifier, their range of adjustment shall include this response.
18.3.2 Method of measurement. The frequency response shall be determined by means of a multifrequency test film complying with American Standard Z22.44-1946. The amplitude of response shall be measured across a resistance load at the output of the preamplifier. The frequency response shall be determined with standard gain. (See Paragraph 18.2.)
18.4 Distortion. Although it is desirable to state a distortion standard which will cover the photocell as well as the preamplifier, a method of measurement which will accomplish this result is not known. Consequently, the present Standard Proposal covers only distortion in the preamplifier.
1 8.4.1 Standard. Total harmonic distortion in the preamplifier at standard output level shall not exceed !/2% in the range from 50 to 6000 cycles per second.
1 8.4.2 Method of Measurement. Test signals from an oscillator shall be applied at the photocell input of the preamplifier and distortion shall be measured with a distortion analyzer at the preamplifier output at standard output level.
1 8.5 Preamplifier Noise Level.
18.5.1 Standard. The noise level of the preamplifier shall be —65 dbm.
1 8.5.2 Method of measurement. The noise level of the preamplifier shall be measured at standard gain (see Paragraph 18.2), with the projector running, the exciter lamp energized and no light entering the photocell.
18.6 Overall Noise Level.
18.6.1 Standard. The overall noise level shall be -55 dbm.
1 8.6.2 Method of Measurement. The overall noise level shall be measured at standard gain (see Paragraph 18.2), with the projector running, the exciter lamp energized and'no film in the machine.
Appendix A
The gate of the projector should be designed to provide easy access to aperture and rails for thorough and effective cleaning and inspection.
NOT APPROVED
August 1952 Journal of the SMPTE Vol. 59
151