Cross-Modulation Tests for Variable-Area Photographic Audio Tracks

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Publisher: SMPTE
Doc Type: Recommended Practice (RP)
Abstract: (1.1) This practice describes the cross-modulation method of measuring high-frequency distortion introduced during the production of variable-area audio motion-picture release prints. Through measurements of distortion at various negative densities, it is possible to choose negative densities that will produce audio prints having minimum distortion and optimum quality under the particular method of processing employed. (1.2) Cross-modulation tests are used extensively in establishing and maintaining photographic control of variable-area audio tracks. In consideration of waveform, output level, and noise reduction, it is necessary for variable-area prints to have high density contrast. At satisfactorily high track densities, an appreciable amount of image spread occurs, producing partial rectification of high frequencies. To compensate for this, an equal and opposite amount of image spread is introduced into the negative. Therefore, to establish the correct negative-and print-density combination, amplitude-modulated high frequencies are recorded and printed over a suitable density range. By measuring the rectified component from the prints, the correct density combinations are indicated.
Release Tag: 20051216-pub
Publication Date: 2005-12-16
Reaffirm Date: 2010-07-01
Stabilized Date: 2015-07-01
DOI: 10.5594/SMPTE.RP104.2005
ISBN: 978-1-61482-131-1
Link: https://doi.org/10.5594/SMPTE.RP104.2005
Group: SMPTE 27C Cinema
Keyword(s): Film, Projection, Test & Measurement, Audio, Sound

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<span class="citation"><cite>SMPTE RP 104</cite>, Cross-Modulation Tests for Variable-Area Photographic Audio Tracks. Available at <a href="https://doi.org/10.5594/SMPTE.RP104" target="_blank" rel="noopener">https://doi.org/10.5594/SMPTE.RP104</a></span>

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doi: 10.5594/SMPTE.RP104.2005
url: https://doi.org/10.5594/SMPTE.RP104.2005

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<cite id="bib-smpte-rp104-2005">SMPTE RP 104:2005</cite>, Cross-Modulation Tests for Variable-Area Photographic Audio Tracks
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SMPTE RP 104, Cross-Modulation Tests for Variable-Area Photographic Audio Tracks
doi: 10.5594/SMPTE.RP104
url: https://doi.org/10.5594/SMPTE.RP104

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<cite id="bib-smpte-rp104">SMPTE RP 104</cite>, Cross-Modulation Tests for Variable-Area Photographic Audio Tracks
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