1、SMPTE RECOMMENDED PRACTICE Specifications for Azimuth Test Film for 16-mm Audio Projectors, Magnetic Type RP 78-2002 Revision of RP 78-1997 Page 1 of 2 pages 1 Scope This practice specifies a test film for use in aligning the azimuth of magnetic head gaps in 16-mm motion-picture audio projectors ope
2、rating at approximately 36 ft (11 m) per minute. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this practice. At the time of publication, the editions indicated were valid. All standards are subject to revision, and
3、patties to agreements based on this practice are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. AES 6-1982, Method for Measurement of Weighted Peak Flutter of Sound Recording and Reproducing Equipment AES 7-1982 (R1992), Method of Meas
4、uring Recorded Flux of Magnetic Sound Records at Medium Wavelengths ANSVSMPTE 109-1 998, Motion-Picture Film (16-mm) - Perforated 1R SMPTE 97-1 999, Motion-Picture Film (16-mm) - 200-Mil Edge-Position Magnetic Audio Record SMPTE 223M-2001, Motion-Picture Film - Safety Film 3 Test film signal 3.1 Fre
5、quency The audio record shall be an original recording which will reproduce at a frequency of 7000 Hz f 100 Hz when the linear speed of the film is 24 perforations per second or approximately 36 ft per minute (7.2 in or 183 mm per second). 3.2 Distortion The total harmonic distortion of the recorded
6、 signals shall not exceed 0.5%. 3.3 Audio record The audio record shall be recorded so that it extends from the perforations on one side of the film to the opposite edge, or from one edge of the film to the other. Copyright O 2002 by THE SOCIEPI OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hart
7、cdale Ave., White Plains, NY 10607 (914)761-1100 Approved July 26,2002 RP 78-2002 3.4 Recorded level The sizimuth test tone shall not be more than 10 dB down from the equivalent reference level of 400 Hz at 185 nanowebers per meter after correct equalization of 70 ps. 3.5 Flutter The weighted peak f
8、lutter of the audio record shall not exceed f 0.1% when measured in accordance with AES 6. 3.6 Azimuth The azimuth of the audio record shall be 90“ k 3to the reference edge of the film. 4 Film stock 4.1 The film stock shall be full-coat, splice-free, and of the low-shrinkage, safety type in complian
9、ce with SMPTE 223M. 4.2 Test films shall be made on a base cut and perforated in accordance with short-pitch dimensions specified in ANSVSMPTE 109. 4.3 The film stock shall be conditioned for 10 days at 2OoC I3OC (68F k 5.4“F) at a relative humidity of (50 I 1 O)% prior to recording. 4.4 The film sh
10、all be recorded and packaged within the temperature and humidity limits specified in 4.3. The recorded film shall be packaged in a metal can and sealed either with a low-moisture permeability plastic tape or a fabric tape having a moisture barrier. 5 Identification Each test film shall be identified
11、 by a suitable identification marking. 6 Calibration 6.1 Flux The short circuit flux shall be determined by means of the calibrated short-gap ferromagnetic core reproducer technique. This technique is described in AES 7. 6.2 Level The signal level specified in 3.4 shall be measured with an rms voltm
12、eter calibrated in decibels with an accuracy of f 0.1 dB over the bandwidth 31.5 Hz to 16 kHz. 6.3 Reproducing head The test film shall be calibrated on a reproducing head made in accordance with ANSVSMPTE 97. NOTE - A test film made in accordance with this practice is available from the Society of Motion Picture and Television Engineers. Page 2 of 2 pages
