ECA 405-1972 Flutter Measurement of Instrumentation Magnetic Tape Recorder Reproducers Recommended Test Method for《磁带录音机和扬声器的摆动测量的推荐测试方法》.pdf
《ECA 405-1972 Flutter Measurement of Instrumentation Magnetic Tape Recorder Reproducers Recommended Test Method for《磁带录音机和扬声器的摆动测量的推荐测试方法》.pdf》由会员分享,可在线阅读,更多相关《ECA 405-1972 Flutter Measurement of Instrumentation Magnetic Tape Recorder Reproducers Recommended Test Method for《磁带录音机和扬声器的摆动测量的推荐测试方法》.pdf(12页珍藏版)》请在麦多课文档分享上搜索。
1、- EIA 405 72 3234b00 00b7850 8 ,- F -i. -2: rn O Flutter Measurement of 7 4 9 Instrumentation Magnetic Recommended Test Method For rn ec w IA STANDARD RS=405 December 1972 Engineering Department ELECTRONIC INDUSTRIES ASSOCIATION EIA 405 72 3234b00 00b785L T NOTICE EIA engineering standards are desig
2、ned to serve the public interest through eliminating mis- understandings between manufacturers and purchasers, facilitating interchangeability and improve- ment of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existenc
3、e of such standards shall not in any respect pre- clude any member or non-member of EIA from manufacturing or selling products not conforming to such standards, nor shall the existence of such standards preclude their voluntary use by those other than EIA members whether the standard is to be used e
4、ither domestically or internationally. Recommended standards are adopted by EIA without regard to whether or not their adoption may involve patents on articles, materials, or processes. By such action, EIA does not assume any liability to any patent owner, nor does it assume any obligation whatever
5、to parties adopting the recommended standards. Published by ELECTRONIC INDUSTRIES ASSOCIATION Engineering Department 2001 Eye Street,N. W., Washington, D. C. 20006 Electronic Industries Association 1972 All rights reserved - Price $3.80 .- Prfnted in U.S.k - EIA 405 72 m 3234600 0067852 L m c-J RS-4
6、05 Page 1 RECOMMENDED TEST METHOD FOR FLUTTER MEASUREMENT OF INSTRUMENTATION MAGNETIC TAPE RECORDER/REPRODUCERS Q (From Standards Proposal No. 1123, formulated under the cognizance of EIA Working Group P-8.7 on Instrumentation Magnetic Recording Components where fc is the frequency of the reference
7、carrier, ff is the highest frequency flutter component to be measured, and a is the peak fractional flutter. If used, the filter response shall roll off at a rate of 18 dB per octave be- yond the cut-off frequencies. 4.4 Frequency Discriminator The discriminator must accept the reproduced reference
8、carrier which has been modulated by flutter and produce an output signal proportional to the modulation. In general, 60 dB amplitude limiting must precede the frequency-sensitive portion of the discriminator in order to meet the dynamic range requirements of the system. 4.5 Bandpass Filter, Flutter
9、A bandpass filter follows the discriminator. Its purpose is to limit the frequency band of the flutter signal and to reject carrier frequency components. The filter response shall be flat within 3 dB from 0.5 Hz to the upper flutter frequency being measured and shall roll off at a rate of 18 dB per
10、octave beyond the cut-off frequencies. Flutter bandpass filter characteristics: Tape Speed Passband of the Flutter cmls in/s Bandpass Filter (Hz) 2.38 15/16 0.5 to 156 4.76 1 7/8 0.5 to 313 9.52 3 314 0.5 to 625 19.05 7 1/2 0.5 to 1,250 38.1 15 0.5 to 2,500 76.2 30 0.5 to 5,000 152.4 60 0.5 to 10,00
11、0 609.6 240 0.5 to 10,000 304.8 120 0.5 to 10,000 - _- RS-405 Page 3 4.6 Magnetic Tape The tape shall be in excellent condition and of a type recommended by the recorder manufacturer. It shall be degaussed so that there will be no residual signal greater than 50 dB below the recorded carrier level.
12、4.7 hdicators and Analyzers The flutter signal from the bandpass filter foilowing the discriminator is a complex one which will, in general, be a random function; but, may additionally contain discrete components. In order to mea- sure this signal adequately statistical techniques shall be used. 4.7
13、.1 Acceptance Tests (Cumulative Flutter) The indicator used for acceptance tests shall be a direct-reading instrument designed to read the peak-to-peak amplitude and to ignore occasional random peaks provided that the value read is exceeded less than 5% of the time. That is, the peak-to-peak flutter
14、 must be within the value read 95 percent of the time. It is recognized that this measurement can be.made in several different ways. A block diagram describing one method is shown in Figure 1. Also, statistical voltmeters which accomplish this result are commercially available. Furthermore, if it is
15、 known that the flutter sig- nal follows a Gaussian amplitude probability distribution, the peak-to-peak measurement described above is four times the true rms value. 4.7.1.1 Frequency Response: 0.5 Hz to 10 kHz. 4.7.1.2 Averaging Time: 5 seconds. 4.7.2 Operational Tests (Cumulative Flutter) An osci
16、lloscope may be used as an indicator for operational tests. 4.7.2.1 Frequency Response: 0.5 Hz to 10 kHz. 4.7.2.2 Sweep Speed: O. 1 second per centimeter. 5. CALIBRATION OF TEST SYSTEM The flutter-measuring system shall be calibrated by simulating the flutter-modulated reproduced car- rier signal. T
17、he simulated flutter signal shall be obtained from a frequency-modulated oscillator, and shall consist of a sine-wave carrier frequency-modulated by a sine-wave modulating signal. The level of the modulated carrier shall be equivalent to that anticipated from the recrder/reproducer output. The perce
18、ntage of modulation shall be accurately determined and compatible with the anticipated flutter O Y am pli tu de. RS-405 Page 4 5.1 Accuracy i The system shall be accurate within +5% of full scale. 5.2 Frequency Response The frequency response of the system shall be uniform within 6 dB over the flutt
19、er bandwidth. 5.3 Noise Susceptibility I The system output noise caused by linear addition of the output noise of the tape recorder/reproducer system and a stable reference carrier at the same level as would be derived from the tape recorder/re- producer system shall be less than 5.0 percent of the
20、specified flutter. An alternative to this test is described in Appendix A. 5.4 Susceptibility to Amplitude Moduktion of the Carrier The system shall be subjected to an amplitude-modulated sine-wave carrier at the same level as would be derived from the tape recorder/reproducer system. The sine-wave
21、modulating frequency shall be varied from 0.5 Hz to the highest flutter frequency of interest. The level of modulation shall be 30 percent for modulating frequencies from 0.5 Hz to 1 kHz. For frequencies above 1 kHz the percentage of modulation shall vary inversely with frequency down to 3 percent a
22、t 1 O kHz. The system output noise for any single frequency shall be less than 5 percent of the specified flutter. 6. TEST PROCEDURE This test is to determine the magnitude of total cumulative flutter over a specified passband. Measure- ments are conducted at one or more points of tape-supply-reel l
23、oading for the specified tapespeed. Results are expressed as the peak-to-peak percentage change of a single recorded frequency during the reproduce process. 6.1 Connect the equipment as shown in Figure 2. 6.2 Adjust the precision signal generator and the discriminator to a carrier frequency suitable
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