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Calibration of Secondary Standard Magnetic Tape Cassettes (Computer Amplitude Reference) \Oo U5753 Phase I No IEFERENCE UTED STATES WMENT OF MMERCE NBS TECHNICAL NOTE 731 PLICATION ''4TIlO»' Calibration of Secondary Standard Magnetic Tape Cassettes (Computer Amplitude Reference) \oo U5753 Phase I no. 731 H70. U.S. PARTMENT OF COMMERCE National Bureau of Standards NATIONAL BUREAU OF STANDARDS The National 1 Bureau of Standards was established by an act of Congress March 3, 1 901 . The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measure- ment system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Center for Computer Sciences and Technology, and the Office for Information Programs. THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consistent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scien- tific community, industry, and commerce. The Institute consists of a Center for Radia- tion Research, an Office of Measurement Services and the following divisions: Applied Mathematics—Electricity—Heat—Mechanics—Optical Physics—Linac Radiation 2—Nuclear Radiation 2—Applied Radiation 2—Quantum Electronics 3— Electromagnetics 3—Time and Frequency 3—Laboratory Astrophysics 3—Cryo- 3 genics . THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research lead- ing to improved methods of measurement, standards, and data on the properties of well-characterized materials needed by industry, commerce, educational institutions, and Government; provides advisory and research services to other Government agencies; and develops, produces, and distributes standard reference materials. The Institute con- sists of the Office of Standard Reference Materials and the following divisions: Analytical Chemistry—Polymers—Metallurgy—Inorganic Materials—Reactor Radiation—Physical Chemistry. THE INSTITUTE FOR APPLIED TECHNOLOGY provides technical services to pro- mote the use of available technology and to facilitate technological innovation in indus- try and Government; cooperates with public and private organizations leading to the development of technological standards (including mandatory safety standards), codes and methods of test; and provides technical advice and services to Government agencies upon request. The Institute also monitors NBS engineering standards activities and provides liaison between NBS and national and international engineering standards bodies. The Institute consists of the following divisions and offices: Engineering Standards Services—Weights and Measures—Invention and Innovation—Product Evaluation Technology—Building Research—Electronic Technology—Technical Analysis—Measurement Engineering—Office of Fire Programs. THE CENTER FOR COMPUTER SCIENCES AND TECHNOLOGY conducts re- search and provides technical services designed to aid Government agencies in improv- ing cost effectiveness in the conduct of their programs through the selection, acquisition, and effective utilization of automatic data processing equipment; and serves as the prin- cipal focus within the executive branch for the development of Federal standards for automatic data processing equipment, techniques, and computer languages. The Center consists of the following offices and divisions: Information Processing Standards—Computer Information—Computer Services —Systems Development—Information Processing Technology. THE OFFICE FOR INFORMATION PROGRAMS promotes optimum dissemination and accessibility of scientific information generated within NBS and other agencies of the Federal Government; promotes the development of the National Standard Reference Data System and a system of information analysis centers dealing with the broader aspects of the National Measurement System; provides appropriate services to ensure that the NBS staff has optimum accessibility to the scientific information of the world, and directs the public information activities of the Bureau. The Office consists of the following organizational units: Office of Standard Reference Data—Office of Technical Information and Publications—Library—Office of International Relations. 1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washing- ton, D.C. 20234. 2 Part of the Center for Radiation Research. 3 Located at Boulder, Colorado 80302. Bureau of Standards 8 1974 Y& Calibration of Secondary 1^1 Standard Magnetic Tape Cassettes (Computer Amplitude Reference] Phase I Sidney B. Geller and Paul A. Mantek Information Processing Technology Division Center for Computer Sciences and Technology • National Bureau of Standards (^ t *"S " ' Washington, D.C. 20234 lu JUL. O *£ \ v -V Jjif/ U.S. DEPARTMENT OF COMMERCE, Peter G. Peterson, Secretory NATIONAL BUREAU OF STANDARDS, Lawrence M. Kushner, Acting Director Issued July 1972 National Bureau of Standards Technical Note 731 Nat. Bur. Stand. (U.S.), Tech. Note 731, 60 pages (July 1972) CODEN: NBTNAE For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Order by SD Catalog No. C13.46.-731). Price 60 cents. TABLE OF CONTENTS PAGE 1. INTRODUCTION 1 2. DIGITAL MAGNETIC TAPE CASSETTES 4 2.1 Digital Cassette Applications 4 2.2 Digital Cassette Construction 5 2.3 Digital Cassette Transports 8 3. EXPERIMENTAL DESIGN FACTORS IN THE REFERENCE CASSETTE PROGRAM 9 3.1 Development of Cassette Groups 9 3.2 Statistical Considerations 9 3.3 Development of Transducer Groups 10 3.4 Summary 13 4. THEORY OF OPERATION OF THE NBS CASSETTE SIGNAL AMPLITUDE MEASUREMENT SYSTEM 14 4.1 System Components 14 4.2 Description of the System Operation 17 4.3 Description of the OA-4 Circuit 24 5. EXPERIMENTAL RESULTS 2 6 5.1 Case Histories of Submitted Cassette 26 Transports ^ 5.2 Cassette Transports Used for Measurements. 26 5.3 Experimental Measurement Data 30 6. COMPONENT LIST 52 7. APPENDIX 53 7.1 Digital Cassette Standardization Progress. 53 7.2 Tape and Leader Dimensions 53 8. REFERENCES . 55 LIST OF FIGURES Figure Number 1 Physical details of a digital magnetic tape cassette 7 2 Block diagram of the interim NBS signal amplitude measurement system 15 in LIST OP FIGURES (Continued) Figure Number Page 3 Block diagram of the interim NBS read channel measurement system 18 4 Read system input circuits. (LD-1C, AT-1C) 19 5 Read system preamplifier (WPR-1) 20 6 Read system peak detect-sample-and-hold system (PD-SH-1, OA-2, OA-3) 21 7 Read system output circuits (OA-4, OA-9, OA-10 22 8 Cassette transport speed measurement curves 38 9 Cassette transport speed measurement curves 39 10 Tape tension test curves 40 11 Tape tension test curves 4l 12 Cassette torque test curves 43 13 Signal amplitude histogram for runs 1 to 15 . 44 14 Signal amplitude histogram for runs 1 to 6. 45 15 Signal amplitude histogram for runs 7 to 12 . 46 16 Signal amplitude histogram for runs 13 to 15. 47 17 Six track chart recorder output curves. ... 49 18 Six track chart recorder output curves. ... 50 19 (J)-H loops for four cassettes 51 IV CALIBRATION OP SECONDARY STANDARD MAGNETIC TAPE CASSETTES (COMPUTER AMPLITUDE REFERENCE) PHASE I. Sidney B. Geller and Paul A. Mantek This Technical Note discusses a method for devel- oping and maintaining a reference system which will produce NBS Secondary Standard Magnetic Tape Cas- settes (Computer Amplitude Reference). It des- cribes both centerline tape search procedures and an interim signal amplitude measurement system for the reference magnetic tape cassette candidates. The results of the initial experiments with cas- sette tapes and transports are given. Key words: Cassette tapes; cassette transport; computer amplitude reference; magnetic tape cas- sette; secondary standard; standard reference material; unrecorded references. 1. INTRODUCTION At the request of industrial users of computer cassette tapes, Government procurement agencies, producers of magnetic computer tapes, and producers of cassette tape handling equip- ment, the National Bureau of Standards is developing a signal amplitude measurement system and will eventually supply unrecorded Secondary Standard Magnetic Tape Cassettes (Com- puter Amplitude Reference) through the NBS Office of Standard Reference Materials. This Technical Note describes the activities in the sig- nal amplitude reference magnetic tape cassette program which is being performed in the NBS Center for Computer Sciences and Technology. The methods that were used for developing the continuing NBS signal amplitude computer reference tape (reel-to-reel) program are briefly described and are being used as a guide for the cassette program. An actual reel of magnetic tape or a magnetic tape cas- sette is the only practical tool that is presently available for adjusting and calibrating the signal amplitude response of a magnetic tape or cassette recording system. The perfor- mance of one of these particular reels or cassettes must typify the performance of the tapes in its own category in order that maximum interchangeability of such storage media can be achieved. Once a system has been calibrated with a reference
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