Dynamic magnetic information storage or retrieval – Recording for selective retention of a special occurrence
Patent
1996-04-12
1999-10-05
Faber, Alan
Dynamic magnetic information storage or retrieval
Recording for selective retention of a special occurrence
360 49, 360 722, 386 65, G11B 500
Patent
active
059633824
DESCRIPTION:
BRIEF SUMMARY
This is a National Stage of PCT/JP95/01054.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods of recording and reproducing and apparatus for recording and reproducing time codes for use in a data recorder, for example.
2. Description of the Related Art
Data recorders, for example, are occasionally required to reproduce a time at which an optional event or the like observed in recorded data has occurred. To meet such a requirement, it has heretofore been customary for a data recorder to record time codes together with data. Time codes established by the IRIG (Inter-Range Instrumentation Group) in the USA, for example, have been used as such time codes for data recorders.
The time codes of IRIG include two types of time codes, i.e., time codes of IRIG(A) and IRIG(B). These time codes will first be described below. The main difference between the time codes of IRIG(A) and IRIG(B) lies in minimum units of the time codes. The minimum unit of the time code of
FIG. 1 of the accompanying drawings shows the time code of IRIG(A). In FIG. 1, the time code of IRIG(A) includes codes for "0.1 second", "second", "minute", "hour", and "day" which are represented by numerical values according to the binary-coded decimal notation.
As shown in a lower portion of FIG. 1, the time code of IRIG(A) is generated by modulating a carrier signal of 10 kHz. A bit clock pulse is generated every 10 cycles of the carrier signal, i.e., every 0.001 second. 100 bits constituted by such bit clock pulses constitute one set of data.
Among one set of data=100 bits, the 0th bit, the 9th bit, and those bits which are spaced from the 9th bit by successive 10 bits, i.e., the 19th bit, . . . , and the 99th bit serve as reference markers (P0.about.P10) each indicating a division of the time code. Each of the reference markers is composed of a greater amplitude corresponding to 8 cycles of the carrier signal and a smaller amplitude corresponding to 2 cycles of the carrier signal.
Between the reference markers, there are provided codes represented by numerical values for "0.1 second", "second", "minute", "hour", and "day". These codes are represented by numerical values according to the binary-coded decimal notation as described above. A binary value "0" is represented by a smaller amplitude corresponding to 2 cycles of the carrier signal, and a binary value "1" is represented by a greater amplitude corresponding to 5 cycles of the carrier signal. The waveform of the carrier signal of the binary value "0" is illustrated in the lower portion of FIG. 1.
The code represented by a numerical value for "second" is formed by 8 bits placed between the first reference marker P0 and the second reference marker P1. Specifically, the 8 bits are used to indicate values of "1", "2", "4", "8", "10", "20", and "40", with one bit left unassigned between "8" and "10". The numerical value for "second" of the time code is expressed by the sum of the values of those bits which have the binary value "1" represented by the waveform of the carrier signal.
Similarly, the code represented by a numerical value for "minute" is formed by 9 bits placed between the second reference marker P1 and the third reference marker P2. Specifically, the 9 bits are used to indicate values of "1", "2", "4", "8", "10", "20", and "40", with one bit left unassigned between "8" and "10". The last bit is left blank.
The code represented by a numerical value for "hour" is formed by 9 bits placed between the third reference marker P2 and the fourth reference marker P3. Specifically, the 9 bits are used to indicate values of "1", "2", "4", "8", "10", and "20", with one bit left unassigned between "8" and "10". The last two bits are left blank.
The code represented by a numerical value for "day" is formed by 9 bits placed between the fourth reference marker P3 and the fifth reference marker P4 and 2 bits following the fifth reference marker P4. Specifically, these 11 bits are used to indicate values of "1", "2", "4", "8", "10", "20", "40", "80", "100", an
REFERENCES:
patent: 5541781 (1996-07-01), Barr et al.
patent: 5646795 (1997-07-01), Suzuki
Faber Alan
Maioli Jay H.
Sony Corporation
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