JPH01155568A - Data recorder - Google Patents

Abstract

PURPOSE:To detect errors of drop-in and the like in at least one of main areas or sub areas by recording check data for detecting the errors of data recorded in the main areas of a tracks and the serial numbers of check data in the sub areas of respective tracks. CONSTITUTION:Main data are recorded in the main areas of two inclined tracks TA and TB constituting one frame being the format of a rotary head type digital audio tape recorder, and error detection data recorded in the tracks and the serial numbers of the frame are recorded in the sub areas. Thus, the error of drop-in can be detected even if it occurs in one of the main areas or the sub areas of respective tracks.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a data recorder that uses a rotating head type digital audio tape recorder (DAT) to record and reproduce data sent from a computer or the like.

[Summary of the invention]

The present invention is a data recorder that uses DAT to record and reproduce data from a computer, etc. in accordance with the DAT format, and the main area of two inclined tracks that constitute one frame in the DAT format. By recording the main data in the subarea and recording the error detection data and frame serial number of the main data recorded in that track in the subarea, it is possible to record drop-in etc. in one of the main area and subarea of each track. Even if an error occurs, it can be easily detected.

[Conventional technology]

In a computer, in order to protect (bank up) data written on a hard disk or the like, such data is transferred to a data streamer (data recorder) and recorded once a day, for example.

As conventional data recorders, ordinary analog audio tape recorders have often been used. However, in such an analog tape recorder, the amount of magnetic tape consumed is extremely large, and the data rate during recording is low, so it takes an extremely long time to transfer and record, and furthermore, it is difficult to locate the beginning of the desired recording section. There were problems such as that it was not possible to do it easily.

Therefore, it has been considered to use a helical scan type digital audio tape recorder using a rotating head, so-called DAT, which has been commercialized in recent years, as a data recorder. When using a DAT as a data recorder, data from a host computer is converted into the DAT format and recorded. In the DAT format, two inclined tracks formed when two heads with different azimuths rotate once are called 1.
In each frame, 16-bit PCM audio data is incremented and recorded, and auxiliary sub-data is also recorded. In that case, as will be described later, each track is formed with a main area where PCM data is recorded and a subarea where sub data is recorded.

In addition, in DAT, when recording a new signal on an already recorded tape, an erasing head is generally not used.
By recording a new signal by so-called double writing, the previous signal is erased. Therefore, for example, if the head momentarily leaves the tape or if double writing is not performed properly due to head clog, the previous signal remains unerased, and this is the cause of data errors called drop-ins. becomes.

As a countermeasure for this, in the DAT format, an error detection code is added to the main area and subarea of each track to be recorded, so that if an unerased part of the track occurs, it will be detected as an error. I have to.

[Problem that the invention seeks to solve]

As described above, in the DAT format, error detection codes are added to each of the main area and subarea of one track so that drop-in can be detected in each area. However, even if such an error detection code is added, if, for example, the entire main area or the entire subarea is left unerased, if the error detection code in that area is normal, , it becomes impossible to detect drop-ins. If the signal to be recorded is an audio signal, the unerased portion of the signal can be eliminated by using the correlation before and after, but when using the DAT as a data recorder, it is generally not possible to use the correlation of the data. Can not. Furthermore, when used as a data recorder, it is required to record and reproduce data more accurately than when handling audio signals.

[Means for solving problems]

In the present invention, check data and frame serial numbers for detecting errors in data recorded in the main area of each track are recorded in the subarea of each track.

[Effect]

Using the data for detecting errors and the continuity of frame numbers, it is possible to detect errors such as drop-in in at least one of the main area and subarea.

〔Example〕

FIG. 1 shows a configuration in which a DAT is used as a data recorder, where .largecircle. is a DAT, 2 is an interface bus, 3 is a host computer, and 4.5 is an inner bus. DATI includes a recording/reproducing section 6, a recording amplifier 7, a reproducing amplifier 8, a signal processing circuit 9, a RAM l0. It mainly consists of a data controller 11, an interface port 12, a system controller 13, a servo and motor drive circuit 14, and the like.

The system controller 13, signal processing circuit 9, and data controller 13 are connected to the absolute frame number A, which will be described later.
It is configured to send and receive predetermined signals such as FNO, check data, mode instructions, logical frame number LFNO, judgment results based on check data, and data transfer instructions.

The recording/reproducing section 6 is provided with a rotating head drum (not shown), and the magnetic tape is wound around the drum in an area of about 90 degrees and is transported by a capstan. This drum has A with different azimuth angles.
, 82 heads are provided, and two inclined tracks are recorded and reproduced on the tape by one rotation of the drum.

The digital data supplied from the host computer 3 via the bus 5.2.4 is transferred to the interface port 1.
2, and further undergoes predetermined signal processing in the data controller 1, RAM 10, signal processing circuit 9, etc. according to instructions from the system controller 13, thereby converting the signal into the DAT format described above. This formatted signal is supplied to the recording/reproducing section 6 through the recording amplifier 7, and is recorded on the magnetic tape by RADs A and B.

Also, the signal recorded on the magnetic tape is head A.

This reproduced signal is supplied to the signal processing circuit 9 through the reproduction amplifier 8, and the digital data taken out after being inversely converted is sent to the host computer through the data controller 11, interface port 12 and bus 4.2.5. 3.

In the above-mentioned apparatus, the format of the DAT recorded on the magnetic tape is as shown in FIG.

In FIG. 2, two inclined tracks TAT are formed on the tape 15 from the lower side as indicated by arrows a in the figure by one rotation of the heads A and B. These two tracks TA and TI constitute one frame. 1
Book track TA (or T.

) consists of 196 blocks, one block is 288
Consists of bits. Of these, 34 blocks at both ends become sub areas, and 128 blocks at the center become the main area.

The subarea is further divided into several sections. That is, from the bottom end of the track, the margin section, the PLL preamble section of the subcode, the first subcode section, the postamble section, the gap section of the block section, the tracking (ATF) signal section, and the gap section between blocks. , preamble section for data PLL, gap section between blocks, A
TF signal section, inter-block camp section, subcode PL
A preamble section, a second subcode section, a postamble section, and a margin section for L are provided. The first of these
and the second subcode portion are each made up of eight blocks, and the other portions are each made up of a predetermined number of blocks. Note that the length scale in the figures is not exact.

The main area consists of 128 data blocks, and each block has a synchronization signal, W+ such as PCM-ID, part, block address, and parity of 8 bits from the beginning of the block, as shown in Figure 3. The next 2
Main data is arranged in a period of 56 bits. When handling audio signals, this main data is PCM data of 16 bits each for the L channel and the R channel. These 16-bit main data are incremented in the main areas of two tracks Ta and Tn (one frame) and arranged together with parity.

In this case, the main area of one frame contains approximately 5760
Bytes of data are recorded. When used as a data recorder, the data sent from the host computer 3 is converted into 16-bit data and treated as the above PCM data, and these data are formatted as shown in Fig. Recorded in the main area of the frame.

That is, in FIG. 4, the above-mentioned 5760 bytes are made up of words (0 to 1439) of 4 bytes (32 bits) each, and each word is composed of 16 bits (2 bytes) each in accordance with the audio signal. It is divided into an L channel and an R channel. In this format, a synchronization part is first provided in 3 words (12 bytes), the first byte of this synchronization part is all "0", the following 10 bytes are all "1", and the last one is
All bytes are set to ``01''.

Next, a portion of the 8 word (32 byte) header is provided. The MSB side 4 bits of the first half byte of the L channel of word 3 in this header part are used as a format ID indicating the format of the data decoder, and the latter 4 bits are left undefined. Also, the remaining 3 of this Vud 3
The byte is a logical frame number (LPNO), which will be described later.
) area, and the 8-bit LFNO provides a binary value indicating frame serial numbers 1 to 23, with 23 frames as one digit, for example.

Subsequent words 7 to 1438 are provided with a data portion of a total of 5728 bytes, and data signals from the host computer 3 are sequentially provided in each word by 4 bytes.

Further, word 1439 is an error detection code (EDC) section, and the error detection code (EDC) for the data string of each data bit viewed in the vertical direction is written for each data signal of the header part and data section mentioned above. generated and provided.

In the DAT format, L channel data and R channel data are alternately distributed and recorded by 2 bytes each on two tracks.For example, tracks are formed on both sides of the diagram. The azimuths (±) of heads A and B are shown.

Therefore, by generating an EDC for a data string in which each data bit is viewed in the vertical direction as described above, it is possible to generate an EDC for two tracks forming one frame.

Therefore, according to this format, it is possible to determine whether the main area remains unerased by performing EDC calculations. That is, in the above-described format, if one track remains unerased, the data for every other track that generates the EDC will be different, and the EDC calculation will not be performed correctly. Therefore, by detecting this value, it is possible to determine whether there is any unerased data.

Next, the above-mentioned logical frame number LFNO will be explained with reference to FIG. 5.

As described above, the LFNO is made up of, for example, 23 frames, and each frame is given a serial number from 1 to 23. That is, every 23 frames 1~23.1~
The frame numbers 23------------ will be repeated. In Figure 5, the entire LFNO consists of 8 bits, of which the MSB is the last frame of the unit, that is, if the unit is 23 frames, it is the 23rd frame. Last frame ID (LASTF-ID)
shall be. In addition, the next 1 bit after the MSB is used as E for error correction.
ECC frame ID (E
CCF-ID) and the next 6 bits are LFN of 1 to 23.
Let it represent O. Therefore, by selecting various LFNOs in the range of 1 to 64, the unit can be selected to have any length other than 23 frames. In that case, the above L
From the ASTF-ID, it can be known that the frame is the last frame of the unit. Also ECCF-
The ID may be multiplexed not only in one frame but also in a plurality of frames.

By using such a unit with an LFNO attached, divisions for each predetermined amount of data become clear, and signal processing becomes easier. Furthermore, by changing the maximum value of LFNO and selecting an appropriate unit length, signal processing can be performed more easily.

Next, the data structure of the first and second subcode sections in the subarea will be explained.

The first and second subcode sections each consist of eight subcode blocks, and can each record 2048 bits of data.

FIG. 6 shows the structure of a subcode block, in which 8-bit identical signals, W, , W, and parity are arranged, and then 256-bit subcode data including parity is arranged. This subcode data consists of four packs, one pack of which consists of 8×8 bits (8 symbols).

The contents of 1 and -2 are different between a block whose block address is EVEN and a block whose block address is ODD, and back numbers (1 to 7) are assigned between the EVEN block and the ODD block as shown. Further, the eighth pack is provided with a C5 code for error detection.

- and of the EVEN block each consist of a 4-bit control code (CTL-ID) and an all-zero code, and h consists of the upper 1 bit of "1", a 3-bit format ID, and a 4-bit block address. ODD
Block 1 consists of a 4-bit program number code (PNO-2, PNO-3), and 6 is the upper one.
It consists of a bit "1", a 3-bit program number code (PNO-1), and a 4-bit block address.

Packs 1 to 7 are divided into 8 words of 8 bits each, and each word includes, for example, a code indicating the lead-in area at the start of recording on the tape, a code indicating the lead-out area at the end of recording, Code indicating recording date and time, absolute frame number, logical frame number
..., etc. are provided along with parity.

FIG. 7 shows the configuration of pack 3 as an example of seven packs.

This pack 3 contains 8 words PC1-8 of 8 bits each.
Consists of. The upper 4 bits of the PCI are provided with a pack number (in this case, "ROOL" indicating pack 3), and the lower 4 bits are provided with a format -D. PO2
is the undetermined part.

The upper 4 bits of PO3 are provided with an area ID indicating the lead-in area or lead-out area. The total of the lower 4 bits of PO3, PO4, and PO2 is 2.
The 0 bit represents the absolute frame number (AFNO). This AF No. is a consecutive number assigned to all frames recorded on one tape. Next, PO2
A check data CD related to the present invention is provided by a total of 16 bits of PCI and PO2, and the PCB is PCI to PC7.
Parity is set for .

The above 16-bit check data CD is included in this pack 3.
This is the exclusive OR of all data (data from the computer) existing in the main area provided on one track (TA or T) provided with. Alternatively, as the check data CD, an error detection signal such as a CRC for all data existing in the main area may be used.

This check data also applies to other packs PCI, PO2-
It is also possible to increase reliability by providing the undetermined portion of No. 4 for multiple writing. In that case, each track is provided with 8 blocks of first and second subcode sections, and there are 7 backs in 2 blocks, so 1
Up to 56 pieces of the same check data CD can be recorded on a book track.

Such check data CD is used as follows.

The check data CD read out from one track during playback is compared with the exclusive OR of the data read out from the main area of that track. As a result, if the two do not match, it is determined that either the entire main area was left unerased or the entire sub area was left unerased (the previous check data CD was also left unerased). can do. Further, when the above two match, it can be determined that either the entire main area and the entire sub area are correct, or both are incorrect. To find out whether the main area or sub area is correct or incorrect, check LFNO and AF.
The determination can be made by the method described below using NO.

FIG. 8 shows the order of determination, and each step 31 to S
4, the determination criterion shown in FIG. 9 is obtained, and based on this determination criterion, the content of the determination shown in FIG. 10 can be known.

In FIG. 8, first, in step S1, data in the main area (hereinafter referred to as main data) is
Check whether the code correction was possible. If the correction cannot be made, it is determined as C in FIG. 10 that there is a dropout in the main data of that track, and a message to that effect is sent. When the correction is successful, the continuity of LFNO in the main area is checked in the next step S2.

If there is no continuity, it is determined as B in FIG. 10 that there is a drop-in on that track, and a message to that effect is sent. When LFNO has continuity,
After checking the main area, proceed to step S3.
to check the subarea. The reproducibility of the pack data is checked using CI code correction, pack parity, multiple coincidence, etc. for the data in the pack of the subarea. If this check fails, check (5) in Figure 10.
), it is determined that there is a drop-in in the subarea data (subdata) and that the main data is correct. When the reproducibility check is completed, check the continuity of AFNO and check data C in step S4.
D is checked on the main data, and based on the results of each check, the judgment criteria shown in FIG. 9 are obtained, and the details of the judgment shown in FIG. 10 are obtained based on these judgment criteria.

The contents of each judgment are as follows: A-(1)-・---------- Main data is correct.

A - (2) ------------1・-1--- There was a drop-in in both main data and sub data.

A-(3)・−・−・−・−There was a drop-in in the main data. AFNO continued from corner to corner.

A-(4)------------There was a drop-in in the sub data. In this case, let the AF No. run automatically and make sure the main data is correct.

A-(5)・----1-・-1--There was a dropout in the sub data. In this case, AFNO is allowed to run by itself and the main data is correct.

Note that a flag is set when a drop-in is detected by the check data CD, and based on this flag, error correction can be performed using an error correction code ECC. Further, in order to prevent misreading of the check data CD and the data in the main area, detection using the check data CD may be performed multiple times.

〔Effect of the invention〕

According to the present invention, since the check data C'D and the frame serial number AFNO for the entire data of the main area in one track are provided in the subarea, drop-in etc. may occur in the entire main area or subarea. It can be easily detected if
The specific details of the error can also be known, and the performance when using the DAT as a data recorder can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an embodiment of the present invention.
A diagram showing the AT format. Figure 3 is a data configuration diagram of the main data block. Figure 4 is a data configuration diagram of the main area of one frame. Figure 5 is a data configuration diagram of logical frame numbers. Figure 6 is a data configuration diagram of the main area of one frame. Figure 7 is a data configuration diagram of a bank of subcode blocks, Figure 8 is a flowchart showing the error determination method, Figure 9 is a diagram showing error determination criteria, and Figure 10 is the content of determination. FIG. In addition, in the symbols used in the drawings, 'rAT, -・---1・Track 1− ・−・−D AT 3・・・−・・−・−・−・Host computer 13・−
・−・・−−−1−−−System controller AFNO
・・・・・・−・・Absolute frame number CD・−
・---111-・Check data.

Claims (1)

[Claims] Two inclined tracks are formed on the recording medium by one rotation of the rotary head, and these two inclined tracks are regarded as one frame, and each frame is continuous with data having a predetermined data format. Each inclined track has a first area in which main data is recorded and a second area in which sub-data including the frame number is recorded. Data for detecting errors in data recorded in the corresponding first area is recorded in the second area of each of the two inclined tracks constituting one frame. A data recorder characterized by: