JPH04195870A - Magnetic reproducing device and magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To correctly reproduce data and to prevent deterioration of video and audio signals without increasing the circuit circuit scale by using an error check circuit and a system control circuit which determines the transmission rate mode in order to select the correct transmission rate. CONSTITUTION:Signals reproduced with a head A7 and a head B8 from a magnetic tape 6 are sent to a reproducing amplifier 10. The output signals from the reproducing amplifier 10 are checked for the rerror number by an error check circuit 11, and the result is used to judge the transmission rate mode in a system control circuit 12 and to turn a switch SW3 to the selected transmission rate mode. Namely, on reproducing data in a magnetic tape 6 in which various digital data of plural transmission rates are recorded, the correct transmission rate is selected by the error check circuit 11 and the system control circuit 12. Thereby, digital data can be correctly reproduced and deterioration of video and audio signals can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic reproducing device for reproducing a recording medium on which digital data of a plurality of transmission rates are mixedly recorded, or The present invention relates to a magnetic recording and reproducing device that records and reproduces information on the same recording medium.

[Prior Art] As described in Japanese Unexamined Patent Publication No. 1-276471, a conventional device can distinguish between different transmission rates by detecting them using a mode identification code in the control signal area of each block. One idea is to add a mode identification signal to the recording medium during recording, such as by frequency multiplexing or time division multiplexing (frequency multiplexing or time division multiplexing) a pilot signal for mode identification into the PCM signal area, preamble area, or video signal, etc. It was getting worse. In addition, the above-mentioned conventional device has been devised as a system compatible with two modes of 16 bits and 12 bits, and three modes including 8 bits of the conventional 8 mm VTR, and has not been considered as a compatible system.

[Problem to be solved by the invention]

The above-mentioned conventional technology has multiple types of digital data transmission rates, and when playing back recording media recorded at different transmission rates depending on the type of tape and the tape running speed at the time of recording, it is possible to reproduce data on the same recording medium. Since signals with different transmission rates are mixed, and the data cannot be reproduced unless the digital signal processing method is selected correctly according to the different transmission rates, it is necessary to reproduce the recorded mode identification signal as well. The problem was that I couldn't do it.

Furthermore, the method of multiplexing mode identification signals has the problem of deterioration of video and audio.

Furthermore, a method of directly measuring the transmission rate is generally difficult and leads to an increase in circuit scale.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic reproducing device or a magnetic recording/reproducing device that can determine a transmission rate mode without increasing the circuit scale and without deteriorating video and audio.

[Means to solve the problem]

In order to achieve the above object, the present invention includes an error check circuit that checks one or a combination of parity, ID detection rate, block address continuity status, CI code, C2 code, and CRC code; If the number of errors as a result of the check is greater than the predetermined number,
The correct transmission rate is selected using a system control circuit that determines the type of magnetic tape, the speed mode when recording data on the magnetic tape, and the transmission rate at the time of playback, and determines the transmission rate mode to be switched to.
This allows the data to be played back correctly.

[Effect]

In the above configuration, an error check is performed on the reproduced digital data by an error check circuit,
If the number of errors is smaller than the predetermined number, it means that the transmission rate mode at the time of playback matches the transmission rate mode at the time of recording, and there is no need to switch the transmission rate mode. If it is thicker, the transmission rate may be different, so use the system control circuit to determine the type of magnetic tape, the speed mode when recording digital data, and the transmission rate at the time of playback, and select the transmission rate mode to switch to. Since the digital data is determined and switched, the digital data can be reproduced correctly.

[Example] Hereinafter, an example of the present invention will be described using FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5. Figure 1 shows an 8mmV circuit with an error check circuit and a system control circuit.
A block diagram of a TR PCM audio recording and reproducing device, FIG. 2 is a flowchart showing a simple algorithm of the present invention,
Figure 3 is a detailed flowchart, Figure 4 is a table showing the type of magnetic tape and the mode discrimination results according to the speed mode when recording data on the magnetic tape, and Figure 5 is the track format (a) and block format of the magnetic tape. (
b) (c).

This device selects two types, I, mode, and N mode, depending on the type of tape. It is also necessary to perform recording and reproduction in the 8-bit mode, which is currently widespread, and it is necessary to support three modes.

Upper NTSC Lower CCf R Unit: Mbps bit In Figure 1, l is the input signal, 2 is the input signal switching SWI, 3 is the recording signal processing circuit, and 4 is the switching SW2.5 that selects the output of the recording signal processing circuit 3. is a recording amplifier, and a horn signal output from the recording amplifier is recorded on the magnetic tape 6 via a head A7 and a head B8 attached to a rotating drum 9. Next, from the magnetic tape 6, head A7
, the signal reproduced by head B8 is input to the reproduction amplifier lO, and the reproduction amplifier output signal is checked for the number of errors in 11 error check circuits. Based on the check result, the transmission rate mode is determined by 12 system control circuits. 13 switching SW3 is switched to the transmission rate mode to be switched. 14 is a reproduction signal processing circuit, 15 is an output signal switching SW4, and 16 is an output signal.

In FIG. 5, (a) shows the track format of the magnetic tape, in which there is a video signal such as a video signal, etc.
A deo signal and a PCM signal are recorded. j7 is a PC
M data area is shown. (b) and (c) correspond to the I" CM data area 17 and show the block format. Here, each part of (b) and (c) will be explained. 18 is the synchronization signal indicating the beginning of the block, and 19 is the block format. Consecutive block addresses for adjacent blocks, 20
is the ID which is the control signal of each block, 21 is the parity of the check word which is the exclusive OR of the block address 19 and ID 20, 22 and 23 are the Cl parity and C2 parity based on the double encoded Reed-Solomon code, 24・2
5 is Q parity using 1 check bit, P parity is coded for each block, and 26 is coded for each block.
It is a c code.

Details of the present invention will be described below with reference to FIGS. 1 and 4.

This will be explained along with FIGS. 2 and 3 using FIG. 5.

First, the magnetic tape 6 containing a mixture of digital data recorded at different transmission rates by heads A7 and B8 attached to the rotating drum 9 in FIG. Obtain the playback amplifier output signal. This reproduction amplifier output signal is passed to the error check circuit 11 in FIG. 1, and when the current mode is 16-bit mode or 12-bit mode, P
Parity 21 of the test word shown in (b) recorded in the CM data area 17. The detection rate of the ID code 20, which is the control signal for each block, the continuous status of block addresses 19, the C1 parity 23 and C2 parity 22 for error correction using double-encoded Reed-Solomon codes, or whether the current mode is 8-bit mode. Time is P parity 2 shown in (C)
5. Parity check for Q parity 24, CRC code 2
6. Detect the number of errors by combining one or some of the consecutive conditions of block addresses 19, and if the detected number of errors is smaller than a predetermined number, the current transmission rate is considered correct and the mode is changed. is not carried out. If the number of errors detected is larger than a predetermined number, it is considered that the current transmission rate is incorrect and the mode is changed. By repeating the above mode change until the number of detected errors falls below a predetermined number, it becomes possible to set the correct mode. The above algorithm is shown in FIG.

In the above, all three modes were selected by error checking, but according to the 8mm VTR standard, as shown in Figure 4, one mode is selected depending on the type of tape used and the tape speed.
A 6-bit mode and a 712-bit mode are determined.

By the way, the type of tape can be determined by the hole in the cassette.
The tape speed can be determined by the A"""F pilot signals, etc., so 16-bit mode/12-bit mode] - The mode is determined based on the tape type and tape speed described above, and is either 16-bit mode/12-bit mode or 8-bit mode. By selecting the mode through error checking,
The speed of mode discrimination can be increased.

This discrimination algorithm is shown in FIG. 3, and will be explained below with reference to the same figure.

The check result of the error check circuit 11 shown in FIG. 1 is input to the system control circuit 12, and first, it is determined whether the cassette is an ME tape or an MP tape based on the holes in the cassette. Now, as shown in Figure 4, if it is an ME tape, it will be 16 bits or 8 bits in L mode, if it is an MP tape, it will be 16 bits in L mode if it is SP mode, depending on the speed mode of the tape when recording data. It can be seen that the LP mode is the 12-bit or 8-bit mode in the N mode. In other words, M.E.
If it is a tape or MP tape in SP mode, there is a 16-bit or 8-bit mode, so the transmission rate during playback is 1.
If it is 6-bit mode, the correct transmission rate is 8-bit mode, so change to 8-bit mode. If the transmission rate during playback is not 16-bit mode, the correct transmission rate is 16-bit mode, so change to 16-bit mode. mode. On the other hand, MP tape LP
If the mode is 12 bit or 8 bit mode,
Change the transmission rate mode in the same way. Switch SW3.13 based on the determination result of this system control circuit.
Switch switch SW4.15 to select the correct transmission rate mode.

According to this embodiment, a plurality of transmission lines 1-
When playing a magnetic tape in which data recorded on the same magnetic tape is mixed, an error check is performed, and based on the check results, the type of tape, the tape speed at the time of recording, and the transmission rate at the time of playback are determined. As a result, the transmission rate mode to be switched can be selected with the smallest circuit scale, and digital data can be reproduced correctly without providing a new transmission rate 1lt1 fixed circuit.

[Effects of the Invention] According to the present invention, when playing back a magnetic tape in which digital data recorded at a plurality of transmission rates coexist on the same magnetic tape, the error check and system control circuit select the transmission rate to be switched to. Therefore, digital data can be reproduced correctly.

Furthermore, since the mode identification signal is not multiplex recorded in the PCM signal area, video signal, etc., there is an effect of preventing deterioration of video and audio due to multiple recording.

[Brief explanation of the drawing]

- Figure 1 shows an embodiment of the present invention.
A block diagram of a TR PCM audio recording and reproducing device, FIG. 2 is a flowchart showing a simple algorithm of the present invention, FIG. 3 is a flowchart showing a detailed algorithm of the present invention, and FIG. 4 is a diagram showing types of magnetic tapes, FIG. 5 is a diagram showing mode discrimination results based on recording speed, and is a format diagram showing an example of a recording format of a magnetic tape. 11...Error check circuit, 12...System control circuit.

Claims (1)

[Claims] 1. A magnetic reproducing device for reproducing a recording medium on which a plurality of digital data having different transmission rates are recorded in a mixed manner;
Alternatively, a magnetic recording/reproducing apparatus for recording and reproducing the digital signals on the same recording medium is provided with an error check circuit for checking errors in the reproduced digital data when reproducing the digital data, and the error check circuit detects errors detected by the error check circuit. 1. A magnetic reproducing device or a magnetic recording/reproducing device, comprising a system control circuit that switches a transmission rate mode when the number of errors detected is larger than a predetermined number. 2. In the magnetic reproduction device or magnetic recording and reproduction device according to claim 1, if the number of errors in the reproduced digital data detected by the error check circuit is greater than a predetermined number, the system control circuit A magnetic reproducing device or apparatus, characterized in that the transmission rate mode to be switched is determined by determining the type of recording medium, the speed mode at the time of recording the recording medium data, and the transmission rate mode at the time of reproduction. Magnetic recording and reproducing device. 3. In the magnetic reproducing device or magnetic recording/reproducing device according to claim 2, when the digital data is reproduced and the number of errors detected by the error check circuit of the reproduced digital data is smaller than a predetermined number. maintains the same transmission rate, and if the number of errors mentioned above is greater than the predetermined number, the magnetic tape is coated metal tape (hereinafter referred to as MP tape) or has a higher sensitivity than MP tape.
Determines whether the tape is a vapor-deposited metal tape (hereinafter referred to as ME tape) with excellent frequency characteristics, and determines whether it is an ME tape or MP tape and is in SP mode, and the transmission rate at the time of playback is 16 bits. mode, change to 8-bit mode, if not 16-bit mode, change to 1
Changed to 6-bit mode, and the transmission rate was 1 when playing MP tape and LP mode.
If it is in 2-bit mode, change it to 8-bit mode,
1. A magnetic reproducing device or magnetic recording/reproducing device, comprising a system control circuit that changes the mode to 12-bit mode if the mode is not 12-bit mode. 4. In the magnetic reproducing device or magnetic recording and reproducing device according to claim 1, when a recording medium in which digital data is recorded in blocks is played back in 16-bit or 12-bit mode, the control signal for each block is ID that is
The detection rate of the code, or the sequence of block addresses indicating the order of the blocks, or the parity of the check word, which is the exclusive OR of the ID code and the block address, or the error due to double-encoded Reed-Solomon code. One of C1 parity and C2 parity for correction
In the case of 8-bit mode, the number of errors is detected by one or a combination of two or more, and in the case of 8-bit mode, parity check is performed using P parity or Q parity using 1 check bit, or coded for each block. A magnetic reproducing device characterized in that it is equipped with an error check circuit that detects the number of errors by one or a combination of error detection using a CRC code, or continuous status of block addresses indicating the order of blocks. device or magnetic recording/reproducing device.