JPH04149806A - Digital signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To monitor the recording state of a magnetic tape by simple constitution by measuring the error rate of a reproduced signal at the time of rewinding the tape, and generating an alarm when the error rate exceeds a normal value. CONSTITUTION:A system control part 10 includes a means 19 for holding a recording/reproducing signal processing part 3, a cylinder driving part 12 and a capstan driving part 13 at a recording mode when the control part 10 receives a recording stop command. After continuing the recording mode for a fixed time, the control part 10 sets up the processing part 3 and the driving part 12 to a reproducing mode, reversely rotates a memory 16, and while rewinding the tape 15 by a regulated length, reproduces a signal. The reproduced signal is read out by a head block 18 and demodulated by a demodulating part 8. The error rate of the reproduced signal is measured by an error detecting code, and when the error rate exceeds the normal value, an alarm is generated from an alarm means 14. Thereby, a user can monitor whether the using state of the tape 15 is always correct or not.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a digital signal recording and reproducing apparatus that converts audio and video signals into digital signals and records and reproduces the digital signals on a magnetic tape.

BACKGROUND OF THE INVENTION In recent years, in the field of magnetic recording and reproduction, recording methods have been changing from analog recording to digital recording.

In the digital signal recording and reproducing method, input signals such as audio and video are encoded into digital codes of O's and 1's, an error detection code is added, and the data is recorded on a magnetic tape via a magnetic head, and the error detection code is used to detect errors. The data is played back while making corrections and corrections based on the results. Therefore, in the case of digital recording, if the recording condition deteriorates due to foreign matter adhering to the magnetic tape, clogging of the magnetic head, etc., and the error rate exceeds a certain level, it becomes impossible to correctly demodulate the digital codes on the magnetic tape. Abnormal noise is superimposed on the playback sound.

A fatal problem may occur, such as the playback sound being interrupted.

To this end, various methods have been proposed for digital signal recording and reproducing equipment to monitor the recording state on the magnetic tape in the recording mode.

Hereinafter, a conventional recording state monitoring system for a rotary head type digital audio tape recorder (hereinafter abbreviated as R-DAT) will be described. In an R-DAT, two heads with different azimuths, which are placed oppositely on a cylinder, operate as a recording head during recording and as a reproducing head during reproduction, thereby performing recording and reproduction. Therefore, in order to check and monitor the recording status on the magnetic tape during recording using the simultaneous playback monitor sound, two additional heads dedicated to playback are installed on the cylinder, realizing the recording status monitoring function with four heads. .

The operation of the R-DAT 4-head system will be explained using FIGS. 5 and 6. FIG. 5 is a block diagram of a conventional example for realizing simultaneous recording and reproduction monitoring, and FIG. 6 is a diagram showing the main parts of a four-head cylinder.

In Figure 5, 30.35 are A/D, respectively.

D/A converter, 31. 36 is a recording system and reproduction system filter, 32 is a recording system signal processing circuit, 33 is a modulation section, 3
4 is a recording section, 37 is a reproduction system signal processing, 38 is a demodulation section, 3
9 is a playback section, 40 is a cylinder section on which four head blocks 41 are mounted, 42 is a system control section that controls the entire system centering on the recording/playback signal processing section, and 43 is a cylinder 4
44 is a capstan drive unit that drives a capstan motor 45 that causes the tape 46 to travel.

FIG. 6 shows the configuration of a four-head cylinder.

As shown in (a), in addition to the two leading heads (A, B) that are standard on a normal R-DAT, the trailing heads (A', B') dedicated to playback are shifted approximately 90 degrees. It is equipped with Here the rotation direction of the cylinder as shown in the figure,
That is, the X direction substantially coincides with the longitudinal direction of the track on the tape, and the Y direction coincides with the width direction of the track.

Therefore, (b).

As shown in (C), in order for the trailing head A'B' to correctly trace the track recorded by the leading heads A and B, the trailing head must be aligned with the leading head in the Y direction, that is, in the height of the cylinder. It must be installed with a fixed amount (h) shift in the horizontal direction, and the installation accuracy must be managed in μ units.

Hereinafter, a conventional after-monitoring operation during recording will be explained using FIGS. 5 and 6. The input audio signal is converted into a digital code by an A/D converter 30, high frequency signal components are removed via a filter 31 for removing aliasing noise, and an error detection code is added by a recording system signal processing 32. The signal is then converted into a recording signal by performing modulation processing in the modulation section 33, and recorded on the magnetic tape 46 by the preceding heads A and B mounted on the cylinder 40 via the recording section 34. The recorded track is traced by the trailing heads A', B' mounted on the cylinder 40, and the recording section 39. The signal is demodulated via the demodulator 38. The demodulated signal is subjected to error detection, correction, and correction processing using an error detection code in a reproduction system signal processing 37. Similar to the recording system, the reproduced digital signal is filtered to remove high-frequency signal components, and then converted to an analog audio signal by a D/A converter 35. As explained above, in this conventional example, the recording state monitoring function is realized by simultaneously monitoring playback during recording and in the recording state in a four-head system, and checking whether there is any abnormal noise in the playback sound.

Problems to be Solved by the Invention However, the above-mentioned configuration requires a dedicated cylinder equipped with 4 heads with high precision and controlled mounting accuracy, a signal processing block dedicated to the reproduction system, etc., and the system configuration is difficult. The problem was that it was complicated and expensive.

The present invention solves the above-mentioned problems and provides a digital signal recording and reproducing apparatus that can monitor the recording state of a magnetic tape with a simple configuration.

Means for Solving the Problems The digital signal recording and reproducing apparatus of the present invention continues the recording mode for a specified time after receiving a recording stop command, then rewinds the magnetic tape by a specified amount in the reproducing mode, and adds a digital code to the digital code at the time of rewinding. It is comprised of means for measuring the error rate of the reproduced signal using the recorded error detection code and issuing a warning when the measured error rate is equal to or higher than a specified value.

Operation The digital signal recording/reproducing device of the present invention has the above-described configuration, and each time the recording mode is canceled, it automatically checks the clogging condition of the head and the recording condition on the tape, and if the recording condition has deteriorated, it automatically checks the recording condition. It is possible to realize a digital signal recording and reproducing apparatus that can monitor the recording state of a magnetic tape with a simple configuration by warning the person.

Embodiment Hereinafter, a digital signal recording/reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a digital recording and reproducing apparatus according to an embodiment of the present invention, in which 1 is an A/D converter, 2 is a recording system filter, 3 is a recording and reproducing system signal processing circuit, 21
1 is a reproduction error counter section, 4 is a modulation section, 5 is a recording section, 8 is a demodulation section, 9 is a reproduction section, 17 is a cylinder section on which two head blocks 18 are mounted, 10 is a recording mode continuation means 19 and a rewinding section. a system control section that controls the entire system including the means 20 and the error rate measuring means 11; 12 a cylinder drive section that drives the cylinder 17; 13 a capstan drive section that drives the capstan motor 16 that runs the tape 15;
4 is a warning means including a display circuit 6 and a display section 7.

The operation of the embodiment of the present invention constructed as described above will be explained with reference to FIGS. 1, 2, 3, and 4. FIG. 2 shows changes in the driving mode, FIG. 3 shows waveforms of various parts at that time, and FIG. 4 shows a flowchart of software processing by the system control section 10. In FIG. 1, in a recording state, an input audio signal is converted into a digital code by an A/D converter 1, and high-frequency signal components are removed through a filter 2 for removing aliasing noise.
An error detection code is added by the recording and reproducing system signal processing 3, and the modulation unit 4 performs modulation processing to convert it into a recording signal. It is recorded on tape 15.

When the system control unit 10 receives a recording stop command (step 1), the system control unit 10 receives the recording/reproduction signal processing unit 3,
The cylinder drive section 12 and the capstan drive section 13 are kept in the recording mode and the recording state is continued for a certain period of time (recording mode continuation means 2 step 2). When a certain period of time has elapsed (step 3), the system control unit 10 sets the recording/reproduction signal processing unit 3 and the cylinder drive unit 12 to the playback mode, and causes the capstan motor 16 to run in reverse via the capstan drive unit 13. , while rewinding the tape 15 by a specified amount, the track portion recorded in step 2 is reproduced (rewinding means 2 step 4). The playback signal is from the head block 18
The signal is read out by the reproducing section 9, amplified by the reproducing section 9, and then demodulated by the demodulating section 8. The demodulated signal is subjected to error detection using an error detection code in the recording/reproduction system signal processing 3, and if an error is detected, correction or correction processing is performed and the signal is returned to the original signal. In R-DAT, the input digital code is divided into blocks,
An error detection code is added and recorded on the tape, so that playback errors can be detected in block units during playback. The detected playback errors are counted by a playback error counter 21 and transferred to the system control unit 10 for each head trace via the recording and playback signal processing unit 3, so that the error detection rate can be measured.

As shown in FIG. 3, if the A head is clogged and recording is not performed correctly, then during playback.

The recording and reproduction signal processing section 3 detects a large number of reproduction errors, counts them in the reproduction error counting section 21, and transmits the counting results to the system control section 10. The system control unit 10 measures the error rate using the error rate measuring means 11 based on the transmitted counting results (error rate measuring means), and if the error rate exceeds the specified value (
In step 5), a lighting command is sent to the warning means 14, and the display section 7 is lit via the display circuit 6 (step 6), thereby sending a message to the user that the recording condition of the tape is not good. When the specified amount of tape 16 is rewound (step 7
), the system control section 10 includes a recording/reproduction signal processing section 3. Cylinder drive unit 12. The entire system including the capstan drive unit 13 is set to a stopped state (step 8), and a series of operations is completed. FIG. 2 shows a series of changes in the tape running mode after the recording stop command is issued.

In this embodiment, the input signal is an audio signal, but it may also be a video signal. Further, in this embodiment, a helical scan recording method using a rotating helad is used, but a recording method using a fixed head is also applicable.

Effects of the Invention As described above, the digital signal recording and reproducing apparatus of the present invention continues the recording mode for a specified time after receiving a recording stop command, then rewinds the magnetic tape by a specified amount in the reproducing mode, and adds a digital code to the digital code at the time of rewinding. The error rate of the reproduced signal is measured using the recorded error detection code, and a warning is issued when the measured error rate exceeds a specified value, allowing the user to record with a simple configuration.

Each time the stop is repeated, the user can be informed whether the current recording state is correct or not, which has a great practical effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a digital signal recording and reproducing apparatus in an embodiment of the present invention, FIG. 2 is a state diagram showing changes in tape running mode in an embodiment of the present invention, and FIG. 3 is a block diagram of a digital signal recording/reproducing apparatus in an embodiment of the present invention. Waveform diagrams of various parts, FIG. 4 shows main parts of a flowchart explaining the present invention in detail, FIG. 5 shows a block diagram of a conventional digital signal recording/reproducing device, and FIG. 6 shows main parts of a conventional 4-head cylinder. It is a diagram. 3... Recording/reproduction system signal processing section, 10... System control section, 11... Error rate measuring means, 13.
...capstan drive unit, 14...warning means,
19... Recording mode continuation means, 20... Rewinding means, 21... Reproduction error counting section. Name of agent: Patent attorney Akira Okaji and 2 others

Claims (1)

[Claims] An apparatus for adding an error detection code to a digital signal and recording and reproducing it on a magnetic tape, comprising: means for continuing a recording mode for a specified time after a recording stop command; and a reproduction mode after recording is stopped. means for rewinding the magnetic tape by a predetermined amount; means for measuring the error rate of the reproduced signal using the error detection code during rewinding; and means for issuing a warning when the measured error rate is greater than or equal to a predetermined value. A digital signal recording and reproducing device.