JPH04155604A - Digital signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To enable monitoring the recording state of a magnetic tape by checking the recording state automatically every time a recording mode is released and by issuing alarms in case of determination in the recording state. CONSTITUTION:Upon receiving stop instructions by recording recording signal on a magnetic tape 20 through a heat block 18, a system controller 12 keeps on recording for a giving time and then sets operation at the reproduction mode to reproduce recording while winding up the tape 20 by a prescribed quantity. Its reproduced signal is input into a recording reproduced signal processor 3 and an envelope detector 10. In case of improper recording due to jamming of the head A, reproduced signal level (b) decreases to make envelop detection level (c) come below a prescribed level with the result that reproduced level detection output (e) shows a low level. In case of low output (e), a reproduced level judge means 13 judges the reproduced level to be below a prescribed value and sends light-up command to an alarm means 14 to light up a display 7.

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 recorded on a magnetic tape via a magnetic head, and the error detection result of the error detection code is recorded. The data is played back while being corrected and corrected based on the data. 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 explained. 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 Radon stem 4 of R-DAT 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-headon 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 nostem control section that controls the entire stem/mainly 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 run.

FIG. 6 shows the configuration of a four-headon 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 for playback are installed at an angle of about 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 trunk on the tape, and the X direction coincides with the width direction of the track.

Therefore, (b).

As shown in (C), in order for the trailing heads A' and B' to correctly trace the tracks recorded and formed by the leading heads A and B, the trailing heads are moved in the X direction relative to the leading heads, that is, in the cylinder direction. It must be installed with a certain amount (h) shifted in the height 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 dinotal 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 recording and reproducing apparatus of the present invention continues the fixed-layer recording mode after receiving a recording stop command, then rewinds the magnetic tape by a specified amount in the reproducing mode, and detects the envelope of the reproduced signal at the time of rewinding. The apparatus also includes warning means for detecting the reproduction signal level and issuing a warning when the detected reproduction signal level is below a specified value.

Function: With the above-described configuration, the digital recording/reproducing apparatus of the present invention automatically checks the clogged state of the head and the recording state on the tape every time the recording mode is canceled, and checks if the recording state has deteriorated. By warning the user, 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.

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 signal recording and reproducing apparatus according to an embodiment of the present invention, in which 1 is an A/D humbverter, 2 is
3 is a recording system filter, 3 is a recording/reproducing system signal processing circuit,
4 is a modulation section, 5 is a recording section, 8 is a demodulation section, 9 is a reproduction section, 1
7 is a cylinder section equipped with two head blocks 18;
10 is an envelope detection unit that detects the envelope of the reproduced signal; 11
12 is a sampling circuit that samples the envelope level at the timing from the recording/reproducing signal processing 3; 12 is a recording mode continuation means 21, a rewinding means 22, and a reproduction level determining means 1;
3/a system control unit controlling the entire stem; 16;
15 is a capstan drive unit that drives a capstan motor 19 that runs the tape 20; 14 is a warning means including a display circuit 6 and a display unit 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 12.

In Figure 1, in the recording state, the input audio signal is A
/D converter 1 converts it into a digital code, high-frequency signal components are removed through filter 2 for removing aliasing noise, error detection code is added through recording/reproduction system signal processing 3, and modulation section 4 modulates the signal. Through processing, it is converted into a recording signal, which is then recorded on a magnetic tape 20 by two head blocks 18 mounted on a cylinder 17 via a recording unit 5.
recorded above.

When the system control unit 12 receives a recording stop command (step 1), the 7-stem control unit 12 controls the recording/reproducing signal processing unit 3,
The cylinder drive section 16 and the capstan drive section 15 are held 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 section 12 sets the recording/reproduction signal processing section 3 and the cylinder drive section 16 to the playback mode, and causes the capstan motor 19 to run in reverse via the capstan drive section 15. , while rewinding the tape 20 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, amplified by the reproducing section 9, demodulated by the demodulating section 8, and input to the recording/reproducing system signal processing 3.

On the other hand, the reproduced signal is also input to the envelope detection section 10, and after envelope detection, the recording and reproduction signal processing 3 is carried out in the sampling circuit 11.
The signal is sampled and held at a predetermined timing supplied by the controller, for example, the timing at the center of the envelope of the reproduced signal, and is input to the system control unit 12.

As shown in FIG. 3, if the A head is clogged and recording is not performed correctly, the playback signal level decreases during playback (b), and the envelope detection level falls below the specified level (as shown by the broken line). c), and the reproduction level detection output (e) based on the sampling pulse (d) supplied from the recording and reproduction signal processing 3 becomes low level. If the reproduction level detection output is low, the reproduction level determining means 13 determines that the reproduction level is below the specified value (step 5), and sends a lighting command to the warning means 14 to light the display section 7 via the display circuit 6 (step 5). Step 6) sends a message to the user that the recording condition of the tape is not good. When the specified amount of tape 20 is rewound (step 7), the system control section 12 controls the recording/reproduction signal processing section 3. The entire system including the cylinder drive section 1B and capstan drive section 15 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 head 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, and then rewinds the magnetic tape by a specified amount in the reproducing mode, and when rewinding, it adjusts the envelope of the reproduced signal. With a simple configuration, the user can check whether the current recording state is correct each time they repeat recording and stopping by detecting the playback signal level and issuing a warning when the playback signal level is below a specified value. This can be communicated to users, and its practical effects are great.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a digital signal recording and reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a state diagram showing changes in the tape running mode in this embodiment, and FIG. 3 is a block diagram of each part when the head is clogged. 4 is a flowchart explaining the present invention in detail. FIG. 5 is a block diagram of a conventional digital signal recording and reproducing device, and FIG.
FIG. 3 is a diagram showing main parts of a head cylinder. 3... Recording/reproduction system signal processing section, 10... Envelope detection section, 11... Sampling circuit, 12.
...system control section, 13.. playback level determination means, 14.. warning means, 15.. capstan drive section, 21.. recording mode continuation means, 22..
・Rewinding means. Name of agent: Patent attorney Akira Okaji and two others Figure 2 Suspended -111- Figure 3 Figure 4

Claims (1)

[Claims] An apparatus for recording and reproducing digital signals on a magnetic tape, comprising means for continuing a recording mode for a specified time after a recording stop command, and winding the magnetic tape by a specified amount in a playback mode after stopping recording. A digital device comprising: means for rewinding; means for detecting the envelope of the reproduced signal during rewinding and determining the level of the reproduced signal; and means for issuing a warning when the detected level of the reproduced signal is below a specified value. Signal recording and reproducing device.