JPH0240106A - Digital signal reproducing device - Google Patents

Abstract

PURPOSE:To perform reproduction at ordinary speed and fast dubbing satisfactorily by providing a data selecting means to take out the prescribed part of a reproducing signal by a head part, a tracking signal detecting means, and a data processing means corresponding to the rotating speed of the head part and tape speed. CONSTITUTION:The rotating speed of the head parts A and B are set at double speed sides, and it is held at a constant level even when the tape speed changes. Since the rotating speed of the head parts A and B in the reproduction at reference tape speed are faster than that in a reference operation, a track is scanned for plural times. However, the appropriate signal out of the reproducing signals obtained by each scan is taken out by the data selecting means, and a reproduction processing is performed by the data processing means. As for a tracking signal, the appropriate one is detected by the tracking signal detecting means similarly. In such a way, it is possible to perform the reproduction at ordinary speed or the fast dubbing satisfactorily without changing the rotating speed of a head.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a digital signal reproducing device, and in particular, a method for reproducing digital signals using a helical scan method using a rotating head at a speed different from the standard. The present invention relates to a digital signal reproducing device suitable for performing the following.

[Prior Art] A signal processing device using a rotating head such as a DAT handles digital signals and has error correction means, so it has the advantage that the sound quality does not change even if dubbing is performed multiple times. There is.

In such cases, analog tape recorders are often capable of dubbing at double or higher speeds, and a similar requirement exists for DATs as well.

By the way, as a means for performing high-speed dubbing in DAT, for example, a method of changing the head tram rotational speed in accordance with the tape speed may be considered.

[Problem to be solved by the invention] However, in such a method, the relative speed of the tape and drum changes during normal playback and tabbing, so the bit rate also changes, and it is difficult to deal with this. Therefore, it becomes necessary to change the characteristics of the equalization circuit and PLL.

Furthermore, it is necessary to stabilize the rotational speed of the drum both during normal playback and during dubbing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a digital signal reproducing apparatus that can perform normal speed reproduction and high-speed tabbing well.

[Means for Solving the Problems] The present invention includes: a helical scan head whose rotational speed is set to double the standard speed; a speed instruction means for instructing a playback tape speed; and rotation of the head. data selection means for extracting a predetermined portion of the signal reproduced by the head unit according to the rotational speed of the head unit and the tape speed; detecting a tracking signal from the signal reproduced by the head unit according to the rotational speed of the head unit and the tape speed; and a data processing means for reproducing data retrieved by the data selection means in accordance with the rotational speed of the head section and the tape speed. .

[Function] According to the present invention, the rotation speed of the head section is set to the double speed side, and this is maintained constant even if the tape speed changes.

When playing back at the standard tape speed, the rotation of the spatula 1 is faster than at the standard time, so the track is scanned multiple times. However, from among the reproduced signals obtained by each of these scans, a suitable one is extracted by the data selection means and reproduced by the data processing means.

)~The tracking signal is similarly detected by a suitable tracking signal detection means.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

First, with reference to FIGS. 1 and 2, the basic playback operation at standard time in the embodiment of the present invention will be explained.

The head configuration is the same as before, with the A head at a +azimuth angle and the B head at a -azimuth angle facing each other at an angle of 180 degrees.
The head is wound at a rotation speed of 10 degrees (JORPM standard recording and playback can be performed.The rotation speed of such a head is
For example, it is fixed at 4000 rpm.

This rotation speed is the standard rotation speed of 11 at normal playback speed.
It is four times that of 00Orp. Therefore, in the case of 4x speed playback, both the tape speed and head speed are 4x, so
This allows for good high-speed playback.

Furthermore, in this embodiment, even during normal playback, the head rotation speed remains constant at 4000 rpm, as shown in the following.

On the other hand, the tape speed changes from 4x speed to 1/4. The velocity vector in this case is as shown in FIG. In the figure, the rotational speed of the drum is F (O
A) - constant as mentioned. On the other hand, if the tape speed is F (AB) at quadruple speed, it is F (AH) at standard time. Therefore, the relative velocity between the two in standard time is F (OH), and the direction of this vector is the l\watt scanning direction on the tape.

As described above, under the condition that the head speed is constant, the scanning direction of the head on the tape becomes different between the quadruple speed and the standard time.

FIG. 2 shows how the head scans the tracks on the tape at the standard time. Note that the tracks in the figure were recorded with both the tape speed and the head speed being four times the standard speed (corresponding to quadruple speed dubbing according to the present invention), and the direction of the track inclination is the vector in Figure 1. F (OB) direction.

In the same figure, r+J in the circle between 1 and 10,
rJ indicates the azimuth angle, and as shown above each track, solid line arrows indicate track scanning by the A head, and broken line arrows indicate track scanning by the B head.

As shown in the figure, each track 10A.

10B, IOC, IOD, etc. Since only the tape speed is 1/4 compared to when recording ) direction scanning is performed.

Among these multiple scans, since the track IOA is the azimuth angle or "+", it is standard It becomes possible to play.

Next, since the track IOB is the azimuth angle or "-", standard playback is possible if the signal obtained by scanning S6, which is scanned by the B head and includes the entire track IOB, is used. be.

Similarly, track lOC is scanned S9. Truck I
In OD, scanning S14. What is necessary is to use the signals obtained respectively by .

Next, the configuration of the apparatus according to the embodiment will be explained with reference to FIG. In the figure, the output sides of heads A and B are connected to the input sides of reproduction amplifiers 12 and 14, respectively, and the output sides of these heads are respectively connected to the switching terminal side of head changeover switch 16.

The common terminal side of the head changeover switch 16 is connected to the waveform circuit 18.
．． They are each connected to the input side of the tracking signal detection circuit 20. Of these, the output side of the waveform equivalent circuit 18 is connected to the input side of the PLL circuit 22, and the output side of the PLL circuit 22 is connected to the input side of the employment data extraction circuit 24.

Then, the output side of this recruitment data extraction circuit 24,
It is connected to a signal processing circuit 26 for frame synchronization, demodulation, two-time axis extension, error correction, D/A conversion, etc. in normal DAT.

The tracking signal detection circuit 20 and adopted data extraction circuit 24 described above include a timing signal generation circuit 28.
are connected to each other, and timing signals indicating the tracking position and data retrieval position are respectively output. Further, the detection signal of the tracking signal detection circuit 20 is output to a tracking control circuit (not shown).

Next, the signal processing circuit 26. A speed changeover switch 30 is connected to the timing signal generation circuit 28 and the tape speed control circuit (not shown), and the tape speed instructed by the operation of the operator of the apparatus is inputted to each of them.

Among these, waveform equivalent circuit 18. The PLL circuit 22 is
It is provided in common for any tape speed.

Next, the speed changeover switch 30 is used to change the playback speed, for example, the standard speed mentioned above.

In addition to the 4x speed, the 2x speed shown in Figure 5, and the 1.3 speed shown in Figure 6
Either double speed or 0.8x speed shown in FIG. 7 is specified as necessary. Specifically, a rotary type bit switch or bush switch is used, and the commanded speed is expressed as a several-bit identification signal and output.

The tape speed control circuit to which this playback speed identification signal is input changes the driving voltage of the capstan motor and reel motor according to the instructed tape speed, and is controlled to the desired tape speed. There is.

Further, as shown in FIG. 2, the adopted data extracting circuit 24 selectively adopts and extracts data obtained by an appropriate scan among a plurality of scans in one track.

Next, without reference to FIG. 4, the reproduction operation at the above-mentioned standard speed will be described. In this case, the standard speed is selected using the speed changeover switch 30.

As shown in FIG. 2, tracks l by heads A and B are
The scanning of S1, S2. S3. The output of the head selector switch 16 is as shown in Fig. 4 (
A).

This head reproduction signal is inputted to the employed data extraction circuit 24 via a waveform equalization circuit 18 and a PLL circuit 22, respectively. A timing signal from a timing signal generation circuit 28 based on a selection signal from the speed changeover switch 30 is input to the adopted data extraction circuit 24.

This timing signal is as shown in FIG. 4(B), and a head reproduction signal corresponding to the logical value rLJ portion is output to the signal processing circuit 26. That is,
By this timing signal, the scanning S explained in FIG.
l, S6°S9. S14. The reproduced signal obtained by . . . will be adopted.

Then, for these reproduced signals, the signal processing circuit 26
Processing is performed according to the playback speed, and the audio is played back.

On the other hand, the head playback signal from the head changeover switch 16 is also input to the tracking signal detection circuit 20 . and,
Similarly, a tracking signal is detected based on the timing signal input from the timing signal generation circuit 28. FIG. 4(C) shows such a timing signal, and the tracking signal of the head reproduction signal is detected based on the state of the logic value rHJ of this signal, and is output to the tracking control circuit. This tracking signal detection position corresponds to PA in FIG.

In the case of this standard speed, the operations from times TA to TB in FIG. 4 are repeated. Furthermore, in the case of other tape speeds to be described later, the operation is repeated at predetermined intervals.

In the above explanation, it has been assumed that the solid line arrow in FIG. and track scanning by head A, that is, track 10 in the figure.
In the case where it is shown in parentheses below, it becomes as follows.

First, since the track IOA is the azimuth angle or "+", standard playback is possible by using the signal obtained by scan S2, which is scanned by the A head and includes the entire track IOA. .

Next, in the L-rack IOB, since the azimuth angle is "-", the scanning by the B head is the track IOB.
Standard playback is possible by using the signal obtained by scanning S5 that includes the entire area.

Similarly, track IOC is scanned SIO.

Track 10D is scanned S13. What is necessary is to use the signals obtained respectively by . In this case, tracking is performed based on the PH position. The same applies to those shown in Figures 1 and 7 without Figure 5.

Next, the case of double speed playback will be explained with reference to FIG. The vector diagram in this case is as shown in FIG. 5(A), and when compared with FIG.
). Therefore, the relative velocity between the tape and the head is vector F(OI).

On the other hand, since the head rotation speed is constant, it is 4000 rpm.
The tape speed is twice the standard speed. This is instructed by the speed selector switch 30.

Therefore, the scanning direction of the head with respect to the track 10 is as shown in FIG. Of each of these scans,
First, since the azimuth angle of the track IOA is "+", double speed playback is possible by using the signal obtained by scanning S21, which is scanning by the A head and includes the entire I-rack IOA. becomes.

Subsequently, since the azimuth angle of the track IOB is "-", it is sufficient to use the signal obtained by the scan S22, which is a scan by the B head and includes the entire track IOB.

Similarly, the track IOC scans S25° and the track IOD scans S26. What is necessary is to use the signals obtained respectively by .

The adopted data retrieval circuit 24 performs these scans S21.
S22. S25. S26. Only the data obtained by . . . is retrieved. In this case, tracking is performed based on the position of the PC.

Next, without reference to FIG. 6, the case of 1.3 times speed playback will be described. The vector diagram in this case is shown in Figure 6 (A
), and when compared with FIG. 1 described above, the tape speed is either the standard tape speed F (AH) or 1.3 times faster than the tape speed F (AJ).

Therefore, the relative velocity between the tape and the head is the vector F
(OJ).

On the other hand, since the head rotation speed is constant, it is 4000 rpm.
The tape speed is 1.3 times the standard speed.

Therefore, the scanning direction of the head with respect to the track 10 is as shown in FIG. Among these scans, first, in the track IOA, the azimuth angle is "+", so if the signal obtained by the scan S31, which is scanned by the A head and includes the entire track IOA, is used. , 1°3x speed playback is possible.

Subsequently, since the azimuth angle of track IOB is "-", it is sufficient to use the signal obtained by scanning S34, which is scanning by the B head and includes the entire track IOB.

Similarly, the track IOC is scanned at S37, and the track IOD is scanned at S40. What is necessary is to use the signals obtained respectively by . In this case, offset tracking is performed by ATF at position PD or PE in the figure.

In normal tracking, the levels of leakage signals from adjacent tracks are made equal on both sides, or in offset tracking, tracking is performed so that the levels of leakage signals from both sides of the track become a certain ratio. As a result, the head scans with a predetermined distance from the track corresponding to the ratio.

Next, the case of 0.8x speed playback will be explained with reference to FIG. The vector diagram in this case is shown in Figure 7 (8), and when compared with Figure 1 above, it is either the standard tape speed F (AH) or the 0.8x tape speed F (AK). .

Therefore, the relative velocity between the tape and the head is the vector F
(OK).

On the other hand, since the head rotation speed is constant, it is 4000 rpm.
The tape speed is 0.8 times the standard speed.

Therefore, the scanning direction of the head with respect to the track IO is as shown in FIG. Among these scans, the azimuth angle of the track IOA is 1+'', so if the signal obtained by the scan S50, which is a scan by the A head and includes the entire track IOA, is used, the azimuth angle is 0.゜8x speed playback is possible.

Subsequently, since the track IOB is the azimuth angle "-", it is sufficient to use the signal obtained by the scan S51 which is a scan by the B head and includes the entire track IOB.

Similarly, the track IOC is scanned at S52, the track IOD is scanned at S54. What is necessary is to use the signals obtained respectively by . In this case as well, as in the case described above, position PF or P
G to apply offset tracking using ATF.

As described above, according to this embodiment, the head rotation speed is set to a relatively high value suitable for high-speed dubbing, and the head rotation speed is kept constant without changing even if the tape speed changes. Therefore, both normal playback and high-speed playback can be performed well, and since the bit rate of the playback output is constant, it is possible to use an equalization circuit or PLL with the same characteristics even if the tape speed changes. There is an effect that it can be done.

Furthermore, since the rotational speed of the drum is constant, there is an effect that the configuration of the tram motor and drum rotation control means can be relatively simplified.

Furthermore, when playing back at standard speed, there is a relatively long time between the adopted data of one track and the adopted data of the next track, so this time can be used to perform processing such as error correction. Another effect is that you can do it with more time.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be applied to, for example, data transmission between DATs as well as high-speed data transmission to a computer.

Furthermore, as is clear from FIG. 5(R) mentioned above, when the speed is between 2x speed and 4x speed, for example 3x speed, 2 tracks of +azimuth and -azimuth "C head A
, H operation is not completed. In other words, the head does not scan the rotating position between the two tracks.

In order to scan the rotational position of the head every two tracks, in the case of a 4x speed device like the above embodiment, the I
Double speed, i'4J divided by a natural number, ie 4/m (m
= 1, 2, 3, ·----).

In this case, the trough kink positions PA, PB, PC, . . Therefore, tracking can be performed relatively easily.

In the above embodiment, the case where a plurality of playback speeds are provided has been described, but it may also be implemented with only a playback speed of, for example, quadruple speed.

[Effects of the Invention] As explained above, according to the present invention, there is an effect that normal speed playback and high speed dubbing can be performed satisfactorily without changing the rotational speed of the head.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the relationship between the velocity vectors of the tape and the head at quadruple speed or standard speed in the embodiment, and FIG.
The figure is an explanatory diagram showing head scanning on a tape at standard speed, Fig. 3 is a circuit block diagram showing the configuration of the embodiment, Fig. 4 is a time chart showing the operation of the embodiment at standard time, and Fig. 5 is 2 FIG. 6 is an explanatory diagram showing the operation at double speed, FIG. 6 is an explanatory diagram showing the operation at 1°3x speed, and FIG. 7 is an explanatory diagram showing the operation at 0°8x speed. 10, IOA, IOB...track, 16...head changeover switch, 18...waveform equalization circuit, 20...
Trough kink signal detection circuit, 22...-PLL circuit, 2
4...Recruitment data cancellation circuit, 26...Signal processing circuit, 28...Timing signal generation circuit, 30...
Speed selector switch, A, B...head. Patent applicant: Japan Hictor Co., Ltd. Representative: Kunio Kakimoto Figure (c) Figure (A)

Claims (1)

[Claims] In a digital signal reproducing device that uses a helical scan method to reproduce digital signals recorded on a tape at a standard or n times tape speed, there is provided a head unit whose rotational speed is set to a double speed side compared to the standard speed. a speed instruction means for instructing a reproduction tape speed; a data selection means for extracting a predetermined portion of a signal reproduced by the head according to the rotation speed of the head and the tape speed; Depending on the tape speed and
tracking signal detection means for detecting a tracking signal from a signal reproduced by the head; and data processing means for performing reproduction processing of the data retrieved by the data selection means according to the rotational speed of the head and the tape speed. A digital signal reproducing device characterized by comprising: