JPH05182306A - Recording method for digital signal - Google Patents

Abstract

PURPOSE:To facilitate the detection of pilot signals for tracking and to facilitate erasing of the pilot signals for tracking at the time of overrecording. CONSTITUTION:Digital signals are formed by forming diagonal tracks on a recording medium (tape) in the state of not forming guard bands by a rotary head. The pilot signals for tracking are recorded independently as recording regions from the digital signals in every other one tracks in the prescribed position AT where the distances from the ends in the longitudinal direction of the respective tracks 14A, 14B are equal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of converting a video signal or an audio signal into a digital signal, and recording the digital signal as a diagonal track on a tape, for example, with a rotary head for each unit time, and particularly for tracking. This relates to the recording method of the pilot signal.

[0002]

2. Description of the Related Art A helical scan type rotary head device records video signals and audio signals on a magnetic tape by forming one diagonal track per unit time,
When playing this, P
It has been considered to make a CM and record and reproduce it. This is because high-quality recording and reproduction can be performed by using PCM.

In this case, in the tracking control for ensuring that the rotary head correctly scans the recording track at the time of reproduction, conventionally, a control signal recorded on one end side in the width direction of the tape by a fixed magnetic head is used. Reproduction is usually performed by the fixed head, and the reproduction control signal and the rotational phase of the rotary head have a constant phase relationship.

However, this method requires a fixed magnetic head for tracking control. Providing such a fixed magnetic head causes inconvenience due to the mounting location and the like of the recording / reproducing apparatus, which is generally small in size.

Therefore, the following method has been considered as a method of tracking control without using the fixed head. This method is, for example, a case of recording / reproducing an analog video signal in a so-called overwriting state (without forming a guard band between tracks). The rotary head is superposed on the track for recording the video signal. By this, the pilot signal for tracking is recorded. In this case, the pilot signal is a signal on the low frequency side where the recording signal of the video signal does not exist when viewed in the frequency spectrum so that it can be easily separated during reproduction.

Next, an outline of this conventional tracking method will be described. The following example is an example in which two rotary heads HA and HB having different so-called azimuth angles are arranged with an angular interval of 180 degrees, and the pilot signal has four frequencies, for example, f _A = 100 kHz, f. _B = 115kH
Signals of z, f _C = 160 kHz and f _D = 145 kHz are used. Then, by one rotating head HA,
As shown in FIG. 1, every other tracks T ₁ and T ₃ are sequentially formed to record an FM-modulated video signal. _A pilot signal of frequency f _A is recorded on the track T ₁ on the track T ₃ . Are recorded with the pilot signals of frequency f _C superimposed on each other. Further, the other rotary head HB sequentially forms every other tracks T ₂ and T ₄ so that
Although the M-modulated video signal is recorded, the pilot signal of the frequency f _B is recorded on the track T ₂ and the pilot signal of the frequency f _D is recorded on the track T ₄ in a superimposed manner. These tracks T ₁ , T ₂ , T ₃ , T ₄ are formed in a so-called overwritten state.

Tracking control during reproduction is performed as follows. In this case, almost the same control is performed for each of the two rotary heads, so control of one head, for example, head HB will be described with reference to FIG. The head HB is in the just tracking state when the track T ₂ or T ₄ is correctly scanned.
The reproduction output of the head HB is supplied to the low-pass filter 2 via the reproduction amplifier 1 so that only the pilot signal on the lower frequency side is extracted. This low frequency component is supplied to the multiplication circuit 3 and is multiplied by the signal of the frequency f _B from the oscillator 4.

When the head HB scans the track T ₂ as indicated by HB ₁ in FIG. 1, the multiplication circuit 3 outputs a signal E _{1 of} f _B -f _A = 15 kHz and f _C -f _B.
= 45 kHz signal E ₂ is obtained. On the other hand, head H
When B scans the track T ₄ as indicated by HB ₂ in FIG. 1, the multiplication circuit 3 outputs f _B −f _C = 15 kHz.
Signal E ₁ , f _C −f _B = 45 kHz signal E ₂ ,
A signal S _{I of} f _D −f _B = 30 kHz is obtained.

Here, the signals E ₁ and E ₂ are
Is the reproduction output of the pilot signal of the adjacent track which is not the track to be scanned. As is apparent from FIG. 1, if the reproduction output levels of the signals E ₁ and E ₂ are equal, the head HB is in a state of correctly scanning the tracks T ₂ and T ₄ , and therefore the signals E ₁ and E 2 are the same. _By controlling the playback levels of ₂ to be equal, the correct tracking state can be achieved.

Therefore, the output of the multiplication circuit 3 is supplied to the bandpass filters 5 and 6, the 15 kHz signal E ₁ is extracted from the bandpass filter 5, and the 45 kHz signal E ₂ is extracted from the bandpass filter 6. , The signals E ₁ and E ₂ are supplied to one and the other input terminals of the differential amplifier 7, respectively, and the output of the difference between the two signals is taken out from this. The output of the differential amplifier 7 controls, for example, the capstan motor to control the transfer of the tape so that the difference output of the differential amplifier becomes zero.

[0011] However, in this case, since the track T ₂ and T ₄ frequency relationship of the pilot signals of the left and right adjacent tracks are reversed, when the head scans the track T _2, scanning the tracks T ₄ It is necessary to reverse the control direction depending on when. Although not available from multiplication circuit 3 the output of the pilot signal of the track T ₂ are when scanning the track T ₂ head HB is, signal f ₄ -f ₂ = 30kHz when scanning the track T ₄ S _I When is detected, the control direction is reversed.

That is, the outputs S _E and S _E (inversion) of opposite polarities from the differential amplifier 7 are supplied to one and the other input ends of the switch circuit 8. On the other hand, the output of the multiplication circuit 3 is supplied to the bandpass filter 9 to extract a 30 kHz signal component, which is supplied to the detection circuit 10 and detected. Then, when the detection circuit 10 detects the signal S _{I of} 30 kHz, the switch circuit 8 is switched to obtain an output of the opposite polarity to that used so as to control the capstan motor. Is.

The same applies to the other rotary head HA.
Frequency from the oscillator circuit 4_AThe signal of is supplied to the multiplication circuit 3.
If it is configured to supply_B-F_A= 15 kHz, f
_D-F _A= 45kHz pilot signal of adjacent track
Since it is obtained as an output, the difference between both pilot signal outputs is
It may be controlled so that it becomes zero. In this case, f_C-F
_A= When the signal of 60 kHz is detected, reverse the control direction.
To do. Note that the tracking system is used for one of the rotary heads.
As a result, the other head has a certain function with respect to the other head.
Because I am in charge, I do not have to perform tracking control
Good.

[0014]

By the way, in the case of the above method, since a relatively low frequency signal is used as the pilot signal, it is difficult to erase and the previously recorded portion is erased. When performing new recording again, there arises a disadvantage that the previous signal remains. Further, although it depends on the modulation method, when the information signal to be recorded has a spectrum in the low frequency region like the PCM signal, it is difficult to separate the pilot signals. Furthermore, since four types of frequencies are used as pilot signals,
There is also a drawback that the configuration becomes complicated.

In view of the above points, the present invention intends to provide a rotary head for tracking control of the rotary head for reproduction utilizing only the reproduction output of the rotary head for reproduction, which does not cause the above-mentioned drawbacks. Is.

[0016]

[Means and Actions for Solving the Problems] A PCM signal can be easily compressed / decompressed on the time axis. Therefore, unlike an analog signal, it is not necessary to record and reproduce the signal continuously in time. Therefore, it is possible to easily record this PCM signal and a signal separate from this by dividing the area into one track. The present invention utilizes this fact, and records a pilot signal for tracking control as the separate signal and devises the recording mode of the pilot signal.

In the present invention, the digital signals are transmitted by the rotary heads 11A and 11B to the diagonal tracks 14A,
14B recording medium 12 with no guard band formed
In the method of forming and recording on each track 14
At predetermined positions _AT where the distances from the longitudinal ends of A and 14B are equal, a tracking pilot signal is recorded on every other track as a recording area independently of the digital signal.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Several embodiments of the present invention will be described below with reference to the drawings. The example shown below is a case where there are two rotary magnetic heads and the following rotary head device is used.

First, regarding this rotary magnetic head device,
As will be described with reference to FIG. 3, the rotary magnetic heads 11A and 11B are arranged at equal angular intervals, that is, at angular intervals of 180 degrees. On the other hand, the magnetic tape 12 is the tape guide drum 1
It is wound over a range of, for example, 90 degrees that is narrower than the 180 degrees of the peripheral surface of No. 3. Then, the rotary heads 11A and 11B move at the rate of 30 revolutions per second and the arrow 15
The tape 12 is rotated in the direction of H and the tape 1
5T is run at a predetermined speed, and the rotary heads 11A and 11B move the magnetic tapes 12A and 14B on the magnetic tape 12 one by one as shown in FIG.
Are formed in a so-called overwritten state, for example. That is, the width (scanning width) W of the head gap is made larger than the track width. In this case, head 1
The width directions of the gaps 1A and 11B are different from the direction orthogonal to the scanning direction. That is, the so-called azimuth angles are made different.

According to the above rotary head device, there occurs a period in which the two rotary heads 11A and 11B are not in contact with the tape 12 (in this example, a period corresponding to an angular range of 90 degrees). If the redundant data is added at the time of recording and the correction process is performed at the time of reproduction by utilizing this period, the device can be simplified.

Then, in this case, as shown in FIG. 4, each of the tracks 14A and 14B is divided into a recording area A _P for the PCM signal and a recording area _AT for the tracking signal indicated by hatching. In the present invention, the method of recording the pilot signal for tracking control is devised in the recording area _AT of the tracking signal as in some examples described below.

Hereinafter, a case where an audio signal is recorded by PCM will be described as an example. 5 to 10 are diagrams for explaining an example thereof. FIG. 5 shows an example of the recording system,
The audio signal S _A is supplied to the A / D converter 22 through the input terminal 21 and becomes a digital PCM signal.
This digital signal is supplied to the recording encoder 23.
In the recording encoder 23, a signal to be recorded as one track (referred to as a signal for one segment), that is, in this example, a digital audio signal for each half rotation period of the rotary heads 11A and 11B is sent to the head. Time compression is performed for a period slightly shorter than the tape contact period, and error correction code generation and addition, interleave processing, and the like are performed.

The output signal of the recording encoder 23 is supplied to the recording processor 24 to add a block synchronizing signal, address data, etc. to a block for each of a plurality of words and to modulate it into a signal suitable for recording and reproduction. ..
The PCM signal from the recording processor 24 is recorded in the recording area A.
It is supplied to a switch circuit 26 for switching between _P and _AT .

The switch circuits 26 and 25 are switched by the switching signal S ₁ (FIG. 6A) and the switching signal S ₂ (FIG. 6C) from the timing signal generating circuit 28. In this case, a signal indicating the rotational phase of the rotary heads 11A and 11B is supplied to the tamming signal generation circuit 28. That is, in the case of this example, the timing signal generating circuit 28 includes the head 11A from the pulse generator 17,
30 Hz indicating the rotation phase of the rotary heads 11A and 11B obtained in synchronization with the rotation of the rotation driving motor 16 of 11B.
Pulse PG is supplied. Further, the pulse PG and the 30 Hz pulse from the timing signal generation circuit 28 are supplied to the phase servo circuit 29, and the rotation phase of the motor 16 is controlled by the servo output.

Therefore, the switching signals S ₁ and S ₂ are synchronized with the rotation of the rotary heads 11A and 11B, and as shown in FIG. 6B, during the half rotation period t _A of the head in which the signal S ₁ is at the high level, the heads are rotated. 11A is in contact with the tape 12, and the head 11B is in contact with the tape 12 within the half-rotation period t _B when the signal S ₁ is at a low level, and the signal S ₂ is a little at the beginning of each contact period. It is made to be high level during the period τ of.

The switch circuit 26 then switches the switching signal S ₁
As a result, the head is switched by switching to the state shown in the figure in the period t _A and to the state opposite to the state shown in the figure in the period t _B. Further, the switch circuit 25 is switched by the switching signal S ₂ to the state shown in the figure when the signal S ₂ is at the low level and to the state opposite to the state shown in the figure when the signal S ₂ is at the high level.

Therefore, except the period τ at the beginning of the contact period of the heads 11A and 11B within the periods t _A and t _B ,
Since the switch circuit 25 is switched to the state shown in the figure, the recording processor 2 is switched according to the switch of the switch circuit 26.
An audio PCM signal for one segment from 4 is supplied to the head 11A through the amplifier 27A during the period t _A , and is supplied to the head 11B through the amplifier 27B during the period t _B , so that each track 14A and track 1 is supplied.
This is recorded in the recording area A _{P of} 4B (see FIG. 6E).

Then, the switch circuit 25 is switched to a state opposite to the state shown in the figure in the period τ at the beginning of the contact period of the heads 11A and 11B. At this time, the signal from the switch circuit 33 is supplied to the switch circuit 26 through the switch circuit 25. The switch circuit 33 is supplied with the pilot signal P from the oscillator 31 having the oscillation frequency f ₁ and the erasing signal E of the pilot signal P from the oscillator 32 having the oscillation frequency f ₂ , and is switched from the timing signal generating circuit 28. It is selectively switched by the signal S ₃ .

The frequency f ₁ of the pilot signal P is a value with a relatively small azimuth loss, for example 100 kHz to 5
The recording frequency is set to about 00 kHz and is recorded at a relatively high level.

The erasing signal E indicates that the recording track always coincides with the previous recording track when the new recording is performed on the previously recorded tape after the previous recorded information is overlaid on the tape and erased. It is used because it is necessary to erase the previously recorded pilot signal, and its frequency f ₂ is sufficiently far from the frequency f ₁ for practical purposes, and the pilot signal is It is a value that can erase P. Also, the recording level of the pilot signal P can be practically erased.

The switching signal S ₃ of the switch circuit 33 is shown in FIG. 6D.
As shown in FIG. 5, the switch circuit 33 is a signal which becomes a high level only in the period τ at the beginning of the contact period of the head 11A in the period t _A , and the switch circuit 33 shifts to the pilot signal P side from the oscillator 31 only in this high level period. Can be switched. In this case, in this example, the high level period of this signal S ₃ is
The length of the period τ / 3 is set, and the length of the period τ is at the center of the period τ.

Therefore, in the middle period of τ / 3 within the period t _A , the pilot signal P from the oscillator 31 is generated.
Is recorded by the head 11A at the center position (shown by hatching in the figure) of the recording area _AT of every other track 14A as shown in FIG.

Further, since the switch circuit 33 is in the state shown in the figure except the period of τ / 3 in the middle of the period τ in the period t _A , the erasing signal E from the oscillator 32 is transmitted to the head 11A as shown in FIG. Are recorded before and after the pilot signal recording position in the recording area _AT of the track 14A (see FIG. 6E).

On the other hand, during the period τ within the period t _B , the switch circuit 25 is switched to the side of the switch circuit 33, but since the switch circuit 33 is still switched to the state shown in the figure, the switch circuit 25 remains within the period t _B. During the initial period τ of the contact period of the head 11B, the erasing signal E is applied to the head 1
1B (see FIG. 6E), and only the erasing signal E is recorded over the entire area _AT of the track 14B as shown in FIG.

In the case of this example, the recording positions of the pilot signals are track 14A, 14B, as is clear from FIG.
When viewed in a direction orthogonal to the longitudinal direction, the two do not overlap with each other. As a technique for this, a technique for aligning the recording position of the horizontal synchronizing signal of the video signal in the direction perpendicular to the longitudinal direction of the track in the VTR can be applied. In this example, assuming that the length of the tape 12 in the longitudinal direction corresponding to the period of τ / 3 is d, the position of the end of each track between the adjacent tracks 14A and 14B is d in the longitudinal direction of the track. It is made different only by / 2.

Next, reproduction of the signal recorded as described above will be described. FIG. 8 shows an example of the reproducing system. Although not shown, the motor 16 is subjected to drum phase servo in the same manner as during recording.

The signals extracted from the tape 12 by the rotary heads 11A and 11B are head amplifiers 41A and 4A.
It is supplied to the switch circuit 42 via 1B. This switch circuit 42 is provided with the timing signal generation circuit 28
With the switching signal S ₁ ′ of Hz, the head 11
A half rotation period including the tape contact period of A, and the head 11B
And a half rotation period including the tape contact period. Therefore, from this switch circuit 42, as shown in FIG.
An intermittent PCM signal such as E is obtained for each segment, and this is supplied to the reproduction processor 43, and the original P
The CM signal is demodulated and supplied to the decoder 44. In the decoder 44, data for each block is detected by the block synchronization signal, and error correction, de-interleaving and the like are performed. The PCM signal from the decoder 44 is supplied to the D / A converter 45,
The analog audio signal is returned to the output terminal 46.

Tracking control is performed as follows. That is, the signal obtained by the switch circuit 42 is supplied to the gate circuit 51. This gate circuit 51
Is supplied with a switching signal S ₁ ′ so that only the reproduction output from the head 11B is taken out.

Now, for example, when the head 11B scans a range of the scanning width W including the track 14B shown by the alternate long and short dash line in FIG.
Scanning is performed across the tracks 14A on both sides of 4B, and the pilot signal P is reproduced in the area _{AT as} shown in FIG. 9A. The reproduction output of the head 11B from the gate circuit 51 is supplied to a narrow band pass filter 52 having a pass center frequency f ₁ to extract only a pilot signal P, which is supplied to a detection circuit 53 for detection. The detection output is sampling and holding circuits 54A and 54B.
Is supplied to. Then, from the timing signal generation circuit 28, a sampling pulse SP of 30 Hz is generated at any point within a period corresponding to a range in which the distance from the position of the end of the track 14B is larger than d and smaller than 3d / 2.
₁ (FIG. 9B) is obtained and is supplied to the sampling and holding circuit 54A.

From the generating circuit 28, the track 14
30 at any point within the period corresponding to the range from the end of B to more than 2d and less than 5d / 2
A sampling pulse SP _{2 of} Hz (C in the same figure) is obtained,
This is supplied to the sampling and holding circuit 54B.
As shown in FIG. 9A, the reproducing head 11B causes the track 14
When scanning over B, as is apparent from FIG. 9, the pulse SP ₁ is applied to the adjacent track 14 on the side opposite to the tape transport direction.
The crosstalk of the pilot signal P of A is sampled, and the tracking signal ST ₁ (FIG. 9D) of the lead phase is obtained from the sampling hold circuit 54A, and the pulse SP ₂ is the pilot of the adjacent track 14A on the tape transfer direction side. The sampling and holding circuit 54B becomes ready for sampling the crosstalk of the signal P.
A tracking signal ST ₂ (FIG. 9E) having a delayed phase can be obtained from.

These tracking signals ST ₁ and ST ₂
Is supplied to one and the other input ends of the differential amplifier 55 as a comparison circuit. Therefore, a difference between both inputs is obtained from the differential amplifier 55, which is supplied to a capstan motor (not shown) to control the tape transfer amount,
The level difference between the outputs ST ₁ and ST ₂ is zero, that is, the head 1
When 1B scans the track 14B, it is controlled so as to straddle the two tracks 14A on both sides by the same amount. That is, the center position in the width direction of the gap of the head 11B is controlled so as to match the center position of the track 14B for scanning.

On the other hand, when the head 11B erroneously scans over the width W so as to include the track 14A during reproduction, the recording area A _T is in a scanning state as shown in FIG. 10A. Then, at this time, the pulse SP ₁ (B in the figure) is in a state of sampling the reproduction output of the pilot signal P of the track 14A, and the output ST ₁ (D in the figure) is obtained at a high level. However, the pulse SP ₂ becomes zero because there is no reproduction output of the pilot signal P at the corresponding reproduction time point, and the lead phase tracking signal is obtained at a high level on the output side of the differential amplifier 55 in this case, and the head 11B scans. The amount of tape transfer is controlled so that the position is largely changed and the track 14B is correctly scanned.

In the above example, the crosstalk of pilot signals from both adjacent tracks is sampled and held at different points in time, but sampling can be performed at the same point in time as follows. 11 to 16 are diagrams for explaining the example, and FIG. 11 is a recording system,
FIG. 14 shows an example of each reproducing system.

In this example, in the example shown in FIG.
As the switching signal of the path 25, its pulse width, that is,
The length of the beginning of the contact period of the heads 11A and 11B
(Area A_TCorresponding to 3d in the example of FIG.
Longer than, for example, a period τ corresponding to 4d₁Signal S_{twenty one}
(FIG. 12C). Then, the area A of the track 14A
_TAs shown in FIG. 13, the recording area of the pilot signal of
and the erasing signal E is recorded for the length of d before and after that.
It Area A of track 14B_TErase signal E only
Recording is the same as in the above example. And in this example
Therefore, the frequency f is used as the pilot signal.₁₁The pilot of
Signal P₁And frequency f₁₂Pilot signal P ₂Alternating with
Switch to record.

That is, in FIG. 11, the oscillator 31 ₁
From the pilot signal P ₁ of frequency f ₁₁ from the oscillator 31 ₂
And the pilot signal P ₂ of frequency f ₁₂ from The switch circuit 34 is switched for each rotation of the head 11A by a signal S ₄ (FIG. 12E) obtained by dividing the head switching signal S ₁ (FIG. 12A) by 1/2. Further, in this example, the area _{AT of the} track 14A is
, The pulse width of the switching signal of the switch circuit 33 which divides into the recording area of the pilot signal and the erasing signal area is the signal S ₃₁ (with the same pulse width as the central length 2d of the period τ ₁ within the period t _A (see FIG. E). The others are constructed in exactly the same way as the example of FIG.

Therefore, in this example, FIG.
In a period t _A, as shown in, become the pilot signals P ₁ to times the length of the example of the region A _T 5 and the P ₂ are recorded alternately recorded traces figures in this area A _T As shown in FIG. That is, when viewed from the direction orthogonal to the longitudinal direction of the tracks, the recording area of the pilot signal of each track is overlapped with the recording area of the adjacent pilot signal by a length of d.

Tracking control during reproduction in the case of this example is performed as follows. That is, the reproduction output of the head 11B from the gate circuit 51 is supplied to the bandpass filter 52 ₁ having the pass center frequency f ₁₁ and the bandpass filter 52 ₂ having the pass center frequency f ₁₂ .

In FIG. 13, the head 11B is the track 1
When scanning the range of the scanning width W including 4B, the pilot signals P ₁ and P ₂ are obtained from the tracks 14A on both sides of the track 14B as shown in FIG. 15A, but 3d / 2 from the end of the track 14B. In the range larger than 5d / 2 and smaller than 5d / 2, both crosstalk signals of the pilot signals P ₁ and P ₂ can be obtained.

Therefore, the crosstalk component of the pilot signal P ₁ is obtained from the bandpass filter 52 ₁ .
This is supplied to the detection circuit 53 ₁ and detected, and the detection output is supplied to the sampling and holding circuit 54A.
Further, the crosstalk component of the pilot signal P ₂ is obtained from the bandpass filter 52 ₂ , and this is the detection circuit 53.
₂ is detected and detected, and the detected output is supplied to the sampling and holding circuit 54B.

Then, the sampling pulse SP ₀ (see FIG. 1) within the period in which the pilot signal P ₁ and the pilot signal P ₂ are simultaneously obtained from the timing signal generating circuit 28.
5B) is obtained, and this is the sampling and holding circuit 54.
Supplied to both A and 54B. Therefore, the difference between the sampling and holding outputs ST ₁ and ST ₂ (FIGS. 15C and 15D) of the detection outputs of the pilot signals P ₁ and P ₂ is obtained from the differential amplifier 55. However, in the case of this example, since the relationship between the lead phase and the lag phase is reversed between the pilot signals P ₁ and P _{2 for} each one of the tracks 14B, the differential amplifier 55 outputs the same phase to the output end 56A. The output signal is obtained and the output signal of the opposite phase is obtained at the output end 56B, and these output signals are switched every one rotation.

Although not shown, the switching may be performed, for example, depending on whether the pilot signal output in the reproduction signal of the head 11A in the preceding half rotation period is the signal P ₁ or P ₂ . That is, this pilot signal P pilot signal P ₁ being reproduced signal of the head 11B _{when 1} will be obtained in phase advance, the pilot signal P ₂ becomes a delayed phase in the reproduced signal of the head 11A in a half rotation period before, Head 11A in the previous half rotation period
This is because when the pilot signal P ₂ is obtained in the reproduction signal of, the relationship is reversed.

The head 11B mistakenly moves the track 14A
A situation in which a part of the tracks 14B on both sides is scanned in my mind.
Area A when in a state_TThe scanning locus in the vicinity is as shown in Fig. 16A.
Becomes, sampling pulse SP₀(Fig. B)
14A pilot signal P ₁Or P₂Only sun
Will be pulled and output ST₁(Figure C) Yes
I output ST₂Is only (D in the same figure) high level?
, The tape transfer amount is greatly changed, and the head 11B
So that the head 14B can be pulled back to the state of being properly scanned.
Done

The above example is the case where the reproduction output of one of the two heads is used for tracking error detection. This is because, as described above, the two heads are fixedly attached to the drum, so that if one head correctly tracks, it can be considered that the other head also tracks almost correctly. Because.

However, more accurately, it is better to perform tracking control for both of the two heads. 17 to 21 show an example of such a case. That is, FIG. 17 shows the recording system of FIG.
8 is a time chart for the explanation, and FIG. 19 is area A.
It is a figure which shows the recording pattern of _T vicinity.

In this example, as shown in FIG. 19, the track 14A is recorded with the pilot signal P of the frequency f ₁ within the range from the end of the track 14A to d to 2d. Although the same as the example shown as 10, the pilot signal P'of the frequency f ₁ is also recorded on the track 14B within the range of 3d to 4d from the end in this example. Therefore, the length of the tracking signal area _AT is 5d from the track end portion for one track in this example, including the area of the erasing signal E.

The recording system of FIG. 17 will be described. This is almost the same as that of FIG. 5, but the switching signal of the switch circuit 25 for determining the length of the area _AT corresponds to the length of 5d. The signal S _{22 having the} pulse width τ ₂ (FIG. 18B) is used, and the switching signal of the switch circuit 33 that determines the recording position of the pilot signal in the area _AT is the period τ within the period t _{A.
In 2} the distance from the end of track 14A is d to 2
A signal S _{32 which} is at a high level for a period corresponding to the range up to d
(FIG. 18C) and a signal S ₃₃ (FIG. 18D) that is at a high level for a period corresponding to a distance from the end of the track 14B in the range of 3d to 4d in the period τ ₂ within the period t _B. The OR output is obtained by being supplied to.

[0057] Thus, the contact period in these heads 11A, signals supplied to 11B of each head 11A and 11B becomes as shown in FIG. 18E, the recording pattern shown in Figure 19 described above in the area A _T .. In the case of this example, the tracking control during reproduction is performed not only based on the error signal from the head 11B but also based on the error signal from the head 11A.

A reproduction signal output from the head 11B (see FIG. 21)
5A), sampling pulses SP ₁ and SP ₂ (FIGS. 21D and E) are transmitted to the sampling and holding circuit 54 through OR gate circuits 57 and 58 as in the example of FIG.
By being supplied to A and 54B, a tracking error signal is obtained in exactly the same manner as in the example of FIG. 5, and tracking control for the head 11B is performed.

On the other hand, regarding the reproduction signal output from the head 11A (see A in the same figure), a sampling pulse SP ₃ for sampling the crosstalk signal of the pilot signal P'from the two tracks 14B adjacent to the track 14A. And SP ₄ (B and C in the figure) are connected to the sampling and holding circuit 54A through OR gates 57 and 58.
And 54B, a tracking error signal is obtained at the output of the differential amplifier 55 in the same manner as for the head 11B, and tracking control for the head 11A is performed.

As described above, in the present invention, the PCM in which the pilot signal for tracking control is to be recorded.
Since it is recorded on the same track as the signal but on a different area, it is easy to detect this pilot signal during playback, and at a later point in time, new recording information is recorded over the previous recording information. In this case, the area is different from the PCM signal and the pilot signal frequency can be relatively high, so that there is an effect that it can be easily erased.

In the above three examples, the timing signal generating circuit 28 is supplied with the pulse PG from the pulse generator 17 as a signal indicating the rotational phase of the rotary heads 11A and 11B. For example, without using the pulse generator 17, the rotary head 11A or 11 is used in a tape stopped state, for example, before recording or reproducing.
It is also possible to record a predetermined signal by B and reproduce it to detect the time point at which the head 11A or 11B starts contact with the tape, and use the detected signal. Further, in the case of the examples of FIGS. 17 to 21, the sampling pulses SP _{1 to} SP ₄ may be formed by utilizing the reproduction output timing of the pilot signal of the track to be scanned.

In the above example, the number of rotary heads is two, but in the present invention, the track on which the pilot signal is recorded and the track portion on which the pilot signal is not recorded may be alternated for each track. Therefore, the number of rotary heads may be one or two or more.

In the above example, the rotary head device is a special one in which the tape is wound and recorded / reproduced over an angle range narrower than the head angle interval. It is needless to say that the present invention can be applied to the case of using the rotary head device for winding.

Further, the tracking signal area A _T is not limited to the track end portion as in the example shown in the figure. Further, the tracking area _AT may be provided at two or more locations per track, for example, at both ends of the track, and further at the center.

[0065]

As described above, according to the present invention,
Since the pilot signal for tracking control is recorded in a different area on the same track as the digital signal to be recorded, it is easy to detect this pilot signal during reproduction. Further, since the pilot signal frequency can be arbitrarily selected, when the new recording information is recorded on the previous recording information at a later time, it is easy to erase the pilot signal recorded previously.

Further, unlike the conventional example described in FIGS. 1 and 2, unlike the conventional example in which four types of pilot signal frequencies are required, in the case of the present invention, the frequency of the pilot signal includes the erasing signal. However, since two or three types may be used, there is an advantage that the configurations of the recording system and the reproducing system are simplified.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a track pattern of an example of a conventional tracking control system.

FIG. 2 is a system diagram of an example of a tracking control method during reproduction.

FIG. 3 is a schematic diagram showing an example of a rotary head device used in an embodiment of the present invention.

FIG. 4 is a schematic diagram showing an example of a recording track pattern of the embodiment.

FIG. 5 is a block diagram showing an example of a recording system according to an embodiment.

FIG. 6 is a timing chart for explaining an example of a recording system according to an embodiment.

FIG. 7 is a schematic diagram showing another example of the track pattern of the embodiment.

FIG. 8 is a block diagram showing an example of a reproduction system according to an embodiment.

FIG. 9 is a timing chart used to describe an example of a reproducing system according to an embodiment.

FIG. 10 is a timing chart used to describe an example of a reproducing system according to an embodiment.

FIG. 11 is a block diagram showing another example of the recording system of the embodiment.

FIG. 12 is a timing chart used to explain another example of the recording system of the embodiment.

FIG. 13 is a schematic diagram showing another example of the track pattern of the embodiment.

FIG. 14 is a block diagram showing another example of the reproducing system of the embodiment.

FIG. 15 is a timing chart used for explaining another example of the reproducing system of the embodiment.

FIG. 16 is a timing chart for explaining another example of the reproducing system of the embodiment.

FIG. 17 is a block diagram showing still another example of the recording system of the embodiment.

FIG. 18 is a timing chart used for explaining yet another example of the recording system of the embodiment.

FIG. 19 is a schematic diagram showing still another example of the track pattern of the embodiment.

FIG. 20 is a block diagram showing still another example of the reproduction system of the embodiment.

FIG. 21 is a timing chart for explaining yet another example of the reproducing system of the embodiment.

[Explanation of symbols]

11A rotating head 11B rotating head 12 tape 22 A / D converter 31 pilot signal oscillator 32 erasing signal oscillator 45 A / D converter 55 differential amplifier as a comparator for obtaining a tracking error signal A _P PCM signal recording area A Recording area for _T tracking signal

Claims (1)

[Claims] 1. A method of recording a digital signal by forming a diagonal track on a recording medium with a rotary head without forming a guard band, and recording the digital signal at a predetermined position where the distance from the end of each track in the longitudinal direction is equal. In the method of recording a digital signal, a tracking pilot signal is recorded on every other track as a recording area independently of the digital signal.