JPH03216844A - Tracking device for dat - Google Patents

Abstract

PURPOSE:To suppress the variance of the gain of tracking servo even in the case of the difference of the level of the pilot signal, which is recorded at the time of sound-recording, between recorders by detecting the recording level of the pilot signal scanned at present and adjusting the gain of a servo loop based on this detected level. CONSTITUTION:A sampling pulse SP2 obtained by delaying a sampling pulse SP1, which is outputted at the time of detecting a synchronizing signal recorded in an ATF(automatic track finding) area, by a prescribed time is delayed by the same time to generate a sampling pulse SP3, and the level of the pilot signal recorded on a track traced at present is kept by this sampling pulse SP3. The loop gain of the feedback control is adjusted in accordance with the kept level of the pilot signal. Thus, the variance of the gain of tracking servo is suppressed though the level of the pilot signal recorded at the time of sound-recording is different by recorders, and the disturbance of head tracking for reproducing is eliminated to prevent the degradation of the error rate and sound breaks due to detracking.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a DAT tracking device, and more particularly to a DAT tracking device that can perform accurate tracking even if the model that recorded the magnetic tape is different from the model that reproduces it. Regarding.

DAT is a digital audio tape recorder (Da
digital audio tape recorder)
It is an abbreviation for digitizing sound waveforms into binary numbers of "1" and "0" and recording and reproducing them on recording tape. This DAT includes a fixed head type S-DAT and a rotating head type R-DAT, but the R-DAT has been commercialized and is becoming more popular in recent years.

The commercialized R-DAT is a VTR (video tape 7”
It uses a helical scan method similar to that used in recorders (recorders), and uses two heads with different azimuths attached to a rotating drum at 180 degrees to alternately scan the magnetic tape diagonally to the running direction of the magnetic tape. track). Therefore, during reproduction, the track must be traced using a head with the same azimuth as the head that recorded the signal, and the DAT (hereinafter all DATs will refer to R-DAT) requires a tracking device.

Tracking in DAT is different from the control track method (tracking method using a control track provided at the edge of the magnetic tape and a fixed head) that has been generally performed in rotating head type magnetic recording/reproducing devices. A tracking signal is included in the signal recorded on the track of
TrackFinding) method is adopted.

This ATF method uses a recording/reproducing head that is slightly wider than the track width recorded by the rotating head, and during recording, the two heads are overlapped with each other while recording a tracking signal to form a track narrower than the head width. During playback, a narrow track is traced with a wide head, and tracking adjustment is performed so that the tracking signals leaking from both tracks are at the same level.

However, if the recording level is higher or lower than the standard recording level due to variations in head sensitivity, recording current, etc. of signal recording models, tracking adjustment may not be successful, and an improvement in this situation is desired.

[Prior Art] FIG. 10 shows the area-divided track format of a conventional DAT. In a DAT, various signals are written on one track by dividing areas (locations). In the center of the track is an area for recording main audio data, and of several areas on both sides of the area, areas indicated by ATF1 and ATF2 are areas for tracking error detection. ATFI and ATF2
In the area indicated by, there is a pilot signal indicated by f1, and f
A sync signal indicated by 2 and f3 is recorded in different predetermined patterns on (±) azimuth track A and (=) azimuth track B during recording.

Next, regarding the tracking adjustment during playback using the areas indicated by ATFI and ATF2, the synchronization signal is S.
The pilot signal is indicated by P and will be explained using FIGS. 11 and 12. Generally, a pilot signal P and a synchronization signal S are recorded in the ATF area in a pattern as shown in FIG. The pilot signal P is recorded at a low frequency with a long recording wavelength, and the head H can also pick up pilot signals of adjacent tracks with different azimuths. On the other hand, the synchronization signal S is recorded at a high frequency with a short recording wavelength, and the synchronization signals of adjacent trunks with different azimuths cannot be surprised by the recording/reproducing head H. Furthermore, recording signals cannot be reproduced using heads with different azimuths; for example, A with a +azimuth
The head reproduces the recorded signal of track A, and the B head having one azimuth reproduces the recorded signal of trunk B.

Furthermore, the width of the recording/reproducing head H of the DAT is wider than the width of one track, and when the head H scans over the track B in the direction shown by the arrow F, a portion L protrudes from the contact track A of the head H. 、． The pilot signal P recorded on the adjacent trunk A is detected by L2.

FIG. 12 shows the configuration of a conventional tracking adjustment device connected to a recording/reproducing head H of a DAT. In the figure, 91 is a magnetic tape, 92 is a capstan, and 93 is a cabstan motor. A signal detected by the head H is amplified by an RF amplifier 94 and sent to a tracking error detection circuit 90. The tracking error detection circuit 90 includes a sync detection circuit 16 that detects the sync signal S, and when the head H reproduces the sync signal S, the pulse generator 16a of the sync detection circuit 16 outputs a sampling pulse SPI. This sampling pulse S
PI is delayed by a predetermined time by the delay circuit 17 and becomes the sampling pulse SP2. The tracking error detection circuit 90 also includes a low pass filter (LPF) 11 that passes the pilot signal P, a level detection circuit 12 that detects the level of the pilot signal P that has passed through the LPFII, and a sampling pulse that converts the output of the level detection circuit 12 into A sample hold (S/H) circuit 13 held by SPI,
An adder circuit 14 that subtracts the output of the S/H circuit 13 from the output of the level detection circuit 12, and an S/H circuit 15 that holds the output of the adder circuit 14 using a sampling pulse SPI.
There is. In this example, the output of the tracking error detection circuit 90 is feed-hacked to the cab stan motor 93 via a motor dryer 95.

Tracking error detection circuit 9 configured as above
0, when the sync detection circuit 16 detects the synchronization signal S and generates the sampling pulse SPI, the hesode H
The level of the Pyro 7} signal P of the track on the right which is being detected is held in the S/H circuit 13. Then, the level of the pilot signal P of the adjacent track on the left detected by the head at that time and the level of the pilot signal P of the adjacent track on the right held in the S/H circuit 13 are determined by the sampling pulse SP2 generated after a predetermined time. The difference is held in the S/H circuit 15.

When head H is scanning the exact center of the track (
When tracking is achieved), the amounts L, , L2 of the head H protruding to the right and left sides are the same, so the sampling pulses SPI, SP are applied as shown in Fig. 10.
The levels of the pilot signals (indicated by f1 in this figure) on both sides obtained by 2 are the same, and the output of the tracking error detection circuit 90 becomes O. However, when the head H shifts to one of the tracks, the level of the pilot signal of the track that has shifted becomes large, the level of the pilot signal of the other trunk becomes small, and the output voltage E, which is approximately proportional to the amount of tracking error, increases. It is obtained from the tracking error detection circuit 90.

Here, L,,L. is the distance between both adjacent tracks and the head, α2 is the playback head sensitivity, playback amplifier gain, α,
Assuming that is the pilot signal recording level, the output voltage E of the tracking error detection circuit 90 is expressed by the following equation.

E=α,・αa(L+Lz)...■ And the amount of change ΔET in the output voltage E with respect to the change in the starting voltage ΔL,, ΔL2 is ΔET-α,・αR (ΔL, -ΔL.)...・Represented by ■, where ΔLI, ΔL2〉0, ΔL, - Δ
L2...■ The following relationship holds true. Substituting the ■formula into the ■formula, ΔE. =
2ΔL+ ・α, ・αeh...■. Since the change in margin ΔL1 is equal to the change in tracking error, the change in tracking error output with respect to the change in tracking error (transfer function of the detector) ΔET/ΔL, is ΔEa/ΔL1−2ΔL1 ・α, ・αE...・It becomes ■. This means that the closed loop gain constructed using the tracking error detector changes depending on the pilot signal recording level of the magnetic tape used during reproduction.

[Problem to be solved by the invention] However, although the upper limit of the pilot signal level is determined by the calibration tape,
If there are variations depending on the recorder, this will lead to variations in the gain of the tracking servo of the playback machine. If the gain is too high, the tracking servo will tend to oscillate,
There is a problem in that the head scanning trajectory is disturbed, and even if the gain is low, the head trajectory is disturbed due to disturbance, resulting in worsening of the error rate and, in extreme cases, sound cut-out.

The present invention was made by paying attention to the fact that pilot signals are also recorded in the scanning track in the ATF area mentioned above. In other words, as long as the head extends far beyond both adjacent tracks, the pilot signal of the track being scanned can be completely picked up, so the accurate recording level of the pilot signal can be detected, and based on this detection level. The present invention attempts to adjust the gain of the servo loop.

Therefore, an object of the present invention is to solve the problems in tracking of the conventional DAT, and to suppress fluctuations in the gain of the tracking servo even if the pilot signal level recorded during recording differs depending on the recorder. DAT that eliminates disturbances in the head trajectory during playback, prevents deterioration of error rate, and prevents sound dropouts due to off-track.
The objective is to provide a tracking device for

[Means to solve the problem]

The structure of a first form of a DAT tracking device of the present invention that achieves the above object is shown in FIG. 1(a). As shown in this figure, the present invention outputs a sampling pulse SPI when a synchronization signal S recorded in a predetermined pattern in the ATF area of the DAT is detected, and this sampling pulse SPI
detects the level of the pilot signal P recorded on the track on the right of the track currently being traced, and detects the level of the pilot signal P recorded on the track on the left using the sampling pulse SP2, which is obtained by delaying the sampling pulse SPI by a predetermined time. This is a DAT tracking device that detects the level and performs tracking adjustment to eliminate the difference between the two levels, and the delay circuit 1 delays the sampling pulse SP2 by the same amount as the predetermined time to create the sampling pulse SP3, and then masks the The signal generation circuit 2 generates a mask signal SW2 based on a head switching signal that switches the output of two heads attached to the drum or a signal SWI related to the drum rotation phase, and the sample hold circuit 3 generates a mask signal SW2 based on a signal SWI related to the drum rotation phase. The level of the pilot signal recorded on the track is stored, and the switching circuit 4 cuts off the input of the sampling pulse SP3 to the sample hold circuit 3 in accordance with the mask signal SW2. Then, the gain adjustment circuit 5 adjusts the loop gain of the feed hack control according to the output of the sample hold circuit 3.

The second embodiment of the DAT tracking device of the present invention is the first embodiment.
This is shown in Figure (5). This type of bag holder is also DAT's ATF.
When a synchronization signal S recorded in a predetermined pattern in the area is detected, a sampling pulse SPI is output, and the level of the pilot signal P recorded in the track to the right of the track currently being traced is detected by this sampling pulse SPI, and Detecting the level of the pilot signal P recorded in the adjacent track on the left by the sampling pulse SP2, which is obtained by delaying the sampling pulse SPI by a predetermined time,
This is a DAT tracking device that performs tracking adjustment to eliminate the difference between two levels, in which a pilot peak holding circuit 6 holds the peak value of the level of a pilot signal P read out by the head, and a gain adjustment circuit 5 controls this pilot peak. The loop gain of feedback control is adjusted according to the output of the holding circuit 6.

[Operation] According to the first embodiment of the present invention, the sampling pulse SP2, which is obtained by delaying the sampling pulse SPI outputted at the time of detection of the synchronization signal S recorded in the ATF area of the DAT by a predetermined period of time, is further delayed by the same period of time. A sampling pulse SP3 is created, and this sampling pulse SP3
The level of the pilot signal recorded on the track currently being traced is held. Then, the loop gain of feedback control is adjusted according to the level of the held pilot signal. In this way, since the level of the pilot signal on the track currently being traced is read, the level of the pilot signal actually recorded during tracing is faithfully read by the head, and the loop gain of feedback control is determined by this level. Adjustable.

Further, in the second embodiment, the pilot signal level is detected by the peak value of the pilot signal, and the loop gain of feedback control can be adjusted based on the detected level.

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

FIG. 2 shows the configuration of a tracking adjustment device according to an embodiment of the present invention connected to a recording/reproducing head H of a DAT.
The same members as in the conventional device shown in FIG. 12 are given the same reference numerals. Also, the magnetic tape, cab scan, cab stan motor, and head are not shown in Figure 2.
The signal detected by the head from the output portion of the RF amplifier is shown.

The tracking error detection circuit 20 to which the output from the RF amplifier is input includes a tracking error detection circuit 90 having the same configuration as the conventional device, a sync detection circuit 16 that detects the synchronization signal S, and a pulse generation circuit that detects the synchronization signal S. a sink detection circuit 16 that outputs the sampling pulse SPI from the section 16a; and a delay circuit l7 that delays the sampling pulse SPI by a predetermined time to generate the sampling pulse SP2.
, an LPF (low pass filter) 11 that passes the pilot signal P, and a pilot signal P that has passed through the LPF 11.
A level detection circuit 12 detects the level of the level detection circuit 12, an S/H (sample hold) circuit 13 holds the output of the level detection circuit 12 using a sampling pulse SPI, and the output of the S/H circuit 13 is subtracted from the output of the level detection circuit 12. An adder circuit 14 and an S/H circuit 15 that holds the output of the adder circuit 14 using a sampling pulse SPI are provided.

In this embodiment, the delay circuit 17 is provided with another delay circuit 21 having the same delay characteristics, and the sampling pulse SP2 is delayed by a predetermined time similar to that described above to produce the sampling pulse SP3. This sampling pulse SP
3 passes through the switching circuit 22 to the S/H [l2+ path 23
The S/H circuit 23 is configured to hold the output of the level detection circuit 12 using the sampling pulse SP3. switching circuit 2
2 is constituted by an analog switch in this embodiment, and when SW2 is a delayed signal (mask signal) of the head switching signal SWI delayed by a predetermined time by a delay circuit 28 and is at a low level, it is ONL and outputs a sampling pulse SP3.
is input to the S/H circuit 23, and operates to cut it off when it is at a high level.

The output of the S/H circuit 23 is input to the inverting input of the comparison circuit 24 and compared with the reference voltage V of the reference voltage generator 25. The output of the comparison circuit 24 is connected to an analog switch 26, which short-circuits the resistor R2 when turned on. This resistor R2 is connected to the S/H circuit 15
This is one of the series resistors R, , R2 for gain adjustment connected to the inverting input of the error amplifier 27 that amplifies the output of the error amplifier 27. Note that R0 is a feedback resistor of the error amplifier 27, and the output of the above-mentioned comparison circuit 24 becomes high level when the pilot signal level held in the S/H circuit 23 is lower than the reference voltage V. . Further, the output of the error amplifier 27 is fed back to a capstan motor (not shown) via a motor driver 95.

Next, the operation of the apparatus configured as described above will be explained using FIG. 3.

FIG. 3(a) shows the output waveform of the RF amplifier, and shows the output envelope of the A head and B head when signals are recorded all over track A and track B. Figure 3(b) shows the waveform of head switching signal S. In order to extract the output of the head that is always in contact with the magnetic tape, the output of head A is selected when the level is low, and the output of head A is selected when the level is high. This allows the output of the B head to be selected during leveling. FIG. 3(C) shows the waveform of the delayed signal (mask signal) S-2 which is delayed by the delay circuit 28 of this head switching signal SWI, and this signal SW2 is approximately 1/4 period of the signal SWI. The waveform is delayed.

Figures 3(d) to (f) show the detected values of the pie-in/white signals, the detected values of the synchronizing signal, and the sampling pulses included in the RF amplifier output shown in (a), with the time enlarged. It shows. Changes in the detected value of the Byrondo signal, the detected value of the synchronizing signal, and the sampling pulse will be explained below over time.

As shown in FIG. 10, when the A head scans the track A, the pilot signal f1 recorded in the ATFI area of the track A being scanned is first reproduced at a high level, and then the protruding portion of the head reproduces the pilot signal f1 recorded in the ATFI area of the track A being scanned. The pilot signal f1 is reproduced at a low level, and while the pilot signal f1 on the right is being reproduced, the synchronization signal f2 of the track A being scanned is being reproduced, and the synchronization signal f2 of the track A being scanning is being reproduced. When the reproduction is finished, the pilot signal f1 of the adjacent track on the left is reproduced at a low level.

At this time, by reproducing the synchronization signal f2, the sync detection circuit l
6 detects the synchronization signal f2 and outputs the sampling pulse SPI
occurs. This sampling pulse SPI is delayed by a predetermined time by a delay circuit I7, and the sampling pulse SPI is
P2, which is further delayed for a predetermined time by the delay circuit 21 and becomes the sampling pulse SP3. The sampling pulses SPI and SP2 cause the levels of the pilot signals f1 on the right and left to be adjusted to the S/H circuit 13 as in the conventional case.
．． It is held at 15. However, at this time, since the mask signal SW2 is at a high level, the switching circuit 2
2 is OFF, and sampling pulse SP3 is S/
It is not input to the H circuit 23.

After scanning the audio recording part, the A head moves to the AT of track A.
When the F2 area is scanned, the protruding portion of the head first reproduces the pilot signal fl on the right side at a low level, and then, while the pilot signal fl on the right side is being reproduced, the synchronization signal f2 of the track A being scanned is reproduced. , the pilot signal f1 on the right side and the synchronization signal f of the track A being scanned.
When the reproduction of track No. 2 is completed, the pilot signal f1 of the adjacent track on the left is reproduced at a low level. After this, ATF
The pilot signal f1 recorded in the second area is reproduced at a high level. At this time, the sync detection circuit 16 detects the synchronization signal f2 and generates the sampling pulse SPI,
This sampling pulse SPI is delayed by a predetermined time by a delay circuit 17 to become a sampling pulse SP2, and further delayed by a delay circuit 21 by a predetermined time to become a sampling pulse SP3. sampling pulse SPI
, SP2, the levels of the pilot signals f1 on the right and left are adjusted to the S/H circuit 13., SP2, as in the conventional case. It is held at 15. Also, at this time, since the mask signal SW2 is at a low level, the switching circuit 22 is ONL, and the sampling pulse SP3 is input to the S/H circuit 23 and the level of the pilot signal f1 recorded on track A is maintained. Ru.

Next, when the B head scans the ATFI area of track B, the protruding part of the head first reproduces the pilot signal f1 on the right side at a low level, and during this reproduction, the synchronization signal f3 of the track 8 being scanned is reproduced. be done. When the reproduction of the pilot signal f1 on the right side is completed, the pilot signal f1 on the adjacent track on the left is reproduced at a low level, and thereafter the pilot signal f1 recorded in the ATFI area is reproduced at a high level.

At this time, the sync detection circuit 16 similarly generates the sampling pulse SPI, the delay circuit 17 generates the sampling pulse SP2, and the delay circuit 21 generates the sampling pulse SP3.

The sampling pulses SPI and SP2 cause the levels of the pilot signals f1 on the right and left to be adjusted by the S/H circuit 13. It is held at 15. Also, at this time, since the delay signal SW2 of the head switching signal is at a low level, the switching circuit 22 is ONL, and the sampling pulse SP3 is manually input to the S/H circuit 23 to generate the pilot signal f1 recorded on track B. level is maintained.

After scanning the audio recording part, when the B head scans the ATF2 area, the pilot signal f1 recorded in the ATF1 area of the track B being scanned is first played back at a high level, followed by the pilot signal f1 on the right side being played back at a low level. During the reproduction, the synchronization signal f3 of the track B being scanned is reproduced.

When the reproduction of the pilot signal f1 on the right side is completed,
The pilot signal f1 of the adjacent track on the left is reproduced at a low level. Similarly, the sync detection circuit 16 generates a sampling pulse SPI, the delay circuit 17 generates a sampling pulse SP2, and the delay circuit 21 generates a sampling pulse SP3.

As in the conventional case, the levels of the pilot signals f1 on the right and left are adjusted by the sampling pulses SPI and SP2 to the S/H circuit 13. However, since the mask signal SW2 is at a high level at this time, the switching circuit 22 is OFF, and the sampling pulse SP3
is not input to the S/H circuit 23.

In this way, the levels of the pilot signals recorded on tracks A and B are detected, but since the head width is larger than the track width, the tracking error is smaller than a certain value, and the head moves to the adjacent tracks. The level of the pilot signal of the track being scanned by the head can be accurately detected even when the track is slightly touched. Therefore, by switching the gain of the pilot signal amplifier before sampling or the amplifier gain after sampling depending on the detected level, it is possible to easily reduce variations in the recording level of the pilot signal.

Therefore, when the level of the pilot signals recorded on tracks A and B, which are input manually from the S/H circuit 23 to the comparator circuit 24, is lower than the reference level V, the output of the comparator circuit 24 becomes high level, and the analog switch 26 is turned on. and resistance R
2 is short-circuited, and the gain of the error amplifier 27 becomes high.

On the other hand, when the level of the pilot signal is higher than the reference level (2), the output of the comparison circuit 24 becomes low level, the analog switch 2G is turned off, and the gain of the error amplifier 27 becomes low.

In addition, by changing the gain of the error amplifier 27 depending on the level of the pilot signal, fluctuations in the tracking servo gain due to variations in the recording level of the pilot signal that occur during recording can be suppressed.
Tracking servo gain can be set high, suppressing disturbances in the head trajectory during playback, preventing deterioration of error rate and sound breakage due to head misalignment.

In the embodiment described above (FIG. 2), the error amplifier 27
Although the gain is switched to two stages by shorting and non-shorting the resistor R2, it is also possible to increase the reference level and switch to three or more stages.

FIG. 4 shows an embodiment in which the gain of the error amplifier 27 is switched in three stages. Since the bag storage structure of this embodiment is almost the same as the structure shown in FIG. 2, the same components will be given the same numbers and their explanation will be omitted. The difference between the fourth device and the device shown in FIG. 2 is that a comparison circuit 34 and an analog switch 36 are provided at the output of the S/H circuit 23, and a gain adjustment resistor R3 is added to the error amplifier 27. . The comparison circuit 34 is connected in parallel to the comparison circuit 24, and has a reference voltage (2) different from the reference voltage (1) of the comparison circuit. Then, the comparator circuit 34 outputs the output of the S/H circuit 23 as the reference voltage ■
When the error exceeds 2, the analog switch 36 is turned OFF and the gain of the error amplifier 27 is lowered.

FIG. 5 shows an embodiment in which the gain of the error amplifier 27 is changed steplessly. Since the apparatus configuration of this embodiment is almost the same as the configuration shown in FIG. 2, the same constituent members are given the same numbers and their explanations will be omitted. The difference between the device in FIG. 5 and the device in FIG. 2 is that an amplifier 4 is connected to the output of the S/H circuit 23.
1 is provided with a variable resistance element 42 whose resistance value changes with voltage. Resistance change element 4 of this example
2 is a CdS photocoupler, which is configured so that when the amount of light emitted from a built-in light emitting diode 42a changes depending on the level of a pilot signal, the resistance value of CdS 42b changes, and the gain of the error amplifier 27 changes in accordance with the change. has been done.

FIG. 6 shows another embodiment of the DAT tracking device of the present invention, in which a tracking error detection circuit 90 is shown.
The configuration is the same as the conventional device and the device shown in Figure 2, but the circuit configuration for detecting the level of the pilot signal is different from that shown in Figures 2 and 4.
This device is different from the device shown in FIGS. Therefore, the same constituent members as before will be given the same numbers and their explanations will be omitted.

In the device shown in FIG. 6, the output of the level detection circuit 12 is input to the addition circuit 14, and the peak hold (P/H)
It is also input to the circuit 5l. The output of the P/H circuit 51 is input to another P/H circuit 52, and the output of the P/H circuit 52 is input to the inverting input of the comparator circuit 240 as in the embodiment shown in FIG. The voltage is inputted to the reference voltage generator 25 and compared with the reference voltage (■) of the reference voltage generator 25. In addition, the P/H circuit 52
The head switching signal SWI is input to the P/H circuit 52.
The peak value held in is reset by this head switching signal SWI. Furthermore, the P/H circuit 51 also includes:
A delayed signal SWD of the head switching signal SWI delayed by a predetermined time by the delay circuit 53 is input, and this signal SW
The peak value held in the P/H circuit 51 by D is reset.
It will be noted. The configuration after the comparison circuit 24 is the same as the device shown in FIG. 2, and the output of the comparison circuit 24 is connected to the analog switch 2
6, and the gain of the error amplifier 27 changes depending on whether the analog switch 26 is turned on or off.

Next, the operation of the apparatus configured as described above will be explained using FIG. 7.

In Figure 7, (a) is the same output waveform of the RF amplifier as in Figure 3 (a), (b) is the level of the pilot signal included in the output waveform of the RF amplifier, and (C) is the heave/node switching signal. (d) shows the waveform of the signal SWD obtained by delaying the head switching signal SWI, (e) shows the output waveform of the P/H circuit 52, and (a) shows the output waveform of the P/H circuit 5l. . Due to the fall of the head switching signal SWI, the P/H
When the circuit 52 is reset, P/H times I! ! 52 holds the output of the P/H circuit 51 at this time. followed by P/
When the H circuit 5l is reset by the delay signal SWD,
Until the P/H circuit 51 is reset next time, the RF
The peak value of the level of the pilot signal included in the amplifier output is detected and held.

Then, when the peak value of the pilot signal held in the P/H circuit 52 is smaller than the reference voltage ■, the comparison circuit 2
4 becomes high level, the analog switch 26 turns ON and short-circuits the resistor R2, and the gain of the error amplifier 27 increases. Conversely, when the peak value of the pilot signal held in the P/H circuit 52 is greater than the reference voltage ■, the output of the comparator circuit 24 becomes low level, the analog switch 26 is turned off, and the gain of the error amplifier 27 is decreases. The output of this error amplifier 27 is the motor driver 9
5 and is fed back to a capstan motor (not shown).

Here, the reason why the gain of the error amplifier is adjusted using the peak value of the pilot signal in the embodiment shown in FIG. 7 will be explained.

As shown in FIGS. 8(A) and 8(a), the tracking error is small and the head traces the target track 100%, as shown in the embodiments shown in FIGS. 2, 4, and 5. As shown in FIG. 8(B), (b), (
As shown in (C) and (C), when the tracking error is large and the head is not tracing 100% of the target track, the level of the pilot signal of the track being scanned, which is maintained by the sampling pulse SP3, will be affected by the tracking error. The problem is that it depends on the value and is smaller than the true value. That is, the level of the pilot signal at the target track varies as shown in FIG. 9 depending on the degree of tracking and tracking error.

Therefore, if the peak value of the pilot signal is taken, even when the tracking error is large, it is possible to detect a Byronoto signal level that is closer to the true value. Further, by taking the peak value of the bironoto signal over several ATF areas, a more accurate pilot signal level can be detected. In other words, if peak detection is performed using the P/H circuit, the one with the higher pilot signal level remains as the output, so a value close to the correct pilot signal level can be obtained, and furthermore, tracking adjustment can be performed using the obtained pilot signal level. In time, the peak value of the true pilot signal will be obtained.

In this way, by correcting the gain of the error amplifier based on the peak value of the pilot signal, variations in the gain of the tracking surfer due to variations in the pilot signal recording level can be suppressed, and tracking errors can be reduced even on magnetic tape with a low pilot signal recording level. increase, and off-track is prevented. Also, false detection is prevented even when the tracking error is large.

In the embodiment described above (FIG. 6), the error amplifier 27
Although the gain is switched to two stages by shorting and non-shorting the resistor R2, it is also possible to increase the reference level and switch to three or more stages as in the modification shown in FIGS. 4 and 5.

(Effects of the Invention) As explained above, according to the present invention, even if the pilot signal level recorded during recording differs depending on the recorder,
This has the effect of suppressing fluctuations in the gain of the tracking servo, eliminating disturbances in the head trajectory during playback, and preventing deterioration of error rate and sound breakage due to off-track.

[Brief explanation of drawings]

Figure 1(a). (b) is a principle block diagram of the DAT tracking device of the present invention, FIG. 2 is a circuit block diagram of an embodiment of the DAT tracking device of the present invention, and FIGS. 3(a) to (f) are FIG. FIG. 4 and FIG. 5 are block diagrams of a modified embodiment of the DAT tracking device of FIG. 2, and FIG. 6 is a circuit diagram of another embodiment of the DAT tracking device of the present invention. 7(a) to (f) are operational waveform diagrams of the device in FIG. 6, and FIG. 8(A) to (C). (a) to (C) are explanatory diagrams showing the relationship between tracking error and pilot signal level, Figure 9 is a diagram showing the relationship between tracking error amount and pilot signal level, and Figure 10 is the ATF on the DAT tape. An explanatory diagram showing the tracking adjustment pattern recorded in the area. Figure 11 is a diagram showing the pilot signal and synchronization signal patterns recorded in the ATF area along with the head size. Figure 12 is a conventional DAT tracking device. FIG. 2 is a configuration diagram showing the configuration of. 11...Low pass filter, 12...Level detection circuit, 13, 15. 23...Sample hold circuit, 1
4...Adder, 16...Synchronization {' signal detection circuit, 17, 21. 28...Delay circuit, 22...Switching means, 24. 34... Comparator, 26. 36...Analog switch, 27...Error amplifier, 42...Resistance change element.

Claims (1)

[Claims] 1. When detecting the synchronization signal (S) recorded in the ATF area of the R-DAT in a predetermined pattern, the sampling pulse (S)
P1) is output, the level of the pilot signal (P) recorded in the track to the right of the track currently being traced is detected by this sampling pulse (SP1), and the sampling pulse (SP1) is delayed for a predetermined time. The level of the pilot signal (P) recorded in the adjacent track on the left is detected by the sampling pulse (SP2),
A DAT tracking device that performs tracking adjustment to eliminate two level differences includes a delay circuit (1) that delays the sampling pulse (SP2) by the same amount as the predetermined time to generate a sampling pulse (SP3), and a drum. A head switching signal that switches the output of two attached heads or a signal related to the rotational phase (SW1
), and a sample hold circuit (3) that records the level of the pilot signal recorded in the track currently being traced by the sampling pulse (SP3). , the sampling pulse (SP3) according to the mask signal (SW2)
a switching circuit (4) that cuts off input to the sample and hold circuit (3); and a gain adjustment circuit (5) that adjusts the loop gain of the feedback control according to the output of the sample and hold circuit (3). A DAT tracking device characterized by having the following. 2. Sampling pulse (
This sampling pulse (SP1)
detects the level of the pilot signal (P) recorded on the track to the right of the track currently being traced, and records it on the track to the left using a sampling pulse (SP2) obtained by delaying the sampling pulse (SP1) by a predetermined time. In a DAT tracking device that detects the level of the pilot signal (P) that is detected and performs tracking adjustment to eliminate the difference between the two levels, the pilot that maintains the peak value of the level of the pilot signal (P) read by the head Peak holding circuit (6
), and according to the output of the pilot peak holding circuit (6),
A DAT tracking device comprising: a gain adjustment circuit (5) that adjusts the loop gain of the feedback control.