JPS63239644A - Tracking controller - Google Patents

Abstract

PURPOSE:To execute a stable tracking control by adjusting the gain of a tracking servo system based on a signal obtained by dividing an error signal by a sampled pilot signal. CONSTITUTION:Tracking control is executed by detecting the crosstalk component of a tracking pilot signal based on a reproduced synchronizing signal independently from the area of a PCM signal. The titled controller is provided with sampling hold circuits 7, 9, 10, 11 sampling a pilot signal on a track scanned by a rotary head at every two heads A, B at the time of reproducing and a dividing circuit 13 dividing a difference between the crosstalk components of pilot signals outputted from both tracks adjacent to a scanning track by the output of each sampling hold circuit. Thus, the variation of tracking servo loop gain due to the recording fluctuation of a pilot signal is absorbed. Consequently, the stable tracking control can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention provides a method for recording PCM signals on diagonal recording tracks on a magnetic tape using a rotating head. and a sync signal for detecting this pilot signal,
Related to a PCM signal recording and reproducing device that performs tracking control by ejecting a crosstalk component of a pilot signal from a track adjacent to a scanning track of a rotary head with reference to a reproduced sync signal during sketching. Technology of rotating head digital audio tape recorder (
For J called R-DAT, Japanese Patent Application Laid-Open No. 61-240
As described in Publication No. 58 CG11820/10), crosstalk of pilot signals from adjacent tracks can be avoided by using only two rotating heads and scanning tracks across adjacent tracks. The ATF tracking control method is used to obtain the components and perform tracking surfing so that their levels are equal.□ In order to perform this kind of tracking control, the A and 8 tracks are equipped with the following components as shown in Figure 2. In the pattern, a 10ft signal (fl), a sync signal signal [r2] of 0.5 block and 1 block, and a sync signal (f3) of 0.5 block and 1 block are recorded.

First, let us explain the operation during normal playback using the third factor.
When the rotary head is scanning the second A track from the bottom of the meat, the A track playback output is amplified to an appropriate value by the amplification process, and then supplied to the band pass filter +21, ATF1 region and AT as shown in l.
Only the pilot signal component in the F2 region is extracted □ This output is supplied to the envelope detector 13+ and converted to DC □ In this case, as shown in Figure 4), the pilot signal (fl) of the same truck is (p3), a signal (pl) based on the crosstalk pilot signal @tf1) of the right track adjacent to this track, and a crosstalk pilot signal (fl) of the left track adjacent to this track. The playback output from the head is also supplied to the equalizer +41 and waveform-equalized, and then sent to the zero-cross comparator (51).
4 (C) based on the detection of the sync signal (f2) of the A track.
), the sampling pulse (SPI) shown in (d) of the same figure and the sampling pulse (S22) shown in (ote) of the same figure are activated by the control logic circuit +6.
The crosstalk component (pl) of the pilot signal is held in the sample and hold circuit (71) by the n sampling pulses +5Pt outputted from 1 and 1, and it is compared with the pilot signal a stalk component (pl) by the comparator IM+. The difference (pl-pl) between the crosstalk components of the equal pie signals is detected by the sampling and holding circuit 19+ by the sampling pulse (SF3).
This output, which is held as a tracking control signal, is supplied to the Kina 1 stun motor servo to track the rotary head to the center of the track to be scanned.

(C) Problems to be Solved by the Invention In the conventional example, since the difference (pl-pl) between pilot signals from both adjacent tracks is used as a traffking error signal, variations in the recording and reproduction level of pilot signals , the loop gain of the tracking control system changes.

For this reason, if the level of the pilot signal is very high, there is no gain margin or phase margin, which may result in an unstable state such as oscillation. Conversely, if the pilot signal level is low, the loop gain will become small. The pulling range of the control a yarn becomes narrow, and even slight speed fluctuations can cause tracking control to deviate.□ In this way, the ATF loop gain fluctuates due to variations in the pilot signal, and stable trafking control can be expected. In order to solve the above-mentioned problems, the present invention provides a method for recording PCM signals on a magnetic tape in diagonal recording tracks using two rotating heads. , PCM signals are divided into regions and record a pilot signal for tracking and a sync signal for detecting this pilot signal, and during playback, crosstalk components of pilot signals from tracks adjacent to the scanning track of the rotating head are recorded. In a PCM signal recording and reproducing apparatus that performs retraging control by detecting the sync signal based on the reproduced sync signal, the pilot signal on the track scanned by the rotary head during reproduction is detected by the two heads A and 82. A sample hold circuit samples each time, and a division circuit divides the difference between the crosstalk components of the pilot signals from both adjacent tracks of the track being scanned by the output of the sample hold circuit. (e) Function: In the present invention, the trawl control device is characterized in that it absorbs fluctuations in the trawl servo loop gain due to Instead of using the difference in crosstalk components as an error signal and returning it to the capstan servo thread, the output is divided by a certain value and sent back.
Sample the I (yellow/) signal of the track, divide the difference between the crosstalk components of the pilot signal obtained while scanning 8 tracks by this value, and then set an appropriate value to prevent the gain from decreasing. □For example, if the level of the pilot signal recorded on the A track is (A-P), the crosstalk component (V,) of the pilot signal of the A track reproduced by the B head is calculated by the following formula. It becomes like this.

va-A-Pf(X) Here, ftx) is a comprehensive representation of the crosstalk element and side lead amount, with the center of the B track to be scanned as the reference, and the head position amount as X. be. Furthermore, A is a proportional constant of the reproduction waveform width, which indicates the fluctuation of the recording level on the tape due to variations in the recording current or differences in the recording capacity of the head. Therefore, when the crosstalk component of the pilot signal of the A track during playback of the B track is divided by the level (A・P) of the pilot signal recorded on the A track, the above-mentioned result can be obtained. The formula becomes: v lBmarof(x) This clearly allows us to remove the proportionality constant.

Since f(x) is unique to each head, if the gain of the servo system is adjusted by f(X), a constant loop gain will always be obtained. The first diagram shows the pros and cons of applying this to R-DAT.
The reproduction output from the head is amplified to an appropriate value in the amplifier, and then supplied to the band pass filter 121, where only the pilot signal component is extracted. Extracted. This output is supplied to the envelope detector 1; ◎This output is supplied to the control logic circuit # (6+, logic circuit +
61 is the timing shown in ys4w<C)(d)(e)(r), and the sampling pulse (SPl)(SF3
) (SF3) (outputting SP4J or sampling pulse tsP1) causes the sample-and-hold circuit 1'h to hold the crosstalk component (Pl) of the Iloft signal, which is then converted to the grosstalk component (Pl) of the pilot signal by the comparator (81). P2], and these (
The difference co1-P2) between the pilot signal components is converted to the sample hold circuit +91 by the sampling pulse (SF3).
10,000, the sampling pulse (SP!l) holds the sample hold times u.
'The signal (P3) based on the signal (fl) is held,
The sampling pulse (SF3)K holds the sample-and-hold circuit (of the B helide in Ill) (signal (P3) based on the Irovt signal (fl)). The difference (
PI-P2) is a signal (P3
), and the difference (Pt - P2) between the crosstalk components of the pilot signal reproduced by the A head is sent to the sample hold circuit aυ based on the pilot I signal of the A head held. 0 will be divided by the signal (P3) By performing this calculation, variations in the recording strength of the pilot signal of each track will be absorbed, and a constant amount of error will always be obtained from A, 8 to 7. In this way, the output of the divider circuit (131) is supplied to the 111m unit (141) and sent to the 1 stun servo system to obtain sufficient loop gain.
Since it is now possible to absorb variations in recording strength for each head, it is now possible to absorb variations in head sensitivity by switching the gain of the intensifier [141] using a head switching pulse. ) Effects of the Invention As mentioned above, the gain of the tracking servo thread is adjusted by the signal obtained by dividing the normal error signal by the sampled pilot signal, so the gain of the tracking servo thread is adjusted. A constant loop gain can be obtained regardless of the recording strength of the pilot signal or the sensitivity difference between the heads, making it possible to perform stable tracking control.In addition, if the tracking is misaligned, the loop gain is automatically increased. 0, which allows for quick retraction.

[Brief explanation of the drawing]

Fig. 1 is a pro-rough diagram of the basic invention QATF tracking control device, Fig. 2 shows the ATF no. It is a diagram illustrating the synchronization of the sync signal with each v sampling pulse. 17. o9 curve aυ...sample hold circuit, α power...switch means, mouth...divider circuit◎

Claims (1)

[Claims] (1) When recording PCM signals on diagonal recording tracks on a magnetic tape by two rotating heads A and B,
A pilot signal for tracking and a sync signal for detecting this pilot signal are recorded in separate areas for the CM signal, and the crosstalk component of the pilot signal from the track adjacent to the scanning track of the rotating head is detected during playback. In a PCM signal recording and reproducing device that performs tracking control by detecting a reproduced sync signal as a reference, a pilot signal on a track scanned by a rotating head during reproduction is sampled for each of two heads A and B. A tracking servo loop due to recording variations in pilot signals is provided by providing a sample hold circuit and a division circuit that divides the difference in crosstalk components of pilot signals from both adjacent tracks of the track being scanned by the output of the sample hold circuit. A tracking control device characterized by absorbing gain fluctuations.