JPH0448429A - Digital magnetic recording and reproducing method - Google Patents

Abstract

PURPOSE:To efficiently detect a tracking state by forming the parts which have different shapes of the frequency components of a signal due to digital information, at different positions in tracks adjacent to each other, superimposing a pilot signal in the signal due to the digital information and recording them. CONSTITUTION:The pilot signals having different frequencies are superimposed in the adjacent tracks among tracks 26 - 29. For example, the pilot signals of frequencies F1, F2, F3, and F4 are recorded in respective tracks 26/29. Frequency changing domains 30 - 37 are frequency spectrums which are different from the other domains. That is, a domain 68 is nearly an NRZ system modulation of a random data, and a domain 69 is the deformation of the form of the frequency spectrum 68. When the signals recorded in such a manner are regenerated, the state of the frequency spectrums of the taken-out signals is changed according to the tracking state of a reproduction head. Thus, the tracking conditions can be detected precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to magnetic recording and reproducing, particularly to digital magnetic recording and reproducing systems.

2. Description of the Related Art Various recording and reproducing apparatuses using magnetic tape as a recording medium have been developed and put into practical use. For example, a video tape recorder (herein referred to as "VTR") is a typical example, and in recent years, the popularity of home VTRs has increased significantly, and their performance has improved significantly. Recently, many functions have been added to the camera, making it small and lightweight and capable of recording for long periods of time. However, in order to achieve long-time recording with a small and lightweight device, it is necessary to increase the recording density and reduce tape consumption. At this time, the trunk width becomes progressively narrower, and as a result, tracking becomes an important technical issue.

Against this background, in current home VTRs, a method has been put into practical use in which a continuous pilot signal is newly superimposed and recorded in addition to the signal that should originally be recorded and reproduced.

By the way, in recent years, the demand for higher image quality in video equipment has been increasing, and research on digital recording VTRs (hereinafter referred to as "DVTRs") has been carried out, supported by rapid advances in semiconductor technology. , DVTRs can achieve high image quality by digitizing, but on the other hand, the amount of data becomes enormous.
Forced to record at even higher density. Therefore, tracking has become one of the more important technologies in DVTR.

Here, as a conventional example, trunking using the above-mentioned pilot signal will be explained with reference to FIGS. 4 and 5.

The fourth view shows the frequency spectrum of the signal recorded on the magnetic tape. In the figure, the horizontal axis represents frequency and the vertical axis represents level. Further, 67 is a luminance signal component, 66 is a low frequency conversion carrier color signal component, 62 to 65 are pilot signals, and 6
8 is a digital signal component.

(69 will be explained later.) The luminance signal of the video signal is FM-modulated through various processes to become the luminance signal component 67, and the carrier chrominance signal of the video signal is low-frequency converted through various processes and converted into a low-frequency carrier. The color signal component becomes 66.

Furthermore, pilot signals 62 to 65 are created to detect trunking errors during reproduction, and these three types of signals are frequency-multiplexed and recorded on the magnetic tape. Pilot signal 62
.about.65 are selectively used for each track.

Next, further explanation will be added together with the recording pattern diagram shown in FIG. In the figure, 70 is a magnetic tape, 71 to 74 are tracks, and 75 and 76 are magnetic heads.

In helical scan recording, diagonal tracks 71 to 74 are created on the magnetic tape 70. During playback, it is necessary for a magnetic head to trace over these trunks 71-74. A case is shown in which the magnetic head 75 is correctly tracing the top of the trunk 71, and a case is shown in which the magnetic head 76 is not correctly tracing the top of the trunk 73, causing trunk deviation in the direction of the adjacent trunk 74. The track 7 does not trace correctly to the trunk 73 like the magnetic hend door 6.
4, the level of the pilot signal included in track 74 will increase and the level of the pilot signal included in track 72 will decrease in the reproduced signal. By monitoring the pilot signal status in this way, the tracking status can be detected.

Problems to be Solved by the Invention However, problems arise when trying to apply such a method to digital recording. The main one is the cocoon talk between the digital signal and the pilot signal. Fourth
This point will be explained with reference to the frequency spectrum shown in the figure. In the figure, 68 is a digital signal component, and usually the digital signal component 68 is the pilot signal 62 to 65.
Energy also exists in the frequency band. □As a result,
Crosstalk occurs between the two.

Therefore, the present invention provides a method in which tracking errors can be detected with high quality in digital recording, and the above-mentioned dots do not occur.

Means for Solving the Problems Therefore, in the present invention, a plurality of magnetic heads are arranged at a plurality of locations on a rotating cylinder, and in a magnetic pattern formed on a magnetic tape by the plurality of magnetic heads, a signal based on digital information is generated. have portions in which frequency components have different shapes, and the portions with different shapes are formed at different positions between adjacent tracks, and a pilot signal is superimposed on the digital signal described above. This is for digital magnetic recording.

When a signal recorded in this way is played back, the state of the frequency spectrum of the extracted signal changes in relation to the tracking state of the playback head, making it possible to accurately detect the trunking situation, and based on this, digital Trunking control can also be achieved with magnetic recording.

Example Embodiments of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, 1 is a video signal input terminal, 2 is an analog-to-digital converter (indicated as "A/D" in Figure 1, and hereinafter "A/D").
3 is the recording side signal processor (the first
4 and 5 are modulators, 6 and 7 are adders, 8 is a pilot signal generator, 9 to 12 are magnetic heads, 13 is a rotating cylinder, 14
is a magnetic tape, 15 and 16 are equalizers/detectors (indicated as "EQ &DET" in Fig. 1), 17 and 18 are demodulators, and 19 is a reproduction side signal processor (in Fig. 1, "PB-PR").
20 is a digital-to-analog converter (indicated as "D/A" in FIG. 1, and hereinafter referred to as "A/D converter"), 21 is a video signal output terminal, and 22 is a video signal output terminal. a pilot signal separator, 23 a tracking error detector (first
24 is a tracking error signal output terminal (denoted as "ERR-EDT" in the figure).

The video signal to be recorded is sent to A/V via video signal input terminal 1.
The signal is applied to the D converter 2, converted into a digital signal, and then applied to the recording side signal processor 3.

The recording side signal processor 3 performs various digital signal processing (for example, time axis conversion, band compression, channel division, error correction encoding, formatting, data conversion, etc.) and supplies the signal to modulators 4 and 5. A pilot signal generator 8 generates a bind signal, which is added to the output signals of modulators 4 and 5 in adders 6 and 7. The output of the adder 6 is applied to the magnetic henodes 9 and 11 mounted on the rotary cylinder 13.
The output of the adder 7 is also recorded on the magnetic tape 14 via the magnetic henodes 10 and 12 mounted on the rotary cylinder 13.

On the other hand, during reproduction, information recorded on the magnetic tape 14 is taken out via the magnetic heads 9 to 12 and supplied to equalizers/detectors 15 and 16 and a pilot signal separator 22.

Pyro 7) The signal separator 22 is composed of a bandpass filter or the like, and extracts the bind signal component from the reproduced signal. The extracted pilot signal component is added to the trunking error detector 23, and a tracking error signal is sent out from the tracking error signal output terminal 24.

On the other hand, the equalizer/detector 15 equalizes the waveform of the reproduced signals from the magnetic heads 9 and 11 and converts them back into digital signals to the demodulator 1.
Send the digital signal to 7. The demodulator 18 demodulates the input digital signal into original data and sends it to the reproduction side signal processor 19. Also, in the equalization/detector 16, the magnetic head 1
The reproduced signals from 0 and 12 are waveform-equalized and returned to digital signals, and the digital signals are sent to the demodulator 18. The demodulator 18 demodulates the input digital signal into original data and sends it to the reproduction side signal processor 19. Playback side signal processor 1
9 performs various digital signal processing (e.g. data inversion,
error correction decoding, deformatting, channel combining,
(band compression inverse conversion, time axis conversion, etc.), is converted back to an analog signal by the D/A converter 20, and is output from the video signal output terminal 21.

Next, the recording pattern shown in FIG. 2 will be shown and further explained. In the figure, 25 is a magnetic tape, 26 to 29
30 to 37 are frequency spectrum changing regions, and 38 and 39 are magnetic heads. In helical scan recording, diagonal tracks 26 to 29 are formed on the magnetic tape 25.
is made.

During playback, these trunks 26 to 29 are magnetically
Nodes 38 and 39 need to be traced. The magnetic heads t'38 and 39 correspond to the magnetic heads 9 and 11 (or 10 and 12) in FIG. Although the magnetic nodes 38 and 39 should originally trace on the tracks 26 and 27, FIG. 2 shows a case where both the magnetic nodes 3B and 39 are shifted to the right in the figure. Tora, Ri26~
29, pilot signals of different frequencies are superimposed between adjacent trunks. For example, tracks 26-2
9, pilot signals of frequencies F1, F2, F3, and F4 are recorded, respectively.

However, the frequency change regions 30 to 37 have a different frequency spectrum from the other regions. This situation can be seen in the fourth
I will explain it along with the episode. In the figure, 68 is a case of NRZ modulation of approximately random data, and 69 is a modified form of the frequency spectrum 68. 30 in Figure 2
For frequencies other than .about.37, the frequency spectrum is 68. For 30.about.37, the output data of the modulators 4 and 5 or the recording side processor 3 is manipulated so as to form a frequency spectrum 69.

Since the magnetic helenoids 38 and 39 are shifted to the right, the contamination from the trunk on the right side of the rack increases more than the contamination from the trunk on the left side.

Further, the trunks 26 and 27 will be extracted and explained in conjunction with FIG. In the figure, 40 and 41 are digital signal sequences recorded in one trunk, 46, 48, 50 and 51 are pilot signal components separated and detected by the pilot signal separator 22, and 42 to 45 are frequency spectrum change regions. , 5
2 to 59 each indicate the time. Tracks 40 and 4
1 corresponds to trunks 26 and 27 in FIG. 2, and frequency spectrum change regions 42 to 45 correspond to frequency spectrum change regions 26 to 33 in FIG. 2, respectively.

It is assumed that frequencies F1, F2, F3, and F4 are superimposed and recorded as pilot signals in the trunks 26 to 29 of FIG. 2, respectively. Further, 46 and 50 each indicate the magnetic head 3.
8 indicates the F2 and F4 components of the signal reproduced from the magnetic head 39, 48 and 51 indicate the Fl and F3 components of the signal reproduced from the magnetic head 39, and 47 and 49 indicate the zero potential of 46 and 48, respectively. Analysis of these pilot signal components is performed in pilot signal separator 22. However, in the frequency spectrum change regions 52 to 45, as shown in the frequency spectrum 69 in FIG. Signals 48 and 5
1, the S/N of the detection results becomes very high at times 52-53 and 56-57. The difference between the signal 46 and the signal 50 and the difference between the signal 48 and the signal 51 are detected by the magnetic head 3.
This represents the tracking states of 8 and 39,
For the above-mentioned reasons, tracking with a very high detection S/N can be achieved by using signals 46 and 50 for times 54-55 and 58-59, and using signals 48 and 51 for times 52-53 and 56-57. An error signal is obtained, allowing highly accurate trunking control.

The present invention has been described above. Incidentally, in the embodiment of the present invention, a case has been shown in which two magnetic heads are arranged at two locations on a rotating cylinder and four types of continuous waves are superimposed as pilot signals, but this is not limited to this and other types of waves may be used. It is also possible to use a combination of head arrangements and pilot signals.

Regarding the frequency spectrum changing regions, two per truck are shown in the figure to simplify the explanation, but the number may be set to suit the actual system.

Effects of the Invention As is clear from the above explanation, the present invention makes it possible to efficiently detect the trunking state in digital magnetic recording and reproducing. This provides a tracking method that uses magnetic tape with high efficiency by setting the magnetic tape at different locations.

[Brief explanation of the drawing]

FIG. 1 is a bronch diagram showing one embodiment of the present invention, FIG. 2 is a recording pattern diagram showing the recording state of FIG. 1, and FIG.
Part 4 is a frequency spectrum diagram showing the frequency spectrum in the conventional method and the present invention, and FIG. 5 is a recording pattern diagram showing the recording state in the conventional method. It is. 3... Recording side signal processor, 4, 5...
Modulator, 6.7... Adder, 8... Pilot signal generator, 9 to 12... Magnetic head, 13... Rotation Nlinder 14...
Magnetic tape, 15.16... Equalization/detector, 1
7゜18... Demodulator, 19... Reproduction signal processor, 22... Pyro, signal separator, 2
3...Trunking error detector, 68.69.
...Frequency spectrum. Name of agent: Patent attorney Shigetaka Awano

Claims (2)

[Claims] (1) Multiple magnetic heads are placed at multiple locations on a rotating cylinder, and in the magnetic pattern formed on the magnetic tape by the multiple magnetic heads, the frequency components of the signal due to digital information will be in different forms. A digital magnetism comprising a plurality of sections, the sections having different shapes are formed at different positions between adjacent tracks, and a pilot signal is superimposed and recorded on the signal based on the digital information. Recording and playback method. (2) A part where a plurality of magnetic heads are arranged at a plurality of locations on a rotating cylinder, and the plurality of magnetic heads reproduce signals recorded on a magnetic tape, and the frequency components in the reproduced signals have different forms. 2. The digital magnetic recording and reproducing method according to claim 1, wherein the tracking error information is obtained by detecting pilot signal components of adjacent tracks.