JPS61292268A - Extracting method for digital synchronizing pattern - Google Patents

Abstract

PURPOSE:To execute a good extraction with a simple constitution by estimating an address from the rotating position of a rotating head and extracting a synchronizing pattern using an estimated value and a reproducing address. CONSTITUTION:A signal reproduced from a tape 1 by a rotation head 2 is supplied to a serial/parallel conversion circuit 4 with being demodulated/ waveform shaped at a reproducing circuit 3, and a data and the address are outputted to output terminals 5 and 6. With supplying a reference signal from a terminal 8 to a survo circuit 9, the rotation of a rotating head 2 is controlled and with supplying the reference signal to an address estimating circuit 10, the address corresponding to the rotating position of the rotating head is formed. The estimated value from the address estimating circuit 10 and the reproducing address from the conversion circuit 4 are supplied to a comparison circuit 11 and when they are allowable coincide a coincidence output is supplied to an AND circuit 12 and a detecting signal from a synchronizing pattern detecting circuit 7 is outputted to a synchronizing signal output terminal 13 through the AND circuit 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital synchronization pattern extraction method suitable for use in, for example, a digital video chip reader.

[Summary of the invention]

The present invention relates to a method for extracting digital synchronization patterns, which enables good extraction with a simple configuration by predicting an address from the rotational position of a rotary head and extracting a synchronization pattern using the predicted value and the playback address. It is something to do.

[Conventional technology]

For example, in a digital video tape recorder, a digitally converted video signal is divided into predetermined amounts, and each predetermined amount is recorded by adding digital synchronization, nine turns, and an address.

That is, for example, as shown in FIG. 2A, the number of scanning lines is 256.
In this book, one field of video signal with a horizontal resolution of 768 bytes is provided with approximately 1.2 times as many redundant pits as a whole, and the number of scanning lines is 28.
0 lines, converted to a horizontal resolution of 832 bytes. This converted data is divided into 208 bytes each as shown in Figure B, and after performing predetermined shuffling, etc., a 2-byte synchronization pattern and a 2-byte address are added to each division according to the recording order. . This signal is 1 as shown in C in the same figure.
Recording is performed using a rotating head so that the field has eight tracks.

- Therefore, in this case, 140 of the above-mentioned divisions, synchronizations, p4 turns, and addresses are recorded in each track. So at the above address.

Five pits of 2 bytes and 16 bits are used as a track address, and the remaining 11 bits form an intra-track address that sequentially steps from one end of the track as a starting point.

By the way, in the above-mentioned apparatus, detection of a synchronization pattern is extremely important when reproducing a signal. In other words, in the above device, is data division synchronous A? If 4 turns (approximately indicated by a turn in the data) are mistakenly detected as a synchronous pattern due to the influence of noise, etc., the division detection will malfunction, and operations such as undoing shuffling will be significantly delayed. There is a risk of malfunction. Note that the lack of a regular synchronization pattern can be easily compensated for by interpolation or the like.

Therefore, conventional methods have been considered to increase the bit length of the synchronization pattern to make false detection less likely to occur. 'However, increasing the bit length of the synchronization pattern does not necessarily reduce the number of data bits, which is particularly inconvenient when performing high-density recording.

On the other hand, it is possible to consider methods such as comparing the relative address calculated from the periodicity of the synchronous arm turn or the addresses of the previous and subsequent divisions with the playback address and detecting a synchronous rambling turn when they match. In either case, a configuration is required to calculate the period and the relative address.Especially when detecting the previous and subsequent addresses, one to two divisions until the subsequent address is detected. It appears that memory etc. to save data is required. Furthermore, when high-speed playback such as so-called search is performed, there is a possibility that the addresses of the previous and subsequent divisions cannot be obtained even though the period has changed.

[Problem that the invention seeks to solve]

Conventional digital synchronization pattern extraction methods have problems such as a reduced number of data pits, an increased circuit configuration, and inability to be applied to high-speed playback.

[Means for solving problems]

The present invention reproduces a digital signal to which a synchronization pattern and an address are added when reproducing a tape recorded with a rotary head so that the synchronization/4 turn and address are at predetermined positions on the track. The rotational position of the rotary head is detected, the address recorded at that position is predicted from the detected rotational position, the predicted value is compared with the reproduced address, and this comparison results in a match. This digital synchronization pattern extraction method extracts the detection output of the synchronization pattern when the synchronization pattern is detected.

[Effect]

According to this method, since the address is predicted based on the rotational position of the rotating head, the address can be predicted extremely easily, and this can be used to extract good synchronization and turns. .

〔Example〕

In FIG. 1, (1) is a digital signal recorded on the nine tags, and from this chip f(1) to a rotary head (2).
The signal is played back. This signal is demodulated and waveform shaped in the reproducing circuit (3) and converted to serial/-4' parallel (sp).
It is supplied to the conversion circuit (4). And this conversion circuit (4
), data and addresses are output to output terminals (5) and (6).

A part of the output of the conversion circuit (4) is also supplied to the synchronization pattern detection circuit (7).

Further, a reference signal for operation is supplied to the terminal (8), and this reference signal is supplied to the servo circuit (9) and the rotating head (
The rotation of 2) is controlled. This reference signal is supplied to the address prediction circuit αQ, and an address corresponding to the rotational position of the rotary head (2) is formed.

That is, in the device described above, each track has 140
Since the length of each division is equal, the respective addresses are recorded in alignment in the longitudinal direction of the tape at each position where the tape is divided into 140 equal parts in the width direction. Furthermore, the 11 bits in the address are values that are sequentially stepped from one end of each track as a starting point, so that each equally divided position in the longitudinal direction.

The same 11 pit addresses are recorded.

On the other hand, the rotational position of the rotary head (2) corresponds to the widthwise position of the tape (1), so that the rotational position of the rotary head (2) and the position of the tape (1) are recorded. Addresses can be predicted.

At that ζ, the predicted value from the address prediction circuit αQ and the conversion circuit (
The playback address from 4) is supplied to the comparator circuit α,
When these match, a match output is supplied to the AND circuit (2). The detection signal from the synchronization pattern detection circuit (7) is outputted to the synchronization signal output terminal (6) through the AND circuit (2).

This is how synchronization patterns are extracted,
Compare the addresses according to the method described above.

Since the synchronization signal is output only when the addresses 9 and 9 match, the synchronization turn is effectively lengthened by 11 bits of the address, which greatly reduces the possibility of false detection. can.

Further, since the address is predicted based on the rotational position of the rotary head (2), the prediction can be easily performed with an extremely simple configuration. Furthermore, prediction can be made without any problem even during high-speed reproduction.

Note that this method is limited to video recorders, but can be applied to other digital devices.

〔Effect of the invention〕

According to the present invention, since the address is predicted from the rotational position of the rotary head, the address can be formed extremely easily, and this can be used to extract a good synchronous arm turn. Ta.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an example of a device implementing the present invention, and FIG. 2 is a diagram for explaining a digital video recorder. (1) is tape, (2) is rotating head, (3) is playback circuit, (4) is serial/9 parallel conversion circuit, (5)
(6) is an output terminal, (7) is a synchronization pattern detection circuit, (
8) is the reference signal input terminal, (9) is the circuit, αQ
is an address prediction circuit, α is a comparison circuit, (6) is an AND circuit, and (2) is a synchronization signal output terminal.

Claims (1)

[Claims] A digital signal to which a synchronization pattern and an address have been added is reproduced when playing back a tape recorded with a rotary head so that the synchronization pattern and address are at predetermined positions on the track. Detect the rotational position of the rotary head, predict the address recorded at that position from the detected rotational position, compare this predicted value with the reproduced address, and if this comparison matches. A digital synchronization pattern extraction method that extracts the detection output of the synchronization pattern when the above synchronization pattern is detected.