JPS61107506A - Digital signal reproducing device - Google Patents

Abstract

PURPOSE:To reproduce accurately and easily a digital signal by discriminating a signal area based on a tracking control signal recorded on each track. CONSTITUTION:As to block number of an area shared by each signal in total 196 blocks, a PCM signal area 23 shares 128 blocks and Sub-Code signal areas 24, 25 share respectively 8 blocks. The generation of jitter might cause the data signal area, in the worst case, one block in forward/reverse directions at the rotation of 180 deg.. Thus, in setting an area increased by 1 block in the forward/reverse directions than the actual PCM signal area, i.e., an area corresponding to 130 blocks to the PCM signal area of a data area discriminating signal, accurate reproduction is attained without mis-detecting a PCM signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a digital signal reproducing apparatus, and more particularly to a reproducing apparatus for a rotating head type magnetic recording apparatus.

[Background of the invention]

A rotary head type magnetic recording device that records PCM signals on a magnetic tape using a rotary head records the PCM signals in a burst form.

Therefore, during reproduction, it is necessary to determine the area in which the PCM signal is recorded.

Conventionally, the method for determining this area is as follows:
The position of the rotating drum was used as a reference as described in No. 102!107. However, the accuracy of the position of the rotating drum depends on the mechanical N degree of the rotating drum, and sufficient accuracy cannot be obtained when compatibility is taken into consideration.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital signal reproducing device that can accurately determine a signal region during reproduction.

[Summary of the Invention] The digital signal reproducing device of the present invention uses a tracking control signal recorded on each track (a signal recorded at two locations on one track) so that the playback head accurately captures the track during playback. Used as a standard.)
By determining the signal region, digital signals can be reproduced accurately and easily.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a reproducing device for a rotating head type PCM recorder. In the figure, 1 is a $900 tape, 2 is a rotating head, and 4 is a rotating head.
5 is a reproduction circuit, 5 is a data identification circuit, 6 is a servo circuit for controlling tape tracking of the rotary head 2, 7 is a tracking control signal detection circuit, 8 is a discrimination circuit for generating a signal for discriminating a data area in a track, 9 is a synchronization signal/block address detection circuit that detects the synchronization signal and data block number; 10 is a demodulation circuit; 1
1 is RAM (random access memory) for data storage
, 12 is a RAM address switching circuit, 13 and 15 are clock generation circuits, and 14 is the demodulated data to RAM1.
16 is a RAM write address control circuit that specifies the address to be corrected to 1, R is an AM correction read address control circuit that specifies the address when correcting and reading data written in AM11, and 17 is error data. 18 is a data bus that communicates data exchange between each circuit and the RAM; 19 is a data interpolation circuit that corrects data errors that cannot be corrected by the vanilla correction circuit; 20 is a D/A (digital-analog) converter, and 21 is an analog signal output terminal.

After the digital signal ' recorded on the magnetic tape is reproduced by a rotary head, the reproduction circuit 4 performs waveform equalization and amplification, and the data identification circuit 5 performs data separation and data identification.

Further, the reproduced signal from the caterpillar circuit 4 is input to a tracking control signal detection circuit 7 to detect a tracking control signal, and the detected tracking control signal is input to a servo circuit 6 that controls tracking.

The output signal from the data identification circuit 5 is demodulated by a demodulation circuit 10, and at the same time, a synchronization signal block address detection circuit 9 detects a synchronization signal and a block address.

Further, the tracking control signal detected by the tracking control signal detection circuit 7 at this time is input to the servo circuit 6 and simultaneously input to the discrimination circuit 8. The discrimination circuit 8 generates a data area discrimination signal that discriminates the output of the data discrimination circuit 5 into a data signal area and a non-data signal area based on the tracking control signal. The data area determination signal is input to the synchronization signal/block address detection circuit 9 and the RAM write address control circuit 14. The synchronization signal/block address detection circuit 9 and the RAM write address control circuit 14 have a data area determination signal of 11.
It operates only when ', specifies an address for RAM writing based on the detected synchronization signal and block address, and writes it to H, AM 11 through the demodulation data bus 1B from the demodulation circuit 10.

The data written in R, AMll is controlled by the RAM read/correction address control circuit 16 and subjected to error correction by the error correction circuit 17, and then sent to the data interpolation circuit 1.
Sent to 9th. Then, the data interpolation circuit 19 performs processing such as average value interpolation and previous value retention, and the D/A converter 20
is converted into an analog signal and output.

In the output signal from the data identification circuit 5, a window is provided to distinguish between a data signal area and a non-data signal area, and by controlling the writing of demodulated data into the RAM, the writing of the data signal into the RAM is improved. This is disclosed in Japanese Patent Laid-Open No. 102307/1983.

However, since the window was determined based on the position of the rotating head, it had to rely on mechanical precision.

The present invention is characterized by using a tracking control signal as the reference for the window, thereby making the position of the window accurate.

That is, data can be reproduced accurately by controlling the writing of data signals into the RAM using a window based on the tracking control signal.

FIG. 2 shows an example of a recording pattern on a magnetic tape that is reproduced by the reproducing apparatus of FIG.

In the same figure, 22 is the track margin, 25 is the PCM
Areas 24 and 25 are areas for recording signals, and areas 24 and 25 are areas for recording Sub-(::ode signals related to PCM signals.
6 and 27 are areas for recording time-sharing tracking control signals used by the rotary head to perform accurate tracking; 2nd is an area for recording pre-angle signals; 29
is the scanning direction of the head, 50 is an area indicating one block in a data signal, 31 is an area for recording a synchronization signal in one block, 32 is an area for recording a control 1+ signal, 33 is an area for recording a block address, 34 is a data area.

The time-division tracking control signals 26 and 27 are pilot signals for tracking control as disclosed in Japanese Patent Laid-Open No. 58-122606, and the preamble signal 2B is a pilot signal as disclosed in Japanese Patent Laid-Open No. 58-145452. This is a synchronous signal.

The PCM signal area 23 is composed of 128 blocks, and each block has a synchronization signal 31. control signal 32
．． A block address 33 is added. Control signal 3
2 is a control signal necessary for reproduction such as sampling frequency and quantization bit count, and block address 33 is an address indicating the number of the block. During playback, the block position is determined by detecting this block address.

Each of the Sub-code signal areas 24 and 25 is composed of eight blocks, and the block configuration is the same as that of the PCM signal area 23. In addition, AFT signal areas 26 and 2
7 is 5 blocks each, )-no ampoule area 28 is 2 blocks.
The block and track margins 22 are 11 blocks long, and one track shown in FIG. 2 has a total length of 11 blocks.
It is 96 blocks long.

FIG. 3 is a timing chart of the data area discrimination signal. In the figure, 35 is a rotary head output signal, 36 is a reproduced data signal, 57' is a tracking control signal, 3rd is a data area discrimination signal, and 39 is a track scanning section.

This corresponds to the head scanning section 39 of the recording pattern J in FIG. The head scanning section 39 is expressed by 90° every 180°.From the rotation output signal 35,
When reproducing digital data, the reproduced data signal 5
6 is obtained.

Further, when a tracking control signal is detected from the rotary head output signal 35, a tracking control 67 is obtained.

PCM signal area 23.8ub - ('ode signal area 2
4 Oyobi 25. The positional relationship of the tracking control signals 26 and 27 on the longevity signal is as shown in FIG.

However, the recorded PCM signal, S u b -
The viscous position of the code signal and the tracking control signal on the track on the magnetic tape varies depending on the assembly accuracy of the head and the like.

Therefore, if the data area is determined based on the position of the rotary head for tapes recorded by different devices, the data area may be different from the actual area.

In contrast, the relative positions of the signals on the track are constant and do not change. Therefore, in the present invention, by determining the data area using the tracking control signals 26 and 27 recorded on the same track, it is possible to generate the data area determination signal 38 that is equal to the actual data area.

FIG. 4 shows the data area discrimination signal generation circuit 8. In FIG. In the figure, 40 and 41 are four tracking control signal inputs, 43 is an OR gate, 44 is a load signal input terminal, 45 and 46 are load 11M input terminals to be applied to the counter, 49 is a switching circuit, and 50 is a load value of the counter. Input terminals 51 are clock or synchronization signal 310 input terminals, 52 are clock input terminals of a counter, 56 are counters, 54 are decoders for setting data areas, and 55 are data area discrimination signal output terminals. Tracking control signal input terminals 40 and 41 each receive tracking control signal 2.
Detection signals 6 and 27 are input. The counter 55 receives a clock from the clock generation circuit 13 or a synchronization signal 31 detected from a data signal to a clock input terminal 52, and a block corresponding to the rotary head 180''.
In this embodiment, it is a counter that counts 392 blocks. The decoder 54 outputs a data area discrimination signal which indicates the data area as 11' and other areas as 'φ' according to the value of the counter 53.

When the detection signal of the tracking control signal 26 is input to the tracking control signal input terminal 40, it becomes a load signal for loading the counter 53 via the OR)·′1 gate 44. At this time, the switching circuit 49 simultaneously selects the counter load value of the tracking control signal 26 at the time of manual operation. Since the number of pro-clocks from the tracking control signal to the PCM signal area is set by the decoder, when the tracking control signal 26 is detected, the original counter value, that is, the value that the counter should be at the time of the tracking control signal, is given as the load value. This makes it possible to operate the counter in accordance with the actual data signal. By inputting the value of this counter 53 to the decoder 54, the PCM signal area is determined. Similarly, when the detection signal of the tracking control signal 27 becomes a load signal,
The value that the counter should have at the time of the tracking control signal 27 is selected as the load value and loaded into the counter 53.

The actual data area discrimination signal 68 is set slightly wider than the data area to provide some margin. This takes into account jitter such as fluctuations in the rotational speed of the rotating head and expansion and contraction of the magnetic tape. It is.

As explained in FIG. 2, the number of blocks in the area occupied by each signal is 128 blocks in the PCM signal area 23 and 8 blocks in each of the 5ub-('ode signal areas 24 and 25) out of 196 blocks in one track. However, due to the occurrence of jitter, in the worst case, the data signal area may fluctuate by about one block back and forth in a 180° rotation.

Therefore, in the PCM signal area of the data area discrimination signal, if you set an area that is one block wider before and after the actual PCM signal area, that is, an area of 130 blocks, accurate reproduction will be possible without missing any PCM signals. I can do it.

Furthermore, the 5ub-Code signal area 24 of the data area discrimination signal is the tracking control signal 27 of the previous track.
Since it is based on , the jitter will also be large. Therefore,
When setting the signal area, it is necessary to provide some margin.

In this embodiment, the 8ub-('ode signal area 24 is set as the 5ub-Code signal area 27 by extending 1.5 blocks forward and backward, that is, an area equivalent to 11 blocks.

Using the data area discrimination signal 38 generated based on the tracking control signal as described above, the synchronization signal/block address detection circuit 9. RAM write address control circuit 1
By controlling 4, data can be exogenously generated accurately.

Another embodiment of the present invention will be described with reference to FIG.

FIG. 5 is taken by the data area discrimination signal generation circuit 8. In the figure, 42 is a terminal for inputting a signal from the synchronization signal/block address detection circuit 9, 43 is an OR gate, and 4
4 is a load signal input terminal, 47 is an address signal input terminal, and 48 is a decoder.

When the tracking control signal is input, the load value of the counter is loaded and the data area is determined.

Since the start of the data area is based on the tracking control signal, it is determined after waiting for one block's worth of margin, as described above. At the end of the data area, in the example of FIG. 4, the data area is counted and determined by a counter.

In this embodiment, the start of the data area is determined in the same way, but the synchronization signal 31 and block address 32 are included in the data.
If it is determined that the data is correct by detecting the data, the signal from the address detection circuit is used as the load signal of the counter, and by loading the value of the block address 32 into the counter, a more accurate data area discrimination signal 3 is generated.
8 can be generated.

Furthermore, even if the tracking control signal is missing, the data area determination signal 38 can be generated accurately.

Note that it is possible to generate the data area discrimination signal 38 using a preamble signal instead of the ATF signal.

In FIG. 2, the preamble signal 28 is 5ub-Cod.
e 1 signal 24. PCM signal 25. Sub-Cod
It is located just before the e2 signal 25. Therefore, if the preamble signal 27 is used as a reference, a more accurate data area discrimination signal 3
8 can be generated. ,
6: A third embodiment of the present invention will be explained with reference to FIG. In the figure, 56 is an input terminal for a detection signal of a tracking control signal for determining the presence or absence of a tracking control signal, 57 is an input terminal for a cylinder position detection signal that is output every rotation by the rotation of the rotary head, and 5B is an input terminal for a detection signal of a tracking control signal, which is used to determine the presence or absence of a tracking control signal. Load signal switching circuit 59 is an input terminal for a load value when the cylinder position detection signal is used as a load signal. When the tracking control signals 26 and 27 are detected, the load value of the counter is selected by the switching circuit 49 from the load value input terminal 45, 46 at the time of the tracking control signal, and the counter 53 loads the load value. and perform the operation.

However, if the tracking control signals 26 and 27 are not detected at this time, the load signal disappears and no loading is performed.

The present embodiment is characterized in that even in such a case, the counter is operated correctly and a data area discrimination signal is generated. When the tracking control signals 26 and 27 are not detected, the load signal is switched by the tracking control signal detection signal. The circuit selects the cylinder position detection signal as the load signal for the counter 53. At this time, the load value 59 at the time of inputting the cylinder position detection signal is simultaneously selected as the load value and loaded into the counter 53. The counter 53 starts counting from this value, and the decoder 54 generates a data area discrimination signal.

Therefore, even when the tracking control signal is not detected, normal operation can be performed by switching the reference of the data area discrimination signal from the tracking control signal to the cylinder position detection signal.

〔Effect of the invention〕

According to the present invention, it is possible to accurately discriminate the PCM signal region and the Sub-Code signal region in the reproduced digital signal.

Therefore, it is necessary to perform accurate reproduction of PCM signals and Sub-Code signals.

Furthermore, when the tracking control signal is lost, by switching to a method of generating the data area discrimination signal 38 based on the position of the cylinder as disclosed in JP-A-58-102507, the tracking control signal is lost. You can also deal with this situation.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a recording device for a rotary head type PCM recorder using the present invention, FIG. 2 is a diagram showing an example of a track recording pattern on a magnetic tape, and FIG. 4 is a timing chart showing a signal reproduced from the track recording pattern shown in the figure and the obtained PCM-Sub-Code area discrimination signal. FIG. 5 is a block diagram showing another embodiment of the discrimination signal generation circuit, and FIG. 6 is a block diagram showing still another embodiment of the discrimination signal generation circuit. 5... Data identification circuit, 7... Tracking control signal detection circuit, 8...
-... Discrimination circuit, 9... Synchronization signal/block address detection circuit,
14...RAM write address control circuit, 23
.....PCM signal, 24...5ub-COde1 signal, 25 ...-.Sub-Code 2 signal, 26.
27...Tracking control signal, 28...
...Preamble signal, 31...Synchronization signal, 32...Control signal, 33...Block address, 34...Data, 35... ... Rotating head output signal, 56...
Reproduction data signal, 37...ATF signal, 3rd...Data area discrimination signal, 39...
-Track scanning section, 40.41...Tracking control signal input terminal, 42...Address detection signal input terminal, 44.
...Counter load signal input terminal, 45.46.
...Load value input terminal, 47...Address input terminal 1. ,,． 48...Decoder, 49...Switching circuit, 50...Counter load value input terminal, 52...
...Counter clock, input terminal, 53...
Counter, 54...Decoder, 55...Data area discrimination signal output terminal, 56...
...Tracking control signal detection signal input terminal, 5
7...Cylinder position detection signal input terminal, 5B.
...Load signal switching circuit, 59...Load value input terminal.

Claims (1)

[Claims] 1. A synchronization signal and a block address are added to a plurality of digital signals to form one block, and the plurality of blocks and at least one tracking control signal are recorded as one track of recording signals by a rotary head. A digital signal reproducing device that reproduces a digital signal recorded on a magnetic recording medium includes an identification circuit that identifies a digital signal from a reproduced signal, a storage circuit that stores the digital signal identified by the identification circuit, and an identification circuit that identifies a digital signal from a reproduced signal; a detection circuit that detects a synchronization signal and a block address of a digital signal; a control circuit that determines a location where a digital signal is to be stored on the storage circuit based on the synchronization signal and block address detected by the detection circuit; A tracking signal detection circuit that detects a tracking control signal, and a position of an area where a digital signal is recorded is estimated from the position of the tracking control signal detected by the tracking signal detection circuit, and a synchronization signal is detected and the digital signal is stored. 1. A digital signal reproducing device comprising a digital signal region discriminating circuit that determines a period during which data is stored in the circuit. 2. The digital signal reproducing device according to claim 1, characterized in that the position of the area where the digital signal is stored is determined based on the block address detected by the detection circuit. Device. 3. The digital signal reproducing device according to claim 1, wherein the position of the area where the digital signal is stored is estimated from the position of the rotary head when the tracking control signal is lost. playback device.