JP2852290B2 - Digital signal reproduction device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal reproducing apparatus, and more particularly to a reproducing apparatus for reproducing a signal from a tape-shaped recording medium by a rotary head. 2. Description of the Related Art In a recording apparatus for recording a PCM signal on a recording medium such as a magnetic tape by using a rotary head, this PC
The M signal is recorded in a burst. Therefore, at the time of reproduction, it is necessary to determine the area where the PCM signal is recorded. As a prior art example for determining this area,
There is one described in JP-A-58-102307.
This example is a technical example of a digital audio tape recorder, and uses the rotational position of a rotary head on which a head is mounted as a reference for area determination. However, the accuracy of detecting the rotational position of the rotary head depends on the mechanical accuracy of the rotary drum device or the like on which the head is mounted. It is extremely difficult to obtain a high precision. SUMMARY OF THE INVENTION An object of the present invention is to accurately discriminate an area where a signal such as a PCM signal recorded on a medium is recorded when the signal is reproduced. It is an object of the present invention to provide a digital signal reproducing apparatus capable of performing the above. A digital signal reproducing apparatus according to the present invention, when reproducing a signal, uses a tracking control signal recorded on each track of a tape-shaped recording medium (recorded at two locations on one track and reproduced). At this time, the reproducing head can accurately detect the track.) Based on a recording information signal such as a reference signal, a signal area of a data signal such as a PCM signal recorded in the same track is determined, and thereby the data signal of the data signal is determined. The reproduction is performed accurately and easily. An embodiment of the present invention will be described below with reference to FIG.
This will be described below. FIG. 1 shows a reproducing apparatus of a rotary head type PCM recorder. In the figure, 1 is a magnetic tape, 2 is a rotary head, 4 is a reproducing circuit, 5 is a data identification circuit, 6 is a servo circuit for controlling the tape tracking of the rotary head 2,
7 is a tracking control signal detection circuit, 8 is a discrimination circuit that generates a signal for discriminating a data area in a track,
9 is a synchronization signal / block address detection circuit for detecting a synchronization signal and a data block number, 10 is a demodulation circuit,
11 is a RAM (random access memory) for storing data, 12 is a RAM address switching circuit, and 13 and 1
Reference numeral 5 denotes a clock generation circuit, and 14 denotes the demodulated data
A RAM write address control circuit for specifying an address to be written to M11, a RAM correction read address control circuit 16 for specifying an address when correcting and reading data written in the RAM 11, and a detection and correction of error data 17 Error correction circuit for performing
Is a data bus for communicating data exchange between the above-described circuits and the RAM, etc., 19 is a data interpolation circuit for correcting a data error that could not be corrected by the error correction circuit 17, and 20 is a D / D A (digital-analog)
The converter 21 is an analog signal output terminal. After the digital signal recorded on the magnetic tape 1 is reproduced by the rotary head 2, it is subjected to a waveform equalizing process and an amplifying process in a reproducing circuit 4. Is identified. The reproduced signal from the reproducing circuit 4 is input to a tracking control signal detecting circuit 7, where the tracking control signal is detected. The detected tracking control signal is further input to a servo circuit 6 for controlling the next tracking. The output signal from the data discriminating circuit 5 is demodulated by a demodulating circuit 10, and at the same time, a synchronizing signal and a block address are detected by a synchronizing signal block address detecting circuit 9. At this time, the tracking control signal detected by the tracking control signal detection circuit 7 is input to the servo circuit 6 and also to the discrimination circuit 8 at the same time. The discrimination circuit 8 generates a data area discrimination signal for discriminating the output of the data discrimination circuit 5 into a data signal area and an area other than the data signal based on the tracking control signal. This data area discrimination 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 operate only when the data area determination signal is "1". That is, here, an address for RAM writing is specified based on the detected synchronization signal and block address, and demodulated data from the demodulation circuit 10 is written to the RAM 11 via the data bus 18. The data written in the RAM 11 is a RAM
After being controlled by the read correction address control circuit 16 and subjected to error correction by the error correction circuit 17, the data is sent to the data interpolation circuit 19. Then, the data interpolation circuit 19
Processing such as average value interpolation and previous value holding is performed by D / A
The signal is converted into an analog signal by the converter 20 and output. By providing a window for distinguishing between the data signal area and the area other than the data signal, and using this window to control the writing of demodulated data to the RAM,
It is disclosed in Japanese Patent Application Laid-Open No. 58-10230 that the data signal output from the demodulation circuit 10 can be favorably written to the RAM.
No. 7 discloses this. However, since the window is determined based on the rotational position of the rotary head, it must depend on mechanical accuracy. The present invention is characterized in that a tracking control signal is used as a reference of the window, whereby the position of the window becomes accurate. That is, by controlling the writing of the data signal to the RAM in a window based on the tracking control signal, the data can be accurately reproduced. FIG. 2 shows an example of a signal recording pattern on the magnetic tape 1 to be reproduced by the reproducing apparatus shown in FIG. In the figure, 22 is a track margin, 23 is an area where a PCM signal is recorded, and 24 and 25 are the PC margins.
An area where a Sub-Code signal related to the M signal is recorded, 26 and 27 are areas where a time-division tracking control signal for performing accurate tracking with the rotary head is recorded, and 28 is an area where a preamble signal is recorded. , 2
9 is a scanning direction of the head, 30 is an area of one block in a data signal, 31 is an area of one block in which a synchronization signal is recorded, 32 is an area of a control signal, and 33 is a block address. An area 34 is an area where a data signal is recorded. The tracking control signals in the time-division tracking control signal areas 26 and 27 are pilot signals for tracking control as disclosed in Japanese Patent Application Laid-Open No. 58-122606.
The preamble signal in the preamble signal area 28 is a signal as disclosed in Japanese Patent Application Laid-Open No. 58-143432. The PCM signal area 23 is composed of 128 blocks, and each block has a synchronization signal,
A control signal and a block address are added. Area 3
The control signal of No. 2 is a control signal necessary for reproduction such as the sampling frequency and the number of quantization bits, and the block address 33 is an address for indicating the order of the block. During reproduction, the position of the block is determined by detecting the block address. Sub-code signal areas 24 and 25
Is composed of eight blocks each, and this block configuration is the same as the area 23 of the PCM signal. The tracking control signal areas 26 and 27 are 5
Blocks, the preamble area 28 has a length of two blocks, and the track margin 22 has a length of 11 blocks. One track shown in FIG. 2 has a total length of 196 blocks. FIG. 3 is a timing chart of the data area determination signal. In the figure, 35 is an output signal of the rotary head, 36 is a reproduced data signal, 37 is a tracking control signal, 38 is a data area discrimination signal, and 39 is a track scanning section. The recording pattern shown in FIG. 2 corresponds to a head scanning section 39 of the output signal 35 of the rotary head. In the present embodiment, two heads are used, and the winding angle of the magnetic tape 1 around the rotating drum device is 90 °. Therefore, in the output signal 35 of the rotating head, the scanning section 39 of the head is 9 times every 180 °.
A section of 0 ° appears continuously. When digital data is reproduced from the output signal 35 of the rotary head, a reproduced data signal 36 is obtained. When the tracking control signal is detected from the output signal 35 of the rotary head, a tracking control signal 37 is obtained. PCM signal area 23, Sub-Code
FIG. 2 shows the positional relationship between the signal areas 24 and 25 and the tracking control signal areas 26 and 27 on the reproduced signal. [0026] However, these PCM signals recorded in each area, Sub-Cod e signal, the tracking control signal 37, the absolute position is varied by the assembling accuracy of the head, respectively, in tracks on the magnetic tape 1 I do. Therefore, if the data area is determined based on the position of the rotary head for a tape recorded by a different device, it may be determined as an area different from the actual area. On the other hand, the relative position between the signals on the track is constant and does not change. Therefore, in the present invention, the area 26 recorded on the same track,
Data area 34 using tracking control signal 37 of 27
The by a Turkey Determine can generate data area determination signal 38 is equal to the actual data area. FIG. 4 is a diagram showing a configuration of the generation circuit 8 of the data area discrimination signal 38. In the figure, 40 and 41 are tracking control signal input terminals, 43 is an OR gate, 44 is a load signal input terminal, 45 and 46 are load value input terminals to be given to a counter, 49 is a switching circuit,
0 is a load value input terminal of the counter, 51 is a clock or synchronization signal input terminal, 52 is a clock input terminal of the counter, 53 is a counter, 54 is a decoder for setting a data area, and 55 is a data area discrimination signal output terminal. It is. The tracking control signal input terminals 40 and 41 receive the detection signals of the tracking control signal 37 for the areas 26 and 27, respectively. The counter 53 supplies the clock from the clock generation circuit 13 or
A synchronization signal detected from the data signal is added, and a block equivalent to the rotary head 180 °, that is, in this embodiment,
This is a counter for counting 392 blocks. The decoder 54 outputs a data area discrimination signal that sets the data area to “1” and the other areas to “0” according to the value of the counter 53. When a detection signal of the tracking control signal 37 of the recording area 26 is input to the tracking control signal input terminal 40, the detection signal is sent to the counter 53 via the OR gate 44.
Is converted to a load signal for performing the loading of At this time, the switching circuit 49 simultaneously selects the counter load value when the tracking control signal 37 is input. The number of blocks from the tracking control signal to the PCM signal area is determined by the decoder 54.
, The tracking control signal 37
Is detected, the original counter value, that is, the value of the counter that can be set at the time of the tracking control signal is given as the load value, whereby the counter can be operated in accordance with the actual data signal. When the value of the counter 53 is input to the decoder 54, the PCM signal area is determined. Similarly, the tracking control signal 37
Is the load signal, the value of the counter at the time of the tracking control signal is selected as the load value and loaded into the counter 53. The actual data area discrimination signal 38 is set slightly wider than the data area. This takes into account fluctuations in the rotation speed of the rotary head and an increase in jitter due to expansion and contraction of the magnetic tape 1. As described with reference to FIG. 2, the number of blocks in an area occupied by each signal is P in 196 blocks in one track.
The CM signal area 23 has 128 blocks and two Sub-Cs.
The ode signal areas 24 and 25 each have 8 blocks,
Due to the occurrence of jitter, the data signal area 34 may fluctuate by about one block back and forth by 180 ° rotation in the worst case. Therefore, in the PCM signal area of the data area discrimination signal, an area extending one block before and after the actual PCM signal area, that is, an area equivalent to 130 blocks is set, so that the PCM signal can be accurately detected without being missed. The reproduction can be performed. The sub-signal of the data area discrimination signal 38
Since the Code signal area 24 is based on the tracking control signal of the immediately preceding track, jitter also increases. Therefore, when setting the signal area, it is necessary to widen the area width in consideration of some margin. In the present embodiment, the sub-code signal area 24 is set as a sub-code signal area 27 that is an area expanded by 1.5 blocks before and after, that is, an area corresponding to 11 blocks. If the synchronization signal / block address detection circuit 9 and the RAM write address control circuit 14 are controlled using the data area determination signal 38 generated based on the tracking control signal as described above, data can be accurately reproduced. Can be. Another embodiment of the present invention will be described with reference to FIG. FIG. 5 shows a circuit 8 for generating the data area determination signal 38. In the figure, reference numeral 42 denotes a terminal for inputting a signal from the synchronization signal / block address detection circuit 9, 43 denotes an OR gate, 44 denotes a load signal input terminal, 47 denotes an address signal input terminal, and 48 denotes a decoder. When the tracking control signal 37 is input, the load value of the counter is loaded and the data area is determined. Since the tracking control signal 37 is used as a reference, the starting point of the data area is determined so as to be an area wider by 1 to 1.5 blocks as described above. In the example of FIG. 4, the end point of the data area is
It is determined by counting the data area by a counter. In the present embodiment, the starting point of the data area is determined as described above. However, when the synchronization signal of the area 31 and the block address of the area 33 are correctly detected in the data, Address value is counter 5
3 and more accurate data area discrimination signal 3
8 is generated. Further, even when the tracking control signal 37 is missing, the data area discrimination signal 38 can be accurately generated. The data area discrimination signal 38 may be generated by using a preamble signal instead of the tracking control signal. In FIG. 2, the preamble signal is immediately before the Sub-Code 1 signal in the region 24, the PCM signal in the region 23, and the Sub-Code 2 signal in the region 25.
Therefore, based on the preamble signal, a more accurate data area determination signal 38 can be generated. A third embodiment of the present invention will be described with reference to FIG. In the figure, reference numeral 56 denotes a tracking control signal 3
7 to determine the presence or absence of the tracking control signal 37.
Is a terminal for inputting the detection signal of the rotation head, 57 is an input terminal of the rotation position detection signal of the rotation head which is output every rotation by rotation of the rotation head, 58 is a switching circuit for switching a load signal,
Reference numeral 9 denotes a load value input terminal when the rotation position detection signal of the rotary head is used as a load signal. When the tracking control signal 37 of the recording areas 26 and 27 is detected, the switching circuit 49 selects the load value of the counter from the load value input terminals 45 and 46 at the time of the tracking control signal. Operate by loading the load value. However, if the tracking control signal 37 for the areas 26 and 27 is not detected at this time, the loading is not performed because the load signal disappears. The present embodiment is characterized in that, even in such a case, the counter operates correctly and the data area discrimination signal 38 is generated. Tracking control signal 3 for areas 26 and 27
When 7 is not detected, the load signal switching circuit selects the rotational position detection signal of the rotary head as the load signal of the counter 53 according to the tracking control signal detection signal. At this time, the load value 59 at the time of inputting the rotational position detection signal of the rotary head is simultaneously selected as the load value and loaded into the counter 53. The counter 53 starts counting from this value, and the data area determination signal 38 is generated by the decoder 54. Therefore, even when the tracking control signal 37 is not detected, normal operation can be performed by switching from the reference tracking control signal 37 of the data area discrimination signal 38 to the rotation head rotation position detection signal. According to the present invention, a PCM signal area and a Sub-Code signal area in a reproduced digital signal can be accurately determined. Therefore, accurate reproduction can be performed in reproducing the PCM signal and the Sub-Code signal. Further, even when the tracking control signal is missing, the system is switched to a method of generating a data area discrimination signal based on the rotational position of the rotary head as disclosed in Japanese Patent Application Laid-Open No. 58-102307. Thus, it is possible to determine the area where the digital data signal is recorded.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing one embodiment of a reproducing apparatus of 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. 3 is a signal obtained by reproducing the track recording pattern of FIG. 2 and a PCM area discrimination signal obtained from the signal, Sub-C;
FIG. 4 is a timing chart showing an ode area determination signal. FIG. 4 is a block diagram showing one embodiment of a generation circuit for generating the determination signal of FIG. 3; FIG. 5 is a block diagram showing another embodiment of the determination signal generation circuit. FIG. 6 is a block diagram showing still another embodiment of the determination signal generation circuit. [Explanation of Symbols] 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: area where PCM signal is recorded 24, an area in which a Sub-Code1 signal is recorded, 25, an area in which a Sub-Code2 signal is recorded, 26, 27, an area in which a tracking control signal is recorded, 28, an area in which a preamble signal is recorded, 31 ... Area where a synchronization signal is recorded 32 Area where a control signal is recorded 33 Area where a block address is recorded 34 Area where a data signal is recorded 35 Output signal of a rotary head 36 Reproduction data 37, a tracking control signal 38, a data area determination signal 39, a 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, 48: Decoder, 49: Switching circuit 50: Counter load value input Terminals 52: Counter clock input terminal 53: Counter 54: Decoder 55: Data area discrimination signal output terminal 56: Tracking control signal detection signal input terminal 57: Rotational head rotation position detection signal input terminal 58: Load Signal switching circuit, 59 ... Load value input terminal.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Kimura 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Home Appliance Research Laboratory, Hitachi, Ltd. (72) Keiji Noguchi 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Inc. Hitachi Video Electronics Co., Ltd. (72) Inventor Hirohide Kobayashi 292, Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture Hitachi Video Engineering Co., Ltd. (72) Inventor Hiroki Fukuda 292, Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture (56) References JP-A-59-16111 (JP, A) JP-A-59-157810 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 20/10

Claims (1)

(57) [Claims] At least a synchronization signal and a block address are added to a plurality of digital data signals to form one data block signal, and a predetermined number of the data block signals are stored in a predetermined data recording area of a track on a tape-shaped recording medium. In a digital signal reproducing device for reproducing a recording signal recorded as a digital data signal for one track by a rotary head, when the recording signal is reproduced by the rotary head, in a predetermined positional relationship with the data recording area, A reference signal detection circuit that detects a reference signal that is recorded on the time axis before the data recording area and is recorded; and a reproduction timing period of the data recording area based on the reference signal detected by the reference signal detection circuit. And a discriminating circuit for discriminating the digital signal. 2. 2. The digital signal reproducing apparatus according to claim 1, wherein the reproducing process of the data block signal is not performed outside the period determined by the determining circuit. 3. The determination circuit determines the reproduction start timing of the data recording area from the detection timing of the reference signal, and determines the reproduction end timing of the data recording area from the block address of the reproduced data block signal. The digital signal reproducing device according to claim 1. 4. A counter for counting any one of a high-frequency clock signal and the synchronization signal; and a load circuit for loading a predetermined value to the counter when the reference signal is detected by the reference signal detection circuit. 2. The digital signal reproducing apparatus according to claim 1, comprising: a decoder configured to determine a reproduction timing period of the data recording area based on the value of the counter. 5. The digital signal according to claim 4, wherein the reference signal is a tracking control signal, and the load circuit is configured to load the counter when the tracking control signal or the block address is detected. Signal playback device. 6. 2. The digital signal reproducing device according to claim 1, wherein the reference signal is a tracking control signal, and the reference signal detection circuit is a tracking control signal detection circuit.