JPH01205706A - Magnetic reproducing device - Google Patents

Abstract

PURPOSE:To rewind a magnetic tape and to reproduce the magnetic tape again when it is detected that the dropout period length of a reproducing signal is a period length which cannot be corrected by an error correcting circuit by cooperating first and second detecting means. CONSTITUTION:By the start of reproducing, a reel motor 15 and a drum motor 16 are driven, data recorded on a magnetic tape 5 are reproduced and amplified by an RF amplifier 6. The dropout period length being outputted from the RF amplifier 6 is detected by an analog comparator 9 and time width on a dropout is counted by a counter 11. The count value of the counter 11 is compared with comparison data by a comparator 12, when it is detected that the dropout period is long and has the period length which is beyond the correction limit of a decoding/error correcting circuit 7 and cannot be corrected, a control circuit 13 rewinds the magnetic tape 5 by the length corresponding to the comparison data and reproduces the same range on the magnetic tape 5 again.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a magnetic reproducing device for reproducing digital data recorded on a magnetic tape. The present invention relates to a magnetic reproducing device for reproducing recorded digital data on a magnetic tape, if any.

(Prior art) When digital data recorded on a magnetic tape by a rotating magnetic head is reproduced by a magnetic reproducing device, parity data is added and recorded during magnetic recording in consideration of reproducing the recorded data. There is. When such a magnetic tape is reproduced, the reproduced digital data is subjected to error data detection and error correction by an error correction circuit. However, error correction circuits also have limitations.

(Problem to be Solved by the Invention) When digital data recorded on a magnetic tape is reproduced using a rotating magnetic head such as the one described above, the dropout of the digital data may exceed the error correction limit of the error correction circuit. In such a case, there is a problem in that the signal cannot be duplicated correctly and correct digital data cannot be obtained even by interpolation or the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic reproducing apparatus that solves the above-mentioned problem by reproducing the same portion when a dropout that cannot be corrected by an error correction circuit occurs.

(Means for Solving the Problems) In order to solve the above problems, the present invention is configured as follows.

In a magnetic reproducing device that reproduces digital data recorded on a magnetic tape, a first detection means detects the length of consecutive dropout periods of a reproduction signal, and the dropout period length detected by the first detection means is incorrect. a second detection means for detecting that the period length cannot be corrected by the correction circuit, and rewinding the magnetic tape in response to the detection output from the second detection means and instructing reproduction of the digital data on the magnetic tape again. and control means.

(Operation) Therefore, according to the present invention, when it is detected by the cooperation of the first and second detection means that the dropout period length of the reproduced signal is a period length that cannot be corrected by the error correction circuit, the control The magnetic tape is rewound by the means;
The magnetic tape is played both times.

As a result, even if the dropout period length is long due to the -temporal angle of 1, it is resolved by replaying. Also, i
If there is a dropout even during T\ playback, the length of the dropout period is detected.

(Example) This invention will be explained below with reference to Examples.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

Magnetic heads 2 and 3 are provided on the drum 1 at an interval of 180 degrees, and a rotating magnetic head 4 is formed. +III, and the magnetic tape 5 is wound around the drum 1 over 90 degrees.

Digital data recorded on the magnetic tape 5 is reproduced by a rotating magnetic head 4, and is supplied to an It F amplifier 6 where it is amplified to a predetermined level. The playback output amplified by the RF amplifier 6 is decoded and sent to l! The reproduced output is supplied to a correction circuit 7, where the reproduced output is decoded, error detection and error correction are performed, the resultant signal is temporarily stored in a buffer memory 8, and then read out from the buffer memory 8.

The contents of the buffer candy 8 are read out in response to a data output 2th/permission signal output from a control circuit I3 to be described later.

On the other hand, the reproduced output amplified by the RF amplifier 6 is supplied to an analog comparator 9 which compares it with a constant level to detect dropouts in the reproduced output, and outputs the dropouts in correspondence with logic levels. The output from the analog comparator 9 is supplied to a counter 11 which is supplied with the output of the oscillator IO for time base input, and counts the number of oscillation output pulses of the oscillator IO during the dropout period detected by the analog comparator 9. Oscillator counting and dropout period! Convert to the number of 0 oscillation output pulses.

To explain this in detail, for example, in the case of a magnetic tape recorded with digital data by a digital audio chip recorder, the output waveform from the RF amplifier "a6" is shown in Figure 2 (
As shown in a). The output waveform in FIG. 2(a) is a burst waveform as shown in the figure because the magnetic heads 2 and 3 are spaced 180 degrees apart, and the magnetic tape 5 is wrapped around the rotating magnetic head 4 at 90 degrees. Become. Further, portions of the TF signal for tracking are located on both sides of the recorded digital data reproduction signal C. Therefore, using the ATF signal and D2,
Obtain the pulse output shown in b), divide this pulse output by 2 to create a gate signal with the waveform shown in Figure 2 (c), and eliminate the dropout in the RF signal only during this gate signal. I'm going to check it out.

The count output of the counter 11 is supplied to a digital comparator 12 and compared with comparison data. Here, the comparison data is set to a count value corresponding to a width beyond which the limit of the error correction circuit is exceeded if a dropout of a width larger than that occurs. The comparison output of the digital comparator 12 is supplied to the control circuit 13.

The control circuit 13 receives a playback start signal from the outside and controls the reel motor 15 and drum motor 16 via the motor control circuit 14 to perform a playback operation, and during this playback, a long-term dropout occurs. When receiving the output signal from the digital comparator 12 when
It outputs a signal to stop the output of the digital data stored in the buffer memory 8, and at the same time instructs the reel motor 15 to rewind the magnetic tape 5 via the dryer control circuit 14 and reproduce the same portion again.

The operation of an embodiment of the present invention configured as shown in Section 111 will be explained.

The control circuit 13 issues an instruction to start lTi production in response to an external reproduction start signal. When a playback start instruction is issued from the control circuit 13, the motor control circuit I4 controls the reel motor 15 and the drum motor!
6 is driven, the magnetic tape 5 is driven to run, and the rotary magnetic head 4 is driven to rotate, and the data recorded on the magnetic tape 5 is reproduced and amplified by the RF amplifier 6. The amplified reproduced signal is decoded and error corrected and stored in the buffer memory 8.

On the other hand, r? The dropout period length in the output from F amplifier 6 is detected by analog comparator 9.

The dropout time range is detected. This time width is determined by counter 1 using the oscillation pulse of oscillator 10 as a time base.
It is counted at 1. Therefore, the count value of the counter 11 is a value obtained by counting the dropout period based on the oscillation cycle of the oscillator 11.

The count value of the counter 11 and comparison data are compared by a digital comparator 12. In this comparison, [Counter 11
When the count value of the counter 11 is less than the comparison data, the continuous dropout period is long and exceeds the correction limit in the decoding/error correction circuit 7, and when the count value of the counter 11 is less than the comparison data, the continuous dropout period is This is a case where the drop period does not exceed the correction limit in the decoding/error correction circuit 7. The digital comparator 12 generates outputs of logic levels corresponding to the case where [count value of counter 11>comparison data] and the case where [count value of counter 11≦comparison data], respectively.

The control circuit 13 that receives the comparison output of the digital comparator 12 outputs a status signal according to the comparison output of the digital comparator 12, and when receiving the former comparison output from the digital comparator 12, the control circuit 13 outputs a status signal corresponding to the comparison output of the digital comparator 12. The reel motor! is read out via the motor control circuit 14. 5, the magnetic tape 5 is rewound, and the same range on the magnetic tape is reproduced again by the same steps as described above.

When the magnetic tape is re-doubled, it is from when the comparator 12 outputs [count value of counter 11>comparison data], and the magnetic tape 5 is rewound to a length corresponding to the comparison data.

Therefore, the range to be reproduced again is the range corresponding to the comparison data on the magnetic tape 5 in which dropouts have occurred continuously.

In addition, when a new magnetic head (confirmation magnetic head) is provided (not shown) facing the magnetic heads 2 and 3 at 90 degrees, and recorded data is monitored during recording by the magnetic heads 2 and 3. In addition, it is also possible to detect the occurrence of an abnormality during the dropout period during recording and check to ensure that highly reliable recording is performed.

(Effects of the Invention) As explained below, according to the present invention, when it is detected that the dropout has continued for a predetermined period or longer, the same recorded data is played back again. Even if this continues for a predetermined period of time or longer, the recorded data can be obtained by reproducing the data again.

Highly reliable data can be reproduced.

Furthermore, deterioration of the magnetic tape can be determined by counting the frequency of dropouts that occur during playback.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a waveform diagram for explaining the dropout detection section of the present invention. 2 and 3...magnetic head, 4...rotating magnetic head. 5...Magnetic tape, 6...RF amplifier, 7...Decoding/error correction circuit, 8...Buzzer memory, 9...
- Analog comparator, 10... oscillator, 11... counter. 12...Digital comparator, 13...Control circuit. 14...Motor control circuit, 15...Reel motor. 15... Drum motor. Patent Applicant Kenwood Co., Ltd. Patent Attorney Nobuo Sunako (and 1 other person) Figure 1 A - - B - (b) (c) - Dingichi Hee "] -

Claims (1)

[Claims] In a magnetic playback device that plays back digital data recorded on a magnetic tape, a first detection means detects the length of consecutive dropout periods of a playback signal, and the dropout period length detected by the first detection means is incorrect. a second detection means for detecting that the period length cannot be corrected by the correction circuit; and control for rewinding the magnetic tape and instructing reproduction of digital data on the magnetic tape again in accordance with the detection output from the second detection means. A magnetic reproducing device characterized by comprising: means.