JPS5830652B2 - Multi truck digital digital camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for converting each coded bit into each track when recording an encoded digital signal using an analog-to-digital converter into a magnetic recording section having multi-tracks. This relates to magnetic recording methods.

Conventionally, for example, an audio signal is converted to an analog-to-digital converter (hereinafter abbreviated as an A-D converter).

) into a 12-bit encoded pulse train, and MS
B (Most 51gn1ficant Bit) to LS B (Least Significant Bit)
t), it has been proposed to record tracks correspondingly from the first track to the twelfth track.

In each track, signal errors occur due to tape modulation noise, head amplifier noise, and dropouts in the tape head system.

In order to detect this signal error, normally, as shown in FIG.
B, that is, the parity bit C1 from the 1st bit to the 3rd bit, and the parity bit C2 from the 4th bit to the 6th bit.
are recorded respectively.

Note that signal errors from the 7th bit onwards to the LSB, that is, up to the 12th bit, are considered to be audibly negligible, so signal error detection is generally not performed.

By the way, as mentioned above, the causes of signal errors are divided into two types: those caused by tape modulation noise and amplifier noise, and so-called dropouts caused by scratches on the tape or dust stuck to the head. On the other hand, the latter reaches from tens of bits to hundreds of bits when it comes to high-density recording.

For example, if a dropout occurs in the first track, one vertical column in FIG. 1 corresponds to one sample of the audio signal, so the dropout will cause signal errors over tens to hundreds of samples.

When a signal error occurs, if signal error compensation is performed to retain the previous value, the previous value of several tens to hundreds of samples will naturally be retained, resulting in a significant deterioration of the reproduced sound quality.

Therefore, an object of the present invention is to provide a method for magnetically recording bits on each track without deteriorating the reproduced sound quality even when such dropout occurs.

In order to achieve the above object, the present invention distributes a parity bit and tracks corresponding to a group of coded bits belonging to the parity bit so that they do not overlap each other for at least one sample.

By doing this, even if a dropout occurs in a certain track, it is possible to prevent a certain encoded bit from being continuously erroneous.

Hereinafter, the present invention will be explained in detail with reference to examples. 3 Figure 2 is a diagram showing the distribution of the 1st to 12th bits and two check bits in each track according to the present invention, and shows the recording pattern on the tape. As can be seen from three figures, the first
The third to third bits are a group belonging to parity bit C3, and the fourth to sixth bits are a group belonging to parity bit C2.

These groups convert each track group on a sample-by-sample basis.

Similarly, parity bits C1 and C2 alternately convert between the 13th track and the 14th track.

Note that even if a signal error occurs in the 7th to 12th bits, it is assumed that it can be ignored audibly, and the track to be recorded is left as is.

With this kind of distribution, even if a dropout occurs in any of the 1st to 6th tracks, the 13th track, and the 14th track, and several tens of sample signal errors occur in succession, a certain bit will always remain in the signal. There is no chance of making a mistake.

Furthermore, even if a dropout occurs in one track recording parity bits, it is not determined that a group of bits belonging to a certain parity bit always causes a signal error.

The distribution of each bit as shown in FIG. 2 can be realized by a combination of gate circuits as shown in FIG.

Terminals 11 to 16 are input terminals for the first to sixth bits, terminals 17 and 18 are input terminals for parity bits C1 and C2, terminal 19 is a timing clock input terminal for distribution, and elements 31 to 46 are gate elements ( and gate), element 47 is an inverting element, and terminals 21 to 26 are the first
Output terminal connecting track to 6th track, terminal 2
7.28 is an output terminal connected to the 13th track and the 14th track.

A timing clock that is inverted for each sample is input to the terminal 19, and the elements 31, 33, 35, 37, 39, 4
The gate signals are 1.43 and 45.

On the other hand, the timing clock inverted by the inverting element 47 is transmitted to the elements 32, 34, 36°38.40, 42,4.
4 and 46, respectively, and become gate signals.

For example, the first bit is transmitted via terminal 11 to element 31 .
32 respectively.

It is gated using a timing clock and its inverted timing clock, and is alternately distributed to terminals 21 and 24 on a sample-by-sample basis.

Similarly, each bit is alternately distributed to predetermined tracks for each sample.

As explained above, each bit can be distributed as shown in FIG. 2 by the distribution circuit shown in FIG. 3.

As mentioned above, with such a distribution, even if a dropout occurs in a certain track, the audibly problematic bits will not continue to cause signal errors.

And even during the period when dropout occurs, 1
For every sample, in the example above, the top three bits will always be reproduced correctly.

Therefore, if the average value of the values before and after the signal error is adopted as a compensation method for signal errors, the average value of the values before and after the signal error will be reproduced correctly because at least the upper 3 bits are correctly reproduced. If signal errors are compensated for, there will be little deterioration in reproduced sound quality.

Of course, the compensation for holding the previous value also involves some deterioration in the reproduced sound quality, but it is quite effective in practice because the circuit configuration is simple.

As explained above, according to the present invention, even if dropout occurs over several tens of bits in any track, at least the upper three bits will be correctly reproduced every other sample, resulting in a significant deterioration in the playback sound quality. PCM with less
A recorder can be realized.

Note that although the above example shows the case where two check bits are used, it can be easily inferred that the same implementation can be achieved with one check bit or any N check bits.

[Brief explanation of drawings]

FIG. 1 shows a recording pattern on a magnetic tape using conventional bit distribution, FIG. 2 shows a recording pattern on a magnetic tape using bit distribution according to the present invention, and FIG. 3 shows a distribution circuit necessary for distribution in an embodiment of the present invention. 11-16... 1st bit to 6th bit input terminal, 17-18... Parity bit C1, C2
Input terminal, 19...Timing clock input terminal, 31-46...--And gate, 47...
... Inverting element, 21-26 ... Signal output terminal connected to the first track to the sixth track, 27-28
. . . Signal output terminal connected to the 13th track and the 14th track.

Claims (1)

[Claims] 1 In a method in which an analog signal such as an audio signal or a video signal is sampled and encoded into parallel n-bit digital signals, and each digital signal is distributed to each track of a recording medium, the distribution of the digital signal at the same sampling time. A multi-track digital magnetic recording characterized in that a parity bit and encoded bits belonging to the parity bit are distributed such that at least parity bits and coded bits belonging to the parity bit do not overlap at distribution destinations of adjacent sampling times. Method