JPS6016741A - Transmission system of digital data - Google Patents

Abstract

PURPOSE:To attain data transmission with good efficiency in response to the permissible range of a data error rate by selecting optionally the number of repetitive transmission times of digital data in response to the effect due to data error. CONSTITUTION:Information signal data recorded on a disc is equally divided into 15 frames (F1-F15) per channel as shown in (A). In (B), 3136 bits of each frame are divided equally into 16 sectors (S1-S16). Each sector (C) consists of 196 bits. While there is data having very narrow permissible range of data error rate and a large effect by data error such that a character to be displayed is changed into an entirely different character if data error exists even in one bit in an information signal, there is data not affected at all. As to the data having the narrow permissible range in data error rate, the repetitive number of transmission times of the data is increased and the repetitive number of transmission times is displayed by a relative sector number code.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a digital data transmission system, and more particularly to a digital data transmission system for transmitting digital data obtained by digitally modulating an information signal with fewer data errors.

PRIOR ART Conventionally, there has been a disk in which an audio signal or an audio signal and a video signal are respectively digitally modulated and then synthesized in time series and recorded on concentric or spiral tracks as, for example, changes in geometric shape. widely known. This disc is called a digital audio disc because the recorded information is mainly audio signals, and the video signals are mainly still images and serve only as auxiliary information to help the imagination of the listener of the audio signals. ing. On the recording track of this digital audio disk, an information signal such as an audio signal is digitally modulated, converted into a digital signal form, frequency modulated, etc., and recorded. For convenience, a track like the above track will be referred to as a ``digital recording track J'' hereinafter.

).

The digital data recorded on such a digital audio disk consists of a predetermined number of words of digital data, a synchronization signal, an address signal, an error check code, and an error correction code that are time-division multiplexed to form one block. are synthesized and recorded in chronological order. That is, a correction code for correcting data errors caused by dropouts or other causes during reproduction is generated and recorded together with the digital data. This applies not only to digital audio discs, but also to digital V
The same applies to TR.

Problems to be Solved by the Invention However, the above error correction code, whether it is an adjacent code, a Hamming code, or a fire code, requires arithmetic processing in the reproduction system, making the reproduction circuit complicated and expensive. There was a problem. Furthermore, as information signal data other than audio signals and video signals, for example, control program signals to be loaded into equipment with a judgment function (such as a personal computer) connected to the outside of the playback device, or graphic information signals (hereinafter referred to as " (hereinafter referred to as "graphics signals"), character information signals (hereinafter referred to as "character signals"), musical note signals that cause a personal computer to perform automatic performance, and furthermore, in the time axis direction, bit direction, or both directions. Compressed audio signals (hereinafter simply referred to as "compressed audio signals") and other digital signal information (hereinafter collectively referred to as "information signal data") can be selectively recorded and reproduced. Despite the fact that in some cases the influence of data errors is large and in others it is small, error correction codes can always correct errors with the same probability.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a digital data transmission system that solves the above problems by arbitrarily selecting the number of repeated transmissions of digital data depending on the magnitude of the influence of data errors.

Means for Solving the Problems The present invention provides digital data obtained by digital modulation with an information signal, k words of digital data (however, k
is a natural number) Each unit is repeatedly transmitted once or multiple times depending on the permissible range of data error rate for the information content, and the digital data for each k word is at least synchronized with a synchronization signal and the error rate within a certain transmission period. A code indicating the number of times of repeated transmission of digital data is added to the digital data for transmission, and one embodiment thereof will be described below with reference to the drawings.

Embodiment FIG. 1 is a diagram showing an example of the signal format of one block of digital signals recorded on a digital audio disk previously proposed by the present applicant. 4 shown in Ch-4
It is placed in one or more positions of each word of information data of the channel and is transmitted. First, to explain the signal format of one block, S indicates the arrangement position of an 8-bit fixed pattern synchronization signal indicating the start of a block. Also, Ch-1 to Ch-4 are each 4
This figure shows the transmission position of one word of 16 bits of information data of four channels obtained by digitally modulating the information signals of the channels separately. This information data may be a digital audio signal obtained by pulse code modulation (PCM) of an audio signal, a digital video signal obtained by PCM of a video signal, or digital information obtained by PCM of the information signal data. There is data. For example, [1] Ch
One word of the digital audio signal of monaural audio is placed in -1, one word of the above digital information data is placed in Ch-2, and the pixel data of the digital audio signal of channel 1 or 2 is placed in Ch-3 and Ch4. and [2] 1 each for Ch-1 to Ch-4.
In the case where one word of each channel's digital information data is arranged, and [3] When each one channel's digital information data is arranged in Ch-1 and Ch-2,
When pixel data of 1 or 2 channels of digital video signal is placed in h-3 and Ch-4, and when [4] Ch-
Each of Channels 1 to 4 has a platform for arranging pixel data of digital video signals of channels 1 to 4, and furthermore, the data arrangement is performed using a combination of digital signals similar to current digital audio disks. There are cases where it is done. Note that since the digital video signal has 8 bits of quantization per pixel, two pixel data are arranged in one word.

Furthermore, P and Q shown in FIG. 1 are respectively 16-bit error correction codes, for example, P=W1■W2■W3■W4 (1) Q=T4・W1■T3・W2■T2・W3■T・W4
(2) This is a signal generated by the following equation. However, (1),
(2) In the formula, W1, W2, W3, W4 are Ch-1 to Ch-
4 16-bit digital signals (usually digital signals in different blocks), T is an auxiliary matrix of a predetermined polynomial, and ■ indicates the modulo-2 addition for each corresponding bit.

Furthermore, in Figure 2, CRC is a 23-bit error check code,
Ch-1 to Ch-4, P, Q arranged in the same block
This is the 23-bit remainder obtained when each word of is divided by the generator polynomial, for example, X23 + X5 + X4 + When the obtained remainder is zero, it is used to detect that there is no error. Furthermore, in FIG. 1, Adr indicates a 1-bit multi-level purchase of a control signal used for random access or the like. This control signal distributes each bit data and transmits one bit in one block, for example, 196 bits.
All bits of the control signal are transmitted by the block (ie, the control signal consists of 196 bits).

Furthermore, U is 2 bits for reserve called user's bits. One block of signals is composed of a total of 130 bits from S to U shown in FIG. 1, and the digital signal (information data of 4 channels) is divided into blocks at a sampling frequency of, for example, a digital audio signal of 44.056 kHz. They are synthesized at the same frequency and transmitted in chronological order.

The above 196-bit control signal has a configuration in which four types of address signals of 49 bits each are synthesized in time series, and these four types of address signals are all in the signal format shown in Figure 2. There is.

In Figure 2, the back side of all 49-bit address signals is SY.
The first 24 bits indicated by NC are synchronization signals whose values differ depending on the four types of address signals. The next 1 bit of the synchronization signal is 2 bits indicating the source mode indicating which of the combinations [1] to [4] the recording signal is, and 2 bits normal indicating whether stop playback is to be performed. - It consists of a stop mode discrimination signal NR/ST, address data is arranged in the next 20 bits, and the last 1 bit is a parity bit.

The relationship between the values of the 2-bit source mode discrimination signal and the 2-bit normal/stop mode discrimination signal NR/ST and their discrimination contents is as shown in FIG. Here, when the value of the normal/stop mode discrimination signal NR/ST is "00", the current disc playback device performs normal playback, and when the value is "11", it performs stop motion playback that repeatedly plays the same track. In the case of stop motion reproduction, the reproduced output audio signal is automatically muted. Therefore, in this embodiment, the above discrimination signal NR
/ST value is "11", which is the value for stop motion playback.
'', the information signal data is selected to indicate that the information signal data is recorded.

That is, as shown in FIG. 4, when the value of the discrimination signal NR/ST is "11" and the value of the source mode signal is "00", Ch-1 to Ch-4 in FIG.
The combination of four channels of information signals transmitted in one word is one channel of monaural digital audio signal, one channel of digital information data of the information signal data indicated by "data", and one channel of digital information data of the information signal data indicated by "data". This is the case when the digital video signal shown by is 1 channel, which is the case [1] above, and similarly, when the value of the source mode signal is "01", it is the case [2] above, and the source mode When the signal value is "10", it is the case [3] above, and when the source mode signal value is "11"
”, it is determined that the case [4] is the case.

On the other hand, when the value of the discrimination signal NR/ST is "00", which is the value for normal reproduction, the value of the source mode signal and
The relationship with the combination with the four-channel information signal is selected to be the same as that of the current digital audio disk. That is, as shown in FIG.
When the value of R/ST is "00" and the value of the source mode signal is "00", Ch-
Indicates that 3 channels of digital audio signals and 1 channel of digital video signals are transmitted in each of Ch-1 to Ch-4, and when "01" indicates that 4 channels of digital audio signals are transmitted, Further, "10" indicates that two types of 2-channel digital audio signals are transmitted, and "11" indicates that 2-channel digital audio signals and 2 channels of digital video signals are transmitted.

In addition, in the address data shown in FIG. 2, if this 49-bit address signal is a time address signal, the track position on the disk where this address signal is recorded will be the same as normal playback from the recording start position on the disk. This is time data that indicates how long the playback time is when the signal is recorded, and in the case of a chapter address signal, it indicates the number of music programs recorded at the track position where the signal was recorded from the disc recording start position. This is data indicating whether or not there are any animals present.

Note that when transmitting a digital video signal related to a still image, for example, pixel data of a luminance signal has a sampling frequency of 9.
MHz, quantization number of 8 bits per pixel is changed to a sampling frequency of 88.112kHz using memory, and 2 types +
The pixel data of the color difference signals (R-Y) and (B-Y) have a sampling frequency of 2.25 MHz and a quantization number of 8 bits per pixel, respectively, and the sampling frequency is 88.112 using memory.
kHz, and each pixel data with 8 bits of quantization bits is arranged in the upper 8 bits and lower 8 bits of one word and transmitted.
Pixel data group for columns and color difference signal for one vertical column (R-Y)
The pixel data group and the pixel data group of the color difference signal (B-Y) for one vertical column are treated as one unit, and are transmitted in time series for each unit. Further, the information signal data is divided into fixed length sectors and recorded, as will be described in detail later.

Each signal unit of one block shown in Fig. 1 above is synthesized in time series and addressed to 294 signals for each rotation (4 field periods).
The digital signal consisting of 0 blocks is further frequency-modulated into a frequency-modulated wave signal with a frequency spectrum as shown by the solid line in FIG. 3, and then, for example, a spiral track (digital recording track) is formed on a disk. recorded.

Here, in FIG. 3, 7.6 MHz indicates the carrier frequency when the data is "1", and 5.8 MHz indicates the carrier frequency when the data is "0". In addition, in the figure, f indicated by a broken line
p1, fp2, and fp3 are reference signals fp1, f, which will be described later.
p2 and fp3 are shown.

FIG. 5 shows an example of a track pattern of a disk on which the above modulated wave signal is recorded. In the figure, the modulated wave signal is recorded in the spiral track indicated by the solid line.
On one side of the track there is a reference signal fp1 as shown by the circle.
is recorded in a burst pattern, and the reference signal fp2 is recorded in a burst pattern on the other side as shown by an x mark. Furthermore, since the reference signals fp1 and fp2 are alternately switched and recorded every rotation, the sides on which the reference signals fp1 and fp2 are recorded with respect to the information recording track are switched every rotation. Note that the reference signal fp3 is recorded as an index signal over a certain period of time at the switching recording position of the reference signals fp1 and fp2.

This track pattern itself is the same as the digital audio disk previously proposed by the applicant, and the signal format (FIG. 2) and modulation signal form (FIG. 3) of the digital signal of the digital recording track are also similar to the digital audio disk. It is the same as that of the disk. However,
In the present invention, as the information data recorded on the disk, the information signal data is recorded once or multiple times in accordance with the signal format shown in FIG. It is characterized by being transmitted repeatedly.

That is, to explain this in more detail, first, the above-mentioned information signal data is divided and recorded into N sectors (where N is a natural number of 2 or more) for one rotation of the disk per channel, and , it will be explained that each sector is recorded in a signal format in which at least a mode code indicating the type (content) of information signal data and an address code indicating the recording track position are added to the digital data. Assuming that a track recorded for one rotation of the disk starting from the recording position of signal fp3 is counted as one track, one digital recording track contains one block of the signal shown in FIG. 1 in block units. A total of 294 images are synthesized chronologically for each
0 blocks are recorded. Therefore, C in Figure 1
One word is placed in h-1 to Ch-4 and transmitted 4
One digital recording track of a channel's digital signal contains 2940 words (294 words) per channel.
0x16 bits) are recorded. Here, among the three types of information signals recorded on the digital recording track, especially video signals, audio signals, and information signal data related to still images, the video signal (digital video signal) and the audio signal (digital audio signal) are The format is selected to be the same signal format as the digital audio disk described above.

On the other hand, the above information signal data is stored in one digital recording track as shown in FIG. 6(A) per channel.
Equally divided into 15 frames as shown in 1 to F15,
Further, each frame of 3136 bits is equally divided into 16 sectors S1 to S16 and recorded, as shown in FIG. Therefore, each sector, as shown in FIG. 6(C),
It consists of 196 bits and its first SYN
A synchronization signal with a predetermined fixed pattern is placed in the 16 bits indicated by C, a label consisting of an address code and a mode code is placed in the next 28 bits, and the next 128 bits are placed in the next 28 bits.
Eight pieces of digital data of 16-bit information signal data are time-division multiplexed into the bits, and a signal format is selected in which an error check code is placed in the remaining 24 bit positions indicated by CRC.

The above error check code is, for example, the 24-bit remainder obtained by dividing the value from the 17th bit to the 171st bit of the same sector by a predetermined generator polynomial, and as a matter of course, it is shown in FIG. This is a completely different code from the error check code placed at the position indicated by the CRC.

Naturally, the bit length of the digital data of the information signal data differs depending on the information content, but here it is applied to a data unit of 128 bits×n (where n is a natural number).

For example, digital data of 8 words or less is stored in the data area of one 128-bit sector, and digital data of 16 words or less is stored in the data area of 9
Digital data larger than a word is applied to a total of 256 bits in each data area of two sectors.
(Same for 17 words or more).

Therefore, the above digital data is applied to fixed length sectors, and the digital data length is 12
When the number is not a natural number multiple of 8 bits, dummy data is inserted into the remaining part of the data area within the sector. This is for data rearrangement, which will be described later.

Furthermore, the 28 bits of the fixed length sector shown by the labels in FIG. 6(C) are selected to have a signal format as shown in FIG. 6(D). In the same figure (D), the first 1
bit and the last 6 bits are each undefined, a total of 5 bits from the 2nd bit to the 6th bit are assigned a frame number, and the next 4 bits and the next 4 bits are each assigned a relative sector. A number and an absolute sector number are respectively arranged, and these 13 bits constitute an address code. The above frame number is a number indicating which frame out of 15 frames of one digital recording track this sector is in, and the absolute sector number is a number indicating which frame this sector is in among the 15 frames in one digital recording track. Indicates the sector number of the sector.

In addition, in FIG. 6(D), from the 15th bit to the 2nd bit
A mode code is placed in a total of 8 bits up to the 2nd bit. This mode code includes a first mode code placed at the position indicated by "mode 1" of the first 4 bits,
It consists of a second mode code placed at the next 4-bit position indicated by "mode 2". The first mode code indicates the type when digital data of the same type of information signal data is transmitted using 16 bits per food.

As described above, these types include control program signals, graphics signals, character signals, musical note signals, compressed audio signals, and the like. Also, the second mode code "Mode 2"
indicates the type of digital data when different types of digital data are transmitted in the upper byte and lower byte of each word of the 128-bit data area indicated by "data" in FIG. 6(C). An example of transmitting different types of digital data in the upper byte and lower byte of each word is to transmit 8 bits of a compressed audio signal in the upper byte and transmit digital data of other types of information data in the lower byte. In this case, the playback device may be able to play back two types of digital data at the same time. For example, while playing back an audio signal obtained by time-axis expanding a compressed audio signal, a program may be run on a personal computer. You can do things like load.

An example of the relationship between the values of the first and second mode codes and the type of digital data is summarized as shown in the following table.

As can be seen from the above table, when the 4-bit value of "Mode 1" is "0000" or "1000", the data content of "Mode 2" is the same as the information signal data recorded on the digital recording track of the disk. It indicates the type of the upper byte and lower byte, and if the value is other than that, it can be determined that the same type of information signal data is being transmitted in one 16-bit word, and the type thereof.

Furthermore, the relative sector number shown in FIG. 6(D) is a code indicating the number of times the information signal data in the sector is repeatedly transmitted in one frame. Here, since there are 16 sectors in one frame, the information signal data in the sector can be repeatedly transmitted (overwritten) up to 16 times. If there is a data error in even one bit in the above information signal, the personal computer connected to the outside of the disc playback device for interactive playback may go out of control, or the display may fail. There is data where the acceptable range of data error rate is extremely narrow and the impact of data errors is large, such as characters that should be replaced with completely different characters, but on the other hand, even small data errors have almost no impact. There is also data that has a wide tolerance range for data error rates. Therefore, in view of the above points, the present invention increases the number of times of repeated transmission of data for which the allowable range of data error rate is narrow, and increases the number of times of repeated transmission of that data for data whose allowable range of arc error rate is wide. The above relative sector number code indicates the number of repeated transmissions.

For example, if digital data is transmitted repeatedly 16 times, 16 sectors S1 to S16 in one frame
Since all eight words of digital data are the same, the values of the relative sector number codes of each sector S1 to S16 are all "0000"("0" in decimal notation). Similarly, when digital data is transmitted repeatedly four times, the digital data of 16 sectors S1 to S16 are transmitted as S1 to S4, S5 to S8, S9 to S12, S1
The value of the relative sector number code is "0000" in each of sectors S1 to S4, and "0001"("1" in decimal notation) in each of sectors S5 to S8. , sector S9~
For S12 people, “0010” (“2” in decimal system)
), and further, in each of sectors S13 to S16, “00
11” (“3” in decimal notation). The same holds true for other numbers of repeated transmissions, and the following table summarizes the number of repeated transmissions and the range of values of relative sector number codes in decimal notation.

In the above table, the number of repeated transmissions "1" means that sectors S1 to S16 in one frame are different digital data and are not repeatedly transmitted (
In this case, the decimal value of the relative sector number code is "0" in sector S1, "1" from sector S2 to sector S16, etc.
It will change by 1 to "15".

In this way, the digital data, which is the digitally modulated wave signal of the information signal data, is recorded on one digital recording track per channel in fixed length units of 15 frames and 240 sectors in total, and each sector is defined as shown in FIG. The signal is recorded in the signal format shown in D). However, a total of 240 sectors recorded on one digital recording track are not recorded in order in frame order.
By rearranging the data order, for example, as shown in FIG. 7, the first sectors S1-1 to S15-1 of the first frame F1 to the fifteenth frame F15 are synthesized and recorded in chronological order, and the next the second sector S1-2 of each frame
- S15-2 are sequentially recorded, and thereafter, sectors in the same order of each frame are sequentially recorded in the same manner as described above.

Here, in FIG. 7, Si-j is the i-th (here, 1 to 1
jth (here 1 to 16) in the frame of 5)
indicates sector Sj.

In this way, a total of 240 sectors are recorded in a distributed order on one digital recording track (interleaved recording) to prevent errors and errors in the event that a part of the reproduced signal is missing due to dropouts etc. during reproduction. This is for reasons such as minimizing the impact of

The rotation speed of the digital audio disk proposed earlier by the applicant is 900 rpm, the number of blocks per rotation is 2940, and the transmission frequency of one block is 4.
4.1kHz, whereas the disk of this example has a frequency of 1kHz.
The number of blocks in the digital recording track for rotation is 294.
0, which is the same as the above-mentioned digital audio disk, but its rotation speed is 899.1 rpm, which is the same as the video disk.
, and the transmission frequency of one block is 44.1kHz.
The difference is that a frequency of 44.056 kHz, which is extremely close to , is selected.

Next, a brief explanation will be given of the procedure for reproducing the above-mentioned disk. A disk reproducing apparatus in which the above-mentioned information signal data is recorded on a digital recording track by assigning 8 words each to fixed-length sectors for one or more channels,
When the last two bits of the 4-bit signal shown as "mode discrimination" in FIG. Although this is originally a stop motion reproduction, various mechanisms and circuits are controlled to perform normal reproduction. Thereby, the information signal data reproduced from the digital recording track can be demodulated and reproduced. In this case, the FM signal reproduced from the digital recording track is FM demodulated into a reproduced digital signal and then stored in a buffer memory, while an error check code is placed at the position indicated by CRC in FIG. Detection is performed using a known method.

Here, the digital data stored in the buffer memory is interleaved digital data as shown in FIG. 7, which is rearranged into the original order by controlling the designation of the read address of this buffer memory. (deinterleaved) is read from this buffer memory. The reproduced digital data read from this buffer memory is sent to the first platform where the error occurred.
Since error correction is performed by a known method using the reproduced error correction codes placed at the positions indicated by P and Q in the figure, and correct digital data is restored, there are almost no data errors, but for example, over a long period of time. Even if error correction using the two error correction codes is not possible due to dropout or the like, in this embodiment, the information signal data is repeatedly transmitted an arbitrary number of times according to the permissible data error rate range of the information content of the information signal data. Therefore, the error rate for important data is extremely low. Furthermore, as shown by the CRC in FIG. 6(C), a 24-bit error check code is provided in each sector, and if an error check using this code determines that there is an error,
The data can be discarded or the effect of data errors can be minimized by means such as pre-hold. In this way, the reproduced sector retrieved with almost no data errors is reproduced after digital data is stored in the memory circuit, and the label data is supplied to a predetermined acquisition circuit.

Note that the sector has a fixed length, and the SYNC
Since the synchronization signal at the position shown in is periodically regenerated, it is possible to transmit data with the same pattern as the synchronization signal, which was not possible when transmitting variable length data. In contrast, digital data within a sector can be demodulated with a simple circuit configuration.

When searching for a desired track position among the digital recording tracks on which the information signal data is recorded, for example, a track number address signal indicating the number of tracks and a frame shown in FIG. 6(D) are used. You can search by specifying the number and relative sector number. If the track position cannot be retrieved in this case, an absolute sector number is specified instead of the above-mentioned relative sector number.

Application Examples It should be noted that the present invention is not limited to the above-mentioned embodiments, and the present applicant has previously filed Japanese Patent Application No. 58-83232 and Japanese Patent Application No. 5
Like the information signal recording disc proposed in No. 8-83234, recording is formed by mixing digital recording tracks with tracks on which modulated wave signals obtained by analog modulation with information signals including video signals are recorded. It can also be applied to disks that have been It can also be applied to discs in which recorded signals are read by irradiating a light beam onto the disc and detecting changes in the light intensity of the reflected or transmitted light, and even if the number of fields recorded per revolution is two. good. Furthermore, the data can be transmitted not only through disks but also through other recording media such as magnetic tape.

In addition, in the present invention, digital data is shown in FIGS.
It is transmitted in the signal format shown in D),
It is not necessary to transmit the signal in the signal format shown in FIG.

Effects As described above, according to the present invention, each k word (8 words in the above embodiment) of digital data is repeatedly transmitted once or multiple times depending on the permissible range of data error rate for the information content. Since the digital data for each k word is transmitted with at least a synchronization signal and a code indicating the number of repeated transmissions added, efficient data transmission can be performed according to the allowable range of data error rate, and data For data with a narrow error rate tolerance range, the data error rate can be reduced more than before, and since no error correction code is transmitted, there is no need for arithmetic processing in the reproduction system. The circuit can be constructed easily and inexpensively, and furthermore, each word of the digital data described above constitutes one block together with other information data, other synchronization signals, an error check code, and an error correction code, and this block unit If it is transmitted every time, it has the advantage that the data error rate can be further reduced by error correction using the above-mentioned error correction code.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the signal format of one block of digital signals recorded on a digital audio disk previously proposed by the present applicant, and FIG. 2 shows a control signal included in the digital signal shown in FIG. 1. A diagram showing an example of the signal format of an address signal when a predetermined number of bits are grouped together, FIG. 3 is a diagram showing an example of the frequency spectrum of a frequency modulated wave signal, etc. to be recorded, and FIG. 4 is a diagram showing the mode in FIG. 2. A diagram showing an example of the relationship between the axis of the discrimination signal and its discrimination content, FIG. 5 is a diagram showing an example of the track pattern of a disk, and FIGS. 6 (A) to (D) are each transmitted by the method of the present invention. FIG. 7 is a diagram illustrating an example of the signal format of a digital signal, and is a diagram schematically showing an example of the recording order of sectors. S, SYNC...Error correction code transmission position, Ch-1~
Ch-4...Digital data transmission position, CRC...
・Error check code transmission position, Adr...Control signal transmission position, F1 to F15...Frame, S1 to S16, S1
-1 to S15-16... Sector. Fig. 1 Fig. 2 Danger/Fig. 1 Fig. 5

Claims (4)

[Claims] (1) Digital data obtained by digitally modulating an information signal is modulated once or multiple times for each k word (k is a natural number) unit of the digital data, depending on the permissible range of data error rate for the information content. Digital data characterized in that it is repeatedly transmitted, and at least a synchronization signal and a code indicating the number of times the digital data is repeatedly transmitted within a certain transmission period are added to each k-word digital data before being transmitted. transmission method. (2) The digital data transmission system according to claim 1, wherein the information signal is an information signal other than an uncompressed audio signal and a video signal. (3) The digital data is recorded and reproduced on the information signal recording disk, and the fixed transmission period is a natural number of the recorded signal transmission period of the spiral or concentric track formed per revolution of the information signal recording disk. 3. The digital data transmission method according to claim 1 or 2, wherein the period is one time. (4) The digital signal consisting of the digital data, synchronization signal and code constitutes one block as information data for each certain number of bits together with other information data, another synchronization signal, an error check code and an error correction code, A digital data transmission system according to any one of claims 1 to 3, characterized in that the digital data is transmitted in block units.