JPS63247975A - Pcm signal recorder - Google Patents

Abstract

PURPOSE:To perform the recording and reproduction with high quality of a voice, by providing a symbol generation circuit, an interleave circuit, an error correction code generation circuit, a block generation circuit, a frame generation circuit, and a code conversion circuit. CONSTITUTION:By sampling an input analog signal with a frequency of 48kHz, a digital signal with a unit of 16 bits can be obtained as the output of an ADC circuit 2. The signal is compressed to the one of 12 bits at a compression symbol generation circuit 3, and a symbol is generated setting 6 bits as one unit. Symbol information is distributed at the interleave circuit 5, and a processing to respond to a burst error at the time of recording and reproduction is performed. Simultaneously, a block is constituted at the block generation circuit with a synchronizing signal in the lead. A corrected code is attached at the error correction code generation circuit 6. An information frame is constituted of the block according to the cycle of a reference synchronizing signal, and code modulation is applied in a symbol unit, and a large amount of information can be recorded efficiently. Asynchronism between the symbol information and the reference synchronizing signal is controlled and absorbed with the quantity of the symbol information in the frame. By constituting a device in such way, it is possible to perform the recording with high density of the information on a limited area. Also, since independence from a video signal is realized, digital dubbing can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for recording PCM signals on a magnetic tape, and particularly to a V14 for recording video signals and PCM audio.

[Conventional technology]

An example of a device (v'rh, ) for recording or reproducing a pair of video signals and PCM audio on a magnetic tape is the l'J: 8m711 video tape. Regarding the 8mz video standard, please refer to the ``B mm video standard 4-bit electronics (1983, 5
26). Q that shows the performance of PCM audio
'), there is a sampling frequency of 13 related to the audio reproduction band, an 8N ratio, and a number of discretization bits related to distortion of 18, respectively.
It is #F (10-8 companding). Also, in satellite broadcasting.

E) There are 2 types of A mode and B mode. CM audio is available, 9 A shade, fs = 2 K, Hz, Ns; 1 a bit (14-1 op instant companding), B mode fs = 48 K
Hz, NS: I6 bits (linear).

On the other hand, for audio-only commercial audio, fs = 44.1K for compact discs (hereinafter referred to as 'D').
Hz, NS: 16 bits (linear). In addition, the digital audio tape recorder (hereinafter referred to as DAT) capable of recording and playback is referred to as rDAT standardization overview” Institute of Electronics, Information and Communication Engineers Vol. 1.70 Nu 1 (198-1)
As listed in 6, 7s = 4s KHz
, Ns = 16 bits (linear) as standard, and fa == 32 K) i z .

Also compatible with 44.1KH2.

The fs of the Q mm video signal described above is the horizontal synchronization of the video signal. Te(・ru.

Even in NS, there is a restriction on the recording area of PCM audio7'J
) and 1[1 bit and low (fl C, also Dfi,
In the case of T, 5,'(J*Ns is the same as satellite and broadcasting, and digital synchronization is possible, so it is called digital dubbing.(,7, 8) In the case of video, f3
is independent from other audio No. 411, so there is no consideration for dubbing or the like.

[Problem that the invention seeks to solve]

In the conventional technology, the sound reproduction band shape, S ratio,
There was a problem that the high sound quality as digital audio against distortion was insufficient, and that no consideration was given to connection with other sound sources [2] digital dubbing.

SUMMARY OF THE INVENTION An object of the present invention is to provide high quality digital audio and enable digital dubbing.

[Means for Solving the Problem] The above purpose is to 1. - Deno of IAbit,・
the 16-bit signal is digitally instantaneously compressed to 12 bits, the 12-bit signal is divided into 2 symbol data corresponding to 6 bits of 1 symbol data, and this symbol data is distributed (interleaved). At the same time, an error correction code, a synchronization signal, and a control signal are added to form a data frame synchronized with the field of the video signal, and the 6-bit symbol data is code-modulated into 8 bits and recorded on a magnetic recording medium. This is achieved by

[Effect]

In the above means, the recording density can be reduced to three-quarters by changing the 4aKf (z-sampled 16-bit digital signal to 12 bits), and by converting 12 bits of data into 6 bits and 2 symbols. By facilitating code modulation, reducing reproduction signal errors during reproduction through interleaving and error correction code addition, and providing margin for increasing and decreasing symbol data for each frame in the data frame structure.

Asynchronous absorption of the video field period and the same sampling wave number is possible, and efficient high-density recording can be performed by code modulation, so PCM recording with high sound quality and digital ping is possible.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a basic block diagram of the present invention. 1 is an analog signal input terminal for the original signal to be recorded. 2 is an analog/digital conversion circuit (ADC), 5 is a compressed symbol generation circuit, 4 is a block generation circuit, 5 is an interleave circuit, and 6 is an error correction code generation circuit.

7 is a frame generation circuit, 8 is a code modulation circuit, 9 is an asynchronous absorption circuit, 10 is a reference synchronization signal input terminal, and 11 is a recording signal output terminal. 100 is a controller that controls the system, and 101 is a control path line with each of the circuits.

The basic operation is shown below. The analog signal input from the analog signal input terminal 1 is sampled at a predetermined period (sampling frequency), and the sampled analog signal m is quantized into N bits and converted into a digital signal.

For example, if the sampling frequency is 48 KHz and the quantization is 16 bits, the output of the ADC 2 will be a digital signal in units of 16 bits. This 16bee71 digital signal.

It is input to the next compressed symbol generation circuit 3. The compressed symbol generation circuit 6 compresses the input 16-bit digital signal into bits so as not to damage the properties of the original analog signal. For example, compress 16 bits/) to 12 bits.

Next, the 12-bit signal is divided into a plurality of parts to create a new data unit in order to facilitate the processing of the digital signal and to take into consideration the error length when recording and reproducing on a medium such as a tape. For example, divide 12 bits into two and divide 6 bits into 1
Unit.

This 1 unit is 1 symbol.

Next, in order to deal with burst errors when the above-mentioned symbol data is recorded and reproduced on a medium, the data is distributed by an interleave circuit 5. At the same time, the block generation circuit configures a block with the synchronization signal at the beginning. In the data within this block, errors that occur during recording and playback are expressed as Ar iF + λ\ Boo
To δ's ffl re 1-cho +f XC meeting
4 Jth 1"l 1st; T: Sign is added by the m number generation circuit 6.

A data frame is constructed from the above blocks according to the period of the reference synchronization signal which is the basis of the recording format. The data is organized into a data frame.

Code modulation is performed in units of the symbols. This has the effect of more efficiently recording more information on the recording medium.

Furthermore, error correction codes are used to generate codes between blocks in data frame generation to improve correction ability. Asynchronous absorption is for controlling the asynchrony between the period (sampling frequency) of symbol data and the reference synchronization signal on the record using the amount of symbol data within a data frame.

(Details will be described later.) FIG. 2 shows an embodiment in which the present invention is applied to a VTR in which an audio signal and a video signal are divided into areas on a magnetic tape and recorded.

In FIG. 2, the same numbers as in FIG. 1 have equivalent functions. Reference numeral 12 denotes a time width compression circuit for dividing the video signal and the audio signal into areas and recording the audio data in predetermined portions. 16 is.

Video signal processing circuit for recording video signals, 14
1 is a modulation circuit for video signals, 15 is a recording amplifier for recording video signals and audio signals on tape, 16 is a recording tape, 17 is a cylinder containing a recording/playback rotary head, and 18 is a video signal input terminal. be. 102
is a system control controller.

103 is a control line. This VTI (, is a so-called rotary head recial scan type VTR that records a video signal 19 diagonally on a tape 16 as shown in
It is. As shown in FIG. 3, the audio signal is recorded as a PCM digital signal in an area that is an extension of the video signal.

Now, returning to FIG. 2, the operation will be explained. The basic movement is the first
Same as the figure. One diagonal line marked a on the tape is called a track, and its time period is synchronized with the field period of the video signal. Signal processing is facilitated by associating this field with the audio data frame described above. However, since the field period and the audio sampling frequency are unrelated, an asynchronous acquisition circuit 9 is provided to control the amount of data within the data frame. The time axis compression circuit 12 compresses data within a data frame in accordance with the field period of the video. The recording amplifier sends a signal to the head while switching between an audio data modulation signal and a video modulation signal.

Next, each major block will be explained. Figure 4 is.

Symbol generation by compressed symbol generation circuit B is shown.

One sample data 21 of 16 bits generated by the ADC circuit 2 is converted by a decoder 22 into compressed data 23 of 12 periods. The appropriate number of conversion bits is 12 bits as a level that does not impair the quality of the audio.

The decoder 220 function can be implemented using so-called digital compression, such as instantaneous linear compression.

In addition, one proof of multiple sample data.

There is a quasi-instantaneous compression means that compresses sample data within one block to a uniform rate based on the maximum value within one block. In this case, it is necessary to transmit the compression level in units of blocks as information, which can be transmitted using an identification word (U) area, which will be described later.

The compressed data 23 is converted to 6 viv2 symbols 24.25 to facilitate signal processing and spread out errors on the tape. 6-bit one symbol also has excellent bit consistency with 6-8 code modulation, which will be described later.

Next, block generation circuit 4. The frame generation circuit 7, interleave processing, and error correction code addition will be explained.

5 and 6 show frame structures when the video signal is in NTSC format, and FIGS. 9 and 10 show frame structures when the video signal is in CCI format. Figure 7 shows the block configuration corresponding to Figures 5 and 9.
FIG. 8 shows a block configuration corresponding to FIGS. 6 and 10.

In FIG. 5, numeral 26 indicates a data frame of an audio signal, which is paired with one field of a video signal to be simultaneously recorded on the tape. A total of 108 blocks constitute one frame, from the left to the vertically elongated block 0 (Block O), Prolift...block 107. B shown in the drawing is a block, and S is a symbol unit. 27 is control data such as a synchronization signal at the beginning of each block, 28 and 29 are audio signal data, 60 is an error correction code (('i code)) that is derived from the data in each block, and 31 is each block This is an error correction code (C2 outer code) that uses the data in between.

The 01 internal code is the lead code word (59, 57) in which 2 symbols of error correction code are added to a total of 37 symbols, including 56 symbols of audio data in the block and 1 symbol of block address data in the control data 27. It is a Solomon code. In addition, the C2 outer code 31 is a code word (27, 25) to which 23 symbols of audio data and 4 symbols of a likelihood error correction code are added between each block (in the horizontal direction on the drawing).
This is a Reed-Solomon code, and four sets of these 27 symbols are used to create a 1jltlrfiJJ10B block. As described above, a double-encoded Reedon-Romon code is formed from the C1 inner code in the vertical direction and the C2 outer code in the horizontal force direction.

Now, the required storage space within a data frame is determined by the audio data sampling frequency and the data frame frequency. In this example, the sampling frequency is set to 48K.
Hz and the field frequency (=frame frequency) of the video signal is 60/1.001 H2 of NTSC, then the audio is the second stereo channel and two symbols of one sampling data.

Number of symbols required for 1 frame: = 48Kx2x2+-1
,001=5205.2. Processing regarding the fractions of 0 and 2 that occur here will be described later.

On the other hand, the capacity (number of symbols) of audio data in one data frame in FIG.

Capacity (number of symbols) = 56 x 46 x 2 = 3512
Therefore, the number of symbols required for one data frame can be efficiently covered.

Similar to FIG. 5, FIG. 6 shows an example of a frame structure for a video signal in the NTSC format.

The difference from FIG. 5 is that in FIG. 5, the CI inner code and the 02 outer code are orthogonal, whereas in FIG. 6, the oblique type is used. In FIG. 6, the C2 outer code 52 generates a code for nine data lines diagonally on the data frame, and the code is placed in each block.

FIG. 7 shows the configuration of the blocks in FIG. 5. The control data 27 includes a synchronization signal (SYN) of 55.
C), sa identifier (IL)), 55 block address (H, AL) DB) and 56 parity (PAR
ITY). Parity 56 is ID54 and B.

At) D) This is an error check code for L35. 57 is audio data of 36 symbols, and in the block of C2 outer code 61 in FIG.
2 outer code (C2-PARITY). 50 is C1
There are two symbols in the inner code (Ci-PARITY).

FIG. 8 shows the configuration of the blocks in FIG. 6. 4-symbol C2 outer code 32 in the block configuration of FIG.
is added.

In FIG. 9, a video signal is constructed into a frame according to the CCI format, which is basically the same as the frame construction in FIG. 5. In CCII (the field frequency is 50Hz, the amount of data in the audio frame is different compared to the NTSC).Audio data 28, 2
9 is a block with 36 symbols vertically and 54 symbols horizontally.
+54, and the total capacity is 3888 symbols.

On the other hand, the number of necessary audio data symbols to be allocated to one frame in CCI)l is.

Number of symbols required for one frame: 48KX2X2+50=
3840, which can be efficiently distributed to the entire capacity.

In FIG. 9, the C1 inner code and C2 outer code of the error correction code are orthogonal, but the frame 39 in FIG. 10 is of the oblique type, and the structure, audio data capacity, etc. are the same.

Next, the control data CD2 shown in FIGS. 7 and 8
7 will be explained. 8YNC55 is located at the beginning of the program and serves as a reference for data insertion as a synchronization signal. ID
3a displays the four feet of the data frame and the type of audio signal, and the frame content is, in the example of FIG. 5, 1 symbol x 8 pixels) x 108 blocks = 864.
It's a bit. Display data as described above can be distributed within the frame. It can also be used as an area for recording information other than audio data. B, AL) 1) I(,
27 indicates the address of the program. In the example in Figure 5, the pro 9 ri is O to 107, for a total of 108 pro/I.
There is.

B, ADDkL27H1 Symbol 6 Heat/To.

Only 64 addresses from ~63 can be displayed. Therefore, it can be distributed by using 2 symbols. Mana, as another method,
There is one shown in FIG. To do this, the data frame is divided into two in the middle, and the difference between before and after 1 is determined by using the least significant bit rID5J of It)34 with #, -1''.Therefore, as shown in FIG. 11, 5&C, rIl)5J.

7 of rAo, Ai, A2, A5, A4, A5J
It displays the block address in bits.

(The areas in the figure are areas used for other information.) Next, the asynchronous absorption shown in Figures 1 and 2, and
The fraction of data mentioned in the explanation of the data frame in FIG. 5 will now be described. FIG. 12 is a frame that is composed of the frame shown in FIG. 9. As mentioned above, the data capacity is 28
Since 88 symbols and required data are 2840 symbols, the difference of 48 symbols becomes an empty area. For example, as shown in the figure, 40 is an empty area. By the way, this frame frequency needs to be recorded on the tape in synchronization with the field frequency of the video that is simultaneously recorded. On the other hand, the amount of audio data is determined by the sampling frequency. Field frequency and sampling frequency are unrelated.

Since it is asynchronous, 48 symbols would remain in an ideal calculation. The amount of data is not necessarily constant28
40 symbols does not necessarily count.

In other words, an indefinite amount of data that increases or decreases around 2840 symbols is included in one data frame and remains constant over a long period. If the write data is set instantaneously, it is possible to absorb the asynchrony between the field frequency and the sampling frequency. The empty area 40 indicated by xs in FIG. 12 is an area useful for asynchronous absorption. Therefore, considering the fluctuation of several tens of symbols, the NTS
It can be seen that in the CO frame format, the data allocation within one frame is 5203.2 symbols, which is a negligible amount even if a fraction occurs.

Also, in order to identify on the playback side that the amount of data stored in each data frame is different, if information is omitted as identification of the amount of data in the data frame in the ID34 area of the CD 27, etc. Data can be played back correctly. In FIG. 12, the empty area 40 is placed at the lower right, but the empty area may be dispersed by interleaving the data.

The data whose data frame structure has been completed passes through the code modulation circuit 8 and is recorded on the tape via the recording amplifier 15. This code modulation circuit is designed to determine how efficiently data can be recorded on a tape and how to reproduce it with fewer errors.As in this embodiment, a rotary transformer is used to perform the code modulation circuit on a circular thread. In consideration of the fact that the DC component is blocked, a recording signal with a small low-frequency spectrum is suitable.

FIG. 13 shows an example of a circuit using the code modulation method.

This is a group coding circuit that converts 6-bit one symbol data into 8-bit data. 41 is an input signal, 42 is an input register, 43 is a decoder circuit, 4
4 is a latch, 45 is an output register, and 46 is an output signal. The 6-bit, 1-symbol data in the input register is converted by the decoder circuit 15 into an 8-bit prescribed pattern. Then, it is sent to an output register, and an output signal 46 is obtained as a serial signal. The latch 44 detects the presence or absence of a DC component in the output pattern one symbol before, and sends that information to the next pattern conversion to control the polarity of the DC component of the pattern to be selected first. be.

The fourteenth example is an example of a reproducing machine that reproduces signals from a tape on which the signals generated in the present embodiment are recorded. A reproduced analog signal 47 obtained from the tape 16 via the head is amplified by a preamplifier 48, and a clock reproduction circuit 49 is used to extract a clock from this reproduced signal. The inserted black lines serve as a reference for data signal processing. Using this clock,
The data detection circuit 5° obtains a digital signal, and the code demodulation circuit reproduces the original digital signal from the code modulated wave.

Also, since the preamplifier output also detects the video signal,
This signal is inputted and a video signal is obtained by the video signal processing circuit 51. 104 and 105 are system control controllers and control path lines.

The reproduced digital signal is expanded by a one-time axis expansion circuit 54, and a digital signal processing circuit 55 performs data dinterleaving and error correction processing to obtain a correctly arranged digital signal. This digital signal is expanded in a symbol data expansion circuit 56 and an audio signal 58 can be obtained via a DAC (digital-to-analog conversion circuit) 57.

Based on the above frame structure, the recording wavelength when using the video signal and the area-divided VTI (for example, the audio PCM area of 8rlLF71 video) is determined.

In the NTSC format, as shown in Figure 5, one frame symbol data is 108 x 42 = 14556 symbols, and since one symbol 6 bits are converted to 8 bits by code modulation, the number of beams in one frame is 4556.
X 8: 5628B bits, the PC'M area compression ratio on the tape is (video to PCM is 18 at the wrap angle of the tape)
0' vs. 2632°) is 0.1462, and the data frame frequency is equal to the field frequency 1. . .

. The transmission rate is Hz.

36288 x 2 = 14.875 Mbps.

0.1462 1.001 The recording wavelength is equivalent to 2 transmission bits, and the relative violation between the tape and the head is 5.752 m, so the shortest recording wavelength is λ
The min is.

Further, by extending the wavelength to the card band area before and after the PCM area, it is possible to make the wavelength longer.

Using f3mm video as an example, compression is achieved by 3/4 by changing the sample data from 16 bits to 12 bits, and redundancy is reduced to 40.5% of the conventional 8mm video by changing the frame structure and arrangement of error correction codes. 295% (
NTSC) K compression, and through 6-8 conversion, it achieves compatibility with the above 12-bit compression while also achieving conventional FM modulation <bi
-p> by compressing it to ll1667 (FM is 2 and 6-8 is 8/6).

As mentioned above, the shortest recording wavelength on the tape is approximately 0.5 μm.
and a conventional CClR 8mm video (0,5411m) close to 1. − It can be realized at the level.

As described above, according to the embodiments, high-density recording is possible, and high-quality audio signals can be recorded and reproduced. Furthermore, it goes without saying that the present invention can be realized not only by synthesis with video signals but also by synthesis of multi-channel PCM audio signals.

〔Effect of the invention〕

According to the present invention, high-density recording is possible in a limited area by using data compression, a frame structure with a highly efficient error correction code, and code modulation, so high-quality audio can be recorded and reproduced. and using zero sampling frequency,
Since it is independent from the video signal, it has the advantage that digital dubbing is possible.

[Brief explanation of drawings]

1...Analog signal. 3... Compressed symbol generation circuit. 4...Block generation circuit. 6...Error correction code generation circuit. 7...Frame generation circuit. 8... code modulation circuit. 9...Asynchronous absorption circuit. 12... Time axis compression circuit. 26...Audio data frame. 27...Control data. 60...Inner code C1゜ 52...Outer code C2゜ 33...Synchronization signal. 34...ID wisdom 55...Blovquatres. 66...Parity. Representative Patent Attorney: Masao Ogawa Figure 3 /Otsu 4th episode Figure 5 1)A Part 4 Figure 9 Figure 1O ,I9 Figure 11 BlθCkO≠ and bowl ax each o', o o o o o o o. 8/θCk107 arrow hakamadon bowl≠xKoxo1 sheep 72 figure Kudzu! 3 Figure

Claims (8)

[Claims] (1) A recording device that records a digital information signal and other information signals on a recording medium, including a symbol generation circuit that unitizes a plurality of bits of the digital information signal into four symbols, and symbol data output from the symbol generation circuit. an interleaving circuit for distributing an array of symbols, an error correction code generation circuit for generating an error correction code for symbol data, and a block generation circuit for generating a block using a synchronization signal, a control signal, the symbol data, and the error correction code. A PCM signal recording device comprising: a frame generating circuit that combines a plurality of the blocks to form a frame; and a code modulating circuit that blocks coding symbol data, error correction codes, etc. in the frame. (2) In the device according to claim 1, the digital information signal is a digital signal obtained by sampling and transcoding an analog audio signal, and the symbol generation circuit digitally compresses the single-sampled digital signal. A PCM characterized in that it includes a compressor and converts the compressed digital signal into one or more symbol data.
Signal recording device. (3) In the device according to claim 1 or 2, the digital information signal is a sampled analog audio signal into a 16-bit digital signal, and the symbol In the generation circuit, the above 1
A PCM signal recording device characterized in that it is a symbol generation circuit that digitally compresses a 6-bit digital signal into 12 bits and divides the 12 bits into 6-bit 2-symbol data. (4) In the device according to claim 1 or 3, the error correction code and control signal are configured to have a 6-bit symbol data structure according to 6-bit symbol data output from a symbol generation circuit. , the code modulation circuit converts each of the 6-bit symbol data into 8
A PCM signal recording device characterized by block coding into bit codes. (5) The apparatus according to claim 1, characterized in that a Reed-Solomon code whose unit is symbol data is used as the error correction code generation circuit, and at least two systems of codes are generated before and after the interleave circuit. PCM signal recording device. (6) In the device according to claim 1, the digital information signal is a digital signal obtained by sampling and code-converting an analog audio signal, and the other information signal is a video signal, and the other information signal is a video signal. video frame period,
A PCM signal recording device characterized in that the frame period of the frame generation circuit is synchronized. (7) A PCM signal recording device according to claim 1 or 6, characterized in that the video frame period and the sampling period of the analog audio signal are synchronized. (8) In the device according to claim 1 or 6, the frame period of the frame containing the audio signal and the sampling period of the analog audio signal are made independent, and the symbol of the code-converted digital signal in the frame is A PCM signal recording device characterized in that the amount of data is increased or decreased for each frame within the frame to absorb asynchrony between the frame period and the sampling period.