JPH04366466A - Magnetic recorder/reproducer - Google Patents

Abstract

PURPOSE:To multiplex second information such as a time code, etc., in a low density without impairing data detecting performance of first information of a main track which is recorded in a high packing density. CONSTITUTION:When first information, 12 bits in parallel, is converted to a 15-bit code by a 12/15 converter 3, only '+1' or '-1' is used as a code ward by a CDS. The above codes having different polarities are corresponded at one set to original 12-bit data, and the polarity of the code word is selected by a DSV control signal 4. The signal 4 can be converted to a code making a CDS zero from second information generated from a time code processor 6, by a modulator 7.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention converts a plurality of pieces of information into digital signals and performs high-density recording (
This relates to devices for storage and playback.

0002

2. Description of the Related Art FIG. 8 is a track pattern diagram of an S-DAT, which is shown in "A study on the tape running mechanism of S-DAT" presented at the AES Tokyo Convention '87. (1) is the main track where digital signals such as digital audio signals and error correction codes that correct code errors stochastically occur due to media defects and noise are recorded, and (2) is where time information is recorded. This is a cue track.

Next, the operation will be explained. When recording a signal on the main track (1), an analog audio signal is first converted into a binary digital signal by A/D conversion, and then a time code and the like are added in addition to an error correction code and a synchronization signal. Thereafter, 8-10 modulation is performed to convert the signal into a signal suitable for magnetic recording and reproduction. Obtained in this way,
The signal recorded on the main track (1) is 64KBP
It has a high density reaching even I. On the other hand, the signal recorded on the cue track (2) has a low density of about 2.5 KBPI obtained by processing time information by a microcomputer or the like and further performing FM modulation.

[0004] During normal playback, among the recorded signals,
The signal from the main track (1) becomes the audio signal. Also, during normal playback, the time information is the time code on the main track (1) or the time code on the cue track (2).
information is used. On the other hand, when searching for the beginning or time of a song at high speed, the tape is fed at about 100 times the speed, making it difficult to reproduce the signal of the main track (1) recorded at high density. Cue track (2)
information is used.

[0005]

[Problem to be Solved by the Invention] Since the conventional device is configured as described above, in order to realize high-speed search, it is necessary to
e-track is required. Since there is only one cue track, there is a problem in that if the signal cannot be reproduced due to clogging of that one head, malfunction may occur.

The present invention was made to solve the above-mentioned problems, and it is possible to retrieve low-density information recorded on cue tracks without impairing the data retrieval accuracy of high-density recorded main tracks. To obtain a magnetic recording/reproducing device which can perform multiplexing on a main track and perform high-speed retrieval even with only the main track.

[0007]

[Means for Solving the Problems] A magnetic recording/reproducing device according to the present invention is capable of converting first information of parallel m (m: natural number) bits related to an audio signal or the like into parallel n (n: natural number, n>m) bits of first information. In a magnetic recording/reproducing apparatus which has a recording encoding means for converting into a code of CD with the second information related to the information
S (Codeword Digital Sum) is 0
DSV (Digital Sum)
Variation) It has a DSV control signal generating means for outputting as a control signal, and the recording encoding means converts the parallel m-bit first information to be converted into a parallel n-bit code whose CDS is +1 and a parallel n-bit code whose CDS is - Corresponding to a pair of parallel n-bit codes that are 1, and depending on the value of the DSV control signal,
The present invention is characterized in that either a code with a CDS of +1 or a code with a CDS of -1 is selectively supplied to the parallel-to-serial conversion means.

[0008]

[Operation] In the present invention, recording encoding is performed according to the value of the DSV control signal. That is, when performing recording encoding, a pair of codes with different polarities is associated with the first information, and a code related to one of the polarities is selected according to the value of the DSV control signal. and recorded after serialization. Here, polarity means CDS
The DSV control signal is a signal generated so that the DSV becomes 0 from the second information related to the time information conventionally recorded on the cue track. DSV corresponds to the amount of charge accumulated in a code.

[0009] When recording and encoding are performed in this manner, the second information is recorded on the main track. In other words, the D of the signal recorded on the main track
The SV fluctuation period has content corresponding to the second information as a result of recording encoding control using the DSV control signal. D
SV fluctuations appear as a low-frequency spectrum in the power spectrum of the signal recorded on the main track, and because low-frequency recording is performed, time information can be obtained from the main track during high-speed searches such as finding the beginning of a song. becomes possible.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In Fig. 1, (3) is a 12-15 modulator, and in addition to information (e.g. audio) converted into a binary digital signal by an A/D converter, error correction codes, synchronization signals, time codes, etc. The added signal divided into 12-bit units is input and converted into a 15-bit code suitable for magnetic recording and reproduction. This 12-15 modulator (3) associates a pair of code words with different polarities in which the charge accumulation (CDS) in the code word is -1 and +1 with one input signal.

(4) is a DSV control signal that determines the polarity of the code output from the 12/15 modulator (3); (5)
is a parallel-to-serial conversion circuit that converts a 15-bit parallel code encoded at fSYM rate into a serial signal and outputs a rate 15 times fSYM at fCH, and (6) is a timer for formatting time information. Code processing circuit (7) converts formatted time information to CD
This is a modulator that converts S into a zero code. (8) is a clock generation circuit that generates a clock for synchronizing the processing of each section, and the time code processing circuit (6) includes:
ftime rate, fFM rate to the modulator (7), fSYM rate to the 12-15 modulator (3) and parallel/serial converter (5), and fCH rate to the parallel/serial converter (5). , and clocks respectively.

FIGS. 2 to 7 are diagrams for supplementary explanation of the operation of FIG. 1. FIG. 2 is a diagram showing the relationship between input data and modulation codes in the 12-15 modulator (3), and FIG. Figure 4 is a power spectrum diagram of the code string obtained when a random signal is input, and Figure 5 is the waveform of the code string and the waveform corresponding to the DSV fluctuation period extracted from the waveform. FIG. 6 is a diagram showing the format of time information, and FIG. 7 is a diagram showing the format of time information, and FIG. It is a DSV fluctuation diagram.

Next, the operation will be explained in detail. When recording and reproducing digital signals magnetically, capacitors, rotary transformers, etc. are interposed at the interface between the electric circuit and the head, so it is impossible to transmit DC components, and generally DC-free signals that do not contain DC components are used. converted. The 12-15 modulator (3) is an information converter for realizing the DC-free, and converts 12-bit input information into a CDS (Codeword Digit) shown in Table 1.
DSV (Digital Sum Variat
ion) does not diverge, a code word with CDS of either +1 or -1 is selected and output by the DSV control signal (4). In addition, the CD that corresponds to the information word
The sign of S is +1 or -1 is 212 (4096) respectively
pcs are required. On the other hand, the number of codes with CDS of +1 or -1 included in 215 (32768) 15-bit signals is 15C7 and 15C8, which is 6435 each.
have each one. Furthermore, when configuring a code, it is necessary to take into consideration the run length (number of consecutive same polarity) limits in the code string, so only codes with a maximum run length of 5 are selected from each of the 6435 codes mentioned above. Said, 409
It suffices if it is associated with the information word 6. Figure 2 shows a part of it.

In FIG. 3, the signal shown in a) (12 bits expressed in hexadecimal) is input to the 12-15 modulator (3),
Code word selection is performed using the DSV control signal (4) having a cycle that is 10 times the information conversion cycle (1/fSYM) shown in b), and a clock fCH that is 15 times the information conversion cycle (1/fSYM).
The state of the DSV fluctuation at the end of the code word obtained as serial data by the parallel-to-serial conversion circuit (5) is shown as c). As can be seen from the figure, the DSV fluctuation is controlled to a finite value within the range of /5/ at the end of the code word, and the period is synchronized with the DSV control signal (4).

FIG. 4 shows the DSV control signal (4) in FIG. 3b.
) is a power spectrum diagram obtained by inputting a random signal to the 12-15 modulator (3). In this case, as shown in the figure, the output of the parallel-to-serial conversion circuit (5) is DC-free and has no DC component, and at a frequency of fCH/150 corresponding to the information of the DSV control signal (4). It has strong spectral components. Furthermore, FIG. 5 shows the modulation waveform of the random signal and this modulation waveform as f.
The waveform after passing through a bandpass filter where o is fCH/150 and Q is about 10 is shown. As shown in this figure, it can be confirmed that a signal with a good waveform and a DSV fluctuation period is extracted. Therefore, the information input to the 12-15 modulator (3) is the first information to be recorded on the main track (1) shown in the conventional example, and the DSV control signal (
It can be understood that by making the information in 4) the second information recorded on the main track (1), two pieces of information can be multiplexed recorded on the main track (1).

Next, a method for recording time information as second information will be explained.

First, a time code processing circuit (6) composed of a microcomputer etc. converts time information into
Convert to the format shown in , that is, a format that can correct code errors on the transmission path. At this time, the transmission rate (ftime) needs to be set to 1/integer in order to record the time information as DSV fluctuation in encoding of the first information. In this example, ftime is fSYM
/16.

[0018] In this way, the time code processing circuit (6)
The signal outputted from the converter is converted into a 4-bit code in binary value by a modulation circuit (7), with 1 data being 1010 and 0 data being 1100, respectively. Thereafter, it is input to the 12-15 modulator (3) as a DSV control signal (4) at fFM having a rate four times that of ftime. Note that the DSV control signal output from the modulation circuit (7) is (4) DS
It is a DC free signal where V becomes 0 at the end of the modulation code,
This ensures that the encoded signal of the first information output from the 12-15 modulator (3) is also DC-free.

In FIG. 7, the signal shown in a') (12 bits expressed in hexadecimal) is input to the 12-15 modulator (3),
When the time information modulated by the modulation circuit shown in b') is input as the DSV control signal (4), the parallel-to-serial conversion circuit (5)
The state of DSV fluctuation at the end of the code word obtained from the output of
). As can be seen from the figure, the first information word is converted into a DC-free code word whose DSV is in the range of /8/, and the second information is converted into a DC-free code word whose DSV modulation period is 8/5f.
It is recorded as 1 when SYM, and 0 when 16/5fSYM.

[0020] As a result of the above, it becomes possible to multiplex record the second information in the low range where the spectral components of the first information are reduced. Note that when this embodiment is applied to a conventional device, the fCH of the conventional device is 120 kHz, and the second information rate is 500 to 1 kBPS. In addition, if Cu
If the second information rate is insufficient for the rate of e-track (2), the information may be divided and recorded on the track.

In order to reproduce the recorded signal with high accuracy, the transmission path conditions for reproduction may be set as follows. First, for the first information, by giving a transmission band from the low frequency range to the fCH band corresponding to the DSV fluctuation cycle changed by the second information, the DSV controlled by the second information A faithful reproduced signal waveform can be obtained without being affected by fluctuations.

Regarding the second information, as shown in FIG. 5, it is possible to extract only the DSV fluctuation information from the reproduced signal by using a low-pass filter with a cutoff frequency of approximately fSYM/6. The extracted second information signal is further converted into a digital signal of 1 and 0 by a comparator, and by counting the period length, it can be converted back to the original time information.

[0023]

[Effect of the invention] As described above, according to the present invention, the second
information (time information) is recorded on the main track.
Since the structure is configured so that the information can be multiplexed into the low frequency part of the main track, even when the relative speed of the tape head becomes several tens of times faster during high-speed searches, the second information recorded on the main track can be processed within the bandwidth of the playback amplifier. As a result, search information that conventionally relied only on the cue track can also be obtained from the main track, which increases the margin against accidents such as head clogging, and has the effect of obtaining highly reliable information. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an information conversion section of a magnetic recording and reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing input data and modulation codes in a 12-15 modulator according to an embodiment of the invention.

FIG. 3 is a DSV fluctuation diagram at the end of a code word after information conversion.

FIG. 4 is a diagram showing a power spectrum generated from a code string.

FIG. 5 is a diagram showing a waveform of a code string and a waveform corresponding to a DSV fluctuation period extracted from the waveform.

FIG. 6 is a diagram showing a format of time information.

FIG. 7 is a DSV fluctuation diagram at the end of a code after information conversion when second information is input as a DSV control signal.

FIG. 8 is a track pattern diagram of a conventional magnetic recording/reproducing device.

[Explanation of symbols]

(3) 12-15 modulator (4) DSV control signal (5) Parallel-serial conversion circuit (6) Time code processing circuit (7) Modulator

Claims (1)

[Claims] [Claim 1] First information of parallel m (m: natural number) bits related to an audio signal etc. is parallelized to n (n: natural number, n>m)
A magnetic recording and reproducing device that has recording encoding means for converting into a bit code and parallel-to-serial converting means for converting this code into a serial code, and records the serial code on a main track on a magnetic recording medium, The recording encoding means includes DSV control signal generation means for converting second information related to time information into a code with a CDS of 0 and outputting it as a DSV control signal;
The parallel m-bit first information to be converted is associated with a pair of a parallel n-bit code whose CDS is +1 and a parallel n-bit code whose CDS is -1, and according to the value of the DSV control signal, A magnetic recording/reproducing device characterized in that either a code with a CDS of +1 or a code with a CDS of -1 is selectively supplied to a parallel-to-serial converter.